A cooperative international research program led by NASA and involving agencies from Germany and Canada, concluded that using biofuels to help power jet engines reduces particle emissions in their exhaust by as much as 50 to 70 percent.
Biofuels are transportation fuels produced from biomass (energy source derived from organic matter) as a substitute for fossil fuel.
The findings are detailed in a study published in the journal Nature, and bodes well for both airline economies and Earth’s environment.
As reported by NASA, During flight tests in 2013 and 2014 near NASA’s Armstrong Flight Research Center in Edwards, California, data was collected on the effects of alternative fuels on engine performance, emissions and aircraft-generated contrails at altitudes flown by commercial airliners. The test series were part of the Alternative Fuel Effects on Contrails and Cruise Emissions Study, or ACCESS.
Aviation-related aerosol emissions contribute to the formation of contrail cirrus clouds that can alter upper tropospheric radiation and water budgets, and therefore climate. Contrails are produced by hot aircraft engine exhaust mixing with the cold air that is typical at cruise altitudes several miles above Earth’s surface, and are composed primarily of water in the form of ice crystals.
Researchers are most interested in persistent contrails because they create long-lasting, and sometimes extensive, clouds that would not normally form in the atmosphere, and are believed to be a factor in influencing Earth’s environment.
Contrails, and the cirrus clouds that evolve from them, have a larger impact on Earth’s atmosphere than all the aviation-related carbon dioxide emissions since the first powered flight by the Wright brothers.
The tests involved flying NASA’s workhorse DC-8 as high as 40,000 feet while its four engines burned a 50-50 blend of aviation fuel and a renewable alternative fuel of hydro-processed esters and fatty acids produced from camelina plant oil. A trio of research aircraft took turns flying behind the DC-8 at distances ranging from 300 feet to more than 20 miles to take measurements on emissions and study contrail formation as the different fuels were burned.
“This was the first time we have quantified the amount of soot particles emitted by jet engines while burning a 50-50 blend of biofuel in flight,” said Rich Moore, lead author of the Nature report.
Researchers plan on continuing these studies to understand and demonstrate the potential benefits of replacing current fuels in aircraft with biofuels. It’s NASA’s goal to demonstrate biofuels on their proposed supersonic X-plane.
The drawback of using biofuels
Unlike fossil fuels, biofuels are a renewable source of energy as they are derived from crops that can be harvested annually, thus making them theoretically unlimited. However, contrary to this belief, biofuels do have restrictions.
The most dire consequence of using biofuel is the threat it imposes to the food supply, thus limiting its production.
We live in a world which has a population of around 7 billion which is already short on food. Hence, there will necessarily be a tradeoff between food crop and biofuel feedstock.
Another drawback of biofuel is its portability. Similar to electricity produced from solar panels and wind energy generated from bulky windmills, biofuels cannot be easily transported. And a fuel that is easily produced, but not easily transported is still limited in its availability.
Furthermore, it can only be produced in nations where abandoned agricultural lands are available. If a land has to be cleared of its native vegetations to grow biofuel feedstock, ecological damage is inevitable.
However, despite its above drawbacks, biofuel is still a more environment-friendly option than fossil fuels.