The fuel of the future.

Hydrogen is the fuel of the future.

That's the claim made by a number of scientists. They think that hydrogen is such a good fuel that ii will one day replace all of the fuels used at present. Could the scientists be correct. Judge for yourself as you read on.

A good fuel should produce large amounts of heat when it burns. Heat energy is measured in kilo-joules’ (kJ). Burning 1g of hydrogen produces 143 k] of heat, enough to boil a large cupful of water. (Burning 1 g of petrol produces 48 kJ. Burning 1 g of natural gas produces 58 k).

A good fuel should be cheap and easy to produce. There is a very small amount of hydrogen gas in the atmosphere, but it

Cannot be easily separated from other gases.

Hydrogen gas can be produced from water, and there is plenty of that. At present, most hydrogen is made by heating steam and natural gas together, or by passing an electric current through water. Unfortunately, these methods are expensive. More energy is needed to make the hydrogen than could be produced by burning it! A recently discovered method, however, could lead to hydrogen being produced more cheaply. It uses light energy from the Sun to split up the water.

A good fuel should be easily transported and stored.

Hydrogen can be stored as a liquid under pressure in strong tanks. It can be transported from one place to another by pipes. That makes

Hydrogen useful in industry and for heating homes, But liquid

Hydrogen storage tanks are really too heavy to carry on vehicles. As a result, the designers of hydrogen-powered buses and cars have had to find other ways of storing the fuel. Most have fitted the vehicles with tanks of metal hydrides, compounds containing hydrogen joined to the metal. These compounds give up hydrogen on heating. (Heat from the vehicle's engine can be used to do this.) But, again the compounds are expensive.

A good fuel should be safe to use.

Like all liquid or gaseous fuels, hydrogen can be dangerous. It can leak through tiny cracks in pipes and form an explosive mixture with air. But if hydrogen does leak, it can quickly escape upwards through the air. Hydrogen's ignition temperature (the temperature at which it catches fire) is actually higher than for many other fuels. And so hydrogen is safe enough to use.