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Fact Sheet – Continuous Lower Energy, Emissions, and Noise (CLEEN) Program

For Immediate Release

August 1, 2014
Contact: Henry J. Price
Phone: (202) 267-3447

The Federal Aviation Administration (FAA) is committed to enhancing aviation’s capacity and efficiency through the implementation of the Next Generation Air Transportation System (NextGen).  

The Continuous Lower Energy, Emissions and Noise (CLEEN) program is the FAA’s principal NextGen environmental effort to accelerate the development of new aircraft and engine technologies and advance sustainable alternative jet fuels. The CLEEN Program is a key element of the NextGen strategy to achieve environmental protection that allows for sustained aviation growth.

The FAA has selected partner companies to participate in CLEEN through a cost-sharing program. These companies are working to develop technologies that will reduce noise, emissions, and fuel burn and enable the aviation industry to expedite integration of these technologies into current and future aircraft from 2015 to 2018.  These technologies include sustainable alternative jet fuels; lighter, more efficient gas turbine engine components; noise-reducing engine nozzles; advanced wing trailing edges; optimized flight trajectories using onboard flight management systems; and open rotor and geared turbofan engines.

Under the CLEEN program, the FAA entered into five-year agreement with Boeing, General Electric (GE), Honeywell, Pratt & Whitney (P&W), and Rolls-Royce.  These companies are matching or exceeding the FAA funding in this cost-sharing program.  Over the five-year period, the FAA expects to invest a total of $125 million. With the funding match from the five companies, the total investment value could exceed $250 million.  To date, matching funds spent from the FAA include:

  • Boeing—$27.4 million
  • GE—$23.2 million
  • Honeywell—$11.6 million
  • P&W—$24.5 million
  • Rolls Royce North America—$11.1 million

Specifically, CLEEN’s goals include developing and demonstrating:

  • 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;
  • Certifiable engine technology that reduces landing and takeoff cycle (LTO) nitrogen oxide (NOx) emissions by 60 percent below the International Civil Aviation Organization (ICAO) standard adopted in 2004;
  • Certifiable aircraft technology that reduces noise levels by 32 dB cumulative, relative to the Stage 4 standard;
  • “Drop-in” sustainable alternative jet fuels, including quantification of benefits – drop in alternative fuels will require no modifications to aircraft or fuel supply infrastructure.

Boeing CLEEN Program
Under CLEEN, Boeing is developing and demonstrating two aircraft technologies that could reduce aircraft fuel burn up to 2 percent.  If used fleet wide in the United States, based on 2009 total gallons burned, a 2 percent reduction would save 340 million gallons with a cost savings of $1.2 billion.  The two technologies being examined by Boeing are an Adaptive Trailing-Edge on the aircraft wing and a Ceramic Matrix Composite (CMC) acoustic nozzle at the engine exhaust.  Boeing has also completed research to determine effects of alternative jet fuels on aircraft fuel systems.

  • In August and September 2012, the first of Boeing’s “ecoDemonstrator” tests demonstrated Adaptive Trailing-Edge, a technology that deploys miniature flaps to improve wing aerodynamic efficiency and decreases noise during approach. Under an agreement with American Airlines, these tests used one of the airline’s pre-delivered 737-800 models for flight testing in Glasgow, MT. 
  • In Spring 2013, Boeing completed ground testing of its Ceramic Matrix Composite (CMC) engine nozzle. Because this technology can withstand higher temperatures and is made of lighter weight material, it lowers fuel consumption. The CMC nozzle technology can also accommodate acoustic treatments  that reduce community noise. Boeing plans to conduct a flight test of the CMC nozzle on a 787 aircraft in the latter half of 2014.
  • Boeing has also completed testing of alternative fuels to determine their impact on  aircraft fuel system materials,  aiding in the understanding and approval of these fuels.

GE CLEEN Program
Under CLEEN, GE is developing and demonstrating four areas of aircraft technology that will reduce fuel burn, emissions and noise.  These technologies are the Open Rotor engine, an advanced engine combustor known as the Twin Annular Premixed Swirler (TAPS) II, Flight Management System–Air Traffic Management (FMS-ATM) System Integration, and Flight Management System-Engine Integration.

  • In January 2012 GE completed core engine tests of the TAPS II Combustor.  Results show landing and take-off nitrogen oxide (NOx) emissions were reduced 60 percent compared to the International Civil Aviation Organization (ICAO) NOx standard adopted in 2004, meeting one of the CLEEN goals. This combustor will be used in CFM International’s LEAP turbofan engine and is expected to enter service in 2016.
  • In January 2012 GE completed scaled Open Rotor wind tunnel tests.  Results indicate aircraft fuel burn on a single aisle aircraft may be reduced 26 percent relative to a CFM International, CFM56-7B engine, and up to 15 dB cumulative noise reduction relative to FAA Stage 4 noise standards.
  • In March 2013, General Electric demonstrated flight trajectory synchronization between aircraft and the En Route Automation Modernization (ERAM) system. Trajectory synchronization will provide pilots and controllers better predictability of an aircraft’s location, enabling fuel savings through more efficient aircraft routing.
  • General Electric also completed modeling of their Flight Management System-Engine Integration technology.  This technology will reduce aircraft fuel burn through efficiencies gained by adaptive engine control, integrated vehicle health management, and integrated flight-propulsion control.

Honeywell CLEEN Program
Under CLEEN, Honeywell is developing and demonstrating technologies that will increase engine efficiency and reduce engine weight.  The CLEEN technologies will contribute 5 percent toward an overall 15.7 percent reduction in fuel burn resulting from an engine upgrade relative to baseline engine technology.  This requires demonstrating seven technologies including new coatings, higher temperature impeller, advanced seals and improved turbine cooling.

  • In 2012 and 2013, Honeywell completed engine tests of two technologies, validating their capability of increased engine temperature and efficiency. Honeywell procured the hardware necessary to conduct engine ground tests of the remaining technologies in 2014 and 2015.
  • In March 2011, Honeywell completed cold fuel testing of an alternative jet fuel blended with Jet-A fuel, demonstrating no clogging will occur at cold temperatures.  This test directly supported ASTM International approval of the hydroprocessed esters and fatty acids (HEFA) jet biofuel blend on July 1, 2011.

Pratt & Whitney CLEEN Program
Under CLEEN, Pratt & Whitney is developing and demonstrating an ultra-high bypass ratio geared turbofan (GTF) engine and associated advanced technologies. Geared turbofan engine technologies will contribute to reduced aircraft noise and fuel consumption because of increased engine efficiency. This engine is projected to reduce single aisle aircraft fuel consumption by 20 percent relative to a CFM International, CFM56-7 engine and 25 dB noise reduction relative to the Stage 4 noise standards. 

  • In June 2012 Pratt & Whitney began NASA wind tunnel tests of an advanced fan. Results were used to validate the CLEEN GTF fan design.
  • Further wind tunnel tests and an engine ground test of the GTF are scheduled for 2014 and 2015.

Rolls-Royce CLEEN Program
Under CLEEN, Rolls-Royce is developing and demonstrating a Dual-Wall Turbine Airfoil and CMC Blade Track, technologies aimed at increasing thermal efficiency in turbine section of the engine. Dual-wall turbine airfoils are projected to provide 20 percent or more reduction in cooling and increased operating temperature capability. The new blade tracks made from CMC material are projected to offer more than a 50 percent reduction in engine cooling and weight savings compared to a metallic design.  Technology benefits will realize up to a 1 percent reduction in fuel consumption. Rolls-Royce has also conducted laboratory and engine component tests of advanced sustainable alternative jet fuels that could be approved for commercial use by ASTM International.

  • In July 2011 Rolls-Royce completed CMC Turbine Blade Track (shroud) component tests.  Engine testing of this technology began in Spring 2013.
  • Rolls-Royce completed laboratory testing of new jet biofuels under development by nine fuel companies.  Four of these jet biofuels were selected for auxiliary power unit and rig tests, which were completed in 2013.



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