Making Electricity - Common Types of Power Stations | What Causes Global Warming

Posted by Sarah Green on December 21st, 2011 filed in Global Warming

The electricity generation process involves a considerable number of energy changes, without regard for the primary power source that is used. Historically, electricity has been generated using fossil fuels, particularly coal. More lately, power stations have begun to use oil and gas as their energy source. Oil-fired power stations are not unusual in oil making countries, eg Indonesia. Gas burns more cleanly and efficiently than coal. It releases half as much carbon dioxide and more than 1000 times less sulphur dioxide per unit of energy.

Burning fossil fuels in power stations

The heat released from burning fossil fuels is used to boil water to produce steam. The steam is heated to really high temperatures in order that it is at high pressure and can turn gigantic steam turbines. Some of the energy of the steam is changed into movement, or kinetic energy, as the turbines spin. The turbines are hooked up to the coils of giant generators. The coils carry a current and act as electromagnets. As the turbines spin, they produce an electric current in the fixed coils surrounding them. This is fed into a power supply grid and carried to wherever in the network it is needed.

Power stations cannot store surplus electricity, so electricity production has to match demand. The power corporations have to judge how much power will be necessary. During times of hot weather, electricity demand may increase as more people use aircon to keep their homes and offices cool. If power firms’ guesses are wrong, folk may experience power cuts.

Power stations are not extremely efficient, and between 50 and 70 percent of the energy contained in the carbon-based fuel is wasted. Some of the heat energy will heat the encompassing air and escape through the boiler chimneys. The heat energy locked up in the steam can’t all be transferred to the spinning turbines. Although the steam is cooler when it leaves compared with when it enters the turbines, it still is warm. The steam is carried to the cooling towers, where it cools adequately to compress back to water. The lukewarm water is then emptied Into a close-by brook or sea, where it may cause thermal (heat) pollution. Luke-warm water holds less oxygen than cold water. The addition of a huge quantity of lukewarm water may cause animals, for example fish, to ‘suffocate’, as they aren’t able to extract enough oxygen from the water.

Mixed heat and energy generation plants

Some power stations, called mixed heat and power generation plants (CHP), try to make use of the waste heat. They pipe the waste hot water to surrounding businesses and houses to provide heating. There are numerous such units in Germany, and many tiny towns are reaping rewards from this cheap energy source. However , this is only possible with tiny and medium-sized energy generation stations that are built close to cities. In many states, especially the United Kingdom, power stations are found in more remote locations and so this power source wouldn’t be as practical as even solar power.

Sarah Green is an environmental campaigner, activist, and robust believer in home made energy. In her spare time, she reports on DIY alternative energy plans and kits.