Super-fast speed — think Tokyo to L.A. in 2 1/2 hours — isn’t the only cool feature of the Zero Emission Hyper Sonic Transport proposed by EADS. At the Paris Air Show this week, the aircraft manufacturer and Airbus parent revealed its proposed passenger aircraft, which would be run on, among other sources, liquid hydrogen and biofuel.

The aircraft, which EADS said could be standard by 2050, would cruise at Mach 4 speeds nearly 20 miles high — inside the Earth’s atmosphere. Demonstration technologies could be ready by the end of this decade.

Companies at the Paris show were buzzing about clean-fuel options. Airbus and Parker Aerospace said they would look into fuel-cell technology that converts hydrogen and oxygen into electricity and creates water as exhaust. The pair said that flight tests could happen by mid-decade.

The Air Transport Assn. of America, the industry trade group, said a slew of member airlines signed letters of intent to partner with Solena Group. The company produces its GreenSky California fuel from biomass at a Santa Clara County facility.

By 2015, Solena plans to have 16 million gallons of jet fuel ready each year, made from urban and agricultural waste that would otherwise end up in landfills.

Carriers including American Airlines, United Continental Holdings, JetBlue Airways, Southwest Airlines and US Airways said they were interested in using the fuel at airports including Oakland, San Francisco and San Jose.

ASTM International, which creates standards for a number of industries, is expected in July to formally approve renewable biofuel blends with tradtional jet fuel for commercial flights.

Also, South San Francisco company Solazyme Inc. said the U.S. Navy successfully demonstrated its algae-based fuel Solajet by combining it with petroleum fuel to fly a MH-60S Seahawk helicopter.

Last month, the Air Force Thunderbirds performed using a mix that included biofuel made from the camelina flower.

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-- Tiffany Hsu

Photo: the Zero Emission Hypersonic Transport -- a commercial aircraft able to transport 50 to 100 people. Credit: EADS / AFP/Getty Images. Video: A U.S. Navy MH-60S Seahawk helicopter became the first Navy aircraft to fly on a 50-50 blend of algae- and petroleum-based fuels. Credit: Naval Air Systems Command