WELLINGTON, New Zealand (AP) -- A test flight of a commercial airliner partially powered by plant oil showed the biofuel could reduce greenhouse gas emissions by up to 65 percent on long-haul flights, Air New Zealand said Friday.
During a two-hour flight in December, one engine of a Boeing 747-400 was powered by a 50-50 blend of oil from the plum-sized fruit known as jatropha and traditional jet fuel.
The test confirmed that up to 1.5 tons (1.35 metric tons) of fuel can be saved on a 12-hour flight -- a little more than 1 percent savings -- said the national carrier's chief pilot, Dave Morgan. The blend would cut carbon dioxide emissions by about 5 tons (4.5 metric tons) -- or at least 60 percent.
Morgan called the fuel savings "significant," though the monetary gain depends on the price of oil.
"At the moment these feed stocks ... are still facing the challenge of reaching cost competitiveness with conventional jet fuel," particularly when the price of oil is around $60 a barrel, Andrew Herdman, director general of the Asia Pacific Airlines Association, told The Associated Press.
Biofuels would become competitive sooner if an emission trading system raised the price of carbon-based fuels, he said.
Air New Zealand obtained the jatropha oil for its test flight from Malawi, Mozambique, Tanzania and India. Seeds from the jatropha -- a bush with round, plum-like fruit -- are crushed to produce a yellowish oil that is refined and mixed with diesel.
Some environmental groups have questioned whether jatropha and other plants used as biofuels are sustainable. They have expressed concerns about the plants' impact if more land and resources are devoted to growing them on a commercial scale.
Herdman warned that while several airlines are testing biofuels and have shown promise, the "drop-ins" as they are called still face "another couple of years' work to demonstrate that it can be certified" as an additive to jet fuel.
"Airlines, we're not too demanding.... It's got to perform exactly the same or better, and it's got to be a competitive price," he said.
Morgan also cautioned that "many more steps" were needed before biofuel could become "a commercial aviation fuel source."