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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Jan. 31, 2018	Feb. 28, 2018
Document And Entity Information
Entity Registrant Name	Ocean Power Technologies, Inc.
Entity Central Index Key	0001378140
Document Type	10-Q
Document Period End Date	Jan. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--04-30
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		18,350,927
Trading Symbol	OPTT
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2018

Consolidated Balance Sheets - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017
Current assets:
Cash and cash equivalents	$ 14,369	$ 8,421
Marketable securities	25	25
Restricted cash- short-term	382	334
Accounts receivable		48
Unbilled receivables	2	296
Litigation receivable	350
Other current assets	767	622
Total current assets	15,895	9,746
Property and equipment, net	657	170
Restricted cash- long-term	154	154
Other noncurrent assets	3	3
Total assets	16,709	10,073
Current liabilities:
Accounts payable	234	586
Accrued expenses	1,689	3,059
Litigation payable	350
Warrant liabilities	241	323
Current portion of capital lease obligations	31	35
Deferred credits payable current	600	600
Total current liabilities	3,145	4,603
Long-term portion of capital lease obligations	1	23
Deferred rent	140
Total liabilities	3,286	4,626
Commitments and contingencies
Ocean Power Technologies, Inc. stockholders' equity:
Preferred stock, $0.001 par value; authorized 5,000,000 shares, none issued or outstanding
Common stock, $0.001 par value; authorized 50,000,000 shares, issued 18,424,939 and 6,313,996 shares, respectively	18	6
Treasury stock, at cost; 74,012 and 48,065 shares, respectively	(300)	(263)
Additional paid-in capital	208,130	193,234
Accumulated deficit	(194,284)	(187,370)
Accumulated other comprehensive loss	(141)	(160)
Total stockholders' equity	13,423	5,447
Total liabilities and stockholders’ equity	$ 16,709	$ 10,073

Consolidated Balance Sheets (Parenthetical) - $ / shares	Jan. 31, 2018	Apr. 30, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued
Preferred stock, shares outstanding
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	18,424,939	6,313,996
Treasury stock, shares	74,012	48,065

Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Income Statement [Abstract]
Revenues		$ 221	$ 289	$ 593
Cost of revenues		363	193	615
Gross profit/(loss)		(142)	96	(22)
Operating expenses:
Product development costs	1,318	950	3,398	3,894
Selling, general and administrative costs	1,576	1,617	4,964	4,859
Total operating expenses	2,894	2,567	8,362	8,753
Operating loss	(2,894)	(2,709)	(8,266)	(8,775)
Gain/(loss) due to the change in fair value of warrant liabilities	14	(104)	82	1,161
Interest income, net	42	24	51	26
Other income	4		4
Foreign exchange gain/(loss)	52	(26)	107	(20)
Loss before income taxes	(2,782)	(2,815)	(8,022)	(7,608)
Income tax benefit	1,119	698	1,119	698
Net loss	$ (1,663)	$ (2,117)	$ (6,903)	$ (6,910)
Basic and diluted net loss per share	$ (0.09)	$ (0.37)	$ (0.48)	$ (1.84)
Weighted average shares used to compute basic and diluted net loss per share	18,150,494	5,783,494	14,441,383	3,763,564

Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (1,663)	$ (2,117)	$ (6,903)	$ (6,910)
Foreign currency translation adjustment	11	3	19	(38)
Total comprehensive loss	$ (1,652)	$ (2,114)	$ (6,884)	$ (6,948)

Consolidated Statement of Stockholders' Equity (Unaudited) - 9 months ended Jan. 31, 2018 - USD ($) $ in Thousands	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total
Balance at Apr. 30, 2017	$ 6	$ (263)	$ 193,234	$ (187,370)	$ (160)	$ 5,447
Balance, shares at Apr. 30, 2017	6,313,996	(48,065)
Net loss				(6,903)		(6,903)
Stock based compensation			250			250
Issuance of restricted stock, net
Issuance of restricted stock, net, shares	178,756
Sale of stock, net of financing costs	$ 12		$ 14,635			$ 14,647
Sale of stock, net of financing costs, shares	11,932,187
Acquisition of treasury stock		$ (37)				(37)
Acquisition of treasury stock, shares		(25,947)
Adoption of accounting standard update related to stock compensation accounting (ASU 2016-09)			$ 11	$ (11)
Other comprehensive loss					19	19
Balance at Jan. 31, 2018	$ 18	$ (300)	$ 208,130	$ (194,284)	$ (141)	$ 13,423
Balance, shares at Jan. 31, 2018	18,424,939	(74,012)

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Cash flows from operating activities:
Net loss	$ (6,903)	$ (6,910)
Adjustments to reconcile net loss to net cash used in operating activities:
Foreign exchange (gain)/loss	(107)	20
Depreciation	79	104
Loss on disposal of property, plant and equipment	5
Compensation expense related to stock option grants and restricted stock	250	998
Change in fair value of warrant liabilities	(82)	(1,161)
Payment for litigation settlement		(500)
Changes in operating assets and liabilities:
Accounts receivable	48
Unbilled receivable	294	(286)
Other assets	(8)	(53)
Accounts payable	(356)	(186)
Accrued expenses	(1,399)	461
Deferred rent	2
Unearned revenues		(39)
Net cash used in operating activities	(8,177)	(7,552)
Cash flows from investing activities:
Purchases of marketable securities	(25)	(25)
Maturities of marketable securities	25	75
Leasehold improvements and purchase of equipment	(554)	(22)
Net cash (used in) provided by investing activities	(554)	28
Cash flows from financing activities:
Proceeds from issuance of common stock and related warrants, net of costs	14,647	12,150
Payment of capital lease obligations	(26)	(70)
Acquisition of treasury stock	(37)	(122)
Net cash provided by financing activities	14,584	11,958
Effect of exchange rate changes on cash, cash equivalents and restricted cash	143	(55)
Net increase in cash, cash equivalents and restricted cash	5,996	4,379
Cash, cash equivalents and restricted cash, beginning of period	8,909	7,030
Cash, cash equivalents and restricted cash, end of period	14,905	11,409
Supplemental schedule of cash flows information:
Cash paid for interest	3	4
Supplemental disclosure of noncash investing activities:
Acquisition of leasehold improvements and equipment through accounts payable	3
Acquisition of leasehold improvements and equipment through accrued expenses	13
Noncash investing and financing activities	$ 16

Background, Basis of Presentation and Liquidity

9 Months Ended

Jan. 31, 2018

Accounting Policies [Abstract]

Background, Basis of Presentation and Liquidity

(1) Background, Basis of Presentation and Liquidity

a) Background

Ocean Power Technologies, Inc. (the “Company”) was founded in 1984 in New Jersey, commenced business operations in 1994 and re-incorporated in Delaware in 2007. The Company is developing and commercializing its proprietary systems that generate electricity by harnessing the renewable energy of ocean waves. The Company uses proprietary technologies that convert the mechanical energy created by the heaving motion of ocean waves into electricity. The Company has designed and continues to develop the PowerBuoy™ product line which is based on modular, ocean-going buoys, which the Company has been periodically ocean testing since 1997. The Company markets its PowerBuoys™ 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 or lease of products and maintenance services, as compared to revenue to support its product development efforts. As the Company continues to advance its proprietary technologies, it expects to continue to have a net decrease in cash from operating activities unless and until it achieves positive cash flow from the planned commercialization of products and services.

b) Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. The interim operating results are not necessarily indicative of the results for a full year or for any other interim period. Further information on potential factors that could affect the Company’s financial results can be found in the Company’s Annual Report on Form 10-K for the year ended April 30, 2017 filed with the Securities and Exchange Commission (“SEC”) and elsewhere in this Form 10-Q.

c) Liquidity/Going Concern

The consolidated financial statements have been prepared assuming the Company will continue as a going concern. The Company has experienced substantial and recurring losses from operations, which have contributed to an accumulated deficit of $194.3 million as of January 31, 2018. As of January 31, 2018, the Company had approximately $14.4 million in cash and cash equivalents on hand. The Company generated revenues of $0.3 million and $0.6 million during each of the nine months ended January 31, 2018 and 2017. Based on the Company’s cash, cash equivalents and marketable securities as of January 31, 2018, the Company believes that it will be able to finance its capital requirements and operations into at least the quarter ending April 30, 2019. The Company will require additional equity and/or debt financing to continue its operations. The Company cannot provide assurances that it will be able to secure additional funding when needed or at all, or, if secured, that such funding would be on favorable terms. These factors raise substantial doubt about the Company’s ability to continue as a going concern.

The consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded assets amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Management is evaluating different strategies to obtain the required additional funding for future operations. These strategies may include, but are not limited to, continued pursuit of business opportunities, additional funding from current or new investors, officers and directors; borrowings of debt; a public offering of the Company’s equity or debt securities; partnerships and/or collaborations. There can be no assurance that any of these future-funding efforts will be successful.

In fiscal 2017 and the nine months ended January 31, 2018, 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 lack of available financing and insufficient capital, performance of PowerBuoys™, its inability to market and commercialize its PowerBuoys™, technology development, scalability of technology and production, dependence on skills of key personnel, concentration of customers and suppliers, deployment risks and laws, regulations and permitting. In order to continue to implement its business strategy, the Company requires additional equity and/or debt financing. The Company closed five equity financing arrangements during the 21-month period ended January 31, 2018. The Company does not currently have any committed sources of debt or equity financing, and the Company cannot assure that additional equity and/or debt financing will be available to the Company as needed on acceptable terms, or at all. Historically, the Company has raised capital through securities sales in the public capital markets. If sufficient additional financing is not obtained when needed, the Company may be required to further curtail or limit operations, product development costs, and/or selling, general and administrative activities in order to reduce its cash expenditures. This could cause the Company to be unable to execute its business plan, take advantage of future opportunities and may cause it to scale back, delay or eliminate some or all of its product development activities and/or reduce the scope of or cease its operations.

On June 2, 2016, the Company entered into a securities purchase agreement, which was amended on June 7, 2016 (as amended, the “Purchase Agreement”) with certain institutional purchasers (the “June Purchasers”). Pursuant to the terms of the June Purchase Agreement, the Company sold an aggregate of 417,000 shares of Common Stock together with warrants to purchase up to an aggregate of 145,952 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.35 of a share of Common Stock at a combined purchase price of $4.60. The net proceeds to the Company from the offering were approximately $1.7 million, after deducting placement agent fees and estimated offering expenses payable by the Company, but excluding the proceeds, if any, from the exercise of the warrants issued in the offering. The warrants have an exercise price of $6.08 per share, became exercisable on December 3, 2016 (“Initial Exercise Date”), and will expire five years following the Initial Exercise Date. The Company paid the placement agents approximately $0.1 million as placement agent fees in connection with the sale of securities in the offering. The Company also reimbursed the placement agents $35,000 for their out of pocket and legal expenses in connection with the offering.

On July 22, 2016, the Company entered into the Second Amendment to the Purchase Agreement (the “Second Amended Purchase Agreement”) with certain purchasers (the “July Purchasers”). Pursuant to the terms of the Second Amended Purchase Agreement, the Company sold an aggregate of 595,000 shares of Common Stock together with warrants to purchase up to an aggregate of 178,500 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.30 of a share of Common Stock at a combined purchase price of $6.75. The net proceeds to the Company from the offering were approximately $3.6 million, after deducting placement agent fees and estimated offering expenses payable by the Company, but excluding the proceeds, if any, from the exercise of the warrants issued in the offering. The Warrants were exercisable immediately at an exercise price of $9.36 per share. The Warrants will expire on the fifth (5th) anniversary of the initial date of issuance.

On October 19, 2016, the Company sold 2,760,000 shares of common stock at a price of $2.75 per share, which includes the sale of 360,000 shares of the Company’s common stock sold by the Company pursuant to the exercise, in full, of the over-allotment option by the underwriters in a public offering. The net proceeds to the Company from the offering were approximately $6.9 million, after deducting underwriter fees and offering expenses payable by the Company.

On May 2, 2017, the Company sold 6,192,750 shares of common stock at a price of $1.30 per share, which includes the sale of 807,750 shares of the Company’s common stock sold by the Company pursuant to the exercise, in full, of the over-allotment option by the underwriters in a public offering. The net proceeds to the Company from the offering were approximately $7.2 million, after deducting underwriter fees and offering expenses payable by the Company.

On October 23, 2017, the Company sold 5,739,437 shares of common stock at a price of $1.42 per share in a best efforts public offering. The net proceeds to the Company from the offering were approximately $7.4 million, after deducting placement fees and offering expenses payable by the Company.

On December 1, 2017, the Company filed a registration statement on Form S-3 with the SEC using a “shelf” registration process, which became effective December 12, 2017. Under this shelf registration process, we may from time to time sell any combination of the securities described in the registration statement in one or more offerings for an aggregate offering price of up to $30 million. The amount to be registered under the shelf registration consists of up to $30 million of an indeterminate amount of common stock, preferred stock, debt securities, warrants and/or units. There is also being registered under the shelf registration a currently indeterminate number of (i) shares of common stock or other securities of us as may be issued upon conversion of, or in exchange for, convertible or exchangeable debt securities and/or preferred stock registered under the registration statement, or (ii) shares of preferred stock, common stock, debt securities or units as may be issued upon exercise of warrants registered by the registration statement, as the case may be. As of January 31, 2018, the Company has not issued any securities under this registration statement.

The sale of additional equity or convertible securities could result in dilution to stockholders. If additional funds are raised through the issuance of debt securities, these securities could have rights senior to those associated with the Company’s Common Stock and could contain covenants that would restrict its operations. Financing may not be available in amounts or on terms acceptable to the Company, or at all. If the Company is unable to obtain required financing, it may be required to reduce the scope of its operations, including its planned product development and marketing efforts, which could materially and adversely harm its financial condition and operating results. If the Company is unable to secure additional financing, it may be forced to cease operations.

Summary of Significant Accounting Policies

9 Months Ended

Jan. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

(2) Summary of Significant Accounting Policies

(a) Consolidation

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.

(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; fair value of warrant liabilities, valuation allowances for receivables and deferred income tax assets; estimated costs to complete projects; 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. Under cost plus contracts, a profit or loss on a project is recognized depending on whether actual costs are more or less than the agreed upon amount.

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, a profit or loss is recognized depending on whether actual costs are more or less than the agreed upon amount. 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. 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.

Generally, revenue under fixed price or cost-plus contracts is recognized using the cost to cost percentage-of-completion method, measured by 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. If an arrangement involves multiple deliverables, the delivered items are considered separate units of accounting if the items have value on a stand-alone basis. Amounts allocated to each element are based on its objectively determined fair value, such as the sales price for the product or service when it is sold separately or competitor prices for similar products or services.

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. 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.

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 of unbilled receivables, and to the extent that such billings and cash collections exceed costs incurred plus applicable profit margin, they are recorded as unearned revenues.

(d) Cash, Cash Equivalents, Restricted Cash and Security Agreements

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. The Company invests excess cash in a money market account.

	January 31, 2018		April 30, 2017
	(in thousands)

Checking and savings accounts	$	1,233	$	4,241
Overnight repurchase account		-		4,180
Money market account		13,136		-
	$	14,369	$	8,421

Restricted Cash and Security Agreements

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

One agreement is between the Company and Barclays Bank. Under this agreement, the cash is on deposit at Barclays Bank and serves as security for letters of credit and bank guarantees that are expected to be issued by Barclays Bank on behalf of OPT LTD, one of the Company’s subsidiaries, under a credit facility established by Barclays Bank for OPT LTD. The credit facility is approximately €0.3 million ($0.4 million) and carries a fee of 1% per annum of the amount of any such obligations issued by Barclays Bank. The credit facility does not have an expiration date, but is cancelable at the discretion of the bank. As of January 31, 2018, there was €0.3 million ($0.4 million) in letters of credit outstanding under this agreement.

The second agreement is between the Company and Santander Bank. Under this agreement, the cash is on deposit at Santander Bank and serves as security for letter of credit issued by Santander Bank for the lease of new warehouse/office space in Monroe Township, New Jersey. The agreement cannot be extended beyond January 31, 2025, and is cancelable at the discretion of the bank. Restricted cash includes the following:

	January 31, 2018		April 30, 2017
	(in thousands)

Barclay's Bank Agreement	$	382	$	334
Santander Bank		154		154
	$	536	$	488

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the statement of financial position that sum to the total of the same such amounts shown in the statement of cash flows.

	January 31, 2018		April 30, 2017
	(in thousands)

Cash and cash equivalents	$	14,369	$	8,421
Restricted cash- short term		382		334
Restricted cash- long term		154		154
	$	14,905	$	8,909

(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 January 31, 2018, and April 30, 2017, all of the Company’s investments were classified as held-to-maturity.

(f) 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 are included in “Foreign exchange gain/(loss)” in the accompanying consolidated statements of operations.

(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. Property and equipment is also 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.

(h) 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:

	Three months ended January 31,						Nine months ended January 31,
Customer	2018			2017			2018			2017

Mitsui Engineering & Shipbuilding		0	%		56	%		75	%		83	%
U.S. Department of Defense Office of
Naval Research		0	%		44	%		25	%		17	%
		0	%		100	%		100	%		100	%

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

(i) Warrant Liabilities

The Company’s warrants to purchase shares of its common stock are classified as warrant liabilities and are recorded at fair value. The warrant liabilities are subject to re-measurement at each balance sheet date and the Company recognizes any change in fair value in its consolidated statements of operations within “Change in fair value of warrant liabilities.” The Company will continue to adjust the carrying value of the warrants for changes in the estimated fair value until such time as these instruments are exercised or expire. At that time, the liabilities will be reclassified to “Additional paid-in capital”, a component of “Stockholders’ equity” on the consolidated balance sheets.

(j) 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 due to their anti-dilutive effect.

In computing diluted net loss per share, options to purchase shares of common stock, warrants on common stock and non-vested restricted stock issued to employees and non-employee directors, totaling 915,183 for the three and nine months ended January 31, 2018 and 680,429 for the three and nine months ended January 31, 2017, were excluded from each of the computations as the effect would be anti-dilutive due to the Company's losses.

(k)

Share-Based Compensation

Costs resulting from all share-based payment transactions are recognized in the consolidated financial statements at their fair values. The following table summarizes share-based compensation related to the Company’s share-based plans by expense category for the three and nine months ended January 31, 2018 and 2017:

	Three months ended January 31,				Nine months ended January 31,
	2018		2017		2018		2017
			(in thousands)

Product development	$	5	$	135	$	11	$	418
Selling, general and administrative		72		235		239		580
Total share-based compensation expense	$	77	$	370	$	250	$	998

(l) Deferred Rent

On March 31, 2017, the Company signed a new 7-year lease for approximately 56,000 square feet in Monroe Township, New Jersey that will be used as warehouse/production space and the Company’s principal offices and corporate headquarters. The lease was classified as an operating lease. Rent payments relating to the Monroe premises are subject to annual increases. The minimum monthly payments will vary over the 7-year term of the lease. The Company will record rent expense on a straight-line basis over the 7-year term of the lease. The difference between rent expense and the monthly lease payment will go to a deferred rent/prepaid rent account. The Landlord has provided the Company a tenant improvement allowance in an amount up to, but not exceeding, $137,563 to be applied to the cost of tenant improvement work. The Company recorded lease incentive liability to deferred rent. The Company will release the lease incentive liability on a straight-line basis over the 7-year term to rent expense.

(m) Recently Issued Accounting Standards

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” ASU 2014-09 outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services. The FASB subsequently issued additional clarifying standards to address issues arising from implementation of the new revenue standard, including a one-year deferral of the effective date for the new revenue standard. Public companies should now apply the guidance in ASU 2014-09 to annual reporting periods beginning after December 15, 2017 and interim periods within those annual periods. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim periods within that annual period. As such, the Company is required to adopt this standard effective in fiscal 2019, which begins May 1, 2018. Companies may use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. The Company has not yet completed its final review of the impact of this guidance; however, the Company anticipates applying the modified retrospective method upon adoption of ASU 2014-09 on May 1, 2018. The impact to the Company could be affected by the nature and terms of potential future contracts with customers, as those contracts may have terms that differ from the Company’s current contracts.

In August 2014, the FASB issued ASU 2014-15, “Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern”, which describes how an entity should assess its ability to meet obligations and sets rules for how this information should be disclosed in the financial statements. The standard provides accounting guidance that will be used along with existing auditing standards. The new standard applies to all entities for the first annual period ending after December 15, 2016, and interim periods thereafter. Early application is permitted. The Company adopted ASU 2014-15 for the fiscal year 2017. The Company’s addition of the standard did not have a material impact on its disclosures. See section (c) “Liquidity/Going Concern” within Note (1) “Background and Liquidity” of the consolidated financial statements included in this Quarterly Report on Form 10-Q for further discussion on the Company’s ability to continue as a going concern.

In January 2016, the FASB issued ASU No. 2016-01, “Recognition and Measurement of Financial Assets and Financial Liabilities”, which makes limited amendments to the guidance in U.S. GAAP on the classification and measurement of financial instruments. The update significantly revises an entity’s accounting related to the classification and measurement of investments in equity securities and the presentation of certain fair value changes for financial liabilities measured at fair value. It also amends certain disclosure requirements associated with the fair value of financial instruments. The update will take effect for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The Company will evaluate the effect of ASU 2016-01 for future periods as applicable.

In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842).” The new standard establishes a right-of-use (ROU) model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods, with early adoption permitted. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The Company is evaluating the effect ASU 2016-02 will have on its consolidated financial statements and disclosures and has not yet determined the effect of the standard on its ongoing financial reporting at this time.

In March 2016, the FASB issued ASU No. 2016-09, “Compensation - Stock Compensation (Topic 718).” The amendments of ASU No. 2016-09 were issued as part of the FASB’s Simplification initiative focused on improving areas of GAAP for which cost and complexity may be reduced while maintaining or improving the usefulness of information disclosed within the financial statements. The amendments focused on simplification specifically with regard to share-based payment transactions, including accounting for forfeitures, income tax consequences, classification of awards as equity or liabilities and classification on the statement of cash flows. The guidance in ASU No. 2016-09 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods. The Company adopted ASU 2016-09 on May 1, 2017. Certain of the amendments are applied using a modified retrospective transition method by means of a cumulative-effect adjustment to equity as of May 1, 2017, while other amendments are applied retrospectively, prospectively or using either a prospective or a retrospective transition method. Upon adoption, the Company is beginning to account for forfeitures as they occur rather than estimate a forfeiture rate and has recorded a cumulative-effect adjustment in equity of approximately $11,000 on the date of initial adoption. In periods subsequent to adoption, a higher expense will be recognized earlier during the respective vesting periods of stock-based awards that are not forfeited. The Company expects that the income tax amendments within ASU 2016-09 will have no impact on its results of operations or cash flows because it is in a net operating loss position with a full valuation allowance.

In August 2016, the FASB issued ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments”, providing additional guidance on eight specific cash flow classification issues. The goal of the ASU is to reduce diversity in practice of classifying certain items. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years and early adoption is permitted. The Company has evaluated the effect ASU 2016-13 will have on its consolidated financial statements and disclosures and has determined the standard will have no impact on its ongoing financial reporting at this time.

In November 2016, the FASB issued ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash”, which amends guidance and presentation related to restricted cash in the statement of cash flows, including stating that amounts generally described as restricted cash and restricted cash equivalents should be included within cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown in the statement of cash flows. An entity is required to provide a disclosure indicating the reconciliation of all cash accounts. The amendments in the ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years and early adoption is permitted. The Company has early adopted ASU 2016-18 effective May 1, 2017. In connection with the adoption of the standard the Company has used a retrospective transition method for each period presented in the statement of cash flows. The Company reclassified $488,000 and $300,000 of restricted cash to cash, cash equivalents and restricted cash, beginning of period for the period April 30, 2017 and April 30, 2016 in the statement of cash flows. The Company reclassified $299,000 of restricted cash to cash, cash equivalents and restricted cash, end of period for the period ended January 31, 2017 in the statement of cash flows.

Marketable Securities

9 Months Ended

Jan. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

(3) Marketable Securities

Marketable securities with initial maturities greater than three months but that mature within one year from the balance sheet date are classified as current assets and are summarized as follows:

	January 31, 2018		April 30, 2017
	(in thousands)
Certificate of Deposit	$	25	$	25

Accrued Expenses

9 Months Ended

Jan. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Accrued Expenses

(4) Accrued Expenses

Accrued expenses consist of the following at January 31, 2018 and April 30, 2017.

	January 31, 2018		April 30, 2017
	(in thousands)

Project costs	$	44	$	898
Contract loss reserve		199		238
Employee incentive payments		554		643
Accrued salary and benefits		389		484
Legal and accounting fees		197		478
Accrued taxes payable		132		132
Other		174		186
	$	1,689	$	3,059

Deferred Credits Payable

9 Months Ended

Jan. 31, 2018

Deferred Credits Payable

Deferred Credits Payable

(5) Deferred Credits Payable

During the year ended April 30, 2001, in connection with the sale of common stock to an investor, the Company received $0.6 million 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 $0.6 million, 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 January 31, 2018, the Company has not generated any emissions credits eligible for purchase under the agreement. As a result, the Company anticipates returning the option fee of $0.6 million. Therefore, the $0.6 million is reflected in the consolidated balance sheets within “Deferred credits payable current” as of January 31, 2018 and April 30, 2017, respectively.

Warrants

9 Months Ended

Jan. 31, 2018

Warrants

Warrants

(6) Warrants

On June 2, 2016, the Company entered into a securities purchase agreement, which was amended on June 7, 2016 (as amended, the “June Purchase Agreement”) with certain institutional purchasers (the “June Purchasers”). Pursuant to the terms of the June Purchase Agreement, the Company sold an aggregate of 417,000 shares of Common Stock together with warrants to purchase up to an aggregate of 145,952 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.35 of a share of Common Stock at a combined purchase price of $4.60. The warrants have an exercise price of $6.08 per share, became exercisable on December 3, 2016 (“Initial Exercise Date”), and will expire five years following the Initial Exercise Date.

On July 22, 2016, the Company entered into a Second Amendment to the Purchase Agreement (the “Second Amended Purchase Agreement”) with certain institutional purchasers (the “July Purchasers”). Pursuant to the terms of the Second Amended Purchase Agreement, the Company sold an aggregate of 595,000 shares of Common Stock together with warrants to purchase up to an aggregate of 178,500 shares of Common Stock. Each share of Common Stock was sold together with a warrant to purchase 0.30 of a share of Common Stock at a combined purchase price of $6.75. The Warrants were exercisable immediately at an exercise price of $9.36 per share. The Warrants will expire on the fifth (5th) anniversary of the initial date of issuance.

Both sets of warrants contain a feature whereby they could require the transfer of assets and therefore are classified as a liability in accordance with ASC 480. As such, the warrants had a value of $0.2 million and $0.3 million at January 31, 2018 and April 30, 2017, respectively, as reflected within “Warrant liabilities” in the unaudited consolidated balance sheets.

An unrealized gain and unrealized loss of approximately $14,000 and $104,000 for the three months ended January 31, 2018 and 2017, and a unrealized gain of approximately $82,000 and $1,161,000 for the nine months ended January 31, 2018 and 2017, respectively, were included within “Change in fair value of warrant liability” in the consolidated statements of operations. The Company determined the fair value using the Black-Scholes option pricing model with the following assumptions:

	January 31, 2018			January 31, 2017

Dividend rate		0.0	%		0.0	%
Risk-free rate		2.3% - 2.4	%		1.9	%
Expected life (years)		3.5 - 3.8			4.5 - 4.9
Expected volatility		137.5% - 145.2	%		129.0% - 138.2	%

Stock-Based Compensation

9 Months Ended

Jan. 31, 2018

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

Stock-Based Compensation

(7) Stock-Based Compensation

In 2007, the Company’s 2006 Stock Incentive Plan (the “2006 Plan”) became effective. A total of 80,321 shares were authorized for issuance under the 2006 Plan. In 2009, an amendment to the 2006 Plan was approved by the Company’s stockholders, increasing the aggregate number of shares authorized for issuance by 85,000 shares to 165,321. On October 2, 2013, a further amendment to the 2006 Plan was approved by the Company’s stockholders, increasing the aggregate number of shares authorized for issuance by an additional 80,000 shares to 245,321. The Company’s employees, officers, directors, consultants and advisors were eligible to receive awards under the 2006 Plan. The 2006 Plan was administered by the Company’s board of directors, who were authorized to delegate authority to one or more committees or subcommittees of the board of directors or to the Company’s officers. The 2006 Plan was terminated in December 2015 and unused shares in that plan were transferred to the 2015 Omnibus Incentive Plan.

In 2015, upon approval by the Company’s stockholders, the Company’s 2015 Omnibus Incentive Plan (the “2015 Plan”) became effective. A total of 240,703 shares were authorized for issuance under the 2015 Omnibus Incentive Plan, including shares available for awards under the 2006 Stock Incentive Plan remaining at the time that plan terminated, or that were subject to awards under the 2006 Stock Incentive Plan that thereafter terminated by reason of expiration, forfeiture, cancellation or otherwise. On October 21, 2016 upon approval by the Company’s stockholders the Company increased the number of shares authorized for issuance to 640,703. If any award under the 2006 Stock Incentive Plan or 2015 Plan expires, is cancelled, terminates unexercised or is forfeited, those shares become again available for grant under the 2015 Plan. The 2015 Plan will terminate ten years after its effective date, in October 2025, but is subject to earlier termination as provided in the 2015 Plan. As of January 31, 2018, the Company has 84,393 shares available for future issuance under the 2015 Plan.

On January 18, 2018, the Company’s Board of Directors adopted the Company’s Employment Inducement Incentive Award Plan (the “2018 Inducement Plan”) pursuant to which the Company reserved 500,000 shares of common stock for issuance under the Inducement Plan. In accordance with Rule 5635(c)(4) and Rule 5635(c)(3) of the Nasdaq Listing Rules, awards under the Inducement Plan may only be made to individuals not previously employees of the Company (or following such individuals’ bona fide period of non-employment with the Company), as an inducement material to the individuals’ entry into employment with the Company. An award is any right to receive the Company’s common stock pursuant to the 2018 Inducement Plan, consisting of a performance share award, restricted stock award, a restricted stock unit award or a stock payment award. As of January 31, 2018, there were 97,297 shares outstanding and 402,703 shares available for grant under the 2018 Inducement Plan.

(a) Stock Options

The Company estimates the fair value of each stock option granted, for both service-based and performance-based vesting requirements, 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 SEC’s Staff Accounting Bulletin No. 110, Share-Based Payment. Expected volatility was based on the Company’s historical volatility over the expected life of the stock option granted. The following assumptions were used for three and nine months ended January 31, 2018 and 2017.

	Three months ended January 31,				Nine months ended January 31,
	2018		2017		2018			2017

Risk-free interest rate		N/A		N/A		2.1	%		1.3	%
Expected dividend yield		N/A		N/A		0.0	%		0.0	%
Expected life (in years)		N/A		N/A		5.5			5.5
Expected volatility		N/A		N/A		128.2	%		96.2	%

A summary of stock options under our stock incentive plans is detailed in the following table.

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2017		237,214		$	14.64		7.6
Granted		170,664		$	1.34
Exercised		-		$	-
Cancelled/forfeited		(14,211	)	$	90.10
Outstanding as of January 31, 2018		393,667		$	6.15		8.2
Exercisable as of January 31, 2018		222,293		$	9.80		7.1

As of January 31, 2018, the total intrinsic value of outstanding and exercisable options was approximately $2,000 and $2,000, respectively. As of January 31, 2018, approximately 145,669 additional options were unvested, which had no intrinsic value and a weighted average remaining contractual term of 9.7 years. There was approximately $177,000 and $224,000 of total recognized compensation cost related to stock options during each of the nine months ended January 31, 2018 and 2017, respectively. As of January 31, 2018, there was approximately $147,000 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 0.7 years. The Company typically issues newly authorized but unissued shares to satisfy option exercises under these plans.

(b) Restricted Stock

Compensation expense for non-vested 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. During the nine months ended January 31, 2018, the Company granted 211,881 shares subject to service-based vesting requirements and no shares subject to performance-based vesting requirements. The achievement or vesting requirement of the performance-based grants is tied to the Company’s total shareholder return (“TSR”) relative to the total shareholder return of three alternative energy Exchange Traded Funds as measured over a specific performance period. No vesting of the relevant shares will occur in instances where the Company’s TSR for the relevant period is below 80% of the peer group.

However, additional opportunities to vest some or all of a portion of the shares in a subsequent period may occur. Compensation expense for these awards with market-based vesting is calculated based on the estimated fair value as of the grant date utilizing a Monte Carlo simulation model and is recognized over the service period on a straight-line basis.

Restricted stock issued and unvested as of January 31, 2018 included zero shares of unvested restricted stock subjected to performance-based vesting requirements.

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

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2017		103,412		$	3.99
Granted		211,881		$	1.27
Vested		(85,104	)	$	4.67
Cancelled/forfeited		(33,125	)	$	2.00
Issued and unvested at January 31, 2018		197,064		$	1.35

There was approximately $73,000 and $775,000 of total recognized compensation cost related to restricted stock for the nine months ended January 31, 2018 and 2017, respectively. As of January 31, 2018, there was approximately $0.2 million of total unrecognized compensation cost related to unvested restricted stock granted under our plans. This cost is expected to be recognized over a weighted average period of 2.2 years.

(c)Treasury Stock

During the nine months ended January 31, 2018 and 2017, 25,947 and 39,882 shares, respectively, of common stock were purchased by the Company from employees to pay taxes related to the vesting of restricted stock.

Fair Value Measurements

9 Months Ended

Jan. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

(8) Fair Value Measurements

The Company measures and reports certain financial and non-financial assets and liabilities on a fair value basis. Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). GAAP specifies a three-level hierarchy that is used when measuring and disclosing fair value. The fair value hierarchy gives the highest priority to quoted prices available in active markets (i.e., observable inputs) and the lowest priority to data lacking transparency (i.e., unobservable inputs). An instrument’s categorization within the fair value hierarchy is based on the lowest level of significant input to its valuation. The following is a description of the three hierarchy levels.

Level 1	Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Active markets are considered to be those in which transactions for the assets or liabilities occur in sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2	Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. This category includes quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in inactive markets.

Level 3	Unobservable inputs are not corroborated by market data. This category is comprised of financial and non-financial assets and liabilities whose fair value is estimated based on internally developed models or methodologies using significant inputs that are generally less readily observable from objective sources.

Transfers into or out of any hierarchy level are recognized at the end of the reporting period in which the transfers occurred. There were no transfers between any levels during the three and nine months ended January 31, 2018 and 2017.

The following information is provided to help readers gain an understanding of the relationship between amounts reported in the accompanying consolidated financial statements and the related market or fair value. The disclosures include financial instruments and derivative financial instruments, other than investment in affiliates.

Following are descriptions of the valuation methodologies used to measure material assets and liabilities at fair value and details of the valuation models, key inputs to those models and significant assumptions utilized.

Warrant Liabilities

The fair value of the Company’s warrant liabilities (refer to Note 6) recorded in the Company’s financial statements is determined using the Black-Scholes option pricing model and the quoted price of the Company’s common stock in an active market, volatility and expected life, is a Level 3 measurement. Volatility is based on the actual market activity of the Company’s stock. The expected life is based on the remaining contractual term of the warrants and the risk-free interest rate is based on the implied yield available on U.S. Treasury Securities with a maturity equivalent to the warrants’ expected life.

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of January 31, 2018.

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	241	$	—	$	—	$	241

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of April 30, 2017.

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	323	$	—	$	—	$	323

The following table provides a summary of changes in fair value of the Company’s warrant liabilities held at January 31, 2018.

Fair Value Measurement Using Significant Unobservable Inputs (Level 3)

	Total
	Warrant
	Liability
	(in thousands)

Fair value – April 30, 2016	$	—
Issuance		1,814
Transfers		—
Change in fair value		(1,491	)
Fair value – April 30, 2017	$	323

Change in fair value		(82	)
Fair value – January 31, 2018	$	241

There were no re-measured assets or liabilities at fair value on a non-recurring basis during the nine months ended January 31, 2018 and 2017, respectively.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies

9 Months Ended

Jan. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

(9) Commitments and Contingencies

(a) Litigation

Shareholder Litigation and Demands

The Company and certain of its current and former directors and officers are defendants in a derivative lawsuit filed on March 18, 2015 in the United States District Court for the District of New Jersey captioned Labare v. Dunleavy, et. al., Case No. 3:15-cv-01980-FLW-LHG. The derivative complaint alleges claims for breach of fiduciary duty, abuse of control, gross mismanagement and unjust enrichment relating to the now terminated agreement between Victorian Wave Partners Pty. Ltd. (VWP) and the Australian Renewable Energy Agency (ARENA) for the development of a wave power station. The derivative complaint seeks unspecified monetary damages and other relief.

On July 10, 2015, a second derivative lawsuit, captioned Rywolt v. Dunleavy, et al., Case No. 3:15-cv-05469, was filed by another shareholder against the same defendants in the United States District Court for the District of New Jersey alleging similar claims for breach of fiduciary duty, gross mismanagement, abuse of control, and unjust enrichment relating to the now terminated agreement between VWP and ARENA. The Rywolt complaint also seeks unspecified monetary damages and other relief. On February 8, 2016, the Court issued an order consolidating the Labare and Rywolt actions, appointing co-lead plaintiffs and lead counsel, and ordering a consolidated amended complaint to be filed within 30 days of the order. On March 9, 2016, the co-lead plaintiffs filed an amended complaint consolidating their claims and seeking unspecified monetary damages and other relief.

On April 21, 2016, a third derivative lawsuit, captioned LaCalamito v. Dunleavy, et al., Case No. 3:16-cv-02249, was filed by another shareholder against certain current and former directors and officers of the Company in the United States District Court for the District of New Jersey alleging similar claims for breach of fiduciary duty relating to the now terminated agreement between VWP and ARENA. The LaCalamito complaint seeks unspecified monetary damages and other relief. The Company has not been formally served and has not yet responded to the complaint.

On June 9, 2016, a fourth derivative lawsuit, captioned Pucillo v. Dunleavy, et al., was filed by another shareholder against certain current and former directors and officers of the Company in the United States District Court for the District of New Jersey alleging similar claims for breach of fiduciary duty, unjust enrichment, and abuse of control relating to the now terminated agreement between VWP and ARENA. The Pucillo complaint seeks unspecified monetary damages and other relief. On August 2, 2016, the parties in the Pucillo lawsuit filed a Stipulation and Proposed Order pursuant to which: (i) the defendants agreed to accept service of the Pucillo complaint; (ii) the parties agreed to stay the Pucillo action pending the filing and resolution of a motion to consolidate the Pucillo action with the Labare and Rywolt actions; and (iii) the parties agreed that the defendants shall not be required to respond to the Pucillo complaint during the pendency of the stay. The Court approved the Stipulation on August 3, 2016.

On October 25, 2016, the Court approved and entered a Stipulation and Order that, among other things, (i) consolidated the four derivative actions; (ii) identified plaintiff Pucillo as the lead plaintiff in the consolidated actions; and (iii) stayed the consolidated actions pending the November 14, 2016 settlement hearing in the now-settled securities class action and further order of the Court.

On October 23, 2017, the parties entered into a Stipulation and Agreement of Settlement to resolve the four consolidated derivative lawsuits. If approved by the Court, the settlement provides for, among other things, the Company to implement certain corporate governance changes, a $350,000 payment to the plaintiffs’ attorneys for attorneys’ fees and costs that will be made by the Company’s insurance carrier, dismissal of the derivative lawsuits, and certain releases. On November 21, 2017, the plaintiffs filed an unopposed motion seeking preliminary approval of the settlement. The Court has not yet ruled on that motion. The Company has accrued $350,000 related to this matter as a probable and reasonably estimable loss contingency during the nine months ended January 31, 2018. The Company also recorded a receivable of $350,000 from its insurance carrier with the offset to the statement of operations.

On May 26, 2017, an attorney claiming to represent two stockholders sent the Company’s Board of Directors a Stockholder Litigation Demand letter (“Stockholder Demand”). The Stockholder Demand alleges that the voting of shares for the 1-for-10 reverse stock split at the 2015 annual meeting of stockholders held on October 22, 2015 was not properly counted, and further alleges that, although the Company reported the reverse stock split as having been passed, if the vote was properly counted the reverse stock split would not have been approved. The Stockholder Demand requests the Board of Directors either to deem the reverse stock split as ineffective and disclose the same or to seek a proper and effective stockholder ratification of the reverse stock split. In addition, the Stockholder Demand requests the Board of Directors to adopt and implement adequate internal controls and systems to prevent the alleged improper voting from recurring. On June 23, 2017, the Company responded to the Stockholder Demand, explained the procedures that were followed for the 2015 annual meeting of stockholders and provided the Oath of the Inspector of Elections and the Certificate of the Inspector of Elections that certified as accurate the results of the voting at the meeting including voting on the reverse stock split proposal. On June 26, 2017, the attorney representing the alleged stockholders replied to the Company’s response, further alleged that the proxy statement underlying the 2015 annual meeting provided voting instructions that allegedly misled the stockholders regarding whether their brokers could vote on the reverse stock split proposal, and renewed their requests of the Board. On July 24, 2017, the Company provided an additional response to the Stockholders Demand, denied the allegations, and declined to take any of the actions requested.

Employment Litigation

On June 10, 2014, the Company announced that it had terminated Charles Dunleavy as its Chief Executive Officer and as an employee of the Company for cause, effective June 9, 2014, and that Mr. Dunleavy had also been removed from his position as Chairman of the Board of Directors. On June 17, 2014, Mr. Dunleavy wrote to the Company stating that he had retained counsel to represent him in connection with an alleged wrongful termination of his employment. On July 28, 2014, Mr. Dunleavy resigned from the Board and the boards of directors of the Company’s subsidiaries. The Company and Mr. Dunleavy have agreed to suspend his alleged employment claims pending resolution of the derivatives litigation described above.

Except for the pending settlement noted previously, we have not established any provision for losses relating to these claims and pending litigation. Due to the stages of these proceedings, and considering the inherent uncertainty of these claims and litigation, at this time we are not able to predict or reasonably estimate whether we have any possible loss exposure or the ultimate outcome of these claims.

(b) Regulatory Matters

SEC Investigation

On February 4, 2015, the Company received a subpoena from the SEC requesting information related to the VWP Project. The Company has provided information to the SEC in response to that subpoena. As part of the same investigation, on July 12, 2016, the SEC issued second subpoena requesting information related to the Company’s April 4, 2014 public offering. The Company has provided information to the SEC in response to that subpoena. The SEC investigation is ongoing and the Company continues to cooperate with the SEC in its investigation. We are unable to predict what action, if any, might be taken by the SEC or its staff as a result of this investigation or what impact, if any, the cost of responding to the SEC’s investigation or its ultimate outcome might have on our financial position, results of operations or liquidity. We have not established any provision for losses relating to this matter.

Spain IVA (sales tax)

In June 2012, 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 $0.3 million 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 totaling €0.3 million ($0.3 million) at the request of the Spanish tax authorities. On January 31, 2017 the Company has received $0.2 million from the Spanish tax authorities as a result of the conclusion of the inquiry. In addition, during February 2017, the Spanish tax authorities approved of the release of the two outstanding letters of credit.

Spain Income Tax Audit

The Company is currently undergoing an income tax audit in Spain for the period from 2008 to 2014, when its Spanish branch was closed. The branch reported net operating losses for each of the years reported. It is anticipated that the Company will be assessed a penalty relating to these tax years for these losses. The Company has estimated this penalty to be $132,000, and as such, for the period ended April 30, 2017 and January 31, 2018, the Company has recorded $132,000 for this penalty to Accrued expenses in its balance sheet.

Income Taxes

9 Months Ended

Jan. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

(10) Income Taxes

New Jersey Net Operating Loss

During the three and nine months ended January 31, 2018, the Company recorded an income tax benefit of $1.1 million, representing the proceeds from the sale of $11.4 million of New Jersey net operating loss carryforwards and research and development tax credits. During the three and nine months ended January 31, 2017, the Company recorded an income tax benefit of $0.7 million representing the proceeds from the sale of $7.8 million of New Jersey net operating loss carryforwards and research and development tax credits.

Other than the sale of New Jersey net operating loss carryforwards, the Company did not recognize any consolidated income tax benefit (expense) during the three and nine month periods ended January 31, 2018 and 2017. The Company has recorded a valuation allowance to reduce its net deferred tax asset to an amount that is more likely than not to be realized in future years. Accordingly, the benefit of the net operating loss that would have been recognized was offset by changes in the valuation allowance.

Recent Tax Legislation

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the “TCJA”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease for the Company from 34% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017.

The TCJA reduced the U.S. federal statutory tax rate for the Company from 34% to 21% effective January 1, 2018. For fiscal year 2018, our blended U.S. federal statutory tax rate is 29.7%. This is the result of using the tax rate of 34% for the number of days from the start of the fiscal year until the date of rate change and the tax rate of 21% for the number of days from the date of rate change until the end of the fiscal year. However, based upon the Company’s historical losses, the Company continues to have a full valuation allowance against all deferred tax assets.

We remeasured our deferred taxes to reflect the reduced rate that will apply when these deferred taxes are settled or realized in future periods. To calculate the remeasurement of deferred taxes, we estimated when the existing deferred taxes will be settled or realized and which deferred taxes will be settled within the current year at the 34% tax rate and those that will reverse after year end at the 21% tax rate. As of January 31, 2018, we have not completed our accounting for the tax effects of the TCJA, however there is no effect on the deferred tax provision since the company has a full valuation allowance.

Uncertain Tax Positions

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. We are currently undergoing an income tax audit in Spain for the period from 2008 to 2014, when our Spanish branch was closed. The branch reported net operating losses for each of the years reported. It is anticipated that we will be assessed a penalty relating to these tax years for these losses. We have estimated this penalty to be $132,000, and as such, for the period ended April 30, 2017 and January 31, 2018, we have recorded $132,000 for this penalty to Accrued expenses in the Balance Sheet. At January 31, 2018 the Company had no other 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. U.S. federal and state income tax returns were audited through fiscal 2014 and fiscal 2010 respectively. Net operating loss and credit carry forwards since inception remain open to examination by taxing authorities, and will continue to remain open for a period of time after utilization.

Operating Segments and Geographic Information

9 Months Ended

Jan. 31, 2018

Segment Reporting [Abstract]

Operating Segments and Geographic Information

(11) 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. During the nine months ended January 31, 2018 and 2017, the Company’s primary business operations were in North America.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Jan. 31, 2018

Accounting Policies [Abstract]

Consolidation

(a) Consolidation

Use of Estimates

(b) Use of Estimates

Revenue Recognition

(c) Revenue Recognition

Cash, Cash Equivalents, Restricted Cash and Security Agreements

(d) Cash, Cash Equivalents, Restricted Cash and Security Agreements

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. The Company invests excess cash in a money market account.

	January 31, 2018		April 30, 2017
	(in thousands)

Checking and savings accounts	$	1,233	$	4,241
Overnight repurchase account		-		4,180
Money market account		13,136		-
	$	14,369	$	8,421

Restricted Cash and Security Agreements

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

	January 31, 2018		April 30, 2017
	(in thousands)

Barclay's Bank Agreement	$	382	$	334
Santander Bank		154		154
	$	536	$	488

	January 31, 2018		April 30, 2017
	(in thousands)

Cash and cash equivalents	$	14,369	$	8,421
Restricted cash- short term		382		334
Restricted cash- long term		154		154
	$	14,905	$	8,909

Marketable Securities

(e) Marketable Securities

Foreign Exchange Gains and Losses

(f) Foreign Exchange Gains and Losses

Property and Equipment

(g) Property and Equipment

Concentration of Credit Risk

(h) Concentration of Credit Risk

	Three months ended January 31,						Nine months ended January 31,
Customer	2018			2017			2018			2017

Mitsui Engineering & Shipbuilding		0	%		56	%		75	%		83	%
U.S. Department of Defense Office of
Naval Research		0	%		44	%		25	%		17	%
		0	%		100	%		100	%		100	%

Warrant Liabilities

(i) Warrant Liabilities

Net Loss Per Common Share

(j) Net Loss per Common Share

Share-Based Compensation

(k)

Share-Based Compensation

	Three months ended January 31,				Nine months ended January 31,
	2018		2017		2018		2017
			(in thousands)

Product development	$	5	$	135	$	11	$	418
Selling, general and administrative		72		235		239		580
Total share-based compensation expense	$	77	$	370	$	250	$	998

Deferred Rent

(l) Deferred Rent

Recently Issued Accounting Standards

(m) Recently Issued Accounting Standards

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Jan. 31, 2018

Schedule of Cash and Cash Equivalents

	January 31, 2018		April 30, 2017
	(in thousands)

Checking and savings accounts	$	1,233	$	4,241
Overnight repurchase account		-		4,180
Money market account		13,136		-
	$	14,369	$	8,421

Schedule of Cash and Cash Equivalents and Restricted Cash

	January 31, 2018		April 30, 2017
	(in thousands)

Cash and cash equivalents	$	14,369	$	8,421
Restricted cash- short term		382		334
Restricted cash- long term		154		154
	$	14,905	$	8,909

Schedule of Revenue by Major Customers by Reporting Segments

	Three months ended January 31,						Nine months ended January 31,
Customer	2018			2017			2018			2017

Mitsui Engineering & Shipbuilding		0	%		56	%		75	%		83	%
U.S. Department of Defense Office of
Naval Research		0	%		44	%		25	%		17	%
		0	%		100	%		100	%		100	%

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs

The following table summarizes share-based compensation related to the Company’s share-based plans by expense category for the three and nine months ended January 31, 2018 and 2017:

	Three months ended January 31,				Nine months ended January 31,
	2018		2017		2018		2017
			(in thousands)

Product development	$	5	$	135	$	11	$	418
Selling, general and administrative		72		235		239		580
Total share-based compensation expense	$	77	$	370	$	250	$	998

Restricted Cash [Member]

Schedule of Cash and Cash Equivalents and Restricted Cash

Restricted cash includes the following:

	January 31, 2018		April 30, 2017
	(in thousands)

Barclay's Bank Agreement	$	382	$	334
Santander Bank		154		154
	$	536	$	488

Marketable Securities (Tables)

9 Months Ended

Jan. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of Marketable Securities

Marketable securities with initial maturities greater than three months but that mature within one year from the balance sheet date are classified as current assets and are summarized as follows:

	January 31, 2018		April 30, 2017
	(in thousands)
Certificate of Deposit	$	25	$	25

Accrued Expenses (Tables)

9 Months Ended

Jan. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of the following at January 31, 2018 and April 30, 2017.

	January 31, 2018		April 30, 2017
	(in thousands)

Project costs	$	44	$	898
Contract loss reserve		199		238
Employee incentive payments		554		643
Accrued salary and benefits		389		484
Legal and accounting fees		197		478
Accrued taxes payable		132		132
Other		174		186
	$	1,689	$	3,059

Warrants (Tables)

9 Months Ended

Jan. 31, 2018

Warrants

Schedule of Fair Value Assumptions Used

The Company determined the fair value using the Black-Scholes option pricing model with the following assumptions:

	January 31, 2018			January 31, 2017

Dividend rate		0.0	%		0.0	%
Risk-free rate		2.3% - 2.4	%		1.9	%
Expected life (years)		3.5 - 3.8			4.5 - 4.9
Expected volatility		137.5% - 145.2	%		129.0% - 138.2	%

Stock-Based Compensation (Tables)

9 Months Ended

Jan. 31, 2018

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

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions

The following assumptions were used for three and nine months ended January 31, 2018 and 2017.

	Three months ended January 31,				Nine months ended January 31,
	2018		2017		2018			2017

Risk-free interest rate		N/A		N/A		2.1	%		1.3	%
Expected dividend yield		N/A		N/A		0.0	%		0.0	%
Expected life (in years)		N/A		N/A		5.5			5.5
Expected volatility		N/A		N/A		128.2	%		96.2	%

Schedule of Stock Option Activity

A summary of stock options under our stock incentive plans is detailed in the following table.

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2017		237,214		$	14.64		7.6
Granted		170,664		$	1.34
Exercised		-		$	-
Cancelled/forfeited		(14,211	)	$	90.10
Outstanding as of January 31, 2018		393,667		$	6.15		8.2
Exercisable as of January 31, 2018		222,293		$	9.80		7.1

Schedule of Non vested Restricted Stock Activity

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

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2017		103,412		$	3.99
Granted		211,881		$	1.27
Vested		(85,104	)	$	4.67
Cancelled/forfeited		(33,125	)	$	2.00
Issued and unvested at January 31, 2018		197,064		$	1.35

Fair Value Measurements (Tables)

9 Months Ended

Jan. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of January 31, 2018.

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	241	$	—	$	—	$	241

The following table presents financial assets and liabilities measured at fair value on a recurring basis as of April 30, 2017.

	Total Carrying Value in Consolidated Balance Sheet		Quoted prices in active markets for identical assets or liabilities (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
	(in thousands)

Warrant liabilities	$	323	$	—	$	—	$	323

Summary of Changes on Value of Warrant Liability

The following table provides a summary of changes in fair value of the Company’s warrant liabilities held at January 31, 2018.

Fair Value Measurement Using Significant Unobservable Inputs (Level 3)

	Total
	Warrant
	Liability
	(in thousands)

Fair value – April 30, 2016	$	—
Issuance		1,814
Transfers		—
Change in fair value		(1,491	)
Fair value – April 30, 2017	$	323

Change in fair value		(82	)
Fair value – January 31, 2018	$	241

Background, Basis of Presentation and Liquidity (Details Narrative) $ / shares in Units, $ in Thousands						3 Months Ended		9 Months Ended
	Oct. 23, 2017 USD ($) $ / shares shares	May 02, 2017 USD ($) $ / shares shares	Oct. 19, 2016 USD ($) $ / shares shares	Jul. 22, 2016 USD ($) $ / shares shares	Jun. 02, 2016 USD ($) $ / shares shares	Jan. 31, 2018 USD ($)	Jan. 31, 2017 USD ($)	Jan. 31, 2018 USD ($) agreements	Jan. 31, 2017 USD ($)	Apr. 30, 2017 USD ($)
Accumulated deficit						$ 194,284		$ 194,284		$ 187,370
Cash and cash equivalents, at carrying value						14,369		14,369		$ 8,421
Revenues							$ 221	$ 289	$ 593
Number of financing agreements closed \| agreements								5
Public offering price								$ 30,000
Over-Allotment Option [Member]
Number of common stock shares sold \| shares		807,750	360,000
Securities Purchase Agreement [Member]
Number of common stock shares sold \| shares					417,000
Warrant to purchase shares common stock \| shares					145,952
Class of warrant or right, number of securities called by each warrant or right \| shares					0.35
Combined purchase price per share \| $ / shares					$ 4.60
Proceeds from issuance or sale of equity					$ 1,700
Class of warrant or right, exercise price of warrants or rights \| $ / shares					$ 6.08
Class of warrant or right, expiration period					5 years
Securities Purchase Agreement [Member] \| Placement Agents [Member] \| Placement Agent Fees [Member]
Payments of stock issuance costs					$ 100
Securities Purchase Agreement [Member] \| Placement Agents [Member] \| Pocket and Legal Expenses [Member]
Payments of stock issuance costs					$ 35
Second Amended Purchase Agreement [Member]
Number of common stock shares sold \| shares				595,000
Warrant to purchase shares common stock \| shares				178,500
Class of warrant or right, number of securities called by each warrant or right \| shares				0.30
Combined purchase price per share \| $ / shares				$ 6.75
Proceeds from issuance or sale of equity				$ 3,600
Class of warrant or right, exercise price of warrants or rights \| $ / shares				$ 9.36
Class of warrant or right, expiration period				5 years
Offering Agreement [Member]
Number of common stock shares sold \| shares	5,739,437	6,192,750	2,760,000
Proceeds from issuance or sale of equity	$ 7,400	$ 7,200	$ 6,900
Share price \| $ / shares	$ 1.42	$ 1.30	$ 2.75

Summary of Significant Accounting Policies (Details Narrative) € in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
	Mar. 31, 2017 USD ($) ft²	Jan. 31, 2018 USD ($) shares	Jan. 31, 2017 USD ($) shares	Jan. 31, 2018 USD ($) shares	Jan. 31, 2017 USD ($) shares	Jan. 31, 2018 EUR (€)	Apr. 30, 2017 USD ($)	Apr. 30, 2016 USD ($)
Antidilutive securities excluded from computation of earnings per share, shares \| shares		915,183	680,429	915,183	680,429
Cumulative effect of new accounting principle in period of adoption		$ 11		$ 11
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents		14,905	$ 11,409	$ 14,905	$ 11,409		$ 8,909	$ 7,030
Monore Township [Member]
Term of lease	7 years
Area of land \| ft²	56,000
Tenant improvement work	$ 137,563
Accounting Standards Update 2016-18 [Member] \| Restatement Adjustment [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents			$ 299		$ 299		$ 488	$ 300
Minimum [Member]
Property, plant and equipment, useful life				3 years
Maximum [Member]
Property, plant and equipment, useful life				7 years
One Agreement [Member] \| Barclays Bank [Member]
Long-term line of credit		400		$ 400
Line of credit facility, commitment fee percentage				1.00%
Letters of credit outstanding, amount		$ 400		$ 400
One Agreement [Member] \| Barclays Bank [Member] \| Euro [Member]
Long-term line of credit \| €						€ 300
Letters of credit outstanding, amount \| €						€ 300

Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017
Cash and cash equivalents	$ 14,369	$ 8,421
Checking and Savings Accounts [Member]
Cash and cash equivalents	1,233	4,241
Overnight Repurchase Account [Member]
Cash and cash equivalents		4,180
Money Market Account [Member]
Cash and cash equivalents	$ 13,136

Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017	Jan. 31, 2017	Apr. 30, 2016
RestrictedCash	$ 536	$ 488
Cash and Cash Equivalents	14,369	8,421
Restricted cash- short term	382	334
Restricted cash- long term	154	154
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	14,905	8,909	$ 11,409	$ 7,030
Barclays Bank Agreement [Member]
RestrictedCash	382	334
Santander Bank [Member]
RestrictedCash	$ 154	$ 154

Summary of Significant Accounting Policies - Schedule of Revenue by Major Customers by Reporting Segments (Details) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Revenues, percentage	0.00%	100.00%	100.00%	100.00%
Mitsui Engineering & Shipbuilding [Member]
Revenues, percentage	0.00%	56.00%	75.00%	83.00%
U.S. Department of Defense Office of Naval Research [Member]
Revenues, percentage	0.00%	44.00%	25.00%	17.00%

Summary of Significant Accounting Policies - Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Total share-based compensation expense	$ 77	$ 370	$ 250	$ 998
Product Development [Member]
Total share-based compensation expense	5	135	11	418
Selling, General and Administrative [Member]
Total share-based compensation expense	$ 72	$ 235	$ 239	$ 580

Marketable Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Certificate of Deposit	$ 25	$ 25

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Project costs	$ 44	$ 898
Contract loss reserve	199	238
Employee incentive payments	554	643
Accrued salary and benefits	389	484
Legal and accounting fees	197	478
Accrued taxes payable	132	132
Other	174	186
Accrued expenses total	$ 1,689	$ 3,059

Deferred Credits Payable (Details Narrative) $ in Thousands	Jan. 31, 2018 USD ($)	Apr. 30, 2017 USD ($)	Dec. 31, 2012 USD ($)	Apr. 30, 2001 USD ($) t
Deferred Credits Payable
Customer advances or deposits, noncurrent				$ 600
Deferred credits payable option details \| t				500,000
Deferred credits payable market discount rate				30.00%
Deferred credits payable market liquidated damages rate				30.00%
Option fee amount			$ 600
Customer advances and deposits, current	$ 600	$ 600

Warrants (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Jul. 22, 2016	Jun. 02, 2016	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Apr. 30, 2017
Fair value adjustment of warrants			$ 14	$ (104)	$ 82	$ 1,161
Warrant [Member]
Derivative liability, current			$ 200		$ 200		$ 300
Securities Purchase Agreement [Member]
Number of common stock shares sold		417,000
Warrant to purchase shares common stock		145,952
Class of warrant or right, number of securities called by each warrant or right		0.35
Combined purchase price per share		$ 4.60
Warrant exercise price per share		$ 6.08
Class of warrant or right, expiration period		5 years
Second Amended Purchase Agreement [Member]
Number of common stock shares sold	595,000
Warrant to purchase shares common stock	178,500
Class of warrant or right, number of securities called by each warrant or right	0.30
Combined purchase price per share	$ 6.75
Warrant exercise price per share	$ 9.36
Class of warrant or right, expiration period	5 years

Warrants - Schedule of Fair Value Assumptions Used (Details) - Warrant [Member]	9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Dividend rate	0.00%	0.00%
Risk-free rate		1.90%
Minimum [Member]
Risk-free rate	2.30%
Expected life (years)	3 years 6 months	4 years 6 months
Expected volatility	137.50%	129.00%
Maximum [Member]
Risk-free rate	2.40%
Expected life (years)	3 years 9 months 18 days	4 years 10 months 25 days
Expected volatility	145.20%	138.20%

Stock-Based Compensation (Details Narrative) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 02, 2013	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Dec. 31, 2009	Jan. 18, 2018	Apr. 30, 2017	Oct. 21, 2016	Dec. 31, 2015	Dec. 31, 2007
Share-based compensation expense		$ 77	$ 370	$ 250	$ 998
Treasury Stock [Member]
Treasury stock, shares, acquired				25,947	39,882
Employee Stock Option [Member]
Stock based compensation, shares outstanding		393,667		393,667				237,214
Share-based compensation intrinsic value of outstanding		$ 2		$ 2
Share-based compensation options, exercisable intrinsic value		$ 2		$ 2
Share-based compensation unvested shares of stock options		145,669		145,669
Share-based compensation weighted average remaining contractual term				9 years 8 months 12 days
Share-based compensation expense				$ 177	$ 224
Unrecognized compensation cost related to non-vested stock options		$ 147		$ 147
Share-based compensation cost expected to recognize weighted-average term				8 months 12 days
Restricted Stock [Member]
Share-based compensation expense				$ 73	$ 775
Share-based compensation cost expected to recognize weighted-average term				2 years 2 months 12 days
Unrecognized compensation cost related to unvested restricted stock		$ 200		$ 200
Restricted Stock [Member] \| Service-based Vesting [Member]
Number of restricted stock shares granted				211,881
Restricted Stock [Member] \| Performance-based Vesting [Member]
Number of unvested restricted stock shares issued		0		0
Stock Incentive Plan 2006 [Member]
Share-based compensation arrangement by share-based payment award, number of shares authorized	245,321					165,321					80,321
Share-based compensation arrangement by share-based payment award, number of additional shares authorized	80,000					85,000
Stock Incentive Plan 2015 [Member]
Share-based compensation arrangement by share-based payment award, number of shares authorized									640,703	240,703
Sharebased compensation arrangement by sharebased payment award options outstanding contractual term				10 years
Common stock, capital shares reserved for future issuance		84,393		84,393
2018 Inducement Plan [Member]
Common stock, capital shares reserved for future issuance							500,000
Stock based compensation, shares outstanding		97,297		97,297
Stock based compensation, number of stock options granted		402,703		402,703

Stock-Based Compensation - Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions (Details) - Employee Stock Option [Member]	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Risk-free interest rate			2.10%	1.30%
Expected dividend yield			0.00%	0.00%
Expected life (in years)	0 years	0 years	5 years 6 months	5 years 6 months
Expected volatility			128.20%	96.20%

Stock-Based Compensation - Schedule of Stock Option Activity (Details) - Employee Stock Option [Member]	9 Months Ended
	Jan. 31, 2018 $ / shares shares
Shares Underlying Options Outstanding, Beginning \| shares	237,214
Shares Underlying Options Outstanding, Granted \| shares	170,664
Shares Underlying Options Outstanding, Exercised \| shares
Shares Underlying Options Outstanding, Cancelled/forfeited \| shares	(14,211)
Shares Underlying Options Outstanding, Ending \| shares	393,667
Shares Underlying Options Outstanding, Exercisable \| shares	222,293
Weighted Average Exercise Price, Beginning Balance \| $ / shares	$ 14.64
Weighted Average Exercise Price, Granted \| $ / shares	1.34
Weighted Average Exercise Price, Exercised \| $ / shares
Weighted Average Exercise Price, Cancelled/forfeited \| $ / shares	90.10
Weighted Average Exercise Price, Ending Balance \| $ / shares	6.15
Weighted Average Exercise Price, Exercisable \| $ / shares	$ 9.80
Weighted Average Remaining Contractual Term (In Years), Beginning	7 years 7 months 6 days
Weighted Average Remaining Contractual Term (In Years), Ending	8 years 2 months 12 days
Weighted Average Remaining Contractual Term (In Years), Exercisable	7 years 1 month 6 days

Stock-Based Compensation - Schedule of Non vested Restricted Stock Activity (Details) - Non-vested Restricted Stock [Member]	9 Months Ended
	Jan. 31, 2018 $ / shares shares
Number of Shares, Issued and unvested, Beginning \| shares	103,412
Number of Shares, Granted \| shares	211,881
Number of Shares, Vested \| shares	(85,104)
Number of Shares, Cancelled/forfeited \| shares	(33,125)
Number of Shares, Issued and Unvested, Ending \| shares	197,064
Weighted Average Price per Share, Issued and Unvested, Beginning \| $ / shares	$ 3.99
Weighted Average Price per Share, Granted \| $ / shares	1.27
Weighted Average Price per Share, Vested \| $ / shares	4.67
Weighted Average Price per Share, Cancelled/forfeited \| $ / shares	2.00
Weighted Average Price per Share, Issued and Unvested, Ending \| $ / shares	$ 1.35

Fair Value Measurements (Details Narrative) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)	9 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Liabilities, fair value adjustment
Assets, fair value adjustment

Fair Value Measurements - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017
Warrant liabilities	$ 241	$ 323
Fair Value, Measurements, Recurring [Member]
Warrant liabilities	241	323
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Warrant liabilities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Warrant liabilities
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Warrant liabilities	$ 241	$ 323

Fair Value Measurements - Summary of Changes on Value of Warrant Liability (Details) - Warrant Liability [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jan. 31, 2018	Apr. 30, 2017
Fair value, beginning	$ 323
Issuance		1,814
Transfers
Change in fair value	(82)	(1,491)
Fair value, ending	$ 241	$ 323

Commitments and Contingencies (Details Narrative) € in Thousands, $ in Thousands			1 Months Ended	9 Months Ended	12 Months Ended
	Oct. 23, 2017 USD ($)	Oct. 22, 2015	Jun. 30, 2012 USD ($)	Jan. 31, 2018 USD ($)	Apr. 30, 2017 USD ($)	Jan. 31, 2017 USD ($)	Jun. 30, 2012 EUR (€)
Estimated litigation liability, current				$ 350
Foreign Tax Authority [Member] \| Tax Authority, Spain [Member]
Input tax			$ 300
Letters of credit outstanding, amount			$ 300
Foreign tax examination refund						$ 200
Foreign Tax Authority [Member] \| Tax Authority, Spain [Member] \| Accounts Payable and Accrued Liabilities [Member]
Income tax examination, penalties expense				132	$ 132
Foreign Tax Authority [Member] \| Tax Authority, Spain [Member] \| Euro [Member]
Letters of credit outstanding, amount \| €							€ 300
Reverse Stock Split [Member]
Stockholders' equity note, stock split, conversion ratio		10
Stipulation [Member]
Litigation settlement, amount awarded to other party	$ 350
Estimated litigation liability, current				350
Insurance settlements receivable				$ 350

Income Taxes (Details Narrative) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
Income Taxes (Details Narrative) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Apr. 30, 2017
Income tax (expense) benefit	$ (1,119)	$ (698)	$ (1,119)	$ (698)
Federal statutory tax rate			29.70%
Unrecognized tax benefits
Maximum [Member]
Corporate tax rate			34.00%
Federal statutory tax rate			34.00%
Income tax rate, description			The TCJA reduced the U.S. federal statutory tax rate for the Company from 34% to 21% effective January 1, 2018. For fiscal year 2018, our blended U.S. federal statutory tax rate is 29.7%. This is the result of using the tax rate of 34% for the number of days from the start of the fiscal year until the date of rate change and the tax rate of 21% for the number of days from the date of rate change until the end of the fiscal year. We remeasured our deferred taxes to reflect the reduced rate that will apply when these deferred taxes are settled or realized in future periods. To calculate the remeasurement of deferred taxes, we estimated when the existing deferred taxes will be settled or realized and which deferred taxes will be settled within the current year at the 34% tax rate and those that will reverse after year end at the 21% tax rate.
Minimum [Member]
Corporate tax rate			21.00%
Federal statutory tax rate			21.00%
New Jersey Division of Taxation [Member]
Income tax (expense) benefit
Proceed from sale of loss carryforwards and tax credits	$ 11,400	$ 7,800	11,400	$ 7,800
Tax Authority, Spain [Member] \| Foreign Tax Authority [Member] \| Accounts Payable and Accrued Liabilities [Member]
Income tax examination, penalties expense			$ 132		$ 132

Operating Segments and Geographic Information (Details Narrative)	9 Months Ended
	Jan. 31, 2018 segments
Segment Reporting [Abstract]
Number of operating segments	1