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Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Apr. 30, 2014	Jun. 30, 2014	Oct. 31, 2013
Document and Entity Information [Abstract]
Entity Registrant Name	Ocean Power Technologies, Inc.
Document Type	10-K
Current Fiscal Year End Date	--04-30
Entity Common Stock, Shares Outstanding		17,545,599
Entity Public Float			$ 25,900,000
Amendment Flag	false
Entity Central Index Key	0001378140
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Well-known Seasoned Issuer	No
Document Period End Date	Apr. 30, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Consolidated Balance Sheets - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Current assets:
Cash and cash equivalents	$ 13,858,659	$ 6,372,788
Marketable securities	14,493,881	13,996,705
Restricted cash	6,124,960
Accounts receivable, net	308,731	796,332
Unbilled receivables	37,410	127,598
Other current assets	568,377	152,962
Total current assets	35,392,018	21,446,385
Property and equipment, net	317,513	700,968
Patents, net	828,298	1,044,902
Restricted cash	1,221,696	1,366,256
Other noncurrent assets	325,310	272,548
Total assets	38,084,835	24,831,059
Current liabilities:
Accounts payable	501,397	510,031
Accrued expenses	2,931,239	3,900,623
Advance payment received from customer	4,709,055
Unearned revenues	992,447	1,117,115
Current portion of long-term debt	100,000	100,000
Total current liabilities	9,234,138	5,627,769
Long-term debt	150,000	250,000
Long-term unearned revenues		232,033
Deferred credits payable-noncurrent	600,000	600,000
Total liabilities	9,984,138	6,709,802
Commitments and contingencies (note 13)
Ocean Power Technologies, Inc. Stockholders’ equity:
Preferred stock, $0.001 par value; authorized 5,000,000 shares, none issued or outstanding	0	0
Common stock, $0.001 par value; authorized 105,000,000 shares, issued 17,593,637 and 10,403,215 shares, respectively	17,594	10,403
Treasury stock, at cost; 37,852 and 33,771 shares, respectively	(130,707)	(123,893)
Additional paid-in capital	180,454,341	159,155,365
Accumulated deficit	(151,640,503)	(140,671,311)
Accumulated other comprehensive loss	(225,733)	(79,786)
Total Ocean Power Technologies, Inc. stockholders’ equity	28,474,992	18,290,778
Noncontrolling interest in Ocean Power Technologies (Australasia) Pty Ltd	(374,295)	(169,521)
Total equity	28,100,697	18,121,257
Total liabilities and stockholders’ equity	$ 38,084,835	$ 24,831,059

Consolidated Balance Sheets (Parentheticals) - $ / shares	Apr. 30, 2014	Apr. 30, 2013
Preferred stock par value (in Dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock par value (in Dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	105,000,000	105,000,000
Common stock, shares issued	17,593,637	10,403,215
Treasury stock, shares	37,852	33,771

Consolidated Statements of Operations - USD ($)	12 Months Ended
Consolidated Statements of Operations - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Revenues	$ 1,498,892	$ 3,616,129
Cost of revenues	1,510,336	3,480,821
Gross (loss) profit	(11,444)	135,308
Operating expenses:
Product development costs	4,564,898	7,327,766
Change in contract loss reserve	(785,000)
Selling, general and administrative costs	9,358,967	9,126,757
Total operating expenses	13,138,865	16,454,523
Operating loss	(13,150,309)	(16,319,215)
Interest income, net	29,656	126,377
Foreign exchange gain (loss)	183,704	(83,416)
Loss before income taxes	(12,936,949)	(16,276,254)
Income tax benefit	1,745,895	1,453,243
Net loss	(11,191,054)	(14,823,011)
Less: Net loss attributable to the noncontrolling interest in Ocean Power Technologies (Australasia) Pty Ltd.	221,862	141,174
Net loss attributable to Ocean Power Technologies, Inc	$ (10,969,192)	$ (14,681,837)
Basic and diluted net loss per share (in Dollars per share)	$ (0.91)	$ (1.42)
Weighted average shares used to compute basic and diluted net loss per share (in Shares)	12,041,824	10,304,044

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
Consolidated Statements of Comprehensive Loss - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Net loss	$ (11,191,054)	$ (14,823,011)
Foreign currency translation adjustment	(128,859)	(511)
Total comprehensive loss	(11,319,913)	(14,823,522)
Comprehensive loss attributable to the noncontrolling interest in Ocean Power Technologies (Australasia) Pty Ltd.	204,774	140,889
Comprehensive loss attributable to Ocean Power Technologies, Inc.	$ (11,115,139)	$ (14,682,633)

Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance at Apr. 30, 2012	$ 10,407	$ (102,388)	$ 158,296,458	$ (125,989,474)	$ (78,990)	$ 32,136,013	$ (28,632)	$ 32,107,381
Balance (in Shares) at Apr. 30, 2012	10,407,389	(23,544)
Net loss				(14,681,837)		(14,681,837)	(141,174)	(14,823,011)
Stock based compensation			814,407			814,407		814,407
Issuance (forfeiture) of restricted stock, net	$ (4)		44,500			44,496		44,496
Issuance (forfeiture) of restricted stock, net (in Shares)	(4,174)
Acquisition of treasury stock		$ (21,505)				(21,505)		$ (21,505)
Acquisition of treasury stock (in Shares)		(10,227)						(10,227)
Other comprehensive loss					(796)	(796)	285	$ (511)
Balance at Apr. 30, 2013	$ 10,403	$ (123,893)	159,155,365	(140,671,311)	(79,786)	18,290,778	(169,521)	18,121,257
Balance (in Shares) at Apr. 30, 2013	10,403,215	(33,771)
Net loss				(10,969,192)		(10,969,192)	(221,862)	(11,191,054)
Stock based compensation			702,091			702,091		702,091
Issuance (forfeiture) of restricted stock, net	$ 80		69,475			69,555		69,555
Issuance (forfeiture) of restricted stock, net (in Shares)	79,822
Stock issued upon exercise of stock options	$ 5		8,528			8,533		$ 8,533
Stock issued upon exercise of stock options (in Shares)	4,266							4,266
Acquisition of treasury stock		$ (6,814)				(6,814)		$ (6,814)
Acquisition of treasury stock (in Shares)		(4,081)						(4,081)
Sale of stock, net	$ 7,106		20,518,882			20,525,988		$ 20,525,988
Sale of stock, net (in Shares)	7,106,334
Other comprehensive loss					(145,947)	(145,947)	17,088	(128,859)
Balance at Apr. 30, 2014	$ 17,594	$ (130,707)	$ 180,454,341	$ (151,640,503)	$ (225,733)	$ 28,474,992	$ (374,295)	$ 28,100,697
Balance (in Shares) at Apr. 30, 2014	17,593,637	(37,852)

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
Consolidated Statements of Cash Flows - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Short-Term [Member]
Changes in operating assets and liabilities:
Unearned Revenues	$ (130,368)	$ 46,451
Long-Term [Member]
Changes in operating assets and liabilities:
Unearned Revenues	(232,033)	232,033
Net cash used in operating activities	(6,497,078)	(10,845,648)
Net loss	(11,191,054)	(14,823,011)
Foreign exchange (gain) loss	(183,704)	83,416
Depreciation and amortization	421,836	502,099
Loss on disposals of property, plant and equipment	195,977	44,067
Impairment of long-lived assets	2,658	7,718
Provision for doubtful accounts	(299,958)
Treasury note discount amortization	5,391	(12,191)
Compensation expense related to stock option grants and restricted stock…	771,646	858,902
Accounts receivable	787,601	264,077
Unbilled receivables	90,188	95,451
Other current assets	(413,901)	685,523
Other noncurrent assets	(34,214)	(93,700)
Accounts payable	(12,363)	105,036
Accrued expenses	(983,835)	1,158,481
Advance payment received from customer	4,709,055
Cash flows from investing activities:
Purchases of marketable securities	(23,982,431)	(16,678,329)
Maturities of marketable securities	23,489,021	25,055,534
Restricted cash	(5,924,960)	75,000
Purchases of equipment	(27,268)	(394,632)
Net cash (used in) provided by investing activities	(6,445,638)	8,057,573
Cash flows from financing activities:
Repayment of debt	(100,000)	(100,000)
Proceeds from the exercise of stock options	8,533
Proceeds from the sale of common stock, net of costs	20,525,988
Acquisition of treasury stock	(6,814)	(21,505)
Net cash provided by (used in) financing activities	20,427,707	(121,505)
Effect of exchange rate changes on cash and cash equivalents	880	(71,092)
Net increase (decrease) in cash and cash equivalents	7,485,871	(2,980,672)
Cash and cash equivalents, beginning of period	6,372,788	9,353,460
Cash and cash equivalents, end of period	$ 13,858,659	$ 6,372,788

Note 1 - Background and Liquidity

12 Months Ended

Apr. 30, 2014

Disclosure Text Block [Abstract]

Business Description and Basis of Presentation [Text Block]


(1)	Background and Liquidity

(a)

Background

Ocean Power Technologies, Inc. (the “Company”) was incorporated in 1984 in New Jersey, commenced business operations in 1994 and re-incorporated in Delaware in 2007. The Company’s developing and is seeking to commercialize proprietary systems that generate electricity by harnessing the renewable energy of ocean waves. The Company markets its products in the United States and internationally. Since fiscal 2002, government agencies have accounted for a significant portion of the Company’s revenues. These revenues were largely for the support of product development efforts. The Company’s goal is that an increased portion of its revenues be from the sale of products and services, as compared to revenue from grants to support its product development efforts. As the Company continues to advance its proprietary technologies, it expects to continue to have a net use of cash in operating activities unless and until it achieves positive cash flow from the planned commercialization of its products and services.

(b)

Liquidity

The Company has incurred net losses and negative operating cash flows since inception. As of April 30, 2014, the Company had an accumulated deficit of $151.6 million. As of April 30, 2014, the Company’s cash and cash equivalents and marketable securities balance was approximately $28.4 million. Based upon the Company’s cash and cash equivalents and marketable securities balance as of April 30, 2014, the Company believes that it will be able to finance its capital requirements and operations through at least the third calendar quarter of 2015. In addition, as of April 30, 2014, the Company’s restricted cash balance was approximately $7.3 million.

During 2014 and 2013, the Company has continued to make investments in ongoing product development efforts in anticipation of future growth. The Company’s future results of operations involve significant risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, risks from sufficiency of capital, technology development, scalability of technology and production, dependence on skills of key personnel, concentration of customers and suppliers, performance of PowerBuoys, deployment risks and laws, regulations and permitting. In order to complete its future growth strategy, the Company will require additional equity and/or debt financing. There is no assurance that additional equity and/or debt financing will be available to the Company as needed. If sufficient financing is not obtained by the Company, we may be required to further curtail or limit certain product development costs, and/or selling, general and administrative activities in order to reduce our cash expenditures.

In June 2013, we established an at the market offering facility (the “ATM Facility”) with Ascendiant Capital Markets, LLC (the “Manager”) via an At the Market Offering Agreement (the “ATM Agreement”). Under the ATM Agreement, we offered and sold shares of our common stock from time to time through the Manager, acting as sales agent, in ordinary brokerage transactions at prevailing market prices. Under the ATM Facility, we issued 3,306,334 shares of our common stock at an average price to the public of $3.02 per share. Net proceeds from the ATM Facility were approximately $9,698,000 during fiscal 2014.

Also in fiscal 2014, we entered into an underwriting agreement (the “Underwriting Agreement”) with Roth Capital Partners, LLC (the “Underwriter”) on April 4, 2014, with respect to the issuance and sale in an underwritten public offering (the “Public Offering”) of an aggregate of 3,800,000 shares of our common stock at a price to the public of $3.10 per share. The Underwriting Agreement contained customary representations, warranties and agreements by us, customary conditions to closing and indemnification obligations, and a 90 day lock-up period that limited transactions in our common stock by us. Net proceeds from the Public Offering were approximately $10,828,000.

Form S-3 limits the aggregate market value of securities that we are permitted to offer in any 12-month period under Form S-3, whether under the ATM Agreement, Underwriting Agreement or otherwise, to one third of our public float. Given the fiscal 2014 share sales, we fully utilized the ATM Agreement and reached the applicable limit under Form S-3. Approximately $18.2 million remains available for issuance under the S-3 Shelf.

Note 2 - Summary of Significant Accounting Policies

12 Months Ended

Apr. 30, 2014

Accounting Policies [Abstract]

Significant Accounting Policies [Text Block]

(2)

Summary of Significant Accounting Policies

(a)

Consolidation and Cost Method Investment

The accompanying consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. Participation of stockholders other than the Company in the net assets and in the earnings or losses of a consolidated subsidiary is reflected as a noncontrolling interest in the Company's Consolidated Balance Sheets and Statements of Operations, which adjusts the Company's consolidated results of operations to reflect only the Company's share of the earnings or losses of the consolidated subsidiary. As of April 30, 2014, there was one noncontrolling interest, consisting of 11.8% of the Company's Australian subsidiary, Ocean Power Technologies (Australasia) Pty. Ltd. (“OPTA”). OPTA owns 100% of Victorian Wave Partners Pty. Ltd. (“VWP”), which is also organized under the laws of Australia.

In addition, the Company evaluates its relationships with other entities to identify whether they are variable interest entities, and to assess whether it is the primary beneficiary of such entities. If the determination is made that the Company is the primary beneficiary, then that entity is included in the consolidated financial statements. As of April 30, 2014, there were no such entities.

The Company, through its subsidiary Ocean Power Technologies, Ltd. (“OPT LTD”), had a 10% investment in Iberdrola Energias Marinas de Cantabria, S.A. (“Iberdrola Cantabria” or “Ibermar”). As of April 30, 2013, the Company had certain outstanding receivables from Ibermar in connection to its 2006 Spain Construction Agreement. The investment in Iberdrola Cantabria and net accounts receivable and unbilled receivables from Ibermar were $0 as of April 30, 2012. During fiscal 2014, the dissolution of Iberdrola Cantabria was approved by the shareholders of Ibermar. In connection with the dissolution of this entity, OPT LTD signed an agreement with Ibermar to cancel all obligations under the 2006 Spain Construction Agreement between Ibermar and the Company. See Note 13.

(b)

Use of Estimates

The preparation of the consolidated financial statements requires management of the Company to make a number of estimates and assumptions relating to the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the period. Significant items subject to such estimates and assumptions include the recoverability of the carrying amount of property and equipment and patents; valuation allowances for receivables and deferred income tax assets; and percentage of completion of customer contracts for purposes of revenue recognition. Actual results could differ from those estimates. The current economic environment, particularly the macroeconomic pressures in certain European countries, has increased the degree of uncertainty inherent in those estimates and assumptions.

(c)

Revenue Recognition

The Company’s contracts are either cost plus or fixed price contracts. Under cost plus contracts, customers are billed for actual expenses incurred plus an agreed-upon fee. Currently, the Company has two types of fixed price contracts, firm fixed price and cost-sharing. Under firm fixed price contracts, the Company receives an agreed-upon amount for providing products and services specified in the contract. Under cost-sharing contracts, the fixed amount agreed upon with the customer is only intended to fund a portion of the costs on a specific project.

Generally, the Company recognizes revenue using the percentage-of-completion method based on the ratio of costs incurred to total estimated costs at completion. In certain circumstances, revenue under contracts that have specified milestones or other performance criteria may be recognized only when the customer acknowledges that such criteria have been satisfied. In addition, recognition of revenue (and the related costs) may be deferred for fixed-price contracts until contract completion if the Company is unable to reasonably estimate the total costs of the project prior to completion. Some revenue contracts may contain complex criteria or uncertainty surrounding the terms of performance and customer acceptance. These contracts are subject to interpretation and management may make a judgment as to the amount of revenue earned and recorded. Because the Company has a small number of contracts, revisions to the percentage-of-completion determination, management interpretation or delays in meeting performance and contractual criteria or in completing projects may have a significant effect on revenue for the periods involved. Upon anticipating a loss on a contract, the Company recognizes the full amount of the anticipated loss in the current period.

Under cost plus and firm fixed price contracts, there is a profit or loss on the project depending on whether actual costs are more or less than the agreed upon amount. Under cost-sharing contracts, an amount corresponding to the revenue is recorded in cost of revenues, resulting in gross profit on these contracts of zero. The Company’s share of the costs is recorded as product development expense.

Unbilled receivables represent expenditures on contracts, plus applicable profit margin, not yet billed. Unbilled receivables are normally billed and collected within one year. Billings made on contracts are recorded as a reduction in unbilled receivables, and to the extent that those billings exceed costs incurred plus applicable profit margin, they are recorded as unearned revenues.

Most of the Company’s projects in fiscal year 2014 were under cost-sharing contracts.

(d)

Cash and Cash Equivalents

Cash equivalents consist of investments in short-term financial instruments with initial maturities of three months or less from the date of purchase. Cash and cash equivalents include the following:

	April 30,
	2014			2013

Checking and savings accounts	$	1,917,176	$	2,184,322
Certificates of deposits and US Treasury obligations		11,499,768	―
Money market funds		441,715		4,188,466
	$	13,858,659	$	6,372,788

(e)

Marketable Securities

Marketable securities with original maturities longer than three months but that mature in less than one year from the balance sheet date are classified as current assets. Marketable securities that the Company has the intent and ability to hold to maturity are classified as investments held-to-maturity and are reported at amortized cost. The difference between the acquisition cost and face values of held-to-maturity investments is amortized over the remaining term of the investments and added to or subtracted from the acquisition cost and interest income. As of April 30, 2014 and April 30, 2013, all of the Company’s investments were classified as held-to-maturity.

(f)

Restricted Cash and Credit Facility

A portion of the Company’s cash is restricted under the terms of three security agreements.

One agreement is between Ocean Power Technologies, Inc. and Barclays Bank. Under this agreement, the cash is on deposit at Barclays Bank and serves as security for letters of credit that are expected to be issued by Barclays Bank on behalf of OPT LTD one of the Company's subsidiaries, under an €800,000 ($996,696) credit facility established by Barclays Bank for OPT LTD. The credit facility is for the issuance of letters of credit and bank guarantees and carries a fee of 1% per annum of the amount of any such obligations issued by Barclays Bank. As of April 30, 2014, there were €278,892 ($385,982) in letters of credit outstanding under this agreement. The credit facility does not have an expiration date, but is cancelable at the discretion of the bank.

The second agreement is between Ocean Power Technologies, Inc. and the New Jersey Board of Public Utilities (NJBPU). The Company received a $500,000 recoverable grant award from the NJBPU. Under this agreement, the Company annually assigns to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. See Note 7.

The third agreement concerns two letters of credit issued by Ocean Power Technologies, Inc. for the benefit of the Oregon Department of State Lands. The two letters of credit relate to the removal of certain of the Company’s anchoring and mooring equipment from the seabed off the coast of Oregon. These letters of credit are secured by two certificates of deposit with PNC Bank. The first letter of credit for $375,000 had a term through August 31, 2014 and the second letter of credit for $470,000 had a term through October 16, 2014. Subsequent to the fiscal year ended April 30, 2014, the Company extended the term of both letters of credit to October 29, 2014 and have secured a third letter of credit relating to this matter in the amount of $355,000 that has a term through October 29, 2014.

The Company has classified the initial grant funding received from the Australian Renewable Energy Agency (“ARENA”) of A$5,595,723 ($5,179,960), which includes an amount required to be submitted as goods and services tax (GST), as restricted cash. This initial funding is subject to claw-back provisions in the grant if certain contractual requirements, including performance criteria, are not satisfied. Subsequent to April 30, 2014, the Company remitted the GST in the amount of A$508,702 ($470,905) to the Australian Tax Office in accordance with local tax laws. This amount had been accrued as of April 30, 2014 and is recorded in accrued expense (note 5).

Cash restricted is as follows:

	April 30,
	2014		2013
Current:
Australian Renewable Energy Agency (ARENA)	$	5,179,960	―
NJBPU agreement		100,000	―
Oregon Department of State Lands		845,000	―
	$	6,124,960	―

	April 30,
	2014		2013
Long Term:
Barclay's Bank Agreement	$	996,696	$	941,256
NJBPU agreement		225,000		425,000
	$	1,221,696	$	1,366,256


(g)	Property and Equipment

Property and equipment is stated at cost, less accumulated depreciation and amortization. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives (three to seven years) of the assets. Leasehold improvements are amortized using the straight-line method over the shorter of the estimated useful life of the asset or the remaining lease term. Expenses for maintenance and repairs are charged to operations as incurred. In the fourth quarter of fiscal 2014, the Company performed its recurring assessment of the realizability of its property and equipment and recorded impairment expenses of approximately $196,000.

(h)

Foreign Exchange Gains and Losses

The Company has invested in certain certificates of deposit and has maintained cash accounts that are denominated in British pounds sterling, Euros and Australian dollars. These amounts are included in cash, cash equivalents, restricted cash and marketable securities on the accompanying consolidated balance sheets. Such positions may result in realized and unrealized foreign exchange gains or losses from exchange rate fluctuations, which gains and losses are included in foreign exchange loss in the accompanying consolidated statements of operations.

	Year Ended April 30,
	2014		2013

Foreign exchange gain (loss)	$	183,704	$	(83,416	)

Foreign currency denominated certificates of deposit and cash accounts:

	April 30,
	2014		2013

Restricted	$	6,176,656	$	941,256
Unrestricted		1,232,111		1,550,458
	$	7,408,767	$	2,491,714

(i)

Patents

External costs related to the filing of patents, including legal and filing fees, are capitalized if expenses related to the filing of a patent are significant. The Company continually re-assesses the remaining useful lives of its long-lived assets and costs are expensed when it is no longer probable that such technology will be utilized. Patents are also reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the patent may not be recoverable. In the fourth quarter of fiscal 2014, the Company performed its recurring assessment of the realizability of its patents and recorded impairment expenses of approximately $3,000. Amortization is recorded over periods ranging from one to five years. Amortization expense was approximately $215,000 and $217,000 for the years ended April 30, 2014 and 2013, respectively. Amortization expense for the next five fiscal years related to the amounts capitalized for patents as of April 30, 2014 is estimated to be approximately $212,000 in the first year decreasing to $100,000 in the fifth year.

(j)

Long-Lived Assets

Long-lived assets, such as property and equipment and patents subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of the asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, then an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset.

The Company reviewed its long-lived assets for impairment for the years ended April 30, 2014 and 2013. The Company recorded impairment charges of approximately $3,000 and $8,000 related to patents in the year ended April 30, 2014 and 2013, respectively.


(k)	Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash balances, bank certificates of deposit and trade receivables. The Company invests its excess cash in highly liquid investments (principally, short-term bank deposits, Treasury bills, Treasury notes and money market funds) and does not believe that it is exposed to any significant risks related to its cash accounts, money market funds or certificates of deposit.

The table below shows the percentage of the Company's revenues derived from customers whose revenues accounted for at least 10% of the Company's consolidated revenues for at least one of the periods indicated:

	Years Ended April 30,
	2014			2013

Mitsui Shipbuilding & Engineering		38	%		20	%
US Department of Energy		34	%		51	%
European Union (WavePort project)		15	%		17	%
UK Government's Technology Strategy Board		12	%		3	%

The loss of, or a significant reduction in revenues from, any of the current customers could significantly impact the Company's financial position or results of operations. The Company does not require its customers to post collateral.

(l)

Net Loss per Common Share

Basic and diluted net loss per share for all periods presented is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Due to the Company's net losses, potentially dilutive securities, consisting of outstanding stock options and non-vested performance-based shares, were excluded from the diluted loss per share calculation because of their anti-dilutive effect.

In computing diluted net loss per share, options to purchase shares of common stock and non-vested restricted stock issued to employees and non-employee directors, totaling 1,569,902 and 1,360,790 for the years ended April 30, 2014 and 2013, respectively, were excluded from the computations as the effect would be anti-dilutive due to the Company's losses.


(m)	Stock-Based Compensation

Costs resulting from all share-based payment transactions are recognized in the consolidated financial statements at their fair values. Compensation cost for the portion of the awards for which the requisite service had not been rendered that were outstanding as of May 1, 2006 is being recognized in the consolidated statements of operations over the remaining service period after such date based on the award's original estimated fair value. The aggregate share-based compensation expense recorded in the consolidated statements of operations for the years ended April 30, 2014 and 2013 was approximately $772,000 and $859,000, respectively.

Valuation Assumptions for Options Granted During the Years Ended April 30, 2014 and 2013

The fair value of each stock option granted during the years ended April 30, 2014 and 2013 was estimated at the date of grant using the Black-Scholes option pricing model, assuming no dividends and using the weighted average valuation assumptions noted in the following table. The risk-free rate is based on the US Treasury yield curve in effect at the time of grant. The expected life (estimated period of time outstanding) of the stock options granted was estimated using the "simplified" method as permitted by the Securities and Exchange Commission's Staff Accounting Bulletin No. 107, Share-Based Payment. Expected volatility was based on the Company’s historical volatility for fiscal 2014 and for fiscal 2013 was based on historical volatility for a peer group of companies for a period equal to the stock option's expected life, calculated on a daily basis.

	Years Ended April 30,
	2014			2013

Risk-free interest rate		1.66	%		0.88	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)	5.91			6.06
Expected volatility		76.40	%		86.15	%

The above assumptions were used to determine the weighted average per share fair value of $1.27 and $1.58 for stock options granted during the years ended April 30, 2014 and 2013, respectively.

(n)

Income Taxes

Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences and operating loss and tax credit carryforwards are expected to be recovered, settled or utilized. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.

The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained upon examination. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest related to unrecognized tax benefits in interest expense and penalties in selling, general, and administrative expenses, to the extent incurred.

(o)

Accumulated Other Comprehensive Loss

The functional currency for the Company's foreign operations is the applicable local currency. The translation from the applicable foreign currencies to US dollars is performed for balance sheet accounts using the exchange rates in effect at the balance sheet date and for revenue and expense accounts using an average exchange rate during the period. The unrealized gains or losses resulting from such translation are included in accumulated other comprehensive loss within stockholders' equity.

(p)

Recent Accounting Pronouncements

On May 28, 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The new standard is effective for the Company on January 1, 2017. Early application is not permitted. The standard permits the use of either the retrospective or cumulative effect transition method. The Company is evaluating the effect that ASU 2014-09 will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting.

Note 3 - Marketable Securities

12 Months Ended

Apr. 30, 2014

Investments, Debt and Equity Securities [Abstract]

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

(3)

Marketable Securities

Marketable securities are classified as current assets and are summarized as follows:

	April 30,
	2014		2013

US Treasury obligations	$	14,493,881	$	13,996,705

The Company had no marketable securities classified as noncurrent assets as of April 30, 2014 and April 30, 2013.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Note 4 - Property and Equipment

12 Months Ended

Apr. 30, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment Disclosure [Text Block]

(4)

Property and Equipment

The components of property and equipment are as follows:

			April 30,
	Life (in years)		2014			2013

Computers and software		3	$	527,244		$	566,353
Equipment		3 to 7		845,424			1,170,473
Office furniture and equipment		3 to 7		283,346			293,880
Leasehold improvements		2		182,285			182,285
				1,838,299			2,212,991
Less accumulated depreciation and amortization				(1,520,786	)		(1,512,023	)
			$	317,513		$	700,968

Depreciation expense was $206,945 and $285,263 for the years ended April 30, 2014 and 2013, respectively.

Note 5 - Balance Sheet Detail

12 Months Ended

Apr. 30, 2014

Disclosure Text Block Supplement [Abstract]

Supplemental Balance Sheet Disclosures [Text Block]


(5)	Balance Sheet Detail

	April 30,
	2014			2013

Accounts receivable, net
Accounts receivable	$	308,731		$	1,086,847
Allowance for doubtful accounts	―				(290,515	)
	$	308,731		$	796,332

Patents
Patents	$	1,536,029		$	1,558,630
Accumulated amortization		(707,731	)		(513,728	)
	$	828,298		$	1,044,902


Accrued expenses
Project costs	$	1,263,293		$	1,698,959
Contract loss reserve	―				785,000
Employee incentive payments		310,370			249,469
Accrued salary and benefits		455,909			547,404
Investment in joint venture	―				173,842
Legal and accounting fees		168,402			214,891
Goods and services tax (GST) due to Australian Tax Office		470,905		―
Other		262,360			231,058
	$	2,931,239		$	3,900,623

Contract loss reserve represents a previous project-specific reserve where the underlying project had encountered technical issues during deployment. While the Company had no specific legal obligation to continue work on the project, management’s intention had been to complete certain elements of the project. Effective as of April 30, 2014, management made a determination not to pursue its efforts to complete the project and reversed the contract loss reserve.

Note 6 - Related Party Transactions

12 Months Ended

Apr. 30, 2014

(6)

Related Party Transactions

In August 1999, the Company entered into a consulting agreement with an individual for the provision of marketing services. The agreement provided for fees at a rate of $950 per day of services provided. The individual became a member of the board of directors in June 2006. In addition, this individual is also the chief executive officer of a company that provided engineering and technical services to the Company. The Company also provided services to the company where this individual is the chief executive officer. This individual did not stand for re-election to the board of directors at the Company’s Annual Meeting on October 4, 2012, and is no longer considered a related party. Accordingly, transactions after such date are not included in the amounts below.

	Year Ended April 30,
	2014		2013
Related party consulting expense	$	-	$	42,000
Expenses for services provided by related party company		-		-
Revenue for services provided to related party company		-		32,000

In April 2014, the Company entered into an Executive Transition Agreement with George W. Taylor, who was formerly employed by the Company as Executive Vice Chairman and served on the Company’s Board of Directors prior to that date. Under this agreement, Dr. Taylor will receive up to fifteen months of consulting fees at a monthly rate of $20,000. As of April 30, 2014, the Company recorded $7,333 in expense relating to this agreement.

Subsequent to fiscal year 2014, the Company entered into an agreement with David L. Keller, who has served as a non-executive director of the Company since October 2013. Under this agreement, Mr. Keller will serve as Interim Chief Executive Officer effective with the June 9, 2014 termination of the Company’s former Chief Executive Officer, Charles F. Dunleavy. Mr. Keller will continue in this position while the Company searches for a permanent replacement and will receive a consulting fee of $1,500 per day of services provided.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Note 7 - Debt

12 Months Ended

Apr. 30, 2014

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

(7)

Debt

The Company was awarded a recoverable grant totaling $500,000 from the NJBPU under the Renewable Energy Business Venture Assistance Program. Under the terms of this agreement, the amount to be repaid is a fixed monthly amount of principal only, repayable over a five-year period beginning in November 2011. The terms also required the Company to assign to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. See Note 2(f).

	April 30,
	2014			2013

Total debt	$	250,000		$	350,000
Current portion of long-term debt		(100,000	)		(100,000	)
Long-term debt	$	150,000		$	250,000

Note 8 - Deferred Credits Payable

12 Months Ended

Apr. 30, 2014

Customer Advances And Deposits Disclosure [Abstract]

Customer Advances And Deposits Disclosure [Text Block]

(8)

Deferred Credits Payable

During the year ended April 30, 2001, in connection with the sale of common stock to an investor, the Company received $600,000 from the investor in exchange for an option to purchase up to 500,000 metric tons of carbon emissions credits generated by the Company during the years 2008 through 2012, at a 30% discount from the then-prevailing market rate. If the Company received emission credits under applicable laws and failed to sell to the investor the credits up to the full amount of emission credits covered by the option, the investor was entitled to liquidated damages equal to 30% of the aggregate market value of the shortfall in emission credits (subject to a limit on the market price of emission credits). Under the terms of the agreement, if the Company did not become entitled under applicable laws to the full amount of emission credits covered by the option by December 31, 2012, the Company was obligated to return the option fee of $600,000, less the aggregate discount on any emission credits sold to the investor prior to such date. In December 2012, the Company and the investor agreed to extend the period for the sale of emission credits until December 31, 2017. As of April 30, 2014, the Company has not generated any emissions credits eligible for purchase under the agreement. The $600,000 has been classified as a noncurrent liability as of April 30, 2014 and 2013.

Note 9 - Common Stock

12 Months Ended

Apr. 30, 2014

Stockholders' Equity Note [Abstract]

Stockholders' Equity Note Disclosure [Text Block]

(9)

Common Stock

During the year ended April 30, 2014, the Company issued 3,306,334 shares of common stock under its ATM Facility for an average purchase price of $3.02 per share, resulting in net proceeds to the Company of approximately $9,698,000, and issued 3,800,000 shares of common stock under the Underwriting Agreement at a price of $3.10 per share, resulting in net proceeds to the Company of approximately $10,828,000. These transactions were registered under the Company’s S-3 Shelf.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707

Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Paragraph d
-Article 4

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 17: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 08
-Article 4

Reference 18: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Note 10 - Preferred Stock

12 Months Ended

Apr. 30, 2014

Disclosure Text Block Supplement [Abstract]

Preferred Stock [Text Block]

(10)

Preferred Stock

The Company has authorized 5,000,000 shares of undesignated preferred stock with a par value of $0.001 per share. As of April 30, 2014, and 2013, no shares of preferred stock had been issued.

Note 11 - Share-Based Compensation

12 Months Ended

Apr. 30, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

(11)

Share-Based Compensation

In 2001, the Company approved the 2001 Stock Plan, which provides for the grant of incentive stock options and nonqualified stock options. A total of 1,000,000 shares were authorized for issuance under the 2001 Stock Plan. As of April 30, 2014, the Company had issued or reserved for issuance 134,575 shares under the 2001 Stock Plan. After the effectiveness of the 2006 Stock Incentive Plan, no further options or other awards have been or will be granted under the 2001 Stock Plan.

In 2007, the Company's 2006 Stock Incentive Plan became effective. A total of 803,215 shares were authorized for issuance under the 2006 Stock Incentive Plan. In 2009, an amendment to the 2006 Stock Incentive Plan was approved by the Company’s stockholders, increasing the aggregate number of shares authorized for issuance by 850,000 shares to 1,653,215. On October 2, 2013, a further amendment to the 2006 Stock Incentive Plan was approved by the Company’s stockholders, increasing the aggregate number of shares authorized for issuance by an additional 800,000 shares to 2,453,215. As of April 30, 2014, the Company had issued share-based awards for 1,337,717 shares of common stock and had reserved an additional 838,549 shares of common stock for future issuance under the 2006 Stock Incentive Plan. The Company's employees, officers, directors, consultants and advisors are eligible to receive awards under the 2006 Stock Incentive Plan; however, incentive stock options may only be granted to employees. The maximum number of shares of common stock with respect to which awards may be granted to any participant under the 2006 Stock Incentive Plan is 200,000 per calendar year. Vesting provisions of stock options are determined by the board of directors. The contractual term of these stock options is up to ten years. The 2006 Stock Incentive Plan is administered by the Company's board of directors, who may delegate authority to one or more committees or subcommittees of the board of directors or to the Company's officers. If the board of directors delegates authority to an officer, the officer has the power to make awards to any of the Company's employees, other than executive officers. The board of directors will fix the terms of the awards to be granted by such officer. No award may be granted under the 2006 Stock Incentive Plan after December 7, 2016, but the vesting and effectiveness of awards granted before that date may extend beyond that date.

(a)

Stock Options

A summary of stock options under the plans described above is as follows:

						Weighted
						Average
				Weighted		Remaining
	Shares Under			Average		Contractual
	Option			Exercise Price		Term
						(In Years)

Outstanding April 30, 2012		1,353,473		$	8.92		6.1

Forfeited		(429,244	)		7.29
Granted		381,759			1.98

Outstanding April 30, 2013		1,305,988			7.43		5.9

Exercised		(4,266	)		2.00
Forfeited		(320,932	)		6.84
Granted		491,502			1.32

Outstanding April 30, 2014		1,472,292			5.53		5.9

Exercisable April 30, 2014		937,457		$	7.58		4.4

As of April 30, 2014, the total intrinsic value of outstanding options was approximately $430,000 and the total intrinsic value of exercisable options was $163,000. As of April 30, 2014, approximately 530,000 additional options were expected to vest, which have approximately $267,000 of intrinsic value and a weighted-average remaining contractual term of 8.6 years. There was approximately $587,000 and $713,000 of total recognized compensation cost related to employees for stock options during the years ended April 30, 2014 and 2013, respectively. As of April 30, 2014, there was approximately $457,000 of total unrecognized compensation cost related to non-vested stock options granted under the plans. This cost is expected to be recognized over a weighted-average period of 2.4 years. The Company typically issues new shares to satisfy option exercises under these plans.

In April 2014, the Company accelerated the vesting of 61,962 options in accordance with its Executive Transition Agreement with George W. Taylor.

Certain options were granted to non-employee directors and consultants during the years ended April 30, 2014 and 2013. The Company has charged compensation expense of approximately $91,000 and $101,000 related to these option grants, the majority of which relates to non-employee directors. These expenses have been included in selling, general and administrative costs in the accompanying consolidated statements of operations for the years ended April 30, 2014 and 2013, respectively.

Subsequent to fiscal year 2014, the Company terminated the employment of Chief Executive Officer Charles F. Dunleavy. At the time of Mr. Dunleavy’s termination, he held 427,357 outstanding options, 304,895 of which were exercisable, at a weighted average per share exercise price of $7.02 and $8.65, respectively. These options were forfeited upon termination.

(b)

Restricted Stock

Compensation expense for restricted stock is generally recorded based on its market value on the date of grant and recognized ratably over the associated service and performance period. There were 96,239 and 31,744 shares of restricted stock granted to employees and non-employee board members with service and/or performance-based vesting requirements during the years ended April 30, 2014 and 2013, respectively.

A summary of non-vested restricted stock under the plans is as follows:

				Weighted
				Average
	Number			Price per
	of Shares			Share


Issued and unvested at April 30, 2012		93,840		$	5.86
Granted		31,744			2.39
Forfeited		(35,918	)		4.70
Vested		(34,864	)		6.02
Issued and unvested at April 30, 2013		54,802			4.52

Granted		96,239			2.19
Forfeited		(16,417	)		5.75
Vested		(37,014	)		3.96
Issued and unvested at April 30, 2014		97,610		$	2.23

There was approximately $60,000 and $28,000 of total recognized compensation cost relating to restricted stock granted to employees during the years ended April 30, 2014 and 2013, respectively. Certain shares of restricted stock were granted to non-employee directors during the years ended April 30, 2014 and 2013. The Company recorded compensation expenses of approximately $34,000 and $16,000 in 2014 and 2013, respectively. As of April 30, 2014, there was approximately $80,000 of total unrecognized compensation cost related to non-vested restricted stock granted under the plans. This cost is expected to be recognized over a weighted-average period of 2.1 years.

(c)

Treasury Stock

During the years ended April 30, 2014 and 2013, 4,081 and 10,227 shares of common stock, respectively, were purchased by the Company from employees to pay taxes related to the vesting of restricted stock.

Note 12 - Income Taxes

12 Months Ended

Apr. 30, 2014

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

(12)	Income Taxes

Loss before income taxes for the years ended April 30, 2014 and 2013 consisted of the following components:

	April 30,
	2014			2013

Domestic	$	(9,532,725	)	$	(13,630,946	)
Foreign		(3,404,224	)		(2,645,308	)
Total loss before income taxes	$	(12,936,949	)	$	(16,276,254	)

The components of income taxes (benefit) for the years ended April 30, 2013 and 2012 were as follows:

	April 30,
	2014			2013

Current:
Federal	$	−		$	−
State		(1,745,895	)		(1,453,243	)
Foreign		−			−
Total current		(1,745,895	)		(1,453,243	)

Deferred:
Federal		−			−
State		−			−
Foreign		−			−
Total deferred		-			-
Total income tax benefit	$	(1,745,895	)	$	(1,453,243	)

Tax Rate Reconciliation

The effective income tax rate differed from the percentages computed by applying the US federal income tax rate of 34% to loss before income taxes as a result of the following:

	Years Ended April 30,
	2014			2013

Computed "expected" tax benefit		(34	)%		(34	)%

Increase (reduction) in income taxes resulting from:

State income taxes, net of federal benefit		(6	)		(5	)

Stock-based compensation expense		1			1

Federal research and development tax credits		(1	)		(1	)

Foreign rate differential		2			2

Other non-deductible expenses		4		―

Expiration of net operating losses and tax credit carryforwards	―				23

Expiration in compensatory options	―				9

Proceeds of sale of New Jersey tax benefits		(13	)		(9	)

Other		10			5

Increase in valuation allowance		24		―

Income tax benefit		(13	)%		(9	)%

Significant Components of Deferred Taxes

The tax effects of temporary differences and carryforwards that give rise to the Company's deferred tax assets and deferred tax liabilities are presented below.

	April 30,
	2014			2013

Deferred tax assets:
Federal net operating loss carryforwards	$	29,724,000		$	25,396,000
Foreign net operating loss carryforwards		6,021,000			5,340,000
New Jersey state operating loss carryforwards		1,411,000			1,741,000
Federal and New Jersey research and development tax credits		2,178,000			2,630,000
Foreign research and development tax credits		—			659,000
Stock compensation		730,000			721,000
Capitalized research and development costs, net of amortization		4,901,000			5,692,000
Unrealized foreign exchange loss		258,000			289,000
Accrued expenses		652,000			610,000
Other		881,000			647,000

Gross deferred tax assets		46,756,000			43,725,000

Valuation allowance		(46,756,000	)		(43,725,000	)

Net deferred tax assets	$	-		$	-

In assessing the realizability of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences and carryforwards become deductible or are utilized. As of April 30, 2014 and 2013, based upon the level of historical taxable losses, valuation allowances of $46,756,000 and $43,725,000, respectively, were recorded to fully offset deferred tax assets. The valuation allowance increased $3,031,000 and $48,000 during the years ended April 30, 2014 and 2013, respectively.

As of April 30, 2014, the Company had net operating loss carryforwards for federal income tax purposes of approximately $87,424,000, which begin to expire in fiscal 2019. The Company also had federal research and development tax credit carryforwards of approximately $2,095,000 as of April 30, 2014, which begin to expire in 2019. The Tax Reform Act of 1986 contains provisions that limit the utilization of net operating loss and tax credit carryforwards if there has been an ownership change, as defined. The Company has determined that such an ownership change, as described in Section 382 of the Internal Revenue Code, occurred in conjunction with the Company's US initial public offering in April 2007. The Company's annual Section 382 limitation is approximately $3,300,000. The Section 382 limitation is cumulative from year to year, and thus, to the extent net operating loss or other credit carryforwards are not utilized up to the amount of the available annual limitation, the limitation is carried forward and added to the following year's available limitation. The Company has not performed additional analysis on ownership changes that may have occurred subsequently to further limit the ability to utilize net tax attributes. As of April 30, 2014, the Company had state net operating loss carryforwards of approximately $20,507,000, which begin to expire in 2026, which also may be limited to utilization limitations. As of April 30, 2014, the Company had foreign net operating loss carryforwards of approximately $23,802,000, which begin to expire in 2024. The ability to utilize these carryforwards may also be limited in the event of a significant change to ownership.

During the years ended April 30, 2014 and 2013, the Company sold New Jersey State net operating losses in the amount of $15,347,000 and $18,673,000, respectively, resulting in the recognition of income tax benefits of $1,746,000 and $1,453,000, respectively, recorded in the Company’s Statement of Operations.

The Company applies the guidance issued by the FASB for the accounting and reporting of uncertain tax positions. The guidance requires the Company to recognize in its consolidated financial statements the impact of a tax position if that position is more likely than not to be sustained upon examination, based on the technical merits of the position. At April 30, 2014 and 2013, the Company had no unrecognized tax positions. The Company does not expect any material increase or decrease in its income tax expense in the next twelve months, related to examinations or uncertain tax positions. US federal and state income tax returns were audited through fiscal 2007 and fiscal 2010, respectively. Net operating loss and credit carryforwards since inception remain open to examination by taxing authorities, and will continue to remain open for a period of time after utilization.

Initial grant funding, net of GST, of approximately A$5,087,000 ($4,709,000) received from ARENA has been estimated by the Company to be non-taxable in the year of receipt due to claw-back provisions in the grant that apply if certain contractual requirements, including performance criteria, are not satisfied.

The Company does not have any interest or penalties accrued related to uncertain tax positions as it does not have any unrecognized tax benefits.

Note 13 - Commitments and Contingencies

12 Months Ended

Apr. 30, 2014

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]


(13)	Commitments and Contingencies

(a)

Operating Lease Commitments

The Company leases office, laboratory, manufacturing and other space in Pennington, New Jersey and Warwick, United Kingdom under operating leases that expire on various dates through April 30, 2015. Rent expense under operating leases was approximately $299,000 and $383,000 for the years ended April 30, 2014 and 2013, respectively. Future minimum lease payments under these operating leases as of April 30, 2014 is $260,000 for the year ending April 30, 2015.


(b)	Litigation

See note 15 for Subsequent Events related to threatened and pending litigation.

In addition, the Company is involved from time to time in certain legal actions arising in the ordinary course of business.

(c)

2006 Spain Construction Agreement

During the year ended April 30, 2014, the dissolution of Ibermar was unanimously approved by the shareholders of Ibermar. OPT LTD held a 10% stake in this entity. During the dissolution of this entity, OPT LTD signed an agreement with Ibermar to cancel all obligations under the 2006 Spain Construction Agreement between Ibermar and OPT LTD. In addition, the Company paid the final 5% stake in the entity that had been accrued in a prior period and received partial payment of an account receivable under the 2006 Spain Construction Agreement that had been fully reserved in a prior period.

As of April 30, 2014, the cancellation of this agreement did not have a material adverse effect on the Company's financial position or results of operations.


(d)	Spain IVA (sales tax)

The Company received notice that the Spanish Tax Authorities are inquiring into its 2010 IVA (value-added tax) filing for which the Company benefitted from the offset of approximately $250,000 of input tax. The Company believes that the inquiry will find that the tax credit was properly claimed and, therefore, no liability has been recorded. The Company issued two letters of credit in the amount of €278,828 ($385,982) at the request of the Spanish tax authorities during fiscal 2014. This is a customary request during the inquiry period.


(e)	Commercial Dispute

The Company was subject to certain claims filed by a contractor and subcontractor in connection with a dispute over a contract to perform certain work for the Company related to the deployment of an anchor/mooring system off the Oregon coast. The Company claimed that the contractor and subcontractor were responsible for damage to the system during the deployment process. In March 2014, the matter was mutually resolved through mediation. The outcome of this mediation did not have a material adverse effect on the Company’s financial position or results of operations.

Note 14 - Operating Segments and Geographic Information

12 Months Ended

Apr. 30, 2014

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

(14)	Operating Segments and Geographic Information

The Company's business consists of one segment as this represents management's view of the Company's operations. The Company operates on a worldwide basis with one operating company in the US and operating subsidiaries in the UK and in Australia. Revenues and expenses are generally attributed to the operating unit that bills the customers.

Geographic information is as follows:

	Year Ended April 30, 2014
	North America			Europe			Asia and Australia			Total
Revenues from external customers	$	1,317,823		$	181,069		$	—		$	1,498,892
Operating loss		(10,102,605	)		(1,180,334	)		(1,867,370	)		(13,150,309	)
Long-lived assets		305,314			12,024			175			317,513
Total assets	$	31,313,240		$	1,003,205		$	5,768,390		$	38,084,835

	Year Ended April 30, 2013
	North America			Europe			Asia and Australia			Total
Revenues from external customers	$	3,497,338		$	118,791		$	—		$	3,616,129
Operating loss		(14,048,062	)		(1,091,473	)		(1,179,680	)		(16,319,215	)
Long-lived assets		675,354			24,128			1,486			700,968
Total assets	$	23,097,183		$	1,518,496		$	215,380		$	24,831,059

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8984-108599

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9054-108599

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8906-108599

+ Details

Note 15 - Subsequent Event

12 Months Ended

Apr. 30, 2014

Subsequent Events [Abstract]

Subsequent Events [Text Block]

(15)

Subsequent Event

On June 10, 2014, the Company announced that it had terminated the employment of Charles F. Dunleavy as Chief Executive Officer and as an employee of the Company, effective June 9, 2014. Mr. Dunleavy was also removed from his position as Chairman of the Board of Directors. David L. Keller, who has served as a non-executive director of the Company since October 2013, assumed the position of Interim Chief Executive Officer, effective June 9, 2014, and will continue in this position while the Company searches for a permanent replacement. Mr. Dunleavy has notified the Company that he has retained counsel to represent him in connection with an alleged wrongful termination of his employment.

The Company also announced that the Board of Directors has appointed a Special Committee, composed of two outside directors and the Interim Chief Executive Officer, to conduct an internal investigation into the agreement between Victorian Wave Partners Pty Ltd, a project-specific operating entity wholly-owned by the Company's subsidiary Ocean Power Technologies (Australia) Pty Ltd, and ARENA. The Special Committee has retained outside counsel to assist in this investigation.

In July 2014, VWP’s Board of Directors concluded that the wave power demonstration project contemplated was no longer commercially viable, and VWP delivered a termination notice to ARENA. In conjunction with the termination notice, VWP advised ARENA of its intent to repay to ARENA the funding given to VWP to date, including interest, within 30 days after the date of the Termination Notice. The parties are currently discussing how the repayment will be made. VWP will also observe other applicable termination provisions in the Funding Deed.

Shareholder Litigation:

On June 13, 2014, the Company and its former Chief Executive Officer Charles Dunleavy were named as defendants in a putative securities class action filed in the United States District Court for the District of New Jersey captioned Roby v. Ocean Power Technologies, Inc., et al., Case No. 3:14-cv-03799-FLW-LHG. The complaint is brought on behalf of a putative class of investors who purchased the Company’s common stock during the period January 14, 2014 through June 9, 2014. The complaint alleges claims for violations of §10(b) and §20(a) of the Securities Exchange Act of 1934 arising out of public statements regarding an agreement between Victorian Wave Partners Pty. Ltd., a project-specific operating entity owned by the Company’s subsidiary, Ocean Power Technologies (Australasia) Pty. Ltd., and the Australian Renewable Energy Agency for the development of a wave power station (the “VWP Project”). On June 13 and June 20, 2014, two additional putative securities class actions captioned Chew, et al. v. Ocean Power Technologies, Inc. et. al., Case No 3:14-cv-03815-MAS-DEA, and Konstantinidis v. Ocean Power Technologies, Inc., et al., Case No. 3:14-cv-04015-FLW-DEA, were filed in the same federal court alleging substantially similar claims. The Chew complaint also names as a defendant Chief Financial Officer Mark Featherstone. On July 22, 2014, a fourth securities class action complaint was filed against the Company, Mr. Dunleavy, and Mr. Featherstone in federal court in New Jersey, captioned Turner v. Ocean Power Technologies, Inc., et al., Case No. 3:14-cv-04592. The Turner complaint is filed on behalf of a putative class of investors who purchased the Company’s common stock during the period January 14, 2014 to July 14, 2014 and also makes allegations relating to the VWP Project. All four complaints seek unspecified monetary damages and other relief. The cases are still in their preliminary stages and defendants have not yet responded to the complaints.

On July 10, 2014, the Company received a demand letter (“Demand Letter”) from a lawyer claiming to represent a shareholder demanding that the Company’s Board of Directors establish an independent committee to investigate and remedy alleged breaches of fiduciary duties by the Board of Directors and management relating to the VWP Project. The Board of Directors will address the Demand Letter at their next scheduled meeting in August or September and respond as appropriate to the allegations in the Demand Letter.

Accounting Policies, by Policy (Policies)

12 Months Ended

Apr. 30, 2014

Accounting Policies [Abstract]

Liquidity Disclosure [Policy Text Block]

Liquidity

Consolidation, Policy [Policy Text Block]

Consolidation and Cost Method Investment

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

Revenue Recognition, Policy [Policy Text Block]

Revenue Recognition

Most of the Company’s projects in fiscal year 2014 were under cost-sharing contracts.

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

Cash equivalents consist of investments in short-term financial instruments with initial maturities of three months or less from the date of purchase. Cash and cash equivalents include the following:

	April 30,
	2014			2013

Checking and savings accounts	$	1,917,176	$	2,184,322
Certificates of deposits and US Treasury obligations		11,499,768	―
Money market funds		441,715		4,188,466
	$	13,858,659	$	6,372,788

Marketable Securities, Policy [Policy Text Block]

Marketable Securities

Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]

Restricted Cash and Credit Facility

A portion of the Company’s cash is restricted under the terms of three security agreements.

Cash restricted is as follows:

	April 30,
	2014		2013
Current:
Australian Renewable Energy Agency (ARENA)	$	5,179,960	―
NJBPU agreement		100,000	―
Oregon Department of State Lands		845,000	―
	$	6,124,960	―

	April 30,
	2014		2013
Long Term:
Barclay's Bank Agreement	$	996,696	$	941,256
NJBPU agreement		225,000		425,000
	$	1,221,696	$	1,366,256

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment

Foreign Currency Transactions and Translations Policy [Policy Text Block]

Foreign Exchange Gains and Losses

	Year Ended April 30,
	2014		2013

Foreign exchange gain (loss)	$	183,704	$	(83,416	)

Foreign currency denominated certificates of deposit and cash accounts:

	April 30,
	2014		2013

Restricted	$	6,176,656	$	941,256
Unrestricted		1,232,111		1,550,458
	$	7,408,767	$	2,491,714

Intangible Assets, Finite-Lived, Policy [Policy Text Block]

Patents

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Long-Lived Assets

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentration of Credit Risk

	Years Ended April 30,
	2014			2013

Mitsui Shipbuilding & Engineering		38	%		20	%
US Department of Energy		34	%		51	%
European Union (WavePort project)		15	%		17	%
UK Government's Technology Strategy Board		12	%		3	%

Earnings Per Share, Policy [Policy Text Block]

Net Loss per Common Share

Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]

Stock-Based Compensation

Valuation Assumptions for Options Granted During the Years Ended April 30, 2014 and 2013

	Years Ended April 30,
	2014			2013

Risk-free interest rate		1.66	%		0.88	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)	5.91			6.06
Expected volatility		76.40	%		86.15	%

The above assumptions were used to determine the weighted average per share fair value of $1.27 and $1.58 for stock options granted during the years ended April 30, 2014 and 2013, respectively.

Income Tax, Policy [Policy Text Block]

Income Taxes

Comprehensive Income, Policy [Policy Text Block]

Accumulated Other Comprehensive Loss

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements

Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Apr. 30, 2014

Accounting Policies [Abstract]

Schedule of Cash and Cash Equivalents [Table Text Block]

	April 30,
	2014			2013

Checking and savings accounts	$	1,917,176	$	2,184,322
Certificates of deposits and US Treasury obligations		11,499,768	―
Money market funds		441,715		4,188,466
	$	13,858,659	$	6,372,788

Schedule of Restricted Cash and Cash Equivalents [Table Text Block]

	April 30,
	2014		2013
Current:
Australian Renewable Energy Agency (ARENA)	$	5,179,960	―
NJBPU agreement		100,000	―
Oregon Department of State Lands		845,000	―
	$	6,124,960	―

	April 30,
	2014		2013
Long Term:
Barclay's Bank Agreement	$	996,696	$	941,256
NJBPU agreement		225,000		425,000
	$	1,221,696	$	1,366,256

Schedule of Foreign Exchange Gain (Loss) [Table Text Block]

	Year Ended April 30,
	2014		2013

Foreign exchange gain (loss)	$	183,704	$	(83,416	)

Schedule Of Foreign Currency Denominated Certificates of Deposit and Cash Accounts [Table Text Block]

	April 30,
	2014		2013

Restricted	$	6,176,656	$	941,256
Unrestricted		1,232,111		1,550,458
	$	7,408,767	$	2,491,714

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

	Years Ended April 30,
	2014			2013

Mitsui Shipbuilding & Engineering		38	%		20	%
US Department of Energy		34	%		51	%
European Union (WavePort project)		15	%		17	%
UK Government's Technology Strategy Board		12	%		3	%

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Years Ended April 30,
	2014			2013

Risk-free interest rate		1.66	%		0.88	%
Expected dividend yield		0.0	%		0.0	%
Expected life (in years)	5.91			6.06
Expected volatility		76.40	%		86.15	%

Note 3 - Marketable Securities (Tables)

12 Months Ended

Apr. 30, 2014

Current [Member]

Note 3 - Marketable Securities (Tables) [Line Items]

Marketable Securities [Table Text Block]

	April 30,
	2014		2013

US Treasury obligations	$	14,493,881	$	13,996,705

Note 4 - Property and Equipment (Tables)

12 Months Ended

Apr. 30, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment [Table Text Block]

			April 30,
	Life (in years)		2014			2013

Computers and software		3	$	527,244		$	566,353
Equipment		3 to 7		845,424			1,170,473
Office furniture and equipment		3 to 7		283,346			293,880
Leasehold improvements		2		182,285			182,285
				1,838,299			2,212,991
Less accumulated depreciation and amortization				(1,520,786	)		(1,512,023	)
			$	317,513		$	700,968

Note 5 - Balance Sheet Detail (Tables)

12 Months Ended

Apr. 30, 2014

Disclosure Text Block Supplement [Abstract]

Schedule of Other Assets and Other Liabilities [Table Text Block]

	April 30,
	2014			2013

Accounts receivable, net
Accounts receivable	$	308,731		$	1,086,847
Allowance for doubtful accounts	―				(290,515	)
	$	308,731		$	796,332

Patents
Patents	$	1,536,029		$	1,558,630
Accumulated amortization		(707,731	)		(513,728	)
	$	828,298		$	1,044,902


Accrued expenses
Project costs	$	1,263,293		$	1,698,959
Contract loss reserve	―				785,000
Employee incentive payments		310,370			249,469
Accrued salary and benefits		455,909			547,404
Investment in joint venture	―				173,842
Legal and accounting fees		168,402			214,891
Goods and services tax (GST) due to Australian Tax Office		470,905		―
Other		262,360			231,058
	$	2,931,239		$	3,900,623

Note 6 - Related Party Transactions (Tables)

12 Months Ended

Apr. 30, 2014

	Year Ended April 30,
	2014		2013
Related party consulting expense	$	-	$	42,000
Expenses for services provided by related party company		-		-
Revenue for services provided to related party company		-		32,000

Note 7 - Debt (Tables)

12 Months Ended

Apr. 30, 2014

Debt Disclosure [Abstract]

Schedule of Debt [Table Text Block]

	April 30,
	2014			2013

Total debt	$	250,000		$	350,000
Current portion of long-term debt		(100,000	)		(100,000	)
Long-term debt	$	150,000		$	250,000

Note 11 - Share-Based Compensation (Tables)

12 Months Ended

Apr. 30, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Compensation, Activity [Table Text Block]

						Weighted
						Average
				Weighted		Remaining
	Shares Under			Average		Contractual
	Option			Exercise Price		Term
						(In Years)

Outstanding April 30, 2012		1,353,473		$	8.92		6.1

Forfeited		(429,244	)		7.29
Granted		381,759			1.98

Outstanding April 30, 2013		1,305,988			7.43		5.9

Exercised		(4,266	)		2.00
Forfeited		(320,932	)		6.84
Granted		491,502			1.32

Outstanding April 30, 2014		1,472,292			5.53		5.9

Exercisable April 30, 2014		937,457		$	7.58		4.4

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

				Weighted
				Average
	Number			Price per
	of Shares			Share


Issued and unvested at April 30, 2012		93,840		$	5.86
Granted		31,744			2.39
Forfeited		(35,918	)		4.70
Vested		(34,864	)		6.02
Issued and unvested at April 30, 2013		54,802			4.52

Granted		96,239			2.19
Forfeited		(16,417	)		5.75
Vested		(37,014	)		3.96
Issued and unvested at April 30, 2014		97,610		$	2.23

Note 12 - Income Taxes (Tables)

12 Months Ended

Apr. 30, 2014

Income Tax Disclosure [Abstract]

Schedule Of Components Of Loss Before Income Taxes [Table Text Block]

	April 30,
	2014			2013

Domestic	$	(9,532,725	)	$	(13,630,946	)
Foreign		(3,404,224	)		(2,645,308	)
Total loss before income taxes	$	(12,936,949	)	$	(16,276,254	)

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	April 30,
	2014			2013

Current:
Federal	$	−		$	−
State		(1,745,895	)		(1,453,243	)
Foreign		−			−
Total current		(1,745,895	)		(1,453,243	)

Deferred:
Federal		−			−
State		−			−
Foreign		−			−
Total deferred		-			-
Total income tax benefit	$	(1,745,895	)	$	(1,453,243	)

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Years Ended April 30,
	2014			2013

Computed "expected" tax benefit		(34	)%		(34	)%

Increase (reduction) in income taxes resulting from:

State income taxes, net of federal benefit		(6	)		(5	)

Stock-based compensation expense		1			1

Federal research and development tax credits		(1	)		(1	)

Foreign rate differential		2			2

Other non-deductible expenses		4		―

Expiration of net operating losses and tax credit carryforwards	―				23

Expiration in compensatory options	―				9

Proceeds of sale of New Jersey tax benefits		(13	)		(9	)

Other		10			5

Increase in valuation allowance		24		―

Income tax benefit		(13	)%		(9	)%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	April 30,
	2014			2013

Deferred tax assets:
Federal net operating loss carryforwards	$	29,724,000		$	25,396,000
Foreign net operating loss carryforwards		6,021,000			5,340,000
New Jersey state operating loss carryforwards		1,411,000			1,741,000
Federal and New Jersey research and development tax credits		2,178,000			2,630,000
Foreign research and development tax credits		—			659,000
Stock compensation		730,000			721,000
Capitalized research and development costs, net of amortization		4,901,000			5,692,000
Unrealized foreign exchange loss		258,000			289,000
Accrued expenses		652,000			610,000
Other		881,000			647,000

Gross deferred tax assets		46,756,000			43,725,000

Valuation allowance		(46,756,000	)		(43,725,000	)

Net deferred tax assets	$	-		$	-

Note 14 - Operating Segments and Geographic Information (Tables)

12 Months Ended

Apr. 30, 2014

Segment Reporting [Abstract]

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]

	Year Ended April 30, 2014
	North America			Europe			Asia and Australia			Total
Revenues from external customers	$	1,317,823		$	181,069		$	—		$	1,498,892
Operating loss		(10,102,605	)		(1,180,334	)		(1,867,370	)		(13,150,309	)
Long-lived assets		305,314			12,024			175			317,513
Total assets	$	31,313,240		$	1,003,205		$	5,768,390		$	38,084,835

	Year Ended April 30, 2013
	North America			Europe			Asia and Australia			Total
Revenues from external customers	$	3,497,338		$	118,791		$	—		$	3,616,129
Operating loss		(14,048,062	)		(1,091,473	)		(1,179,680	)		(16,319,215	)
Long-lived assets		675,354			24,128			1,486			700,968
Total assets	$	23,097,183		$	1,518,496		$	215,380		$	24,831,059

Note 1 - Background and Liquidity (Details) - USD ($)	12 Months Ended
Note 1 - Background and Liquidity (Details) - USD ($)	Apr. 30, 2014	Apr. 30, 2013
ATM Facility [Member]
Note 1 - Background and Liquidity (Details) [Line Items]
Stock Issued During Period, Shares, New Issues (in Shares)	3,306,334
Share Price (in Dollars per share)	$ 3.02
Proceeds from Issuance of Common Stock	$ 9,698,000
Underwriting Agreement [Member]
Note 1 - Background and Liquidity (Details) [Line Items]
Stock Issued During Period, Shares, New Issues (in Shares)	3,800,000
Share Price (in Dollars per share)	$ 3.10
Proceeds from Issuance of Common Stock	$ 10,828,000
Retained Earnings (Accumulated Deficit)	(151,640,503)	$ (140,671,311)
Cash, Cash Equivalents, And Marketable Securities	28,400,000
Restricted Cash and Cash Equivalents	7,300,000
Proceeds from Issuance of Common Stock	20,525,988
Shelf Registration Amount Remaining of Offering Amount	$ 18,200,000

Note 2 - Summary of Significant Accounting Policies (Details) - Cash and Cash Equivalents - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Checking and Savings Accounts [Member]
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	$ 1,917,176	$ 2,184,322
Certificates Of Deposits And US Treasury Obligations [Member]
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	11,499,768
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	$ 441,715	$ 4,188,466

Note 2 - Summary of Significant Accounting Policies (Details) - Cash Restricted Under Security Agreements - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Australian Renewable Energy Agency [Member]
Current:
Restricted Cash And Cash Equivalents, Current	$ 5,179,960
NJBPU Agreement [Member]
Current:
Restricted Cash And Cash Equivalents, Current	100,000
Long Term:
Restricted Cash And Cash Equivalents, Noncurrent	225,000	$ 425,000
Oregon Department of State Lands [Member]
Current:
Restricted Cash And Cash Equivalents, Current	845,000
Barclays Bank Agreement [Member]
Long Term:
Restricted Cash And Cash Equivalents, Noncurrent	$ 996,696	$ 941,256

Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Exchange Gain (Loss) - USD ($)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Foreign Exchange Gain (Loss) [Abstract]
Foreign exchange gain (loss)	$ 183,704	$ (83,416)

Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Currency Denominated Certificates of Deposit and Cash Accounts - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Restricted [Member]
Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Currency Denominated Certificates of Deposit and Cash Accounts [Line Items]
Foreign currency denominated certificates of deposit and cash accounts	$ 6,176,656	$ 941,256
Unrestricted [Member]
Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Currency Denominated Certificates of Deposit and Cash Accounts [Line Items]
Foreign currency denominated certificates of deposit and cash accounts	1,232,111	1,550,458
Foreign currency denominated certificates of deposit and cash accounts	$ 7,408,767	$ 2,491,714

Note 2 - Summary of Significant Accounting Policies (Details) - Revenues by Major Customers	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Mitsui Engineering And Ship Building [Member]
Revenue, Major Customer [Line Items]
Revenue	38.00%	20.00%
US Department of Energy [Member]
Revenue, Major Customer [Line Items]
Revenue	34.00%	51.00%
European Union (WaverPort Project) [Member]
Revenue, Major Customer [Line Items]
Revenue	15.00%	17.00%
UK Government's Technology Strategy Board [Member]
Revenue, Major Customer [Line Items]
Revenue	12.00%	3.00%

Note 2 - Summary of Significant Accounting Policies (Details) - Weighted Average Fair Value Assumptions for Stock-Based Compensation	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Weighted Average Fair Value Assumptions for Stock-Based Compensation [Abstract]
Risk-free interest rate	1.66%	0.88%
Expected dividend yield	0.00%	0.00%
Expected life (in years)	5 years 332 days	6 years 21 days
Expected volatility	76.40%	86.15%

Note 3 - Marketable Securities (Details) - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Investments, Debt and Equity Securities [Abstract]
Marketable Securities, Noncurrent	$ 0	$ 0

Note 3 - Marketable Securities (Details) - Marketable Securities That Mature Within One Year - USD ($)	Apr. 30, 2014	Apr. 30, 2013
US Treasury obligations [Member]
Note 3 - Marketable Securities (Details) - Marketable Securities That Mature Within One Year [Line Items]
US Treasury obligations	$ 14,493,881	$ 13,996,705
US Treasury obligations	$ 14,493,881	$ 13,996,705

Note 4 - Property and Equipment (Details) - USD ($)	12 Months Ended
Note 4 - Property and Equipment (Details) - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Property, Plant and Equipment [Abstract]
Depreciation	$ 206,945	$ 285,263

Note 4 - Property and Equipment (Details) - Components of Property and Equipment	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful Life	3 years
Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful Life	7 years
Office Furniture And Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful Life	3 years
Office Furniture And Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful Life	7 years
Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful Life		3 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful Life		7 years

Note 5 - Balance Sheet Detail (Details) - Balance Sheet Detail - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Accounts receivable, net
Accounts receivable	$ 308,731	$ 1,086,847
Allowance for doubtful accounts		(290,515)
	308,731	796,332
Patents
Patents	1,536,029	1,558,630
Accumulated amortization	(707,731)	(513,728)
	828,298	1,044,902
Accrued expenses
Project costs	1,263,293	1,698,959
Contract loss reserve		785,000
Employee incentive payments	310,370	249,469
Accrued salary and benefits	455,909	547,404
Investment in joint venture		173,842
Legal and accounting fees	168,402	214,891
Goods and services tax (GST) due to Australian Tax Office	470,905
Other	262,360	231,058
	$ 2,931,239	$ 3,900,623

Note 6 - Related Party Transactions (Details) - USD ($)	1 Months Ended		3 Months Ended
Note 6 - Related Party Transactions (Details) - USD ($)	Apr. 30, 2014	Aug. 31, 1999	Jul. 29, 2014
Director [Member]
Note 6 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Amounts of Transaction		$ 950
Former Executive Vice Chairman [Member] \| Consulting Fees [Member]
Note 6 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 7,333
Former Executive Vice Chairman [Member]
Note 6 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Term of Agreement	15 months
Related Party Transaction, Monthly Consulting Fee	$ 20,000
Interim Chief Executive Officer [Member] \| Subsequent Event [Member]
Note 6 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Daily Consulting Fee			$ 1,500

Note 6 - Related Party Transactions (Details) - Related Party Transactions	12 Months Ended
	Apr. 30, 2013 USD ($)
Related Party Transactions [Abstract]
Related party consulting expense	$ 42,000
Revenue for services provided to related party company	$ 32,000

Note 7 - Debt (Details) - USD ($)	1 Months Ended
Note 7 - Debt (Details) - USD ($)	Nov. 30, 2011	Apr. 30, 2014	Apr. 30, 2013
New Jersey Board of Public Utilities [Member]
Note 7 - Debt (Details) [Line Items]
Long-term Debt	$ 500,000
Long Term Debt Payment Terms	5 years
Long-term Debt		$ 250,000	$ 350,000

Note 7 - Debt (Details) - Long-term Debt - USD ($)	Apr. 30, 2014	Apr. 30, 2013
Long-term Debt [Abstract]
Total debt	$ 250,000	$ 350,000
Current portion of long-term debt	(100,000)	(100,000)
Long-term debt	$ 150,000	$ 250,000

Note 8 - Deferred Credits Payable (Details)	Apr. 30, 2014 USD ($)	Jan. 31, 2014	Apr. 30, 2013 USD ($)	Apr. 30, 2001 USD ($) T
Customer Advances And Deposits Disclosure [Abstract]
Customer Advances and Deposits				$ 600,000
Deferred Credits Payable Option Details (in US Ton) \| T				500,000
Deferred Credits Payable Market Discount Rate				30.00%
Deferred Credits Payable Market Liquidated Damages Rate		30.00%
Customer Advances or Deposits, Noncurrent	$ 600,000		$ 600,000

Note 9 - Common Stock (Details)	12 Months Ended
Note 9 - Common Stock (Details)	Apr. 30, 2014 USD ($) $ / shares shares
ATM Facility [Member]
Note 9 - Common Stock (Details) [Line Items]
Stock Issued During Period, Shares, New Issues \| shares	3,306,334
Share Price \| $ / shares	$ 3.02
Proceeds from Issuance of Common Stock	$ 9,698,000
Underwriting Agreement [Member]
Note 9 - Common Stock (Details) [Line Items]
Stock Issued During Period, Shares, New Issues \| shares	3,800,000
Share Price \| $ / shares	$ 3.10
Proceeds from Issuance of Common Stock	$ 10,828,000
Proceeds from Issuance of Common Stock	$ 20,525,988

Note 10 - Preferred Stock (Details) - $ / shares	Apr. 30, 2014	Apr. 30, 2013
Disclosure Text Block Supplement [Abstract]
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share (in Dollars per share)	$ 0.001	$ 0.001
Preferred Stock, Shares Issued	0	0

Note 11 - Share-Based Compensation (Details)	12 Months Ended
Note 11 - Share-Based Compensation (Details)	Apr. 30, 2014
Maximum [Member] \| Stock Incentive Plan 2006 [Member]
Note 11 - Share-Based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Contractual Term	10 years

Note 11 - Share-Based Compensation (Details) - Stock Options Under the Plans - $ / shares	1 Months Ended	12 Months Ended
	Apr. 30, 2012	Apr. 30, 2014	Apr. 30, 2013
Stock Options Under the Plans [Abstract]
Shares Under Options	1,353,473	1,305,988
Weighted Average Exercise Price	$ 8.92	$ 7.43
Weighted Average Remaining Contractual Term	6 years 36 days	5 years 328 days	5 years 328 days
Exercisable April 30, 2014		937,457
Exercisable April 30, 2014		$ 7.58
Exercisable April 30, 2014		4 years 146 days
Exercised		(4,266)
Exercised		$ 2.00
Shares Underlying Options, Forfeited		(320,932)	(429,244)
Weighted Average Exercise Price,Forfeited		$ 6.84	$ 7.29
Shares Underlying Options, Granted		491,502	381,759
Weighted Average Exercise Price, Granted		$ 1.32	$ 1.98
Shares Under Options		1,472,292	1,305,988
Weighted Average Exercise Price		$ 5.53	$ 7.43

Note 11 - Share-Based Compensation (Details) - Non-Vested Restricted Stock Under the Plans - Non-vested Restricted Stock [Member] - $ / shares	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Note 11 - Share-Based Compensation (Details) - Non-Vested Restricted Stock Under the Plans [Line Items]
Number of Shares	97,610	54,802
Weighted Average Price Per Share	$ 2.23	$ 4.52
Number of Shares, Granted	96,239	31,744
Weighted Average Price Per Share, Granted	$ 2.19	$ 2.39
Number of Shares, Forfeited	(16,417)	(35,918)
Weighted Average Price Per Share. Forfeited	$ 5.75	$ 4.70
Number of Shares, Vested	(37,014)	(34,864)
Weighted Average Price Per Share, Vested	$ 3.96	$ 6.02

Note 12 - Income Taxes (Details) - Apr. 30, 2014 - Grant Funding [Member]	USD ($)	AUD ($)
ARENA [Member]
Note 12 - Income Taxes (Details) [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	$ 4,709,000	$ 5,087,000
Restricted Cash and Cash Equivalents, Noncurrent	$ 5,179,960	$ 5,595,723

Note 12 - Income Taxes (Details) - Components of Loss Before Income Taxes - USD ($)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Components of Loss Before Income Taxes [Abstract]
Domestic	$ (9,532,725)	$ (13,630,946)
Foreign	(3,404,224)	(2,645,308)
Total loss before income taxes	$ (12,936,949)	$ (16,276,254)

Note 12 - Income Taxes (Details) - Components of Income Taxes (Benefit) - USD ($)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Current:
Federal	$ 0	$ 0
State	(1,745,895)	(1,453,243)
Foreign	0	0
Total current	(1,745,895)	(1,453,243)
Deferred:
Federal	0	0
State	0	0
Foreign	0	0
Total deferred	0	0
Total income tax benefit	$ (1,745,895)	$ (1,453,243)

Note 12 - Income Taxes (Details) - Effective Income Tax Rate Reconciliation	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Effective Income Tax Rate Reconciliation [Abstract]
Computed "expected" tax benefit	(34.00%)	(34.00%)
Increase (reduction) in income taxes resulting from:
State income taxes, net of federal benefit	(6.00%)	(5.00%)
Stock-based compensation expense	1.00%	1.00%
Federal research and development tax credits	(1.00%)	(1.00%)
Foreign rate differential	2.00%	2.00%
Other non-deductible expenses	4.00%
Expiration of net operating losses and tax credit carryforwards		23.00%
Expiration in compensatory options		9.00%
Proceeds of sale of New Jersey tax benefits	(13.00%)	(9.00%)
Other	10.00%	5.00%
Increase in valuation allowance	24.00%
Income tax benefit	(13.00%)	(9.00%)

Note 12 - Income Taxes (Details) - Deferred Tax Assets and Deferred Tax Liabilities - USD ($)	Apr. 30, 2014	Apr. 30, 2013
New Jersey State [Member]
Deferred tax assets:
New Jersey state operating loss carryforwards	$ 1,411,000	$ 1,741,000
Domestic Tax Authority [Member]
Deferred tax assets:
Deferred Tax Assets: Research Credits	2,178,000	2,630,000
Foreign Tax Authority [Member]
Deferred tax assets:
Deferred Tax Assets: Research Credits		659,000
Federal net operating loss carryforwards	29,724,000	25,396,000
Foreign net operating loss carryforwards	6,021,000	5,340,000
Stock compensation	730,000	721,000
Capitalized research and development costs, net of amortization	4,901,000	5,692,000
Unrealized foreign exchange loss	258,000	289,000
Accrued expenses	652,000	610,000
Other	881,000	647,000
Gross deferred tax assets	46,756,000	43,725,000
Valuation allowance	(46,756,000)	(43,725,000)
Net deferred tax assets	$ 0	$ 0

Note 13 - Commitments and Contingencies (Details)	12 Months Ended
Note 13 - Commitments and Contingencies (Details)	Apr. 30, 2014 USD ($)	Apr. 30, 2013 USD ($)	Apr. 30, 2014 EUR (€)
Spanish Tax Authorities [Member]
Note 13 - Commitments and Contingencies (Details) [Line Items]
Input Tax	$ 250,000
Ibermar [Member]
Note 13 - Commitments and Contingencies (Details) [Line Items]
Investment Owned, Percent	10.00%		10.00%
Ownership Percentage Paid	5.00%
Operating Leases, Rent Expense	$ 299,000	$ 383,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months	260,000
Letters of Credit Outstanding, Amount	$ 385,982		€ 278,828

Note 14 - Operating Segments and Geographic Information (Details)	12 Months Ended
	Apr. 30, 2014
UNITED STATES
Note 14 - Operating Segments and Geographic Information (Details) [Line Items]
Number of Reportable Segments	1
UNITED KINGDOM
Note 14 - Operating Segments and Geographic Information (Details) [Line Items]
Number of Reportable Segments	1
AUSTRALIA
Note 14 - Operating Segments and Geographic Information (Details) [Line Items]
Number of Reportable Segments	1
Number of Operating Segments	1

Note 14 - Operating Segments and Geographic Information (Details) - Geographic Segment Information - USD ($)	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	$ 1,317,823	$ 3,497,338
Operating loss	(10,102,605)	(14,048,062)
Long-lived assets	305,314	675,354
Total assets	31,313,240	23,097,183
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	181,069	118,791
Operating loss	(1,180,334)	(1,091,473)
Long-lived assets	12,024	24,128
Total assets	1,003,205	1,518,496
Asia and Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	0	0
Operating loss	(1,867,370)	(1,179,680)
Long-lived assets	175	1,486
Total assets	5,768,390	215,380
Revenues from external customers	1,498,892	3,616,129
Operating loss	(13,150,309)	(16,319,215)
Long-lived assets	317,513	700,968
Total assets	$ 38,084,835	$ 24,831,059

Label	Element	Value
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued	$ 0
Impairment of Intangible Assets, Finite-lived	us-gaap_ImpairmentOfIntangibleAssetsFinitelived	$ 3,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1,569,902
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1,360,790
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	$ 1,520,786
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	1,512,023
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1	163,000
Impairment of long-lived assets	us-gaap_ImpairmentOfLongLivedAssetsHeldForUse	196,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue	430,000
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	772,000
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	$ 859,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	$ 1.27
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	$ 1.58
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount	$ 3,031,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount	48,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	$ 212,000
Long-term Line of Credit	us-gaap_LineOfCredit	$ 278,892
Long-term Line of Credit	us-gaap_LineOfCredit	$ 385,982
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners	11.80%
Operating Loss Carryforwards, Limitations on Use	us-gaap_OperatingLossCarryforwardsLimitationsOnUse	$3,300,000
Amortization of Intangible Assets	us-gaap_AmortizationOfIntangibleAssets	$ 215,000
Amortization of Intangible Assets	us-gaap_AmortizationOfIntangibleAssets	$ 217,000
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	$ 800,000
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	$ 996,696
Line of Credit Facility, Commitment Fee Percentage	us-gaap_LineOfCreditFacilityCommitmentFeePercentage	1.00%
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	$ 1,838,299
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	2,212,991
Unrecognized Tax Benefits	us-gaap_UnrecognizedTaxBenefits	0
Unrecognized Tax Benefits	us-gaap_UnrecognizedTaxBenefits	0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	$ 100,000
Former Executive Vice Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Accelerated Vesting, Number	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAcceleratedVestingNumber	61,962
Upon Termination Agreement [Member] \| Subsequent Event [Member] \| Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	427,357
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	$ 7.02
Expected To Vest [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue	$ 267,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber	530,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1	8 years 219 days
Including Non-employee Compensation [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	$ 457,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	2 years 146 days
New Jersey State Operating Loss Sold [Member]
Operating Loss Carryforwards	us-gaap_OperatingLossCarryforwards	$ 15,347,000
Operating Loss Carryforwards	us-gaap_OperatingLossCarryforwards	$ 18,673,000
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	us-gaap_FiniteLivedIntangibleAssetUsefulLife	5 years
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	us-gaap_FiniteLivedIntangibleAssetUsefulLife	1 year
Leasehold Improvements [Member]
Useful Life	us-gaap_PropertyPlantAndEquipmentUsefulLife	2 years
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	$ 182,285
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	182,285
Equipment [Member]
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	845,424
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	$ 1,170,473
Computers And Software [Member]
Useful Life	us-gaap_PropertyPlantAndEquipmentUsefulLife	3 years
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	$ 527,244
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	566,353
Office Furniture And Equipment [Member]
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	283,346
Property, plant and equipment	us-gaap_PropertyPlantAndEquipmentGross	$ 293,880
Stock Plan 2001 [Member]
ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInceptionToDate	optt_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInceptionToDate	134,575
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	1,000,000
Stock Incentive Plan 2006 [Member]
Common Stock, Capital Shares Reserved for Future Issuance	us-gaap_CommonStockCapitalSharesReservedForFutureIssuance	838,549
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized	850,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized	800,000
ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInceptionToDate	optt_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInceptionToDate	1,337,717
ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesGrantsPerParticipant	optt_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesGrantsPerParticipant	200,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	803,215
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	1,653,215
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	2,453,215
New Jersey Boardof Public Utilities [Member]
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	$ 500,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards	us-gaap_OperatingLossCarryforwards	$ 23,802,000
Foreign Tax Authority [Member] \| Australian Taxation Office [Member]
Goods and services tax (GST) due to Australian Tax Office	optt_GoodsAndServicesTaxDueToForeignOffice	$ 508,702
Goods and services tax (GST) due to Australian Tax Office	optt_GoodsAndServicesTaxDueToForeignOffice	$ 470,905
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	us-gaap_OperatingLossCarryforwards	20,507,000
Federal [Member]
Deferred Tax Assets: Research Credits	us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsResearch	2,095,000
Operating Loss Carryforwards	us-gaap_OperatingLossCarryforwards	87,424,000
First Letter Of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	375,000
Third Letter Of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	355,000
Second Letter Of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	$ 470,000
Iberdrola Cantabria [Member]
OwnershipPercentage	optt_OwnershipPercentage	10.00%
Accounts Receivable, Net	us-gaap_AccountsReceivableNet	$ 0
Nonvested Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	$ 5.86
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	93,840
Options Granted To Consultants [Member]
Issuance of Stock and Warrants for Services or Claims	us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims	$ 91,000
Issuance of Stock and Warrants for Services or Claims	us-gaap_IssuanceOfStockAndWarrantsForServicesOrClaims	101,000
Non Employee Directors [Member]
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	34,000
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	16,000
Restricted Stock [Member]
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	60,000
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	$ 28,000
Number of Shares, Granted	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	96,239
Number of Shares, Granted	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	31,744
Restricted Stock [Member] \| Including Non-employee Compensation [Member]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized	$ 80,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	2 years 36 days
Exercisable [Member] \| Upon Termination Agreement [Member] \| Subsequent Event [Member] \| Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	304,895
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	$ 8.65
Employee Stock Option [Member]
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	$ 587,000
Allocated Share-based Compensation Expense	us-gaap_AllocatedShareBasedCompensationExpense	$ 713,000