Different methods of generating electricity have advantages and disadvantages.
Power stations fuelled by fossil fuels or nuclear fuels are reliable sources of energy. This means they can provide power whenever it is needed. However, their start-up times vary according to the type of fuel used.
This list shows the start-up times for different types of fuel going from the shortest to the longest.
Nuclear power stations and coal-fired power stations usually provide 'base load' electricity - they are run all the time because they take the longest time to start up. Oil-fired and gas-fired power stations are often used to provide extra electricity at peak times, because they take the least time to start up.
Fossil fuels took millions of years to form in the Earth's crust, and can never be replaced once they have been used. If we keep using these fuels they will eventually run out. We call fuels that will run out 'non-renewable'. Oil and gas will be the first to run out and then coal.
When fossil fuels burn, they release carbon dioxide into the atmosphere. Research shows that a major contributor to the green-house effect and global warming is our overuse and burning of fossil fuels.
Coal and gas also release sulphur dioxide gas when they are burned. Sulphur dioxide can cause breathing problems for living creatures and is also a major part of acid rain.
The fuel for nuclear power stations is relatively cheap, but the power stations themselves are expensive to build. It is also very expensive to dismantle old nuclear power stations and to store their radioactive waste, which is a dangerous health hazard.