Originally Posted by
NYU SOM
Correct. In fact, it's the second law of thermodynamics. The first law says you can't create or destroy energy, you can only get it to change form. There has to be an energy input in this system. For example, you could have a nuclear power plant make electricity. You use that electricity to split water into H2O into H2 and O2, you can then burn the H2 along with O2. If each step is 100% efficient then the energy you get from burning the H2 and O2 together is the same amount of energy that the nuclear power plant generated.
Unfortunately the second law of thermodynamics says that you can't be 100% efficient.
This guy appears to say that he splits the water using electrolysis, that requires electricity. Perhaps he could plug the car in at night and use a giant battery on the car, but the energy has to come from somewhere.
In the case of gasoline the energy is stored in the chemical bonds, gasoline is at a higher energy state than CO2 and O2, by converting gas into these components you convert energy from a chemical energy to mechanical energy and heat. Water is already at a lower energy state than H2 and O2, therefore water can't be used as a form of energy.
There is no free lunch.
A good explanation. I think people forget that gasoline (petroleum) is actually solar power. Plants used the solar power input, over the course of millions of years, to put those chemical bonds in place. Millions of years to store it, and we will need only about 200 years to release it all!