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Originally Posted by eco.conduite.free.fr
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BMW has had H2 "demonstration cars" for a few years as well. An ICE will do OK running on H2 (as it will on propane or methane), and do a lot better if optimized for the fuel. Primary issues with H2 cars are:
- Fuel availability - Right now, no cost-effective way of generating H2 is commercially available. Generating H2 gas via solar panels is possible, but the issues of compressing the gas (see density) or chilling to liquid are immense.
- Fuel transport - H2 is a 'cockroach element' that can pass through many 'conventional' materials. Coupled with pressures and temperatures (for liquid form), transport becomes problematic. Like most gaseous fuels, venting and over-pressure are a challenge to manage.
- Energy density - BTU for a given volume. Compressed gas is low density, liquid form is a problem for handling. NASA's grief with the shuttle is a good example of the operational challenges with H2 as a fuel.
- Fuel storage. Liquid leakage/boil-off and even compressed 'diffusion' are both problems.
The most fundamental issue of H2 on an ICE is simple efficiency - for a given storage volume, an ICE presents such poor efficiency as to make the vehicle unacceptable in range when fueled by H2. Even fuel cells have a range issue, and their efficiency is much higher.