Plans on how the algae fulled planes would work
Plans on how the algae fuelled planes would work (EADS)

Engineers are planning to build the first "hybrid" airliner propelled by a combination of wind, electricity and biofuel from algae.

Aerospace company EADS, maker of Airbus aircraft, and engine manufacturer Rolls-Royce are working to build a passenger aircraft that would produce 75% less carbon dioxide than a typical plane.

Using a similar principle to the hybrid engines used in some Toyotas, the designers are hoping to make planes less dependent on kerosene-based fuels.

Jean Botti, chief technical officer of EADS, said: "Microalgae are considered one of the most promising pathways for the production of biofuels for Aviation.

"We have already proved that it is technically possible to fly with Algae Oil. Now we need to demonstrate that the industrial production of algae-based biofuel is both ecologically and economically viable."

Biofuel made from algae is a more realistic means of providing power than electricity alone, since an electric plane would not be able to carry more than a handful of passengers. However, the hybrid system thought up by EADS and Rolls-Royce - where batteries are recharged during the flight by another energy source - could one day power airliners carrying up to 120 passengers for two hours.

Under this new design, the plane would be propelled by six electric fans on the back of its wings.

The engine would be powered by biofuel made from microalgae, which would generate the electrical power.

Algae can be grown on poor quality land and pond water, and emit eight times fewer hydrocarbons than kerosene when combusted.

During take-off and flight, the plane's fans will draw power from a lithium battery, which the engine will recharge once the aircraft has reached cruising altitude.

The plane will initially just "glide" its way towards its destination, with the fans acting like wind turbines to generate electrical energy to top up the battery for the extra power it will need for landing.

"It's just like having an energy-efficient car, which has a hybrid system," said Henner Wapenhans, head of technology strategy at Rolls-Royce.

Botti believes that this type of plane could be fully operational within 20 years.