The Continuous Lower Energy, Emissions and Noise (CLEEN) program is a NextGen effort to accelerate development and commercial deployment of environmentally promising aircraft technologies and sustainable alternative fuels. The aircraft technologies focus on reduction in aircraft noise, emissions, and fuel burn.

Under this program, FAA has awarded five-year agreements to Boeing, General Electric, Honeywell, Pratt & Whitney, and Rolls-Royce. These companies will match or exceed the awards in this cost-sharing program. The total federal investment is expected to be $125 million over five years.

Specifically, CLEEN goals include developing and demonstrating:

  • Certifiable aircraft technology that reduces noise levels by 32 dB cumulative, relative to the Stage 4 standard;
  • Certifiable engine technology that reduces landing and takeoff cycle (LTO) nitrogen oxide emissions by 60 percent below the International Civil Aviation Organization (ICAO) standard adopted in 2004;
  • Certifiable aircraft technology that reduces aircraft fuel burn by 33 percent relative to current subsonic aircraft technology, and which reduces energy consumption and greenhouse gas emissions;
  • Use of "drop in" sustainable alternative jet fuels in aircraft systems and quantifying benefits
  • Suitability of new technology for engine and aircraft retrofit to accelerate penetration into the commercial fleet
Corners of the Trade
NextGen CLEEN Goals
(2015-2018) *
(cum below Stage 4)
-32 dB
LTO NOx Emissions
(Below CAEP 6)
Aircraft Fuel Burn -33%

* Timeframe for introduction into market

For more information on the CLEEN Program, its benefits, and accomplishments to date, please see the CLEEN Program Fact Sheet.

The next CLEEN Consortium Meeting is tentatively scheduled for May 5-7, 2015, in Washington, D.C. While the majority of this meeting will consist of closed door reviews, a public open session will be held on May 6. Please contact for more information.

A complementary piece of the CLEEN Program to the technology and fuel development activities is an independent technology modeling and assessment. This was initially done through the now complete PARTNER Center of Excellence Project 36 with Georgia Tech. A new project has been established under the Aviation Sustainability Center of Excellence (ASCENT) to model and assess aircraft technology for CLEEN, as well as other emerging technologies and their impacts on aircraft environmental metrics.

See more information on the full scope of FAA's alternative fuels activities.

To learn more about the CLEEN program, please visit the links below:

The CLEEN II solicitation was released September 29, 2014. For information and materials on the CLEEN II solicitation: