Tuesday, April 18, 2006

 

Energy - Hydrogen

Hydrogen cars cannot replace the current transportation demands that gasoline-powered cars provide. The energy density just isn't there. Even if the storage, transportation, energy return on energy invested, and tank size problems can be solved, then ranges and required energies to create the hydrogen result in a greatly reduced energy capacity.

To create hydrogen from methane, use the following recipe.

CH4 (g) + H2O + e > 3H2(g) + CO(g)

Greenhouse gases are still created. The energy used to make the steam (the H2O) is usually produced by burning fossil fuels. Essentially, the pollution has been moved around a bit. Using nuclear power to heat the steam might work, but more plants would need to be built or else diverted from electricity production.

To create hydrogen from water, use the following recipe.

2H2O + e = 2H2(g) + O2(g)

This requires 286kJ per mole. This energy is required by the chemistry of reaction and can never be reduced.

It can be somewhat difficult to get a real picture of hydrogen due to the politicization of this particular technology and the constant rah-rah positive pep talks from the government. The "roadmap" from the DOE reads like a real estate newsletter, with occasional dips into reality.

Hydrogen as a replacement for electricity production will probably be a component of future energy technologies, but declaring it a replacement for gasoline in cars, at this point, is really not believable.


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