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). NextGen will also help the FAA reach its goal of reducing aviation’s environmental footprint and securing and diversifying air transportation’s energy supply.
The Continuous Lower Energy, Emissions and Noise (CLEEN) program is the FAA’s principal NextGen environmental effort to develop and demonstrate new technologies, procedures and sustainable alternative jet fuels.
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—$21.4 million
- GE—$20.2 million
- Honeywell—$8.9 million
- P&W—$14.6 million
- Rolls Royce North America—$10.5 million
Specifically, CLEEN’s goals include developing and demonstrating:
- Certifiable aircraft technology that reduces aircraft fuel burn by 33 percent relative to 2009 subsonic aircraft technology, and reducing energy consumption and greenhouse gas emissions;
- Certifiable engine technology that reduces landing and takeoff cycle (LTO) nitrogen oxide emissions by 60 percent over the International Civil Aviation Organization (ICAO) standard adopted in 2004;
- Certifiable aircraft technology that reduces noise levels by 32 dB cumulative, relative to the ICAO noise standards; and
- “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 will demonstrate 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 at a cost savings of $1.2 billion. The technologies being examined by Boeing are Adapative Trailing-Edge and Ceramic Matrix Composite (CMC) acoustic engine nozzles. Boeing has also completed research to determine effects of alternative jet fuels on aircraft fuel systems.
- In August through September 2012, the first of Boeing’s “ecoDemonstrator” tests will include the Adaptive Trailing-Edge. Under an agreement with American Airlines, these tests will use one of the airline’s pre-delivered 737-800 models for flight testing in Glasgow, MT. Adaptive Trailing-Edge will allow improvement in wing aerodynamic efficiency and is projected to also decrease aircraft noise during approach.
- In late 2013 the second of the “ecoDemonstrator” tests will examine the CMC acoustic engine nozzle on a B787 aircraft. This technology will reduce weight and increase the temperature capability of future engine nozzles, reducing aircraft fuel burn by 1 percent. Boeing will conduct ground tests on a Rolls-Royce Trent 1000 engine in October 2012, followed by a flight test in 2013 on Boeing’s second series of tests.
GE CLEEN Program
Under CLEEN, GE will develop and demonstrate three aircraft technologies 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, and Flight Management System–Air Traffic Management (FMS-ATM) System Integration.
- 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 with up to 15 dB margin to current Stage 4 noise standards.
- 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 ICAO Civil Aviation Environmental Protection (CAEP) 6 standards, meeting one of the CLEEN goals. This combustor will be used in CFM International’s LEAP-X turbofan engine and is expected to be commercialized in 2015.
- In collaboration with Lockheed Martin, GE will demonstrate data synchronization between the onboard flight management system and ground-based air traffic management system. This simulation is scheduled for August 2013. Such FMS-ATM integration will lead to system wide reductions in fuel burn, emissions and noise by optimizing flight operations.
Honeywell CLEEN Program
Under CLEEN, Honeywell will demonstrate a 15 percent reduction in fuel burn by increasing engine efficiency and reducing engine weight. This requires demonstrating seven technologies including new coatings, higher temperature impeller, advanced seals and improved turbine cooling. Honeywell will also complete engine and flight tests of a 100 percent jet biofuel.
- In April 2012, Honeywell completed engine tests of two technologies.
- In late 2012, Honeywell will complete engine component tests of the remaining five technologies in preparation for engine tests in 2013.
- In March 2011, Honeywell completed cold fuel testing of alternative jet fuel blended with Jet-A fuel, demonstrating no clogging will occur at cold temperatures. This test directly supported approval of this jet biofuel blend by ASTM International on July 1, 2011 which has enabled use in commercial aircraft on a global level.
P&W CLEEN Program
Under CLEEN, P&W will demonstrate a Geared Turbofan (GTF) engine that is projected to reduce single aisle aircraft fuel burn by 20 percent with significant margin to Stage 4 noise standards.
- In June 2012 P&W began NASA wind tunnel tests of an advanced fan. Results will be used to validate the CLEEN GTF fan design.
- Engine ground tests of the GTF are scheduled for late 2014 and flight tests in mid 2015.
Rolls-Royce CLEEN Program
Under CLEEN, Rolls-Royce will demonstrate a Dual-Wall Turbine Blade and CMC Blade Track, increasing engine efficiency and reducing engine weight. Rolls-Royce is also conducting 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 endurance tests will begin in October 2012.
- Rolls-Royce manufactured Dual-Wall turbine blades using rapid prototyping and advanced casting technologies. Engine endurance tests are scheduled for 2015.
- Rolls-Royce completed laboratory testing of new jet biofuels under development by nine fuel companies. Four of these jet biofuels were selected for engine rig tests, which started in March 2012.