Airliners Of The Future?

[The Sky Sailor (PDF) experimental solar-powered aircraft design. It's designed to operate autonomously in the Martian atmosphere. Image credit: Blazing Wings.]

There was an interesting bit of news in the New York Times today about biofuels:

Air New Zealand tested a jet fuel made from the jatropha plant on Tuesday as the airline searches for an affordable and environmentally friendly alternative to crude oil.

For two hours, pilots tested the oil, in a 50-50 blend with conventional jet fuel in one of the four Rolls-Royce engines powering a Boeing 747-400 aircraft — the first test flight by a commercial airline using jatropha oil.

Airline Flies a 747 on Fuel From a Plant

In contrast to other biofuel sources like corn, jatropha is easy to grow:

Unlike other biofuel crops like soybeans and corn, jatropha needs little water or fertilizer and can be grown almost anywhere — even in sandy, saline or otherwise infertile soil. Each seed produces 30 to 40 percent of its mass in oil, giving it a high per-acre yield, specialists said.

Airline Flies a 747 on Fuel From a Plant

There's a site called Jatropha World, which promotes the growing of jatropha for biofuels, among other uses. It even has a form page that has individual reports on how the plant can be grown in a number of countries. From the look of the list of countries, a tropical or subtropical climate is required. Nevertheless, that includes quite a few countries, including India and Australia, that can grow the stuff.

Maybe the most significant part of the NYT report is buried at the bottom of the article:

The International Air Transport Association, which represents 230 airlines, wants its members to use 10 percent alternative fuels by 2017. The association has the goal that airlines will be able to fly carbon-free in 50 years, with the help of technologies like fuel cells and solar energy.

Airline Flies a 747 on Fuel From a Plant

Since airliners typically have a useful life of thirty years or so, this would imply that the next generation of airliners will have to include at least some carbon-free designs. Whether that will be possible remains to be seen, since jet engines don't run on either solar energy or fuel cells. I'm not aware of any such designs now. The only things I'm aware of are experimental designs. These are low powered, and more like gliders with small engines than commercial airliners. It's quite an ambitious goal, given the circumstances.