ClearSign Reports Successful Sub 5ppm Department of Energy/Small Business Innovation Research Flexible Fuel Burner Testing

Partnered with National Energy Technology Laboratory to Advance Flexible Fuel, Ultra-Low NOx Combustion for Industrial Operations

TULSA, OK / ACCESS Newswire / March 11, 2026 / ClearSign Technologies Corporation (NASDAQ:CLIR) ("ClearSign" or the "Company"), a leader in advanced combustion and sensing technologies that help industrial operators dramatically reduce emissions, increase efficiency and safety, and support the use of cleaner fuels including hydrogen, announces today that, in conjunction with the U.S. Department of Energy's ("DOE") National Energy Technology Laboratory ("NETL"), under its Small Business Innovation Research ("SBIR") program, it has successfully completed the testing of its ClearSign Core^™ Flexible Fuel, 100% Hydrogen Capable process burner branded as ClearSign Core^™ 2.

"We are very pleased to publicly report the success of this flexible fuel burner development project," said Jim Deller, Ph.D., Chief Executive Officer of ClearSign. "We are thankful for the SBIR program funding that allowed us to develop and demonstrate a technology designed to meet the real-world needs of U.S. refineries and chemical processing facilities. This technology enables compliant and cost-effective use of fuels ranging from 100% hydrogen, the full gamut of petrochemical and refinery hydrocarbon fuel gas blends, and natural gas in industrial heating operations. We believe that these ultra-low NOx results and ease of use are unmatched by any other burner that we know of in the market."

Many industrial operators in these industries currently have access to a variety of opportunity fuels or specific gas compositions that traditionally require extremely costly heater modifications to meet regulatory nitrogen oxide ("NOx") emission limits in place to help protect air quality and respiratory health.

ClearSign's "Flexible Fuel Ultra-Low NOx Process Burner" project, which is nearing its scheduled completion and marking a significant 2.5-year effort, resolves this issue by facilitating fuel flexibility without compromising emissions compliance with the simple replacement of burner technology. This innovative technology allows industrial facilities to enhance operational flexibility, reduce costs associated with fuel procurement and regulatory emissions compliance, and reduce disruptions to operations - all of which may provide Americans with more affordable energy.

The ClearSign Core burner, scaled to 8 million British thermal units per hour, has demonstrated consistent performance across a range of fuel compositions, including 100% hydrogen, natural gas and various intermediate blends. This technology has also achieved NOx emissions that are consistently below 5 parts per million ("ppm") across this entire range of fuel gas blends. This is accomplished through integrated features such as internally induced flue gas recirculation, fuel-lean premixing and a patented distal flameholder, all contained within a compact burner head designed for easy retrofitting into existing heater infrastructure.

"NETL's investment in ClearSign's technology is opening up significant operational advantages for the industry," said Drew O'Connell, NETL federal project manager. "This solution allows companies to effectively utilize a broader spectrum of available fuels, ensuring they operate within permitted NOx limits without needing additional post-combustion controls like selective catalytic reduction or diluents."

This project, which was made possible through a $1.65 million SBIR Phase II award from the DOE, is now progressing to the next stage to implement commercial field installations at operational industrial sites.

ClearSign expects that this advancement will significantly improve operational resilience and competitiveness within the domestic refining and chemical production sectors, aligning with NETL's commitment to providing technological solutions for U.S. industrial needs, increasing industry partnerships and advancing hydrocarbon technologies.

This initiative underscores the impact of DOE's SBIR program, which NETL helps administer, by empowering small businesses, such as Tulsa-based ClearSign, to develop technologies that are expected to address national industrial challenges and strengthen U.S. manufacturing innovation.

NETL is a DOE national laboratory dedicated to innovating and accelerating the nation's energy solutions in hydrocarbon, geothermal energy and critical minerals production. With research sites in Albany, Oregon; Morgantown, West Virginia; and Pittsburgh, Pennsylvania, NETL operates as one laboratory to create advanced energy technologies that support DOE's mission and enable affordable, reliable and secure energy to fuel human prosperity.

About ClearSign Technologies Corporation

ClearSign Technologies Corporation designs and develops products and technologies for the purpose of decarbonization and improving key performance characteristics of industrial and commercial systems, including operational performance, energy efficiency, emission reduction, safety, the use of hydrogen as a fuel and overall cost-effectiveness. Our patented technologies, embedded in established OEM products as ClearSign Core^™ and ClearSign Eye^™ and other sensing configurations, enhance the performance of combustion systems and fuel safety systems in a broad range of markets, including the energy (upstream oil production and down-stream refining), commercial/industrial boiler, chemical, petrochemical, transport and power industries. For more information, please visit www.clearsign.com.

For further information:

Investor Relations:

Matthew Selinger
Firm IR Group for ClearSign
+1 415-572-8152
[email protected]

Cautionary note on forward-looking statements

All statements in this press release that are not based on historical fact are "forward-looking statements." You can find many (but not all) of these statements by looking for words such as "approximates," "believes," "hopes," "expects," "anticipates," "estimates," "projects," "intends," "plans," "would," "should," "could," "may," "will" or other similar expressions. While management has based any forward-looking statements included in this press release on its current expectations on the Company's strategy, plans, intentions, performance, or future occurrences or results, the information on which such expectations were based may change. These forward-looking statements rely on a number of assumptions concerning future events and are subject to a number of risks, uncertainties and other factors, many of which are outside of the Company's control, that could cause actual results to materially differ from such statements. Such risks, uncertainties and other factors include, but are not limited to, the Company's ability to successfully complete engineering orders for its customers; the Company's ability to generate equipment and installation orders following an initial engineering order from customers; the Company's ability to successfully deliver, install, and meet the performance obligations of the Company's burners in the California market and any other markets the Company may sell products in; the Company's ability to further expand the sale of ultra-low NOx process, flare and boiler burners; the Company's ability to further validate its burners' performance in commercial applications and complete field installations at operational industrial sites; the Company's ability to, through its technologies, provide increased operational flexibility, cost reductions and uninterrupted operations to its customers; the Company's ability to improve operational resilience and competitiveness within the domestic defining and chemical production sectors; the Company's ability to continue expanding its customer base in the refining industry; the Company's ability to effectively compete in the flare industry and to retain its existing customers in such industry; the Company's ability to provide low emissions retrofit solutions based on continuously changing air permit requirements at the federal and state level; the Company's ability to continue innovating and expanding its scope of product and service applications; the Company's ability to expand its engagement with current and future customers beyond burner technology and into broader emission and system integration solutions; general business and economic conditions; the performance of management and the Company's employees; the Company's ability to obtain financing; whether the Company's technology will be accepted and adopted and other factors identified in the Company's Annual Report on Form 10-K and other periodic and current reports filed with the U.S. Securities and Exchange Commission and available for review at www.sec.gov. Furthermore, the Company operates in a competitive environment where new and unanticipated risks may arise. Accordingly, investors should not place any reliance on forward-looking statements as a prediction of actual results. The Company disclaims any intention to, and, except as may be required by law, undertakes no obligation to, update or revise forward-looking statements to reflect events or circumstances that subsequently occur or of which the Company hereafter become aware.

SOURCE: ClearSign Technologies

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