NASA project seeks to assess biofuel environmental performance at altitude and impact on contrails formation
Contrails stream from the engines of NASA's DC-8 flying laboratory in this photo taken from an HU-25 Falcon flying in trail about 300 feet behind (photo: NASA)
Thu 7 March 2013 – A team of NASA researchers has begun a programme of flight tests that will compare the environmental impacts from emissions and contrails of a blended fuel containing 50 per cent biofuel against those from conventional jet fuel. The project, titled the Alternative Fuel Effects on Contrails and Cruise Emissions – or ACCESS for short, also aims to provide a greater understanding about contrails formation in general, to allow for a better assessment of the potential environmental benefits of aviation biofuels. It builds on NASA’s past research into alternative aviation fuels that focused on ground-based emissions tests on fuels from a variety of sources. The flight testing is being carried out at the administration’s Dryden facility in California using a DC-8 aircraft.
The DC-8 will conduct a series of flights at altitudes up to 40,000 feet. In each flight, it will be trailed by an HU-25 Falcon jet equipped with more than a dozen instruments at distances ranging from 300 feet to in excess of 10 miles.
The DC-8 test platform will use one of two fuels for each flight: either conventional JP-8 military jet fuel, or a 50-50 blend of fuel consisting of JP-8 and hydrotreated biofuel. Once at cruising altitude, the Falcon aircraft will gather data on the role of the DC-8’s emissions in forming contrails and the changing composition of its exhaust plumes as they mix with the air.
“We believe this study will improve understanding of contrails formation and quantify potential benefits of renewable alternative fuels in terms of aviation’s impact on the environment,” said Ruben Del Rosario, Manager of NASA’s Fixed Wing Project.
The biofuel used by NASA in its tests is sourced from camelina plants, a crop that is seen as a particularly valuable potential source of biofuel for aviation. It is a dry-land crop that requires little nitrogen or water to grow and that can be rotated into agricultural production without adversely affecting food production.
The in-flight ACCESS research is a continuation of work already undertaken by NASA involving alternative aviation fuels. Previously, in 2009 and 2011, it conducted ground-based emissions tests on hydrotreated biofuels and synthetic fuels derived from coal and natural gas.
As well as assessing the contrails and emissions from the 50-50 biofuel-powered DC-8, NASA’s Falcon aircraft will also trail some commercial flights over California in order to gain more data on the formation of contrails.
The ACCESS project is a collaboration between NASA’s Aircraft Operations Facility in Dryden and research teams based at its Glenn Research Center in Cleveland, Ohio and its Langley Research Center in Hampton, Virginia.
The test flights began on February 28 and are expected to last three weeks. A second phase of flights for the ACCESS project is expected to be carried out in 2014.