When Virgin Airlines flew a Boeing 747 jetliner from London to Amsterdam a year ago February with one of the engines partly fueled by coconut oil and babassu oil, it was for the biofuels movement an historic event, sort of like Louis Bleriot’s first flight across the English Channel.

The flight was initially dismissed as a stunt, but as crude oil prices hit $147 a barrel last summer the idea of powering huge jetliners with some blend of renewable energy resources no longer seemed pie in the sky. Even as crude prices have collapsed, the airline industry is still getting serious about alternative fuels.

The conversion of vegetable crops to biofuels, which are more environmentally friendly than fossil fuels, has nonetheless drawn the fire of environmentalists for a variety of reasons, not least because the conversion of soyabean and wheat acreage to corn for biofuels in the earlier part of this decade was held partly responsible for the dramatic spike in food prices that ended in mid-2007. The airline industry says it has no intention of cannibalizing food production for biofuels, using substitute biofuels like camelina and jatropha oil and algae instead.

But the amount of fuel needed to keep a 397,000 kg 747 in the air is enormous. A Boeing 747-400 consumes an average of 3,600 gallons of fuel per hour. And, although the industry has foresworn corn-based ethanol, the yardstick for corn conversion to biofuels gives some idea of what it would take. A hectare of corn in the United States theoretically produces roughly 1,055 gallons of biofuel. Thus it would take three hectares of corn to keep a single 747 in the air for an hour. The global aviation industry consumes about 240 million gallons of jet fuel a day. That would requre 200,000 hectares a day by the industry, or 73mn hectares of corn a year -- 46.4 percent of the current corn area grown globally.

Coordinated by the Boeing Company’s biofuels division, three more demonstration flights using various blends of biofuels were conducted in December and January, the last being a test flight by Japan Airlines. The results of the four test flights are being watched closely in the industry, which is determined to find an alternative even if it only replaces a small portion of ultimately finite supplies of conventional crude oil.

The JAL 747 that took off from Tokyo’s busy Haneda Airport on an overcast and rainy day in late January and circled over the Pacific Ocean. On landing, Captain Kobayashi said that the performance of the bio-fueled engine seemed indistinguishable from the other three engines. That echoed reports from the three previous flights and is exactly what promoters of sustainable aviation fuels want to hear.

The demonstration flight used a blend of 84% camelina oil, 16% jatropha oil and under one percent algae oil. The three biofuels were mixed 50-50 with kerosene in one of the aircraft’s four engines. It was the first demonstration flight using camelina oil and the first one to use a blend of three different biofuels. Put another way, the JAL aircraft was powered by fuel made from feedstock grown in Montana (camelina), Tanzania, (jatropha) and Hawaii (algae oil).

During the one-hour flight the JAL crew put the aircraft through several normal and sub-normal maneuvers, including quickly accelerating, decelerating, and stopping and restarting the engine. This activity conforms with the maneuvers that other test flights have been put through.

In December an Air New Zealand 747 took off from Auckland flying on a blend of jatropha oil and jet fuel, the first flight using the African weed. In early January a Continental Airlines Boeing 737 flew around Houston on a blend of jatropha and algae oil. It was the only demo flight using a twin-engine jet.

The goal said Jennifer Holmgren, director of renewable resources and chemicals for U.S.-based Honeywell UOP, is to develop a "drop-in" generic biofuel. By drop-in she means a fuel that requires no engine modifications, can be made from several different feedstocks and is chemically identical to ordinary jet fuel. It can be used as economic conditions dictate.

The economics of using biofuels in aircraft are hard to pin down at this stage. Holmgrem asserted that the blend used in the JAL flight could be produced for the equivalent of $115 per barrel, or about $2.50 a gallon. That is only an estimate. The actual cost of the fuel, which had to be specially produced and shipped to Japan for the demonstration flight, was higher.

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Of course, the industry and regulators will not rely solely on the initial impressions of pilots relayed immediately on landing to a clutch of reporters and TV crews. But Nicole Piasecki, president of Boeing Japan, said that her company hoped to have biofuel certified for use on "revenue-generating flights" in three to four years.

Camelina is a vegetable oil crop grown mostly in the northern plains of the U.S. and western Canada. It is technically a vegetable oil crop but is considered a second-generation biofuel as it has little food value and is used primarily as a biofuel feed stock. It was sourced from Sustainable Oils based in Bozeman, Mont. and Seattle. Chief Executive Tom Todaro was in Tokyo for the demonstration and said that his company has already contracted with farmers to plant 10,000 acres dedicated to camelina. "The infrastructure is in place".

"By 2011 we hope to be making 100 million gallons of camelina oil a year and a billion gallons 10 years after that. Of course, it will not be in double-digit figures as a percentage of petroleum-based jet fuel used in aviation. But it is a beginning," he said.

The Four Biofuels Tests Airline Aircraft Engine Feedstock

Virgin Airlines B747 GE coconut oil, babassu oil

Air New Zealand B747 Rolls-Royce jatropha oil

Continental B737 CFM jatropha oil, algae

Japan Airlines B747 Pratt camelina, jatropha, algae

The airlines say they plan to use only second-generation biofuels, that is fuels from plants that are not staple foods, such as corn or sugar cane, indeed are not even food. Camelina is now used as a rotation crop, planted on land that is allowed to lie fallow to absorb moisture in dry-wheat-growing areas. The crop itself does not require much water.

Of course, any plants grown on arable, or even marginally arable land, could be in competition with food stuffs. In Theory camelina could become so lucrative that farmers would convert wheat growing land to camelina, instead of simply planting it on fallow land.

Perhaps the only true second-generation biofuel in the mix is algae oil. It is grown on the surface of open ponds. It is also said to be 100% carbon-free. The drawback is that there isn’t much of the stuff available, and it is unlikely that there will be in the near future.

Sapphire Energy, one of several new companies working to produce jet fuel from algae oil as a alternative fuel, projects producing 10,000 barrels a day in five years. But that is almost literally a drop in the bucket compared to the mount of petroleum-based jet fueled consumed every day.

The airlines began to look seriously at potential new fuel sources when crude oil prices went through the roof last summer leading some airlines to file for bankruptcy and caused other to find ways to cut costs or impose fuel surcharges. Although prices have slackened considerably, the industry does not want to get burned again.

All the demonstration flights were taken on jets made by Boeing which has been coordinating all of the tests. "We’re the common thread, enabling the [biofuels] industry," said Darren Morgan, Director of Biofuels Strategy for the Boeing Commercial Aircraft Co. "We help bring feed stock and fuel processors and airlines together." He noted that there had been no untoward incidents in the four demonstration flights so far. "The fuels have met or exceeded expectations."