Pressure on the aviation industry to bear its share of the planned reductions in greenhouse gas emissions could force it to switch to alternative fuels such as hydrogen, according to speakers at a London conference on aerospace propulsion.

A report by Daimler-Benz Aerospace (Dasa) Airbus says the projected 1.5-2% year-on-year growth in powerplant efficiency will be outstripped by the expected 4-5% annual growth in air transport, while the industry may have to cut greenhouse-gas emissions by up to 8% over 1990 levels by the year 2010, following agreement at the United Nations summit in Kyoto, Japan, on 10 December.

Speaking during the Aerospace Propulsion Conference at The Royal Aeronautical Society in London on 9 December, Dr Heinz Klug of the Dasa Airbus Cryoplane project says that even though aircraft contribute only 2-3% of greenhouse gases "-aviation cannot evade these problems, but will have to contribute its share to the reduction".

Cryoplane project manager Hans Pohl says the first conventionally fuelled Dornier 328JET prototype, which is due to make its maiden flight in January, is to be used for hydrogen-fuel research after the flight-test programme is complete. "Development will start in the middle of next year," he adds, with Russian design house Tupolev providing the fuel system and AlliedSignal the auxiliary power unit (APU) to be used in the initial test. The original plan was to use a 328 turboprop but this has been dropped in favour of the turbofan.

In 1996, an Airbus A320 APU was "modified for hydrogen combustion and successfully tested in the full power regime", demonstrating nitrous-oxide emissions 70% below the level with kerosene using a "micromix" combustor, says Klug. The combustor uses a large number of small nozzles to optimise temperature distribution.

The 328JET will be fitted with two 3,000litre under-wing tanks and is scheduled to fly in early 2000 to test the APU, and by the end of 2002 the Pratt & Whitney Canada PW306B engines will also be tested using hydrogen, says Pohl.

Source: Flight International