Gas fired power stations are more efficient than coal. In the first stage of energy production the burning gas travels through the turbine which spins it and generates electricity. Secondly the heat produced by the burning gas is used to boil water and spin the turbine and generator as described in the coal fired power station. These power stations are as a consequence of this are more efficient, around 60%. Again if the wasted heat is used to heat homes this rises to around 80%.
Natural
gas is found near Taranaki. The natural gas is
pumped from below ground and sent in large pipelines to power plants. The gas
can either be used to heat water to make steam, which drives a steam turbine.
Alternatively the gas is ignited and expands to drive a gas turbine e.g. the
Taranaki and Otahuhu power stations.
It is estimated that New Zealand will run out of natural gas within the next twenty years.
It is estimated that New Zealand will run out of natural gas within the next twenty years.
Advantages of gas fired power stations are:
- It is cheap to send gas from the field to the power station.
- Gas can be used twice to make electricity. The gas itself turns one turbine, and then the steam from the water heated by the gas turns another turbine - this means that gas power stations are very efficient.
- Gas power stations don't take up a lot of room
Disadvantages of using gas are:
- It takes the earth so long to make gas that it won't be replaced – it is a non-renewable energy source.
- As world gas reserves drop, gas is getting expensive. It is also difficult and costly to find new fields.
- Burning gas creates CO2, which contributes to climate change.
- Extracting gas is creating cavities in the Earth