A gas power station turns the chemical energy in
natural gas into electrical energy that can be used in homes and
businesses.
Natural gas (1) is pumped into the gas turbine
(2), where it is mixed with air (3) and burned, converting its chemical
energy into heat energy. As well as heat, burning natural gas produces a
mixture of gases called the combustion gas. The heat makes the
combustion gas expand. In the enclosed gas turbine, this causes a
build-up of pressure.
The pressure drives the combustion gas over the
blades of the gas turbine, causing it to spin, converting some of the
heat energy into mechanical energy. A shaft connects the gas turbine to
the gas turbine generator (4), so when the turbine spins, the generator
does too. The generator uses an electromagnetic field to convert this
mechanical energy into electrical energy.
After passing through the gas turbine, the
still-hot combustion gas is piped to the heat recovery steam generator
(5). Here it is used to heat pipes full of water, turning the water to
steam, before escaping through the exhaust stack (6). Natural gas burns
very cleanly, but the stack is still built tall so that the exhaust gas
plume (7) can disperse before it touches the ground. This ensures that
it does not affect the quality of the air around the station.
The hot steam expands in the pipes, so when it
emerges it is under high pressure. These high-pressure steam jets spin
the steam turbine (8), just like the combustion gas spins the gas
turbine. The steam turbine is connected by a shaft to the steam turbine
generator (9), which converts the turbine’s mechanical energy into
electrical energy.
After passing through the turbine, the steam
comes into contact with pipes full of cold water. In coastal stations
this water is pumped straight from the sea (10 and 11). The cold pipes
cool the steam so that it condenses back into water. It is then piped
back to the heat recovery steam generator to be reused.
Finally, a transformer converts the electrical
energy from the generator to a high voltage. The national grid uses high
voltages to transmit electricity efficiently through the power lines
(12) to the homes and businesses that need it (13). Here, other
transformers reduce the voltage back down to a usable level.
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