- Hydrogen planes
Hydrogen planes are airplanes that use
hydrogen as afuel source.As an alternative to
jet fuel , hydrogen has a higherenergy density per unit "mass" but a lowerenergy density per unit "volume", and containing the hydrogen at high pressure would require a heavy container. If hydrogen were available in quantity from renewable energy sources, its use in aircraft would produce fewer greenhouse gasses (water vapor and a small amount of nitrogen) than current aircraft, and therefore it would, be better for the environment. However, currently little hydrogen is produced using renewable energy sources, and there are several serious obstacles to the use of hydrogen in aircraft and other vehicles. [ [http://www.h2-vehicles.com/hydrogen-aircraft.htm "Hydrogen aircraft" at H2-Vehicles.com] ] According to research at thePennsylvania State University in 2006, large commercial hydrogen aircraft could be built by 2020 but "will probably not enter service until closer to 2040." [ [http://www.engr.psu.edu/symposium2006/papers/Session%203E%20-%20Energy/Maniaci.doc Maniaci, David C. "Operational Performance Prediction of a Hydrogen-Fueled Commercial Transport" 2006 symposium paper] ]The
European Union has developed a research project in cooperation withAirbus and 34 other partner companies for ahydrogen powered aircraft dubbed CRYOPLANE. [ [http://ec.europa.eu/research/transport/news/article_786_en.html The EU Comission Research department: Cryoplane project] ] According to the technical assessment of the project, hydrogen-fueled aircraft engines will be as efficient as the current kerosene ones but storage and weight related problems still remain to be solved. Unmanned hydrogen planes have been tested, and in February 2008Boeing tested a manned flight of a small aircraft powered by a hydrogen fuel cell. "The Times " reported that "Boeing said that hydrogen fuel cells were unlikely to power the engines of large passenger jets but could be used as backup or auxiliary power units onboard." [Robertson, David (3 April 2008). [http://business.timesonline.co.uk/tol/business/industry_sectors/transport/article3675188.ece "Boeing tests first hydrogen powered plane"] , "Times Online".]The
Soviet Union successfully tested a Tu-154 plane flying on liquid hydrogen in April 1988.Properties of hydrogen aircraft
Hydrogen aircraft are usually designed so that the liquid hydrogen fuel is carried in the body, to minimise surface area and reduce boil-off. Normal aircraft use wings for storing fuel.
Because hydrogen has such a low density, the
ballistic coefficient of a hydrogen fuelled aircraft relative to a similarly sized aircraft would be much lower. In addition hydrogen has a much lower energy density. The combination of effects means that the hydrogen aircraft have low range, although the higher specific energy helps reduce the deficit as it halves the specific fuel consumption. Nevertheless, it turns out that most hydrogen aircraft designs are very big, both in length and diameter.References
ee also
*
Hyfish
*Smartfish
*Hydrogen economy
*Hydrogen vehicle External links
* [http://www.h2-vehicles.com/hydrogen-aircraft.htm Information about hydrogen aircraft]
* [http://www.hydrogenplanes.com Hydrogen planes information site]
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