ClearSign Achieves Major Milestone: 2PPM NOx Demonstrated

          ClearSign Achieves Major Milestone: 2PPM NOx Demonstrated

Company meets aggressive 2013 milestone, dropping NOx a further 33% to 2PPM.

Sets new 2013 goal of 1PPM or lower.

PR Newswire

SEATTLE, Sept. 11, 2013

SEATTLE, Sept. 11, 2013 /PRNewswire/ -- ClearSign Combustion Corporation
(NASDAQ: CLIR) today announced that it has measured and documented a further
33% reduction in emissions of Nitrous Oxides (NOx), now down to 2 parts per
million (PPM) from its previous record of 3 PPM announced in June. This marks
a major milestone in the development of ClearSign's Duplex™ Burner
Architecture, and marks the early achievement of an aggressive 2013 target for
the company.

The announcement occurred during a live web conference yesterday, attended by
members of the media and potential partners and customers. A roundtable of
subject matter experts provided context and discussed the market implications
of the achievement. The panel included current and former managers and leading
researchers at Marathon Petroleum Corporation, Chevron Corporation, The Energy
Solutions Center and the University of California, Berkeley.

The web conference has been archived and is available for viewing here, or by
visiting clearsign.com

"Earlier this year, we set what we believed was an aggressive goal of
achieving 2 PPM of NOx by the end of 2013, using a combination of ClearSign's
Electrodynamic Combustion Control™ (ECC™) and our Duplex™ Burner Architecture
technologies," said ClearSign CEO, Rick Rutkowski. "Today, I am extremely
proud to report that we have not only achieved this important objective but,
thanks to the efforts of our development team, made it happen much earlier
than we anticipated. We plan to continue our efforts and have set a new
stretch goal of dropping NOx by a further 50% to 1PPM or lower by the end of
this year."

Richard Biljetina, Director, Industrial Markets at the Energy Solutions Center
provided context and noted, "The important thing to understand is just how
difficult it is to get below 10 or 15 PPM [of NOx]. Current solutions such as
FGR [Flue Gas Recirculation] have very high efficiency penalties and SCR
[Selective Catalytic Reduction] has very high cost penalties. So at ESC, what
we are looking for, for our customers, are burners that do the job in the
burner itself using techniques such as internal recirculation, or exactly the
type of things you're hearing about from ClearSign. Because truly, if we can
achieve 2 PPM without any efficiency penalties at very reasonable cost, that
would be a extremely great accomplishment."

Rutkowski added, "The use of conventional Low NOx and Ultra Low NOx burners
has typically involved significant costs to owners not only in the form of
capital and construction costs but in the form of penalties to energy
efficiency and process throughput and even maintenance costs. Moreover, these
increased costs become more severe as lower levels of NOx emissions are
pursued. Energy efficiency is reduced by requirements for supplemental FGR and
increased O2 levels and by constraints to operating range (turndown). By
contrast, we believe ClearSign's Duplex Burner technology promises to reverse
this trend by potentially eliminating these requirements and removing the
constraint to operating range."

Dr. Michael Frenklach, professor of Mechanical Engineering at the University
of California, Berkeley, commenting on today's announcement, offered, "I'm
very impressed by your results. Not only are you bringing NO down, but you are
maintaining CO [at low levels] as well. This needs to be studied much more.
This is an important accomplishment. I think that accomplishing this... may
offer independent control of NOx from other pollutants, for example
hydrocarbons... this would be a major step forward."

Filtration+Separation magazine estimates in its April 2013 issue that the
market for NOx control technology will be $11 billion in 2014, of which
non-utility [commercial and industrial boiler applications] will comprise over
$2 billion annually. Reporting in the American Society of Mechanical
Engineers, the McIlvaine Company projects double-digit growth in this market,
placing NOx control at #4 on its list of the top ten most promising growth
markets in energy, air and water.

About ClearSign Combustion Corporation

ClearSign Combustion Corporation designs and develops technologies that aim to
improve key performance characteristics of combustion systems including energy
efficiency, emissions control, fuel flexibility and overall cost
effectiveness. Our Electrodynamic Combustion Control™ (ECC™) platform
technology improves control of flame shape and heat transfer and optimizes the
complex chemical reactions that occur during combustion in order to minimize
harmful emissions. For more information about the Company, please visit
www.clearsign.com

Cautionary note on forward-looking statements

This press release includes forward-looking information and statements within
the meaning of the Private Securities Litigation  Reform Act of 1995 and the
provisions of Section27A of the Securities Act of 1933, as  amended, and
Section21E of the Securities Exchange Act of 1934, as amended. Except for
historical information contained in this release, statements in this release
may constitute forward-looking statements regarding our assumptions,
projections, expectations, targets, intentions or beliefs about future events
that are based on management's belief, as well as assumptions made by, and
information currently available to, management. While we believe that our
expectations are based upon reasonable assumptions, there can be no assurances
that our goals and strategy will be realized. Numerous factors, including
risks and uncertainties, may affect our actual results and may cause results
to differ materially from those expressed in forward-looking statements made
by us or on our behalf. Some of these factors include the acceptance of
existing and future products, the impact of competitive products and pricing,
general business and economic conditions, and other factors detailed in our
Quarterly Report on Form 10-Q and other periodic reports filed with the SEC.
We specifically disclaim any obligation to update or revise any
forward-looking statement whether as a result of new information, future
developments or otherwise.

SOURCE ClearSign Combustion Corporation

Website: http://www.clearsign.com
Contact: Media, Bronwyn Wallace, Hill+Knowlton Strategies, (713) 752-1929,
bronwyn.wallace@hkstrategies.com; or Investor Relations, (206) 673-4848,
investors@clearsign.com