Hydrogen

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Hydrogen is a chemical element. It is the simplest atom in the Universe. On a periodic table of the elements, hydrogen is on the top row, usually either on the left or on its own above the transition metals. Its symbol in science is H. Scientists give atoms what they call an atomic number, and the number they have for hydrogen is 1. In its pure form hydrogen is most commonly found on Earth as a gas. Hydrogen is often found in water, but a water molecule is actually made up of one oxygen atom with two hydrogen atoms stuck on one side. The most important thing about hydrogen is that it's the fuel that keeps the Sun burning.

Pure hydrogen, though, is normally found in groups of two atoms. Scientists call this diatomic. Hydrogen will have a chemical reaction when mixed with most other elements. It has no color nor smell.

It is:

• A gas at room temperature
• A non-metal
• The lightest of all the elements in the periodic table
• The lightest element in the Universe
• The most common element in the Universe

However, hydrogen is very uncommon in the Earth's atmosphere. It is mostly found in water (where it is combined with oxygen) and in all organic compounds and living things. Hydrocarbons, like fossil fuels, are compounds where hydrogen is combined with carbon.

The name "hydrogen" comes from the Greek word for water, 'υδορ (pronounced /HEEW-dor/).

Hydrogen has two different isotopes which are heavier types of the Hydrogen atom, they are called: deuterium and tritium. These other types of Hydrogen are important in nuclear energy.

[change] Hydrogen as fuel (fusion)

Scientists believe atoms are made of protons, neutrons and electrons. From a physics point of view, hydrogen has one proton, and its variants (atoms that are very like hydrogen), deuterium and tritium, also have neutrons.

Nuclear fusion is a very powerful source of energy. It relies on forcing hydrogen atoms together to make helium and energy, exactly as happens in a star like the Sun, or in a hydrogen bomb. This needs a large amount of energy to get started, and is not easy to do yet. A big advantage over nuclear fission, which is used in nuclear power stations, is that no waste is produced, and no toxic fuel like uranium is needed. There is a lot of deuterium in seawater. There is more than 600 million tons of hydrogen undergoing fusion every second on the sun.

[change] Burning Hydrogen

1. Water can be easily broken down into hydrogen and oxygen with electricity, but it takes a lot of electricity to get a usable amount of hydrogen.

2. Burning hydrogen combines with oxygen molecules to make steam (pure water).

3. A fuel cell combines hydrogen through a catalyst with an oxygen molecule releasing an electron as electricity.

[change] Hydrogen power grid

For these reasons, many people believe hydrogen power will eventually replace technologies such as diesel-electric engines and biodiesel fuel.

But it is not correct to see hydrogen as a fuel if it is used in a fuel cell. It is more of a replacement for the power grid. Such a grid and infrastructure with new vehicles might be first made in Iceland, a country that has much free geothermal energy and is quite small. Because it imports all fossil fuel, it would help Iceland to completely stop using it. The huge advantage of hydrogen is that when burnt in an engine or in a fuel cell, there is no pollution - just a small amount of water. It's a pain to store, though - it has to be kept under high pressure - and cooled as well. For vehicles, it seems more realistic to use liquid fuels, at least at present.

If we did move to a hydrogen economy where could the hydrogen come from? Well, there are many places - it can be extracted from water (but this of course will use more energy than you would get back by using it in a fuel cell or an engine). It can be extracted from various types of plant material - corn is possible, though pretty inefficient. Generally it is probably better to refine such material into a more conventional fuel like ethanol.