Note 5 - Patent	12 Months Ended
Note 5 - Patent	Dec. 31, 2018
Notes to Financial Statements
Patents and Intellectual Property [Text Block]	Note 5 – Patent The Company owns US Patent No. 6,306,248 (the “PSC Patent”), which is the underlying technology upon which the BRP Patent is based. The Company acquired the PSC Patent on October 22, 2008 pursuant to a Patent Purchase Agreement (“Agreement”) with World Waste Technologies, Inc. (“WWT”). As part of the acquisition of the PSC Patent, we also became the licensor of such technology under the existing license agreement between Bio-Products International, Inc., the licensee (“Bio-Products”) and WWT. The Company has paid WWT $600,000 and issued warrants to purchase 1,800,000 shares of Common Stock at $0.10 per share and 500,000 shares of Common Stock at $0.11 per share. WWT assigned all of its rights, title and interest in the note, warrants, security agreement and purchase agreement to Vertex Energy, Inc. (“Vertex”) as a result of a merger in March 2009. The warrants had an exercisable term of five years which expired on October 22, 2014. The cost of the PSC Patent acquisition of $600,000 is recorded as a long-term asset on the Balance Sheet. On September 1, 2010, the Company issued a promissory note to CMS Acquisition, LLC (“CMS”) in the amount of $100,000 and bearing interest at 6.0% per annum. The note is secured with a security interest in the PSC Patent. In connection with the financing, the Company issued a warrant to CMS to purchase 2,000,000 shares of Common Stock at a price of $0.05 per share. The warrant is exercisable at any time for five years from the date of issuance or re-issuance. The note was originally to mature on February 28, 2011. The Company and CMS have entered into various amendments extending the due date, the most recent of which was April 26, 2017, which extended the due date to April 26, 2018. As consideration in these amendments, the Company has: (i) paid $30,000 towards accrued interest to date and principal on the Note, (ii) increased the interest rate to 10% as of May 15, 2011, ( iii) re-dated the original warrants to April 26, 2017, ( iv) issued new warrants for 300,000 shares of Common Stock with an exercise price of $0.05 and exercisable at any time until April 26, 2022, ( v) issued new warrants for 150,000 shares of Common Stock with an exercise price of $0.10 and exercisable at any time until April 26, 2022, and (vi) approved the assignment of the note by CMS to the WL Meyer Legacy Trust as of the March 17, 2015 amendment. As of December 31, 2018, $72,696 face value of this note is outstanding. For more information on this note, see Item 7 – Management’s Discussion and Analysis of Financial Condition and Results of Operations – Debt.

CleanTech Biofuels, Inc. 10-K