Alternative jet fuels: Decades away?
While alternative automotive fuels are being produced and used at a record pace, alternative jet fuels are not receiving the same amount of attention. While it is not as obvious as pulling up to the pump every few days, increasing gas prices are having a significant impact on airline ticket prices. Both government and corporate researchers are investigating alternative fuels for commercial jet engines, but widespread use seems to be decades away. One major obstacle faced by alternative jet fuels is the harsh conditions they are transported and used in, and for now alternative jet fuels are currently more expensive than traditional ones. Most commercial airplanes use a form of light kerosene, which is heavier than gasoline but lighter than diesel fuel. One alternative under investigation is biodiesel, but it freezes at a much higher temperature than the traditional jet fuel, which is a problem when considering the temperature at 35,000 feet. Scientists are working on ways to keep the fuel from freezing easily. Just like in automotive applications, we are likely to see blends of biodiesel and jet fuel appear first. Hydrogen is an other alternative, which would require little modification to the jet engine, but just as is the case with cars, storage is a major issue. One other concern is the amount of water produced by a hydrogen burning jet engine. While in cars the water is released close to the surface, at altitude, the hydrogen burning jet engines could become a cloud-making machine, the impact of which is unclear. [Source: MSNBC]
Reader Comments (Page 1 of 1)
Howard Lee Harkness 8:43AM (6/26/2006)
The first crash of a hydrogen-fueled airliner would put a permanent stop to that nonsense -- except that the shear expense will prevent that first flight anyway. In addition to having a very wide range of explosive mixture, hydrogen is a grossly inefficient storage mechanism for energy. Consider the fact that there are more hydrogen atoms in a gallon of kerosene than in a gallon of liquid hydrogen, and a gallon of liquid hydrogen has less than 10% of the usable energy content of a gallon of kerosene.
The technical challenges of using biodiesel are a couple of orders of magnitude easier to deal with than trying to use hydrogen to power aircraft. Adding some insulation and a heater/recirc pump to the fuel tanks is far more feasible.
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Tim Russell 3:53PM (6/26/2006)
Unless a cheap way to produce Hydrogen is found it will remain a poor energy storage medium. The costs of compressing or liquifying it add to the equation against using it. I think time is better spend on things like waste to fuel in producign biodiesel etc. That being said something must be cleared up.
"The first crash of a hydrogen-fueled airliner would put a permanent stop to that nonsense -- except that the shear expense will prevent that first flight anyway."
Ah the Hindenburg argument. Sorry but how is a bunch of buring hydrogen which being lighter than air will rise when released worse than liquid jet fuel which when it leaks will pool, stick to things and people and burn. In a crash it mixes with air and explodes. Hydrogen when released will become a gas and will rise. Humm, buring liquid sticking to things or buring gas rising.
Years ago popular mechanics had a story on hydrogen powered aircraft. The Govt already tested it in the 50's or 60's and it worked well.
Also:
In 1988, a triple-jet-powered, modified Tupolev-154 airliner was flown in the former Soviet Union using liquid hydrogen as a fuel. Daimler-Benz Aerospace Airbus (DASA), in cooperation with Russia, is developing a liquid-hydrogen-powered aircraft. The only drawback is that adjustments in manufactured parts and components will be necessary to handle the cryogenic liquid hydrogen. The cryogenic temperature range is from -150 degrees Celsius (-238 degrees Fahrenheit) to -273 degrees Celsius (-460 degrees Fahrenheit).
So your "first flight" happened almost 2 decades ago.
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Ian 2:04AM (6/27/2006)
Arg! The Hindenburg BS again. It would be nice if people actually knew why the airship exploded. It had nothing to do with hydrogen and everything to do with static build up on the skin of the ship and the water proof coating used on that skin, a mixture that was mostly aluminum oxide, a key ingredient in solid rocket motor fuel. Due to heavy rains some panels held more of a charge than others. When the ship was grounded some panels discharged faster than others and an electrical arc resulted between at least two of the panels which ignited the coating and went up in a big billowing ball of fire. That’s the reason the ship continued to float a bit even while burning: the gasbags were not immediately breached or on fire. All of the flame and conflagration was burning aluminum oxide and diesel fuel.
Doesn't anybody watch the Discovery Channel anymore? Oh the humanity!
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Tim Russell 11:46AM (6/27/2006)
I did see that show as well and knew that fact.
I thought I'd point out the other problem with people's H2 explosion fear.
In a crash I see leaking jet fuel as more dangerous. Liquid fuels pool on the ground and can soak clothing and coat objects making them flammable or more flammable. Crash sites usually have a few ignition sources around so no need to discuss further the outcome. Usually the result is a crash followed by fire in short order. Liquid H2 once free from it's tank will quickly change to a gas state and being lighter than air will rise. It will not be sprayed around on the ground, pool, soak clothing etc. Therefore the danger would be less. Sure there may be some fire from the leak in a tank and it might even be blowtorch like but it would be a localized event by the breach.
Supercold liquids can cause freeze injurys so crash survivors may be injured by this but probably no more than are burned by jet fuel fires. So we could call that even.
So now that we put the fear factor to rest my only problem with H2's use is the energy cost of producing and storing it. Some of these things will be overcome, maybe we'll develope clean stationary souces of power that are so cheap to operate that the cost of producing and compressing/liquifing H2 for a transportation fuel are worth it considering the benifits.
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