Continental Airlines today completed the first alternative fuels trial in the US with a twin engine aircraft powered in part by a biofuel blend consisting of algae.
Continental pilots operated a Boeing 737-800 using a blend of 50% jet fuel and 50% biofuel derived from algae (2.5%) and jatropha plant (47.5%) oils to power the right CFM International CFM56-7B engine. The left engine flew on 100% jet fuel.
"It went absolutely textbook," Continental flight test captain Rich Jankowski says, adding that he did not expect that much difference between the fuels.
During the roughly two-hour trial in Houston, Continental recorded various flight parameters and ran acceleration and deceleration checks, two inflight engine shut-downs and restarts--one wind milling start and one starter assist--and a simulated landing and go-around, Jankowski says.
The aircraft also simulated the highest, most difficult altitude the airline flies, Quito, Ecuador, he adds.
Findings include the thrust setting of the engines was the same, but fuel flow and exhaust gas temperature was slightly less for the engine using the biofuel blend, Jankowski says.
The biofuel-blend-powered engine burned slightly less fuel than the engine powered by Jet A for the same thrust setting, Continental manager of training standards captain Jackson Seltzer explains.
The right engine used 3,600lbs of the biofuel blend and the left engine burned 3,800lbs of jet fuel, he says.
Both fuels emit roughly the same amount of CO2 inflight, but overall emissions savings are realized during the production of biofuels, which unlike Jet A, absorb CO2, Continental chairman and CEO Larry Kellner says.
The aircraft, which operated with an experimental aircraft type certificate, will return to revenue service by midday tomorrow after a borescope inspection of the engine, fuel filters are changed and the fuel tank is washed out with Jet A, Seltzer says.
Continental does not have plans to participate in a second trial and while other carriers have expressed interest, it is unlikely additional demonstrations will occur this year after a 30 January test by Japan Airlines.
"We're encouraging people to look at the data collected to see what's missing before [new trial] flights," Boeing managing director for environmental strategy Billy Glover says, adding he does not expect fuel-certifying organization ASTM International to request additional commercial aircraft alternative fuel demonstrations. Instead, Glover says he expects ASTM will request endurance testing on specific engine components.