What is hydrogen?
Hydrogen is the lightest, simplest and most abundant chemical element in the universe. On earth, it occurs in almost limitless quantities as a constituent of water (H2O) and in fossil fuels such as natural gas (CH4) and in other organic matter. In its molecular form (H2), it is a colourless, odourless, non-toxic, highly combustible gas.
How is hydrogen produced?
55 million tonnes of hydrogen are currently produced each year. Most of this is produced by ‘reforming’ natural gas, a process in which gas and water are reacted at high temperature to produce hydrogen and carbon dioxide. Another process, electrolysis, produces hydrogen by passing an electric current through water. If renewable electricity is used, no carbon dioxide or other pollutants are produced and this is the best method for producing totally clean hydrogen.
Why should we use hydrogen for clean energy?
In many ways, hydrogen is the perfect fuel. In combination with renewable electricity, it can be produced, stored and used to generate heat and electricity without producing any greenhouse gases or air pollutants. It has the potential to be a completely clean, inexhaustible fuel that can act as an energy carrier in much the same way as the fossil fuels that we are currently used to.
Why isn’t hydrogen widely used as a fuel today?
Hydrogen is used daily by many large scale industries for the production of petrol, chemicals, foods and electronics. Until the early 1970s, hydrogen was widely used in the UK as a fuel for domestic heating and cooking in the form of town gas. Production of town gas, mostly from coal, was a dirty process and the decline of coal reserves and discovery of large amounts of natural gas resulted in a large scale conversion. Historically, petroleum products have been used as transport fuel because of their wide availability and the ease of transporting them as liquids.
Is hydrogen dangerous?
Yes. Like all fuels, hydrogen gas is highly flammable and it can form explosive mixtures with air. In many ways, hydrogen is safer than petrol and diesel. The chance of forming explosive mixtures is limited by the fact that hydrogen is 14 times lighter than air. A gaseous hydrogen “spill” diffuses away so quickly that it escapes into space. It does not pool on the ground around the leak and it does not pollute the ground or groundwater.
Hydrogen in vehicles is stored at high pressure in highly engineered cylinders which are extremely strong.