Can aviation go green with algae-based biofuels?

Virgin Atlantic thinks it can green commercial aviation with biofuels:

When a Virgin Atlantic Boeing 747 took off for a 40-minute flight from London to Amsterdam Feb. 24, it represented an aviation breakthrough. For the first time a commercial airliner took aloft on other than fossil fuels. One of the plane's four engines was fired on a 20 percent biojet fuel blend. The aim of the test flight was to explore how a biofuel performs in high altitude cold temperatures…

The next test aims to validate sustainability. When the Air New Zealand test takes place, it will be with a second generation feedstock. Of the possibilities, two are worth noting: algae and jatropha. Both grow on non-agricultural land. Algae can employ saline water, and jatropha grows in dry conditions on degraded lands, in fact helping accumulate carbon in the soil. There are solid indications that biojet from jatropha or algae could provide massive amounts of fuel, and at costs lower than petroleum-based jet fuel.

Boeing's own presentation on alternative fuels shows that land use issues are part of the sustainable biojet program's DNA. "If the world airline fleet used 100% biojet fuel from soybeans, it would require 322 billion litres," the presentation says. At 560 liters of oil per hectare that would require 5,750 million square kilometers, about the size of Europe. But algae could produce up to 94,000 liters per acre, shrinking land requirements to 35,000 square kilometers, about a Belgium's worth of land.