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Earnings Per Share [Text Block]

Earnings Per Share

Basic earnings (loss) per share ("EPS") is computed by dividing the net income (loss) for the period by the weighted-average number of common shares outstanding during the period. Diluted earnings (loss) per share includes the dilutive effect of common stock equivalents and is computed using the weighted-average number of common stock and common stock equivalents outstanding during the reporting period. Diluted EPS for the

three

and

six

months ended

June 30, 2019

and

2018

excluded common stock equivalents because the effect of their inclusion would be anti-dilutive or would decrease the reported loss per share.

The following table sets forth securities outstanding that could potentially dilute the calculation of diluted EPS.

	Three and Six Months Ended June 30,
	2019		2018
Warrants to purchase common stock - liability classified (see Note 7)		55,963		58,902
Warrant to purchase common stock - equity classified		6		6
2020 Notes		1,020,595		1,116,637
Outstanding options to purchase common stock (see Note 10)		2,361		358
Stock appreciation rights (see Note 10)		132,566		68,638
Unvested restricted common stock (see Note 10)		1,538,184		16
Total		2,749,675		1,244,557

Note 3 - Revenues From Contracts With Customers; Other Revenues

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Text Block]

Revenues from Contracts with Customers; Other Revenues

The Company’s current and historical revenues have consisted of the following: (a) ethanol sales and related products revenue, net; (b) hydrocarbon revenue; and (c) grant and other revenue, which primarily has historically consisted of revenues from governmental and cooperative research grants.

Ethanol sales and related products revenues.

Ethanol sales and related products revenues are sold to customers on a “free-on-board, shipping point” basis. Each transaction occurs independent of any other sale, and once sold, there are

future obligations on the part of the Company to provide post-sale support or promises to deliver future goods or services.

Hydrocarbon revenue.

Hydrocarbon revenues include sales of ATJ, isooctene and isooctane and is sold mostly on a “free-on-board, shipping point” basis. Each transaction occurs independent of any other sale, and once sold, there are

future obligations on the part of the Company to provide post-sale support or promises to deliver future goods or services.

Grant and other revenues.

Grant and other revenues primarily have historically consisted of governmental and cooperative research grants, of which the

Northwest Advanced Renewables Alliance

grant, funded by the United States Department of Agriculture, comprised the majority of those revenues since

2014.

This grant consists of a non-reciprocal arrangement, and therefore, does

not

qualify as a contract pursuant to ASC

606,

Revenues from Contracts with Customers

. Other revenues have included historically occasional short-term (less than

one

-year) consulting services and leases of certain storage facilities located at the Company's Luverne Facility.

The following table sets forth the components of the Company’s revenues between those generated from contracts with customers and those generated from arrangements that do

not

constitute a contract with a customer (in thousands).

	Three Months Ended June 30 , 2019
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	4,966	$	—	$	4,966
Hydrocarbon revenue		92		—		92
Grant and other revenue		—		28		28
	$	5,058	$	28	$	5,086
Timing of Revenue Recognition
Goods transferred at a point in time	$	5,058	$	—	$	5,058
Services transferred over time		—		28		28
	$	5,058	$	28	$	5,086

	Three Months Ended June 30 , 2018
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	8,813	$	—	$	8,813
Hydrocarbon revenue		607		—		607
Grant and other revenue		—		—		—
	$	9,420	$	—	$	9,420
Timing of Revenue Recognition
Goods transferred at a point in time	$	9,420	$	—	$	9,420
Services transferred over time		—		—		—
	$	9,420	$	—	$	9,420

	Six Months Ended June 30, 2019
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	10,630	$	—	$	10,630
Hydrocarbon revenue		831		—		831
Grant and other revenue		—		28		28
	$	11,461	$	28	$	11,489
Timing of Revenue Recognition
Goods transferred at a point in time	$	11,461	$	—	$	11,461
Services transferred over time		—		28		28
	$	11,461	$	28	$	11,489

	Six Months Ended June 30, 2018
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	17,031		—	$	17,031
Hydrocarbon revenue		607		—		607
Grant and other revenue		25		—		25
	$	17,663	$	—	$	17,663
Timing of Revenue Recognition
Goods transferred at a point in time	$	17,638	$	—	$	17,638
Services transferred over time		25		—		25
	$	17,663	$	—	$	17,663

Goods transferred at a point-in-time.

For the

three

and

six

months ended

June 30, 2019

and

2018,

there were

contracts with customers for which consideration was variable or for which there were multiple performance obligations for any given contract. Accordingly, the entire transaction price is allocated to the goods transferred. As of

June 30, 2019

and

December 31, 2018,

there were

remaining unfulfilled or partially fulfilled performance obligations.

All goods transferred are tested to ensure product sold satisfies contractual product specifications prior to transfer. The customer obtains control of the goods when title and risk of loss for the goods has transferred, which in most cases is “

free-on-board, shipping point".

All material contracts have payment terms of between

one

three

months and there are

return or refund rights.

Services transferred over time.

For the

three

and

six

months ended

June 30, 2019

and

2018,

there were

contracts for which consideration was variable or for which there were multiple performance obligations for any given contract. Accordingly, the entire transaction price is allocated to the individual service performance obligation. As of

June 30, 2019

and

December 31, 2018,

there were

material unfulfilled or partially fulfilled performance obligations.

For the

three

and

six

months ended

June 30, 2019

and

2018,

revenues were recognized ratably over time, as the performance obligation was satisfied and benefit to the customer was transferred on a ratable basis over time.

Contract Assets and Trade Receivables.

As of

June 30, 2019

and

December 31, 2018,

there were

contract assets or liabilities as all customer amounts owed to the Company are unconditional and the Company does

not

receive payment in advance for its products. Accordingly, amounts owed by customers are classified as account receivables on the Company’s consolidated balance sheets. In addition, due to the nature of the Company’s contracts, there are

costs incurred or to be paid in the future that qualify for asset recognition as a cost to fulfill or obtain a contract. The Company did

not

incur any impairment losses on any receivables as all amounts owed were paid or current as of

June 30, 2019

and

December 31, 2018.

Note 4 - Leases, Right-to-Use Assets and Related Liabilities

6 Months Ended

Jun. 30, 2019

Lessee, Operating Leases [Text Block]

Leases, Right-to-Use Assets and Related Liabilities

The Company enters into various arrangements which constitute a lease as defined by ASC

842,

Leases,

as part of its ongoing business activities and operations. Leases represent a contract or part of a contract that conveys the right to control the use of identified property, plant or equipment (an identified asset) for a period of time in exchange for consideration. Such contracts result in both (a) right-to-use assets, which represent the Company’s right to use an underlying asset for the term of the contract; and (b) a corresponding lease liability which represents the Company’s obligation to make the lease payments arising from the contract, measured on a discounted basis.

The contracts for the Company are comprised of facility, equipment and transportation leases necessary to conduct the Company’s day-to-day operations for which the Company maintains control of right-to-use assets and incurs the related liabilities.

The Company elected to adopt both the (a) short-term lease exemption for those leases with initial terms of

twelve

months or less; and (b) the practical expedient to

not

separate lease components from non-lease components, if applicable. Leases which qualify for the short-term scope exception consist of certain residential rents for executive apartments, certain of the Company’s railcar leases, and other equipment leases. There were

leases containing variable lease payments and

none

of the Company’s leases contained extension or termination options which were necessary in determining the value of the right-to-use asset and related liabilities. The Company assumed a

12.0%

discount rate, which is consistent with the stated rate on the Company’s

2020

Notes (as defined below) and represents the best approximation of the rate implicit in the Company’s leases.

Upon adoption of ASC

842,

Leases,

which was effective

January 1, 2019,

the Company recognized a total of

$1.2

million of right-to-use assets and related lease liabilities. Within the unaudited consolidated balance sheet at

June 30, 2019, (

$0.4

million of right-to-use assets with a remaining term of exceeding

twelve

months are included in

"Deposits and other assets"

, and for the related lease liabilities, (ii)

$0.3

million are included in

"Accounts payable and accrued liabilities"

for the current portion, and (iii)

$0.3

million are included in

"Other long-term liabilities"

for the non-current portion.

There are

two

contractual agreements related to equipment improvements at the Luverne Facility that were

not

recognized as of

June 30, 2019

as a result of operating contingencies which must be satisfied before the Company is obligated under the terms of the contract. The total estimated fair value of unrecognized right-to-use assets and related lease liabilities relating to these contracts was approximately

$3.0

million as of

June 30, 2019.

The following table presents the (a) costs by lease category and (b) other quantitative information relating to the Company’s leases.

	Three Months Ended		Six Months Ended
	June 30, 2019		June 30, 2019
Lease Cost
Financing lease cost	$	—	$	—
Operating lease cost		386		731
Short-Term lease cost		15		32
Total lease cost	$	401	$	763

Other Information
Cash paid for the measurement of lease liabilities
Operating cash flows from finance leases			$	—
Operating cash flows from operating leases				731
Financing cash flows from financing leases				—
Right-to-use assets obtained in exchange for new finance lease liabilities				—
Right-to-use assets obtained in exchange for new operating lease liabilities				—
Weighted-average remaining lease term, financing leases (months)				—
Weighted-average remaining lease term, operating leases (months)				25.0
Weighted-average discount rate - financing leases				—	%
Weighted-average discount rate - operating leases				12.0	%

Note 5 - Inventories

6 Months Ended

Jun. 30, 2019

Inventory Disclosure [Text Block]

Inventories

The following table sets forth the components of the Company’s inventory balances (in thousands).

	June 30 ,		December 31,
	2019		2018
Raw materials
Corn	$	17	$	29
Enzymes and other inputs		246		204
Finished goods
Ethanol		243		182
Isobutanol		336		549
Jet Fuels, Isooctane and Isooctene		607		394
Distiller's grains		45		54
Work in process - Agri-Energy		226		214
Work in process - Gevo		127		89
Spare parts		1,482		1,451
Total inventories	$	3,329	$	3,166

Work in process inventory includes unfinished jet fuel, isooctane and isooctene inventory.

Note 6 - Property, Plant and Equipment

6 Months Ended

Jun. 30, 2019

Property, Plant and Equipment Disclosure [Text Block]

Property, Plant and Equipment

The following table sets forth the Company’s property, plant and equipment by classification (in thousands).

	Useful Life			June 30 ,			December 31,
	(in years)			2019			2018
Construction in progress				$	7,585		$	3,478
Plant machinery and equipment		10			16,305			16,285
Site improvements		10			7,062			7,055
Luverne retrofit asset		20			70,842			70,842
Lab equipment, furniture and fixtures and vehicles		5			6,574			6,574
Demonstration plant		2			3,597			3,597
Buildings		10			2,543			2,543
Computer, office equipment and software		3			1,850			1,848
Leasehold improvements, pilot plant, land and support equipment	2	to	5		2,549			2,542
Total property, plant and equipment					118,907			114,764
Less accumulated depreciation and amortization					(50,909	)		(47,728	)
Property, plant and equipment, net				$	67,998		$	67,036

Included in cost of goods sold is depreciation of

$1.6

million during the

three

months ended

June 30, 2019

and

2018;

and

$3.1

million during the

six

months ended

June 30, 2019

and

2018.

Included in operating expenses is depreciation of

$0.03

million and

$0.1

million during the

three

months ended

June 30, 2019

and

2018,

respectively; and

$0.1

million and

$0.2

million during the

six

months ended

June 30, 2019

and

2018,

respectively

Note 7 - Embedded Derivatives and Derivative Warrant Liabilities

6 Months Ended

Jun. 30, 2019

Discussion of Hybrid Instruments and Embedded Derivatives [Text Block]

Embedded Derivatives and Derivative Warrant Liabilities

2020

Notes Embedded Derivative

June 2017,

the Company issued

12%

convertible senior secured notes due

2020

(the

“2020

Notes”) in exchange for its

12.0%

convertible senior secured notes due

2017

(the

“2017

Notes”). The

2020

Notes contain the following embedded derivatives: (i) a Make-Whole Payment (as defined in the indenture governing the

2020

Notes (the

“2020

Notes Indenture”)) upon either conversion or redemption; (ii) right to redeem the outstanding principal upon a Fundamental Change (as defined in the

2020

Notes Indenture); (iii) issuer rights to convert into a limited number of shares in any given

three

month period commencing

nine

months from the issuance date and dependent on the stock price exceeding

150%

of the then in-effect conversion price over a

ten

-business day period; and (iv) holder rights to convert into either shares of the Company’s common stock or pre-funded warrants upon the election of the holders of the

2020

Notes.

Embedded derivatives are separated from the host contract and the

2020

Notes and carried at fair value when: (a) the embedded derivative possesses economic characteristics that are

not

clearly and closely related to the economic characteristics of the host contract; and (b) a separate, stand-alone instrument with the same terms would qualify as a derivative instrument. The Company has concluded that certain embedded derivatives within the

2020

Notes meet these criteria and, as such, must be valued separate and apart from the

2020

Notes as

one

embedded derivative and recorded at fair value each reporting period.

The Company used a binomial lattice model in order to estimate the fair value of the embedded derivative in the

2020

Notes. A binomial lattice model generates

two

probable outcomes, whether up or down, arising at each point in time, starting from the date of valuation until the maturity date. A lattice was initially used to determine if the

2020

Notes would be converted by the holder, called by the issuer, or held at each decision point. Within the lattice model, the following assumptions are made: (i) the

2020

Notes will be converted by the holder if the conversion value plus the holder’s Make-Whole Payment is greater than the holding value; or (ii) the

2020

Notes will be called by the issuer if (a) the stock price exceeds

150%

of the then in-effect conversion price over a

ten

-business day period and (b) if the holding value is greater than the conversion value plus the Make-Whole Payment at the time.

Using this lattice model, the Company valued the embedded derivative using a “with-and-without method”, where the value of the

2020

Notes including the embedded derivative is defined as the “with” and the value of the

2020

Notes excluding the embedded derivative is defined as the “without”. This method estimates the value of the embedded derivative by comparing the difference in the values between the

2020

Notes with the embedded derivative and the value of the

2020

Notes without the embedded derivative. The lattice model requires the following inputs: (i) price of Gevo common stock; (ii) Conversion Rate (as defined in the

2020

Notes Indenture); (iii) Conversion Price (as defined in the

2020

Notes Indenture); (iv) maturity date; (v) risk-free interest rate; (vi) estimated stock volatility; and (vii) estimated credit spread for the Company.

As of

June 30, 2019,

the estimated fair value of the embedded derivatives w

$0.

Any change in the estimated fair value of the embedded derivatives represents an unrealized gain which has been recorded as

$0.1

million gain and

$0.4

million gain from the change in fair value of embedded derivatives in the consolidated statements of operations for the

three

and

six

months ended

June 30, 2019,

respectively.

The following table sets forth the inputs to the lattice model that were used to value the embedded derivatives.

	June 30 ,			December 31,
	2019			2018
Stock price	$	1.97		$	1.96
Conversion Rate per $1,000		67.95			67.95
Conversion Price	$	14.72		$	14.72
Maturity date		March 15, 2020			March 15, 2020
Risk-free interest rate		2.00	%		2.57	%
Estimated stock volatility		55	%		150	%
Estimated credit spread		27	%		31	%

Changes in certain inputs into the lattice model can have a significant impact on changes in the estimated fair value of the embedded featured within the

2020

Notes. For example, the estimated fair value will generally decrease with: (

) a decline in the stock price; (

) decreases in the estimated stock volatility; and (

) a decrease in the estimated credit spread.

Derivative Warrant Liability

The following table sets forth information pertaining to shares issued upon the exercise of such warrants as of

June 30, 2019.

	Issuance Date	Expiration Date	Exercise Price as of June 30 , 2019		Shares Underlying Warrants on Issuance Date		Shares Issued upon Warrant Exercises as of June 30 , 2019		Shares Underlying Warrants Outstanding as of June 30 , 2019 (1)
2014 Warrants	08/05/2014	08/05/2019	$	65.50		2,500		1,526		974
Series A Warrants	02/03/2015	02/03/2020	$	3.80		5,542		5,222		320
Series C Warrants	05/19/2015	05/19/2020	$	53.43		1,075		—		1,075
Series D Warrants	12/11/2015	12/11/2020	$	40.00		25,125		25,078		47
Series F Warrants	04/01/2016	04/01/2021	$	40.00		25,733		11,692		14,041
Series I Warrants	09/13/2016	09/13/2021	$	220.00		35,650		—		35,650
Series K Warrants	02/17/2017	2/17/2022	$	3.80		312,516		308,660		3,856
						408,141		352,178		55,963

(

)

This table does

not

include

six

equity-classified warrants issued between

2008

through

2012,

with strike prices of

$345

per share.

The agreements governing the above warrants include the following terms:

•

certain warrants have exercise prices which are subject to adjustment for certain events, including the issuance of stock dividends on the Company’s common stock and, in certain instances, the issuance of the Company’s common stock or instruments convertible into the Company’s common stock at a price per share less than the exercise price of the respective warrants;

•

warrant holders

may

exercise the warrants through a cashless exercise if, and only if, the Company does

not

have an effective registration statement then available for the issuance of the shares of its common stock. If an effective registration statement is available for the issuance of its common stock a holder

may

only exercise the warrants through a cash exercise;

•

the exercise price and the number and type of securities purchasable upon exercise of the warrants are subject to adjustment upon certain corporate events, including certain combinations, consolidations, liquidations, mergers, recapitalizations, reclassifications, reorganizations, stock dividends and stock splits, a sale of all or substantially all of the Company’s assets and certain other events; and

•

in the event of an “extraordinary transaction” or a “fundamental transaction” (as such terms are defined in the respective warrant agreements), generally including any merger with or into another entity, sale of all or substantially all of the Company’s assets, tender offer or exchange offer, or reclassification of its common stock, in which the successor entity (as defined in the respective warrant agreements) that assumes the successor entity is

not

a publicly traded company, the Company or any successor entity will pay the warrant holder, at such holder’s option, exercisable at any time concurrently with or within

days after the consummation of the extraordinary transaction or fundamental transaction, an amount of cash equal to the value of such holder’s warrants as determined in accordance with the Black-Scholes option pricing model and the terms of the respective warrant agreement. In some circumstances, the Company or successor entity

may

be obligated to make such payments regardless of whether the successor entity that assumes the warrants is a publicly traded company.

There were

warrants exercised during the

six

months ended

June 30, 2019.

Note 8 - Accounts Payable and Accrued Liabilities

6 Months Ended

Jun. 30, 2019

Accounts Payable and Accrued Liabilities Disclosure [Text Block]

Accounts Payable and Accrued Liabilities

The following table sets forth the components of the Company’s accounts payable and accrued liabilities in the consolidated balance sheets (in thousands).

	June 30 ,		December 31,
	2019		2018
Accounts payable - trade	$	1,571	$	1,944
Accrued legal-related fees		176		206
Accrued employee compensation		1,221		1,648
Accrued interest		346		—
Accrued production fees		325		255
Accrued utilities and supplies payable		223		344
Accrued taxes payable		48		101
Current lease obligations		294		—
Other accrued liabilities		82		376
Total accounts payable and accrued liabilities	$	4,286	$	4,874

Note 9 - Debt

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Text Block]

Debt

2020

Notes

The following table sets forth information pertaining to the

2020

Notes which is included in the Company’s consolidated balance sheets (in thousands).

	Principal Amount of 2020 Notes		Debt Discount			Debt Issue Costs			Total 2020 Notes		2020 Notes Embedded Derivative			Total 2020 Notes and 2020 Notes Embedded Derivative
Balance - December 31, 2018	$	13,775	$	(979	)	$	(242	)	$	12,554	$	394		$	12,948
Amortization of debt discount		—		553			—			553		—			553
Amortization of debt issue costs		—		—			141			141		—			141
Paid-in-kind interest		138		—			—			138		—			138
Change in fair value of 2020 Notes embedded derivative		—		—			—			—		(394	)		(394	)
Balance - June 30, 2019	$	13,913	$	(426	)	$	(101	)	$	13,386	$	—		$	13,386

April 19, 2017,

the Company entered into an Exchange and Purchase Agreement (the “Purchase Agreement”) with WB Gevo, LTD, (the “Holder”), the holder of the

2017

Notes, and Whitebox Advisors LLC, in its capacity as representative of the Holder (“Whitebox”). Pursuant to the terms of the Purchase Agreement, the Holder agreed to exchange all of the outstanding principal amount of the

2017

Notes for an equal principal amount of the

2020

Notes, plus an amount in cash equal to the accrued and unpaid interest (other than interest paid in kind) on the

2017

Notes. On

June 20, 2017,

the Company cancelled the

2017

Notes.

The

2020

Notes will mature on

March 15, 2020

and are secured by a

first

lien on substantially all of the Company’s assets. The

2020

Notes bear interest at a rate equal to

12%

per annum (with

potentially payable as PIK Interest (as defined and described below) at the Company’s option), payable on

March 31,

June 30,

September 30,

and

December 31

of each year. Under certain circumstances, the Company has the option to pay a portion of the interest due on the

2020

Notes by either (a) increasing the principal amount of the

2020

Notes by the amount of interest then due or (b) issuing additional

2020

Notes with a principal amount equal to the amount of interest then due (interest paid in the manner set forth in (a) or (b) being referred to as “PIK Interest”). In the event the Company pays any portion of the interest due on the

2020

Notes as PIK Interest, the maximum aggregate principal amount of

2020

Notes that could be convertible into shares of the Company’s common stock will be increased. Additional shares of the Company’s common stock

may

also become issuable pursuant to the

2020

Notes in the event the Company is required to make certain make-whole payments as provided in the

2020

Notes Indenture.

The

2020

Notes are convertible into shares of the Company’s common stock, subject to certain terms and conditions. The initial conversion price of the

2020

Notes is equal to

$14.72

per share of common stock, or

0.0679

shares of common stock per

principal amount of

2020

Notes (the “Conversion Price”).

Each Holder has agreed

not

to convert its

2020

Notes into shares of the Company's common stock to the extent that, after giving effect to such conversion, the number of shares of common stock beneficially owned by such Holder and its affiliates would exceed

4.99%

of the Company's common stock outstanding at the time of such conversion (the

“4.99%

Ownership Limitation”); provided that a Holder

may,

at its option and upon

sixty-one

(

) days’ prior notice to the Company, increase such threshold to

9.99%

(the

“9.99%

Ownership Limitation”). If a conversion of

2020

Notes by Whitebox would exceed the

4.99%

Ownership Limitation or the

9.99%

Ownership Limitation, as applicable, the Purchase Agreement contains a provision granting the holder a fully funded prepaid warrant for such common stock with a term of

nine

months, subject to a

six

month extension, which it can draw down from time to time.

The

2020

Notes do

not

contain any anti-dilution adjustments for future equity issuances that are below the Conversion Price, and adjustments to the Conversion Price will only generally be made in the event that there is a dividend or distribution paid on shares of the Company’s common stock, a subdivision, combination or reclassification of the Company’s common stock, or at the discretion of the Board of Directors of the Company in limited circumstances and subject to certain conditions.

Under certain circumstances, the Company

may

file

one

or more registration statements on Form S-

or amend filings in order to register shares of common stock for sale or resale, as necessary, in connection with the

2020

Notes.

Note 10 - Equity Incentive Plans	6 Months Ended
Note 10 - Equity Incentive Plans	Jun. 30, 2019
Notes to Financial Statements
Stock Incentive Plans Disclosure [Text Block]	10. Equity Incentive Plans 2010 Stock Incentive Plan . In February 2011, the Company’s stockholders approved the Gevo, Inc. 2010 Stock Incentive Plan (as amended and restated, the "2010 Plan"). The 2010 Plan provides for the grant of non-qualified stock options, incentive stock options, stock appreciation rights, restricted stock awards, restricted stock units and other equity awards to employees and directors of the Company. During the second quarter of 2019, the Company granted restricted stock awards vesting over two years to its employees and directors and were included in the shares reserved for issuance. At June 30, 2019, a total of 1,673,111 shares of common stock were reserved for issuance upon the exercise of outstanding stock option awards, stock appreciation rights, and restricted stock awards under the 2010 Plan, and an additional 1,725,615 shares were available for grant. On July 2, 2019, the Company issued 254,500 in common stock in relation to restricted stock awards granted on August 9, 2018. Employee Stock Purchase Plan . In February 2011, the Company’s stockholders approved the Employee Stock Purchase Plan (the "ESPP"). The offering periods for the ESPP are from January 1 to June 30 and from July 1 to December 31 of each calendar year. The Company has reserved 190 shares of common stock for issuance under the ESPP, of which 190 shares as of June 30, 2019 are available for future issuance. The purchase price of the common stock under the ESPP is 85% of the lower of the fair market value of a share of common stock on the first or last day of the purchase period. There were no purchases of common stock under the ESPP during the three and six months ended June 30, 2019.

Note 11 - Stock-Based Compensation

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement [Text Block]

11.

Stock-Based Compensation

The Company records stock-based compensation expense during the requisite service period for share-based payment awards granted to employees and non-employees.

The following table sets forth the Company’s stock-based compensation expense (reversal) for the periods indicated (in thousands).

	Three Months Ended June 30 ,					Six Months Ended June 30 ,
	2019			2018		2019			2018
Stock options and employee stock purchase plan awards
Research and development	$	—		$	9	$	—		$	18
Selling, general and administrative		—			11		—			41

Restricted stock
Research and development		33			17		61			34
Selling, general and administrative		139			17		345			58

Stock appreciation rights
Research and development		(34	)		—		(18	)		—
Selling, general and administrative		(31	)		86		(18	)		86
Total stock-based compensation	$	107		$	140	$	370		$	237

Note 12 - Commitments and Contingencies

6 Months Ended

Jun. 30, 2019

Commitments and Contingencies Disclosure [Text Block]

12.

Commitments and Contingencies

Legal Matters

. From time to time, the Company has been, and

may

again become, involved in legal proceedings arising in the ordinary course of its business. The Company is

not

presently a party to any litigation that it believes to be material and is

not

aware of any pending or threatened litigation against the Company that it believes could have a material adverse effect on its business, operating results, financial condition or cash flows.

Leases

. Upon adoption of ASU

2016

02,

the Company identified

three

lease agreements that qualify as “operating” based on the terms and conditions at the commencement date for each lease. These include the lease for the Company’s office and research facility in Englewood, Colorado, with a term expiring in

July 2021

and leases of plant equipment and transportation equipment with expiration dates in

June 2019

used by Agri-Energy at the Luverne Facility.

All other leases qualified for the short-term scope exemption. These consist of corporate apartments in Colorado, which have initial lease terms of less than

twelve

months, and additional leases of transportation equipment located at both the Luverne Facility and the South Hampton Facility with original lease terms of less than

twelve

months.

Rent expense for the

three

months ended

June 30, 2019

and

2018

was

$0.4

million in both periods, and for the

six

months ended

June 30, 2019

and

2018

was

$0.8

million and

$0.9

million, respectively.

The table below shows the future minimum payments under non-cancelable short-term and operating leases and at

June 30, 2019 (

in thousands).

	Short-Term Leases		Operating Leases
2019 (remaining)	$	337	$	210
2020		230		425
2021		3		215
2022		—		—
2023 and thereafter		—		—
Total	$	570	$	850

The Company entered into a

five

-year software licensing agreement on

April 2, 2018.

Future contractual payment obligations total approximately

$0.4

million as of

June 30, 2019.

This licensing agreement is accounted for as an intangible asset and is out of the scope of ASU

2016

02,

Leases.

Indemnifications

. In the ordinary course of its business, the Company makes certain indemnities under which it

may

be required to make payments in relation to certain transactions. As of

June 30, 2019

and

December 31, 2018,

the Company did

not

have any liabilities associated with indemnities.

The Company, as permitted under Delaware law and in accordance with its amended and restated certificate of incorporation and amended and restated bylaws, indemnifies its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity. The duration of these indemnifications, commitments and guarantees varies and, in certain cases, is indefinite. The maximum amount of potential future indemnification is unlimited; however, the Company has a director and officer insurance policy that

may

enable it to recover a portion of any future amounts paid. The Company accrues for losses for any known contingent liability, including those that

may

arise from indemnification provisions, when future payment is probable.

such losses have been recorded to date.

Environmental Liabilities

. The Company’s operations are subject to environmental laws and regulations adopted by various governmental authorities in the jurisdictions in which it operates. These laws require the Company to investigate and remediate the effects of the release or disposal of materials at its locations. Accordingly, the Company has adopted policies, practices and procedures in the areas of pollution control, occupational health and the production, handling, storage and use of hazardous materials to prevent material environmental or other damage, and to limit the financial liability which could result from such events. Environmental liabilities are recorded when the Company’s liability is probable and the costs can be reasonably estimated.

environmental liabilities have been recorded as of

June 30, 2019

December 31, 2018.

Note 13 - Fair Value Measurements

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Text Block]

13.

Fair Value Measurements

Accounting standards define fair value, outline a framework for measuring fair value and detail the required disclosures about fair value measurements. Under these standards, fair value is defined as 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 in the principal or most advantageous market. Standards establish a hierarchy in determining the fair market value of an asset or liability. The fair value hierarchy has

three

levels of inputs, both observable and unobservable. Standards require the utilization of the highest possible level of input to determine fair value.

Level

– inputs include quoted market prices in an active market for identical assets or liabilities.

Level

– inputs are market data, other than Level

that are observable either directly or indirectly. Level

inputs include quoted market prices for similar assets or liabilities, quoted market prices in an inactive market and other observable information that can be corroborated by market data.

Level

– inputs are unobservable and corroborated by little or

market data.

These tables present the carrying value and fair value, by fair value hierarchy, of our financial instruments, excluding cash and cash equivalents, accounts receivable and accounts payable at

June 30, 2019

and

December 31, 2018,

respectively (in thousands).

			Fair Value Measurements at June 30 , 2019 (In thousands)
	Fair Value at June 30 , 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Recurring:
Derivative Warrant Liability	$	19	$	—	$	—	$	19
2020 Embedded Derivative Liability		—		—		—		—
Total Recurring Fair Value Measurements	$	19	$	—	$	—	$	19


Nonrecurring
Corn and finished goods inventory	$	865	$	17	$	848	$	—
Total Non-Recurring Fair Value Measurements	$	865	$	17	$	848	$	—

			Fair Value Measurements at December 31, 2018 (In thousands)
	Fair Value at December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Recurring:
Derivative Warrant Liability	$	22	$	—	$	—	$	22
2020 Embedded Derivative Liability		394		—		—		394
Total Recurring Fair Value Measurements	$	416	$	—	$	—	$	416


Nonrecurring
Corn and finished goods inventory	$	1,047	$	29	$	1,018	$	—
Total Non-Recurring Fair Value Measurements	$	1,047	$	29	$	1,018	$	—

The following table provides changes to those fair value measurements using Level

inputs for the

six

months ended

June 30, 2019.

There were

transfers in or out of Level

inputs and there were

purchases, issues, sales or settlements of Level

inputs during the

six

months ended

June 30, 2019.

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (in thousands)

	Derivative Warrant Liability			2020 Notes Embedded Derivative
Opening Balance	$	22		$	394
Gains for the period included in earnings		(3	)		(394	)
Closing balance	$	19		$	—

Inventories.

The Company records its corn inventory at fair value only when the Company’s cost of corn purchased exceeds the market value for corn. The Company determines the market value of corn and dry distiller’s grain based upon Level

inputs using quoted market prices. The Company records its ethanol, isobutanol and hydrocarbon inventory at market using Level

inputs.

2020

Notes Embedded Derivative

. The Company had estimated the fair value of the embedded derivative on a stand-alone basis to be

nil

June 30, 2019

and

$0.4

million at

December 31, 2018

based upon Level

inputs. Changes in the fair value of the embedded derivative is recognized each reporting period as a “

Change in fair value of

2020

Notes embedded derivative

” in the consolidated statements of operations and statements of cash flows. See Note

Embedded Derivatives and Derivative Warrant Liabilities, for the fair value inputs used to estimate the fair value of the embedded derivative.

Derivative Warrant Liability

. The Company valued the Series F Warrants and Series K Warrants using a Monte-Carlo model (Level

) and other warrants using Black-Scholes models comprised of some inputs requiring the use of Monte-Carlo models (Level

). The Company has estimated the fair value of the derivative warrant liability to be

$0.02

million as of

June 30, 2019

and

December 31, 2018.

Certain of the Company’s financial instruments consist of cash and cash equivalents, accounts receivable, accounts payable and

2020

Notes for which the carrying value on the Company’s consolidated balance sheets approximates their fair values due to the short maturities.

While the Company believes that its valuation methods are appropriate and consistent with other market participants, it recognizes that the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.

- 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

Note 14 - Segments

6 Months Ended

Jun. 30, 2019

Segment Reporting Disclosure [Text Block]

14.

Segments

The Company has determined that it has

two

operating segments: (i) Gevo segment; and (ii) Gevo Development/Agri-Energy segment. The Company organizes its business segments based on the nature of the products and services offered through each of its consolidated legal entities. Transactions between segments are eliminated in consolidation.

Gevo Segment

. The Gevo segment is responsible for all research and development activities related to the future production of isobutanol, including the development of our proprietary biocatalysts, the production and sale of bio jet fuel, the Company’s retrofit process and the next generation of chemicals and biofuels that will be based on the Company’s isobutanol technology. The Gevo segment also develops, maintains and protects its intellectual property portfolio, develops future markets for its isobutanol and provides corporate oversight services.

Gevo Development/Agri-Energy Segment

. The Gevo Development/Agri-Energy segment is currently responsible for the operation of the Company’s Luverne Facility and the production of ethanol, isobutanol and related products.

	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Revenues:
Gevo	$	92		$	607		$	831		$	632
Gevo Development / Agri-Energy		4,994			8,813			10,658			17,031
Consolidated	$	5,086		$	9,420		$	11,489		$	17,663

Loss from operations:
Gevo	$	(2,960	)	$	(2,315	)	$	(5,633	)	$	(4,791	)
Gevo Development / Agri-Energy		(3,533	)		(2,064	)		(6,488	)		(4,587	)
Consolidated	$	(6,493	)	$	(4,379	)	$	(12,121	)	$	(9,378	)

Interest expense:
Gevo	$	767		$	904		$	1,522		$	1,729
Gevo Development / Agri-Energy		—			—			—			—
Consolidated	$	767		$	904		$	1,522		$	1,729

Depreciation and amortization expense:
Gevo	$	50		$	76		$	102		$	160
Gevo Development / Agri-Energy		1,559			1,563			3,119			3,125
Consolidated	$	1,609		$	1,639		$	3,221		$	3,285

Acquisitions of plant, property and equipment:
Gevo	$	62		$	2		$	62		$	2
Gevo Development / Agri-Energy		1,877			54			4,081			121
Consolidated	$	1,939		$	56		$	4,143		$	123

Revenue by geographic area:
United States	$	4,994		$	8,813		$	10,658		$	17,056
Other		92			607			831			607
Consolidated	$	5,086		$	9,420		$	11,489		$	17,663


	June 30 ,			December 31,
	2019			2018
Total assets:
Gevo	$	102,981		$	105,379
Gevo Development / Agri-Energy		144,376			140,982
Intercompany eliminations		(143,564	)		(139,326	)
Consolidated	$	103,793		$	107,035

Note 15 - Subsequent Events	6 Months Ended
Note 15 - Subsequent Events	Jun. 30, 2019
Notes to Financial Statements
Subsequent Events [Text Block]	15. Subsequent Events DVO, Inc . On July 17, 2019, the Company entered into an agreement with DVO, Inc. to purchase an anaerobic digester to be installed at a dairy farm near its Luverne Facility for up to $4.4 million as part of the development of its biogas business. Gevo will be invoiced monthly based on the percent complete. The anaerobic digester is expected to be put into production in the second quarter of 2020.

Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2019
Accounting Policies [Abstract]
Nature of Business [Policy Text Block]	Nature of Business. Gevo, Inc. (“Gevo” or the “Company,” which, unless otherwise indicated, refers to Gevo, Inc. and its subsidiaries) is a renewable chemicals and next generation “low-carbon” fuel company focused on the development and commercialization of renewable alternatives to petroleum-based products. Low-carbon fuels reduce the carbon intensity, or the level of greenhouse gas emissions (“GHG”), compared to standard fossil-based fuels across their lifecycle. The most common low-carbon fuels are renewable fuels. Gevo is focused on the development and production of mainstream fuels like gasoline and jet fuel using renewable feedstocks that have the potential to lower GHG at a meaningful scale and enhance agricultural production, including food and other related products. In addition to serving the low-carbon fuel markets, through Gevo's technology, Gevo can also serve markets for the production of chemical intermediate products for solvents, plastics and building block chemicals. In addition to its ethanol production capabilities, the Company developed proprietary technology that uses a combination of synthetic biology, metabolic engineering, chemistry and chemical engineering to make isobutanol and hydrocarbon products from isobutanol that can displace petrochemical incumbent products. The Company has been able to genetically engineer yeast, whereby the yeast produces isobutanol from carbohydrates. The Company’s technology converts its renewable isobutanol to alcohol-to-jet (“ATJ”), isooctane, isooctene and para-xylene (building block for polyester) at its hydrocarbons demonstration plant located at South Hampton Resources, Inc’s facility in Silsbee, Texas (the “South Hampton Facility”). In addition, the Company’s production facility located in Luverne, Minnesota (the “Luverne Facility”) has production capacity of about 20 million gallons per year of ethanol, 45 - 50 kilotons of animal feed, and 3 million pounds of corn oil. As of June 30, 2019, the Company continues to engage in research and development, business development, business and financial planning, optimizing operations for low-carbon ethanol, isobutanol and related hydrocarbons production, and raising capital to fund future expansion of its Luverne Facility. Ultimately, the Company believes that the attainment of profitable operations is dependent upon future events, including (i) completing certain capital improvements at the Luverne Facility to produce low-carbon ethanol side-by-side with low-carbon isobutanol; (ii) completing the Company’s development activities resulting in commercial production and sales of low-carbon ethanol, isobutanol, or isobutanol derived products and/or technology; (iii) obtaining adequate financing to complete the Company’s development activities, including the build out of low-carbon ethanol capacity and further isobutanol and hydrocarbon capacity; (iv) gaining market acceptance and demand for the Company’s products and services; (v) attracting and retaining qualified personnel; and (vi) the achievement of a level of revenues adequate to support the Company’s cost structure.
Financial Condition [Policy Text Block]	Financial Condition . For the six months ended June 30, 2019 and 2018, the Company incurred a consolidated net loss of $13.2 million and $14.0 million, respectively, and had an accumulated deficit of $442.6 million at June 30, 2019. The Company’s cash and cash equivalents at June 30, 2019 totaled $29.2 million and are expected to be used for the following purposes: (i) operating activities of the Luverne Facility; (ii) operating activities at the Company’s corporate headquarters in Colorado, including research and development work; (iii) capital expenditures primarily associated with the Luverne Facility, including capital expenditures to “de-carbonize” the Luverne Facility; (iv) exploration of strategic alternatives and new financings; and (v) debt service and repayment obligations. The Company is actively working on refinancing and negotiating its 2020 Notes that mature on March 15, 2020. The Company expects to incur future net losses as it continues to fund the development and commercialization of its product candidates. To date, the Company has financed its operations primarily with proceeds from multiple sales of equity and debt securities, borrowings under debt facilities and product sales. The Company’s transition to profitability is dependent upon, among other things, the successful development and commercialization of its product candidates and the achievement of a level of revenues adequate to support the Company’s cost structure. The Company may never achieve profitability or positive cash flows, and unless and until it does, the Company will continue to need to raise additional cash. Management intends to fund future operations through additional private and/or public offerings of debt or equity securities. In addition, the Company may seek additional capital through arrangements with strategic partners or from other sources. Gevo may seek to restructure its debt and will continue to address its cost structure. Notwithstanding, there can be no assurance that the Company will be able to raise additional funds, or achieve or sustain profitability or positive cash flows from operations.
At-the-market Offering Program, Policy [Policy Text Block]	At-the-Market Offering Program. In February 2018, the Company commenced an at-the-market offering program, which allows it to sell and issue shares of its common stock from time-to-time. The at-the-market offering program was amended multiple times during 2018 to increase the available capacity under the at-the-market offering program by an aggregate of approximately $84.9 million. During the first quarter of 2019, the Company issued 3,244,941 shares of common stock under the at-the-market offering program for gross proceeds of $9.9 million. The Company paid commissions to its sales agent of approximately $0.2 million and incurred other offering related expenses of $0.01 million. There were no sales under the at-the-market offering program during the second quarter of 2019.
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation. The unaudited consolidated financial statements of the Company (which include the accounts of its wholly-owned subsidiaries Gevo Development, LLC (“Gevo Development”) and Agri-Energy, LLC (“Agri-Energy”)) have been prepared, without audit, pursuant to the rules and regulations of the SEC. Accordingly, they do not include all information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. These statements reflect all normal and recurring adjustments which, in the opinion of management, are necessary to present fairly the financial position, results of operations and cash flows of the Company at June 30, 2019, and are not necessarily indicative of the results to be expected for the full year. These statements should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included under the heading “Financial Statements and Supplementary Data” in Part II, Item 8 of the Company’s Annual Report on Form 10 -K for the year ended December 31, 2018.
Reverse Stock Split [Policy Text Block]	Reverse Stock Split. On June 1, 2018, the Company effected a reverse stock split of the outstanding shares of its common stock by a ratio of one -for- twenty (the “Reverse Stock Split”), and its common stock began trading on the Nasdaq Capital Market on a Reverse Stock Split-basis on June 4, 2018.
Income Tax, Policy [Policy Text Block]	Income Taxes. There is no provision for income taxes because the Company has incurred operating losses since inception.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements Financial Instruments - Credit Losses. Measurement of Credit Losses on Financial Instruments. In June 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-13, Financial Instruments - Credit Losses Measurement of Credits Losses on Financial Instruments (“ASU 2016-13”), which replaces accounting for credit losses for most financial assets, including trade accounts receivable, and certain other instruments that are not measured at fair value through income. ASU 2016-13 replaces the current “incurred loss” model, in which losses are recognized when a loss is incurred as of the date of the balance sheet, to an “expected credit loss” model, which includes a broader range of information to estimate expected credit losses over the lifetime of the financial asset. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019. It is expected that the adoption of this standard will primarily apply to the valuation of the Company’s trade accounts receivables. The Company sells primarily to a small quantity of large customers with significant balance sheets and those financial assets are often settled within one-to-two weeks after the completion of the corresponding sales transaction. While the Company is in the process of evaluating the impact, if any, that the adoption of this standard will have on the Company’s financial statements, it does not currently anticipate that this will have a material impact on the Company’s consolidated financial statements. Adoption of New Accounting Pronouncements . Leases . In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”). ASU 2016-02 requires most contracts which convey over a period of time the right to use or control the use of an asset to be recognized on a company’s financial statements. The objective is to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. ASU 2016-02 was effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The standard required using the modified retrospective transition method and apply ASU 2016-02 either at the (i) latter of the earliest comparative period presented in the financial statements or commencement date of the lease, or (ii) beginning of the period of adoption. The Company adopted the standard effective January 1, 2019 with no retrospective adjustment to prior periods presented in the financial statements. There was no impact to the opening balance of retained earnings as of January 1, 2019 as a result of the adoption of this standard. As a result of adopting ASU 2016-02, the Company recognized $1.2 million in right-to-use assets and related lease liabilities at January 1, 2019. The Company elected to both (i) elect the short term lease scope exception for leases with original terms of twelve months or less and (ii) the package of practical expedients, which included the ability to classify leases as operating under the new standard, ASU 2016-02 , for those leases existing prior to January 1, 2019 that were previously classified as operating under Accounting Standards Codification ("ASC") 840, Leases , the superseded accounting standard for the accounting for leases. Derivatives and Hedging . Accounting for Certain Financial Instruments with Down Round Provisions. In July 2017, the FASB issued ASU No. 2017-11, Derivatives and Hedging Accounting for Certain Financial Instruments with Down Round Provisions (“ASU 2017-11”), which was effective for fiscal years beginning after December 15, 2018. The standard simplifies the accounting for certain equity-linked financial instruments and embedded features with down round features that reduce the exercise price when the pricing of a future round of financing is lower. Currently, the existence of such features require classification outside of equity and recognition of changes in the fair value of the instrument in earnings each reporting period. This standard eliminates the need to remeasure the instruments at fair value and allows classification within equity. The adoption of this standard has not materially impacted the Company’s accounting, as current liability classified financial instruments and embedded derivatives that require separation from the host instrument have features other than down-round provisions that require current accounting and classification.

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Topic 954
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 220
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=116657188&loc=SL116659661-227067

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Note 2 - Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Three and Six Months Ended June 30,
	2019		2018
Warrants to purchase common stock - liability classified (see Note 7)		55,963		58,902
Warrant to purchase common stock - equity classified		6		6
2020 Notes		1,020,595		1,116,637
Outstanding options to purchase common stock (see Note 10)		2,361		358
Stock appreciation rights (see Note 10)		132,566		68,638
Unvested restricted common stock (see Note 10)		1,538,184		16
Total		2,749,675		1,244,557

Note 3 - Revenues From Contracts With Customers; Other Revenues (Tables)

6 Months Ended

Jun. 30, 2019

Disaggregation of Revenue [Table Text Block]

	Three Months Ended June 30 , 2019
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	4,966	$	—	$	4,966
Hydrocarbon revenue		92		—		92
Grant and other revenue		—		28		28
	$	5,058	$	28	$	5,086
Timing of Revenue Recognition
Goods transferred at a point in time	$	5,058	$	—	$	5,058
Services transferred over time		—		28		28
	$	5,058	$	28	$	5,086

	Three Months Ended June 30 , 2018
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	8,813	$	—	$	8,813
Hydrocarbon revenue		607		—		607
Grant and other revenue		—		—		—
	$	9,420	$	—	$	9,420
Timing of Revenue Recognition
Goods transferred at a point in time	$	9,420	$	—	$	9,420
Services transferred over time		—		—		—
	$	9,420	$	—	$	9,420

	Six Months Ended June 30, 2019
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	10,630	$	—	$	10,630
Hydrocarbon revenue		831		—		831
Grant and other revenue		—		28		28
	$	11,461	$	28	$	11,489
Timing of Revenue Recognition
Goods transferred at a point in time	$	11,461	$	—	$	11,461
Services transferred over time		—		28		28
	$	11,461	$	28	$	11,489

	Six Months Ended June 30, 2018
Major Goods/Service Line	Revenues from Contracts with Customers		Other Revenues		Total
Ethanol sales and related products, net	$	17,031		—	$	17,031
Hydrocarbon revenue		607		—		607
Grant and other revenue		25		—		25
	$	17,663	$	—	$	17,663
Timing of Revenue Recognition
Goods transferred at a point in time	$	17,638	$	—	$	17,638
Services transferred over time		25		—		25
	$	17,663	$	—	$	17,663

Note 4 - Leases, Right-to-Use Assets and Related Liabilities (Tables)

6 Months Ended

Jun. 30, 2019

Lease, Cost [Table Text Block]

	Three Months Ended		Six Months Ended
	June 30, 2019		June 30, 2019
Lease Cost
Financing lease cost	$	—	$	—
Operating lease cost		386		731
Short-Term lease cost		15		32
Total lease cost	$	401	$	763

Other Information
Cash paid for the measurement of lease liabilities
Operating cash flows from finance leases			$	—
Operating cash flows from operating leases				731
Financing cash flows from financing leases				—
Right-to-use assets obtained in exchange for new finance lease liabilities				—
Right-to-use assets obtained in exchange for new operating lease liabilities				—
Weighted-average remaining lease term, financing leases (months)				—
Weighted-average remaining lease term, operating leases (months)				25.0
Weighted-average discount rate - financing leases				—	%
Weighted-average discount rate - operating leases				12.0	%

Note 5 - Inventories (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Inventory, Current [Table Text Block]

	June 30 ,		December 31,
	2019		2018
Raw materials
Corn	$	17	$	29
Enzymes and other inputs		246		204
Finished goods
Ethanol		243		182
Isobutanol		336		549
Jet Fuels, Isooctane and Isooctene		607		394
Distiller's grains		45		54
Work in process - Agri-Energy		226		214
Work in process - Gevo		127		89
Spare parts		1,482		1,451
Total inventories	$	3,329	$	3,166

Note 6 - Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2019

Property, Plant and Equipment [Table Text Block]

	Useful Life			June 30 ,			December 31,
	(in years)			2019			2018
Construction in progress				$	7,585		$	3,478
Plant machinery and equipment		10			16,305			16,285
Site improvements		10			7,062			7,055
Luverne retrofit asset		20			70,842			70,842
Lab equipment, furniture and fixtures and vehicles		5			6,574			6,574
Demonstration plant		2			3,597			3,597
Buildings		10			2,543			2,543
Computer, office equipment and software		3			1,850			1,848
Leasehold improvements, pilot plant, land and support equipment	2	to	5		2,549			2,542
Total property, plant and equipment					118,907			114,764
Less accumulated depreciation and amortization					(50,909	)		(47,728	)
Property, plant and equipment, net				$	67,998		$	67,036

Note 7 - Embedded Derivatives and Derivative Warrant Liabilities (Tables)

6 Months Ended

Jun. 30, 2019

Defined Benefit Plan, Assumptions [Table Text Block]

	June 30 ,			December 31,
	2019			2018
Stock price	$	1.97		$	1.96
Conversion Rate per $1,000		67.95			67.95
Conversion Price	$	14.72		$	14.72
Maturity date		March 15, 2020			March 15, 2020
Risk-free interest rate		2.00	%		2.57	%
Estimated stock volatility		55	%		150	%
Estimated credit spread		27	%		31	%

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Issuance Date	Expiration Date	Exercise Price as of June 30 , 2019		Shares Underlying Warrants on Issuance Date		Shares Issued upon Warrant Exercises as of June 30 , 2019		Shares Underlying Warrants Outstanding as of June 30 , 2019 (1)
2014 Warrants	08/05/2014	08/05/2019	$	65.50		2,500		1,526		974
Series A Warrants	02/03/2015	02/03/2020	$	3.80		5,542		5,222		320
Series C Warrants	05/19/2015	05/19/2020	$	53.43		1,075		—		1,075
Series D Warrants	12/11/2015	12/11/2020	$	40.00		25,125		25,078		47
Series F Warrants	04/01/2016	04/01/2021	$	40.00		25,733		11,692		14,041
Series I Warrants	09/13/2016	09/13/2021	$	220.00		35,650		—		35,650
Series K Warrants	02/17/2017	2/17/2022	$	3.80		312,516		308,660		3,856
						408,141		352,178		55,963

Note 8 - Accounts Payable and Accrued Liabilities (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]

	June 30 ,		December 31,
	2019		2018
Accounts payable - trade	$	1,571	$	1,944
Accrued legal-related fees		176		206
Accrued employee compensation		1,221		1,648
Accrued interest		346		—
Accrued production fees		325		255
Accrued utilities and supplies payable		223		344
Accrued taxes payable		48		101
Current lease obligations		294		—
Other accrued liabilities		82		376
Total accounts payable and accrued liabilities	$	4,286	$	4,874

Note 9 - Debt (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Debt [Table Text Block]

	Principal Amount of 2020 Notes		Debt Discount			Debt Issue Costs			Total 2020 Notes		2020 Notes Embedded Derivative			Total 2020 Notes and 2020 Notes Embedded Derivative
Balance - December 31, 2018	$	13,775	$	(979	)	$	(242	)	$	12,554	$	394		$	12,948
Amortization of debt discount		—		553			—			553		—			553
Amortization of debt issue costs		—		—			141			141		—			141
Paid-in-kind interest		138		—			—			138		—			138
Change in fair value of 2020 Notes embedded derivative		—		—			—			—		(394	)		(394	)
Balance - June 30, 2019	$	13,913	$	(426	)	$	(101	)	$	13,386	$	—		$	13,386

Note 11 - Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Share-based Payment Arrangement, Cost by Plan [Table Text Block]

	Three Months Ended June 30 ,					Six Months Ended June 30 ,
	2019			2018		2019			2018
Stock options and employee stock purchase plan awards
Research and development	$	—		$	9	$	—		$	18
Selling, general and administrative		—			11		—			41

Restricted stock
Research and development		33			17		61			34
Selling, general and administrative		139			17		345			58

Stock appreciation rights
Research and development		(34	)		—		(18	)		—
Selling, general and administrative		(31	)		86		(18	)		86
Total stock-based compensation	$	107		$	140	$	370		$	237

Note 12 - Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]

	Short-Term Leases		Operating Leases
2019 (remaining)	$	337	$	210
2020		230		425
2021		3		215
2022		—		—
2023 and thereafter		—		—
Total	$	570	$	850

Note 13 - Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

			Fair Value Measurements at June 30 , 2019 (In thousands)
	Fair Value at June 30 , 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Recurring:
Derivative Warrant Liability	$	19	$	—	$	—	$	19
2020 Embedded Derivative Liability		—		—		—		—
Total Recurring Fair Value Measurements	$	19	$	—	$	—	$	19


Nonrecurring
Corn and finished goods inventory	$	865	$	17	$	848	$	—
Total Non-Recurring Fair Value Measurements	$	865	$	17	$	848	$	—

			Fair Value Measurements at December 31, 2018 (In thousands)
	Fair Value at December 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Recurring:
Derivative Warrant Liability	$	22	$	—	$	—	$	22
2020 Embedded Derivative Liability		394		—		—		394
Total Recurring Fair Value Measurements	$	416	$	—	$	—	$	416


Nonrecurring
Corn and finished goods inventory	$	1,047	$	29	$	1,018	$	—
Total Non-Recurring Fair Value Measurements	$	1,047	$	29	$	1,018	$	—

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (in thousands)

	Derivative Warrant Liability			2020 Notes Embedded Derivative
Opening Balance	$	22		$	394
Gains for the period included in earnings		(3	)		(394	)
Closing balance	$	19		$	—

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Note 14 - Segments (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Segment Reporting Information, by Segment [Table Text Block]

	Three Months Ended June 30,						Six Months Ended June 30,
	2019			2018			2019			2018
Revenues:
Gevo	$	92		$	607		$	831		$	632
Gevo Development / Agri-Energy		4,994			8,813			10,658			17,031
Consolidated	$	5,086		$	9,420		$	11,489		$	17,663

Loss from operations:
Gevo	$	(2,960	)	$	(2,315	)	$	(5,633	)	$	(4,791	)
Gevo Development / Agri-Energy		(3,533	)		(2,064	)		(6,488	)		(4,587	)
Consolidated	$	(6,493	)	$	(4,379	)	$	(12,121	)	$	(9,378	)

Interest expense:
Gevo	$	767		$	904		$	1,522		$	1,729
Gevo Development / Agri-Energy		—			—			—			—
Consolidated	$	767		$	904		$	1,522		$	1,729

Depreciation and amortization expense:
Gevo	$	50		$	76		$	102		$	160
Gevo Development / Agri-Energy		1,559			1,563			3,119			3,125
Consolidated	$	1,609		$	1,639		$	3,221		$	3,285

Acquisitions of plant, property and equipment:
Gevo	$	62		$	2		$	62		$	2
Gevo Development / Agri-Energy		1,877			54			4,081			121
Consolidated	$	1,939		$	56		$	4,143		$	123

Revenue by geographic area:
United States	$	4,994		$	8,813		$	10,658		$	17,056
Other		92			607			831			607
Consolidated	$	5,086		$	9,420		$	11,489		$	17,663


	June 30 ,			December 31,
	2019			2018
Total assets:
Gevo	$	102,981		$	105,379
Gevo Development / Agri-Energy		144,376			140,982
Intercompany eliminations		(143,564	)		(139,326	)
Consolidated	$	103,793		$	107,035

Note 1 - Nature of Business, Financial Condition, Basis of Presentation and Reverse Stock Split (Details Textual) $ in Thousands		3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 01, 2018	Jun. 30, 2019 USD ($) shares	Mar. 31, 2019 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)
Net Income (Loss) Attributable to Parent, Total		$ (7,090)	$ (6,136)	$ (11,492)	$ (2,502)	$ (13,226)	$ (13,994)
Retained Earnings (Accumulated Deficit), Ending Balance		(442,552)				(442,552)		$ (429,326)
Cash and Cash Equivalents, at Carrying Value, Ending Balance		$ 29,155				29,155		33,734
Proceeds from Issuance of Common Stock						9,647	$ 22,415
Income Tax Expense (Benefit), Total						$ 0
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset									$ 1,200
Operating Lease, Liability, Total									$ 1,200
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	20
At-the-market Offering [Member]
Increase (Decrease) in At-the-Market Offering of Stock								$ 84,900
Stock Issued During Period, Shares, New Issues \| shares		0				3,244,941
Proceeds from Issuance of Common Stock						$ 9,900
Payments of Stock Issuance Costs						10
At-the-market Offering [Member] \| Sales Agent [Member]
Payments of Stock Issuance Costs						$ 200

Note 2 - Earnings Per Share - Securities that Potentially Dilute Calculation of Diluted Earnings Per Share (Details) - shares	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Antidilutive securities (in shares)	2,749,675	1,244,557
Share-based Payment Arrangement, Option [Member]
Antidilutive securities (in shares)	2,361	358
Stock Appreciation Rights (SARs) [Member]
Antidilutive securities (in shares)	132,566	68,638
Restricted Stock [Member]
Antidilutive securities (in shares)	1,538,184	16
Convertible 2020 Notes [Member]
Antidilutive securities (in shares)	1,020,595	1,116,637
Warrant [Member]
Antidilutive securities (in shares)	55,963	58,902
Warrants Classified as Equity [Member]
Antidilutive securities (in shares)	6	6

Note 3 - Revenues From Contracts With Customers; Other Revenues (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 5,058	$ 9,420	$ 11,461	$ 17,663
Contract with Customer, Asset, after Allowance for Credit Loss, Total	0		0		$ 0
Contract with Customer, Asset, Credit Loss Expense (Reversal)	0	0	0	0
Contract with Customer, Liability, Total	0		0		0
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,058	9,420	11,461	17,638
Transferred at Point in Time [Member] \| Variable Consideration or Multiple Performance Obligations [Member]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Revenue, Remaining Performance Obligation, Amount	0		0		$ 0
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Transferred over Time [Member] \| Variable Consideration or Multiple Performance Obligations [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 0	$ 0	$ 0	$ 0

Note 3 - Revenues From Contracts With Customers; Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 5,058	$ 9,420	$ 11,461	$ 17,663
Other revenues	28		28
Total revenues	5,086	9,420	11,489	17,663
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,058	9,420	11,461	17,638
Other revenues
Total revenues	5,058	9,420	11,461	17,638
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Other revenues	28		28
Total revenues	28		28	25
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	4,966	8,813	10,630	17,031
Other revenues
Total revenues	4,966	8,813	10,630	17,031
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	92	607	831	607
Other revenues
Total revenues	92	607	831	607
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Other revenues	28		28
Total revenues	$ 28		$ 28	$ 25

Note 4 - Leases, Right-to-Use Assets and Related Liabilities (Details Textual) $ in Thousands	Jun. 30, 2019 USD ($)	Jan. 01, 2019 USD ($)
Leases Containing Variable Payments	0
Leases Containing Extension or Termination Options	0
Lessee, Operating Lease, Discount Rate	12.00%
Lessee, Operating Lease, Lease Not yet Commenced, Amount	2
Lessee, Operating Lease, Right-of-Use Asset, Not yet Commenced, Fair Value	$ 3,000
Lessee, Operating Lease, Liability, Not yet Commenced, Fair Value	3,000
Deposits and Other Assets [Member]
Operating Lease, Right-of-Use Asset	400
Accounts Payable and Accrued Liabilities [Member]
Operating Lease, Liability, Total	300
Other Noncurrent Liabilities [Member]
Operating Lease, Liability, Total	$ 300
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset		$ 1,200
Operating Lease, Liability, Total		$ 1,200

Note 4 - Leases, Right-to-Use Assets and Related Liabilities - Lease Costs (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Lease Cost
Financing lease cost
Operating lease cost	386	731
Short-Term lease cost	15	32
Total lease cost	$ 401	763
Operating cash flows from finance leases
Operating cash flows from operating leases		731
Financing cash flows from financing leases
Right-to-use assets obtained in exchange for new finance lease liabilities
Right-to-use assets obtained in exchange for new operating lease liabilities
Weighted-average remaining lease term, financing leases (months) (Month)
Weighted-average remaining lease term, operating leases (months) (Month)	2 years 30 days	2 years 30 days
Weighted-average discount rate - financing leases
Weighted-average discount rate - operating leases	12.00%	12.00%

Note 5 - Inventories - Components of Inventory Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Finished goods:
Spare parts	$ 1,482	$ 1,451
Total inventories	3,329	3,166
Corn [Member]
Raw materials:
Raw materials	17	29
Enzymes and Other Inputs [Member]
Raw materials:
Raw materials	246	204
Ethanol [Member]
Finished goods:
Finished goods	243	182
Isobutanol [Member]
Finished goods:
Finished goods	336	549
Jet Fuels, Isooctane and Isooctene [Member]
Finished goods:
Finished goods	607	394
Distiller's Grains [Member]
Finished goods:
Finished goods	45	54
Agri-Energy [Member]
Finished goods:
Work in process	226	214
Gevo [Member]
Finished goods:
Work in process	$ 127	$ 89

Note 6 - Property, Plant and Equipment (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Cost, Depreciation		$ 1,600	$ 3,100
Depreciation, Nonproduction	$ 30	$ 100	$ 100	$ 200

Note 6 - Property, Plant and Equipment - Property, Plant and Equipment by Classification (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Property, plant, and equipment, gross	$ 118,907	$ 114,764
Less accumulated depreciation and amortization	(50,909)	(47,728)
Property, plant and equipment, net	67,998	67,036
Construction in Progress [Member]
Property, plant, and equipment, gross	7,585	3,478
Machinery and Equipment [Member]
Property, plant, and equipment, gross	$ 16,305	16,285
Property, plant and equipment, useful life (Year)	10 years
Site Improvement [Member]
Property, plant, and equipment, gross	$ 7,062	7,055
Property, plant and equipment, useful life (Year)	10 years
Retrofit Assets [Member]
Property, plant, and equipment, gross	$ 70,842	70,842
Property, plant and equipment, useful life (Year)	20 years
Lab Equipment, Furniture and Fixtures, and Vehicles [Member]
Property, plant, and equipment, gross	$ 6,574	6,574
Property, plant and equipment, useful life (Year)	5 years
Demonstration Plant [Member]
Property, plant, and equipment, gross	$ 3,597	3,597
Property, plant and equipment, useful life (Year)	2 years
Building [Member]
Property, plant, and equipment, gross	$ 2,543	2,543
Property, plant and equipment, useful life (Year)	10 years
Computer, Office Equipment, and Software [Member]
Property, plant, and equipment, gross	$ 1,850	1,848
Property, plant and equipment, useful life (Year)	3 years
Leasehold Improvements [Member]
Property, plant, and equipment, gross	$ 2,549	$ 2,542
Leasehold Improvements [Member] \| Minimum [Member]
Property, plant and equipment, useful life (Year)	2 years
Leasehold Improvements [Member] \| Maximum [Member]
Property, plant and equipment, useful life (Year)	5 years

Note 7 - Embedded Derivatives and Derivative Warrant Liabilities (Details Textual)	1 Months Ended	3 Months Ended		6 Months Ended		60 Months Ended
	Jun. 30, 2017	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($)	Dec. 31, 2012 $ / shares shares	Dec. 31, 2018 USD ($)	Apr. 19, 2017
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net, Total		$ 148,000	$ (511,000)	$ 394,000	$ 2,347,000
Class of Warrant or Right, Issued During Period \| shares						6
Class of Warrant or Right, Issued During Period, Exercise Price \| $ / shares						$ 345
Class of Warrant or Right, Exercises in Period \| shares				0
Convertible 2020 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage	12.00%							12.00%
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	150.00%
Debt Instrument, Convertible, Threshold Consecutive Trading Days	10
Number of Embedded Derivative	1
Embedded Derivative, Fair Value of Embedded Derivative, Net, Total		0		$ 0			$ 400,000
Convertible 2020 Notes [Member] \| Embedded Derivative, 2020 Convertible Notes [Member]
Embedded Derivative, Fair Value of Embedded Derivative, Net, Total		0		0
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net, Total		$ 100,000		$ 400,000
Convertible 2017 Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage	12.00%

Note 7 - Embedded Derivatives and Derivative Warrant Liabilities - Schedule of Inputs to Lattice Model Used to Value Embedded Derivatives (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2019 $ / shares shares	Dec. 31, 2018 $ / shares shares
Stock price (in dollars per share)	$ 1.97	$ 1.96
Conversion Rate per $1,000 (in shares) \| shares	67.95	67.95
Conversion Price (in dollars per share)	$ 14.72	$ 14.72
Maturity date	Mar. 15, 2020	Mar. 15, 2020
Measurement Input, Risk Free Interest Rate [Member]
Risk-free interest rate	0.02	0.0257
Measurement Input, Price Volatility [Member]
Risk-free interest rate	0.55	1.5
Measurement Input, Entity Credit Risk [Member]
Risk-free interest rate	0.27	0.31

Note 7- Embedded Derivatives and Derivative Warrant Liabilities - Schedule of Shares Issued Upon Exercise of Warrants (Details) - $ / shares

6 Months Ended

Jun. 30, 2019

Dec. 31, 2018

55,963

^[1]

408,141

352,178

2014 Warrants [Member]

Aug. 05, 2014

Aug. 05, 2019

$ 65.50

974

^[1]

2,500

Series A Warrants [Member]

1,526

Feb. 03, 2015

Feb. 03, 2020

$ 3.80

320

^[1]

5,542

Series C Warrants [Member]

5,222

May 19, 2015

May 19, 2020

$ 53.43

1,075

^[1]

1,075

Series D Warrants [Member]

Dec. 11, 2015

Dec. 11, 2020

$ 40

^[1]

25,125

Series F Warrants [Member]

25,078

Apr. 01, 2016

Apr. 01, 2021

$ 40

14,041

^[1]

25,733

Series I Warrants [Member]

11,692

Sep. 13, 2016

Sep. 13, 2021

$ 220

35,650

^[1]

35,650

Series K Warrants [Member]

Feb. 17, 2017

Feb. 17, 2022

$ 3.80

3,856

^[1]

312,516