 SEATTLE, March 23, 2021 PRNewswire -- ClearSign Technologies Corporation Nasdaq: CLIR ClearSign or the Company, an emerging leader in industrial combustion and sensing technologies that improve energy, operational efficiency and safety while dramatically reducing emissions, today provided an update on operations for the fourth quarter and year ended on December 31, 2020. The Company will disclose its full financial results in the Annual Report on Form 10-K to be filed with the U.S. Securities and Exchange Commission in the coming weeks and, as a result, all numbers are preliminary. 