When I was in high school, I happened upon a report at a library that described the benefits of hydrogen as a fuel. Hydrogen is everywhere. It is one of the most common elements in the universe. One proton, one electron, just hanging out.
Hydrogen and oxygen make up what we know as water. We know it as H2O two atoms of hydrogen and one atom of oxygen. Water covers 78% of the surface of our home, the Earth. Hydrogen is a limitless source of energy for all practical concerns.
Hydrogen is therefore, a component of all life, too. Every organic molecule, proteins, enzymes, even fuels, have hydrogen in its composition.
Using hydrogen as a fuel is novel in the sense that when you burn hydrogen, what you get is water vapor. That's it. Scientists have tried for many years to make hydrogen an economical fuel. In terms of abundance, it's a great fuel. In terms of extracting hydrogen from other substances, not so great.
For example, electrolysis is a common method for extracting hydrogen from water. We call that process "splitting water". We've known how to do it for centuries, but it takes a lot of energy to crack it. Some have made very interesting advances in splitting water, but we still need to get the energy from somewhere.
Dr. Daniel Nocera has found a way to split water using a catalyst and sunlight. This is ingenious in conception and design. The catalyst can even make water potable when exposed to sunshine while splitting water. There are still many bugs to work out, but this seems like a viable option in the near future.
One big problem with using hydrogen as fuel in a car is storage. Hydrogen has a very low density - fill a balloon with hydrogen and it rises, like helium, only better. This is great for balloons and blimps, not so great for storage as fuel.
So scientists have been working out ways to store it. They've found all sorts of metals and ceramics to store it, but none are very practical or economical. Storing hydrogen in another fuel for cracking later is probably our best option. Toyota and the UK's Science and Technology Facilities Council may be able to bring a hydrogen car to market as soon as 2015 with a novel concept: store the hydrogen as ammonia and then crack the ammonia in the car.
This is a tantalizing option. The catalyst is cheap and easy to produce, using abundant elements, and ammonia can be stored in low pressure containers. This could be the breakthrough we've been looking for to create a hydrogen fuel economy.