WHAT IS HYDROGEN?
Hydrogen is the most common and simplest of all the elements. It has an atomic weight of 1. However, you wont find hydrogen just laying around, it is almost always bound up with something else. The most common element on earth it bonds with is oxygen. This little beastie is Di-hydrogen-monoxide. It has been known to be fatal if inhaled in quantities as small as a spoon full, can scald in its vapor form, and is the main ingredient in almost all poisons. You guessed it h20. Good old water.
HOW DO WE PRODUCE HYDROGEN?
Hydrogen is in water but is also present in methane (natural gas) and this is where most of today's hydrogen comes from. Steam reforming of methane produces lots of hydrogen but also lots of co2, a green house gas. A much better way to produce hydrogen would be to use solar or wind power, or in a pinch nuclear power (however this comes with its own problems) to electrolyze water.
WHAT IS ELECTROLYZING?
Electrolyzing is the process of breaking down water into oxygen and hydrogen. The equation goes something like this.
h20 + energy = h2 + o2
(the extra hydrogen's tend to bond together)
So as you can see when you use solar or wind or nuclear power to electrolyze "bust up" water you get hydrogen and oxygen. The oxygen almost always combines with some hydrogen so you also get some water vapor. Lucky for us this process works even better when there is some salt in the water. If only we could find some place where there is lots and lots of salt water....
CAN HYDROGEN BE USED AS A FUEL?
Because hydrogen is always bound up with something else, it always takes energy to bust it loose. Because of this hydrogen is not a good fuel. It can be thought of as a storage medium for energy. Using solar or wind power to bust hydrogen loose from water can be looked at as "storing" the energy from the sun or wind "in" the hydrogen. Then we can ship the hydrogen around. Its almost as if the hydrogen is a battery we are using to store up energy to be used later.
But when we are thinking of hydrogen as a "fuel" that is if we are going to use it in a fuel cell or even just burn it, it's great stuff. When you burn natural gas you get all sorts of harmful bad stuff you would never want to breath in. And you get a bunch of co2 that causes global warming. And natural gas is the "cleanest" fossil fuel. When you burn hydrogen (or use it in a fuel cell) the only thing you get is oxygen and water vapor. That means if you car ran on hydrogen and you were feeling a little groggy one morning you could take a nice hit off of your tail pipe as a pick me up (I wouldn't recommend doing this with any other kind of fuel)
WHAT ARE FUEL CELLS?
So what is a fuel cell? Well the fancy definition is "an electrochemical device that converts the results of a chemical reaction directly to electricity". What that really means is it makes electricity without burning something or turning a generator. This is great because it means all we have to do is keep pumping in the chemicals it needs to run and we will keep getting energy. Most fuel cells run on hydrogen (hence why they are mentioned in this section). Fuel cells like solar cells have a limited amount of power they can put out. But like solar cells they can be combined together to achieve more power (much like using two "AA" batteries in your walkman instead of one). This combination is called a stack. Stacks can be sized to the load. So a small stack could power a calculator, a large stack could power an entire building or even an entire town.
WHAT ARE THE BENEFITS OF USING HYDROGEN?
Hydrogen is good because when used to produce power it doesn't produce any harmful byproducts. It is also the most plentiful element on our planet. If we use wind or solar power to produce hydrogen from sea water, we could easily run just about anything with fuel cells or by directly burning hydrogen. Many places already have fuel cell busses, and both the UK and California have started to open hydrogen fueling centers. Soon you could be filling up your car with hydrogen and blissfully pumping oxygen and water vapor out of your tailpipe as you went to work every day.
WHAT ARE SOME DRAWBACKS TO USING HYDROGEN?
Hydrogen does not occur alone in nature. The amount of energy it takes to break hydrogen loose from water, means that it is not efficient to use hydrogen as a fuel. If we are using wind or solar power to create hydrogen we would be better served to simply use that power directly. Only when we have lots of extra wind or solar energy laying around (something that wont happen any time soon) would using that energy to create hydrogen be a good idea.
Hydrogen is also very hard to transport, being the lightest element on earth means that its very hard to keep in a container. If you cool it down so it becomes a liquid you have to keep that container very cool. All of this takes energy. More energy currently than you will get from using the hydrogen as a fuel.
WHAT IS THIS HYDROGEN ECONOMY I HAVE HEARD ABOUT?
The hydrogen economy would be one based on hydrogen and not oil. Cars, trucks, power plants, everything would run on hydrogen. This is not going to happen anytime soon. Currently it takes too much energy to produce hydrogen . If we had enough surplus solar and wind energy we could use the extra to create hydrogen. Once this happens we will have a hydrogen economy. Most people that talk about the hydrogen economy are talking about a time 50 years in the future.