Energy world

Energy sources: Gas

Status: Non-renewable

How was it formed?

Scientists are still unsure about the source of gas. It is usually found with oil deposits and the leading theory suggests that they both formed millions of years ago in places where dead organic material built up on the bottom of oceans, riverbeds or swamps, and got mixed with mud and sand. Over time, more sediment piled on top, and the resulting heat and pressure changed the organic layer into a dark and waxy substance known as kerogen.

The molecules in kerogen eventually break up into shorter and lighter molecules composed of mostly carbon and hydrogen atoms. Depending on how liquid or gaseous this mixture is, it will turn into either crude oil or natural gas.

How is it used to generate electricity?

Gas is burned in a turbine, like a jet engine on a plane, but bigger. This turns a generator, producing electricity. The hot exhausts gases are then used to heat water to make high pressure steam, which is fed into a steam turbine, which turns another generator, making even more electricity. It is very efficient!

Sometimes, the steam from the back end of a turbine can be used to provide heat to houses or offices. It can also be used for processes such as making paper or chemicals.

Where can you find it?

North Sea and Irish Sea. It is also found in Russia, Eastern Europe, Norway, the Middle East and Africa.

Advantages and disadvantages of using gas to generate electricity

Advantages

Gas is light and easy to transport by pipeline

Large amounts of electricity can be generated from one gas-fired power station

Gas-fired power stations are normally built near rivers and the gas pipeline network but they can be built anywhere

Disadvantages

Burning gas produces carbon dioxide, which contributes to the greenhouse effect

Gas is not renewable. There is a limited supply, which will eventually be used up

The UK is importing most of its gas. This means that our energy supplies may become quite costly if wholesale prices rise

How many power stations in the UK?

36 (100MW and above)

How much does it cost to produce?

2p to 3p/kWh

What is the carbon cost?

370kg/mWh

The future?

Gas reserves will last until late in the 21st century.