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Graphic element Research > Growth > Research projects > Aeronautics projects > Future flight
Graphic element Future flight

Economy and society today are characterised by a high degree of mobility, and indeed depend upon it. Without the free and cost-effective movement of products and people, our global economic system would simply not work. Demand for air transport is currently increasing by some 4 to 5% per year and expectations with regard to the availability of efficient transportation will undoubtedly continue to grow, especially in the newly emerging economies of Asia and South America.

While air traffic has been on the increase for many decades now, the sustainability of its growth is uncertain under today's technical conditions. Since the Earth Summit held in Rio de Janeiro in 1992, the need to reduce carbon dioxide emissions has been widely accepted, and at the Kyoto summit on climate change in 1997, industrial countries agreed to reduce their emissions by 5.2% by 2008/2012. Despite the stern warnings issued at these global summits and subsequent measures to redress environmental degradation, fossil fuel resources will eventually run out of their own accord.
Under such conditions, it is evident that improvements in conventional aircraft and engine technology and in the efficiency of the air traffic system will not fully off-set the effects of increased emissions resulting from the projected growth in aviation.

Search for an alternative fuel
Of the possible alternative energy carriers, liquid hydrogen, currently in use in rocket boosters and in some experimental land vehicles, would seem to be among the most suitable for use in aircraft. It can be produced from water by electrolysis using electrical energy from renewable resources, and it releases only water and very small amounts of nitrogen oxides upon combustion.

With that in mind, 35 partners from 11 European countries, representing industry, research entities and universities have come together in a comprehensive "system analysis" of liquid hydrogen fuelled aircraft. According to project co-ordinator Heinz Guenter Klug of EADS Airbus, all of the partners, big and small, are playing important roles in what he hopes will be a long-awaited success. Dubbed CRYOPLANE, the project will assess the technical feasibility, safety, environmental compatibility and economic viability of using liquid hydrogen as an aviation fuel.
Among the goals are the delineation of aircraft configurations for all categories of commercial aircraft, from business jets to A3XX-type very large long-range aircraft, as well as new concepts. Performance and fuel efficiency will be quantified. The architecture of the new liquid hydrogen fuel system and its potential synergies with other aircraft systems will be assessed. New engine concepts will be defined, with emphasis on minimising nitrogen oxide emissions. Aircraft-specific safety aspects will be studied and a hydrogen-specific fire protection system will be elaborated.
Finally, and perhaps most importantly, the CRYOPLANE project will attempt to indicate possible strategies for making a smooth transition to the new fuel. Airport infrastructure for fuel production and distribution will be considered and ground and flight operations will be analysed.
An unusual aircraft configuration

Four litres of liquid hydrogen are required to store the same amount of energy contained in just a single litre of kerosene. The necessarily large volume of fuel will therefore require changes in the configuration of the aircraft. In addition, holding tanks for liquid hydrogen have to be either spherical or cylindrical in shape. Tanks on top of the fuselage are a possible solution for big passenger aircraft. The high-energy content of the new fuel in relation to its weight will allow an increase in the payload fraction of the aircraft. Safety can be expected to be at least equal to, and in certain respects even significantly better, than that of kerosene-fuelled aircraft.

  No change without incentives

The development of air traffic within a specific country depends in large part on its economic power. In 1996, the USA, with only 4.6% of the world's population, generated 41% of the world's air traffic, while China and India with 37% of world population contributed only 3.4%. Thus, there is still a huge potential for growth in global air traffic and, given the environmental constraints already mentioned, someone is going to have to step in and close the gap.
The transition from fossil fuels to liquid hydrogen will not be an easy one, says Klug. Liquid hydrogen is expensive to produce and operators are likely to resist making the switch if there are no convincing economic reasons to do so. The new aircraft will have to be accompanied by new emission regulations, depending on how it is decided to implement the Kyoto agreement. An emission charge, for example, could provide the economic motivation for switching to clean energy sources. While this need not make the cost of buying a plane ticket prohibitively more expensive, it will provide the incentive to airline operators.
Once the system analysis is complete, technology development and ground and flight testing are expected to take at least 10 years.

For more information on EADS and CRYOPLANE see:

Search for an alternative fuel
An unusual aircraft configuration
No change without incentives

Key data

Funding provided under the New perspectives in aeronautics key action is pushing forward the search for alternatives to fossil fuels. The aircraft industry is likely to gain from research into liquid hydrogen fuel, helping it keep up with increasing demand while meeting the need for greater environmental protection.

Project: CRYOPLANE - Liquid hydrogen fuelled aircraft - system analysis

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