Thursday, January 10, 2013

Alternative energy for aviation

As high oil prices cut into airline profits, companies and governments are researching alternatives to traditional oil-based jet fuels for aviation. The quest for synthetic aviation fuels goes back to World War II when Nazi Germany’s lack of resources led it to develop processes to convert coal into gasoline.

More recently, the U.S. military has been working toward synthetic fuels as a means of protecting its ability to operate in the event of an interruption of oil supplies. In 2006, the Air Force operated a B-52 Stratofortress using a 50/50 blend of JP-8 jet fuel and a natural gas based synthetic fuel according to the Sohbet Karbuz blog. In 2012, the Air Force flew an A-10 Thunderbolt on Alcohol-to-Jet fuel (ATJ), which is derived from cellulose from wood or plants according to Oil

National Defense magazine says that the Navy is taking a different strategy. Where the Air Force is a consumer of alternative fuel technology from existing companies, the Navy has provided seed funding to try to spur the domestic biofuels industry. The Navy has certified several of its aircraft, including the F-18 Hornet, the MH-60 Seahawk, and the MV-22 Osprey to operate on a 50/50 blend of JP-5 and hydrotreated renewable fuel (HRF) according to the Congressional Research Service.

"Eventually, it is possible that aircraft will see JP-8 consisting of all these alternatives," Air Force Certification Division chief Jeff Braun told Oil "You won't be able to determine the difference and you won't care, because all perform as JP-8."

Currently, the big difference is in the cost. The ATJ fuel that the Air Force purchased in 2012 cost $59 per gallon according to Reuters. At the same time, traditional jet fuel cost $3.60 per gallon.

NASA is also researching alternative aviation fuels. Using a DC-8 at NASA’s Dryden Flight Research Center in California, the space agency has tested fuels based on coal and natural gas.

There has been a movement toward alternative fuel in private industry as well. Much of the private interest in alternative fuels may stem from the European Union’s attempt to impose a carbon tax on aircraft flying to and from Europe. Consequently, airlines are more interested in biofuels than in fuels derived from coal or natural gas.

In 2006, CAAFI, the Commercial Aviation Alternative Fuels Initiative, was formed by governmental groups and trade associations to help develop alternative jet fuels. In 2011, Boeing and Aeromexico operated the first transatlantic flight to use biofuels. The flight from Mexico City to Madrid was on a 777-200ER powered by a mixture of 70 percent jet fuel and 30 percent combination jet fuel and oil from the Jatropha Curcas, an oilseed plant native to Mexico. In 2012, Airbus and China Petroleum and Chemical Corporation (Sinopec) entered into an agreement to create a biofuel for the Chinese market. Several other airlines have used biofuel mixtures on flights as well.

Piston engine aircraft face a different fuel challenge. Piston airplanes are typically powered by 100 low lead avgas. Lead is a gasoline additive that boosts octane ratings of the fuel. Leaded gasoline was banned for automobile use in the United States in 1986 because it was a public health hazard. Low lead fuel is still being used in light airplanes, however.

The most likely fuel to replace 100LL is diesel. Although diesel fuel does not address concerns about the availability and environmental impact of petroleum-based fuels, it does provide a proven replacement for leaded avgas. A number of engine manufacturers have already certified diesel aircraft engines and Cessna is even offering a diesel version of its 182 Turbo Skylane.

Others have more radical solutions. In July 2012, electric vehicle pioneer Chip Yates set a speed record for electric aircraft. Flying a Long-ESA, a modified Long-EZ, Yates became the first person to fly an electric airplane faster than 200 miles per hour. Ironically, the flight, which reached a speed of 202.6 mph, ended prematurely when a “dead cell killed propulsion” and forced Yates to make a dead stick landing. The report in Wired does not indicate the normal endurance of the Long-ESA.

Another aircraft doesn’t use fuel at all. Bertrand Piccard plans to fly his airplane, the Solar Impulse, around the fuel using only solar power. The Solar Impulse has flown during the day and at night and has already set five world records including absolute height (30,300 feet), duration (26 hours, 10 minutes, 19 seconds) and free distance (693.5 miles). At an average flying speed of 43 mph, the Solar Impulse is noticeably slower than Chip Yates’ Long-ESA.

At present, alternative forms of energy to power airplanes are more costly than oil, less efficient, or both. If oil prices continue to rise, however, today’s research in nontraditional fuels or sources of energy may result in new technologies that are more cost effective.

Originally published on

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