Aircraft

Boeing believes that biofuel blends will eventually be cheaper for airlines to use than conventional kerosene if the price of a barrel of crude oil remains above the $100 mark.

Having initially expected its studies of alternative fuels to last only a few months, the manufacturer has continued its work for two years after discovering promising techniques for reducing airline emissions.

"It looks like we've overcome the feasibility challenges," says Boeing energy and emissions technology leader Dave Daggett.

"Right now it doesn't look like this is going to be a really low-cost option, but we could probably make a biojet fuel that costs less than current fuel right now," he adds. "Plants, with algae showing particular promise, could supply biofuel to satisfy the world's aviation needs."

Daggett thinks the planned inclusion of aviation in Europe's emissions trading scheme is "what's driving the interest from a lot of the airlines. We're interested in it because our customers are interested in it."

For example, "lifecycle" carbon dioxide emissions for algae-derived biofuels would be up to 70% lower than conventional fuel, taking into account the CO_² absorbed during cultivation in sewage water, says Daggett. The fuel could be used as a drop-in replacement for kerosene without requiring engine modifications.

"We feel pretty confident now that it's going to meet the requirements. Algae really looks promising," says Daggett. "The scenario that we like has to do with using this waste water. We think that's a pretty good path that we would want to go down."

The oil harvested from algae cultivated in sewage represents up to 60% of its biomass, and the process has the added benefit of discharging clean water.

Boeing is hoping that the first biojet fuel blend will be certificated by 2013. It is participating in a biofuel demonstration flight due to take place later this month using a Virgin Atlantic 747.