- Gas Turbine Power Plant Definition: A gas turbine power plant is defined as a facility that generates electricity using high-pressure, high-temperature air to turn a turbine instead of steam.
- Working Principle: Gas turbine power plants operate by compressing air, heating it, and then using the high-energy air to turn a turbine and generate electricity.
- Construction Advantages: These power plants are simpler, smaller, and cheaper to build and operate compared to steam turbine power plants.
- Instant Start: Gas turbine power plants can start quickly, making them useful as auxiliary power sources.
- Efficiency Drawbacks: They have lower efficiency due to the need to use a significant part of the turbine’s energy to run the air compressor and the loss of heat through exhaust gases.
In all power generating stations except solar power generating stations, an alternator generates electrical energy. An alternator is a rotating machine that produces electricity only when it spins. So, there must be a prime mover to turn the alternator. The main setup in power plants is to rotate the prime mover, enabling the alternator to generate electricity. In a gas turbine power plant, high-pressure and high-temperature air is used instead of steam to rotate the turbine.
The basic working principle of a gas turbine power plant is the same as a steam turbine power plant. The difference is that a steam turbine uses compressed steam to rotate the turbine, while a gas turbine uses compressed air.
In a gas turbine power plant, air is compressed in a compressor. This compressed air then goes through a combustion chamber, where its temperature rises. The high-temperature, high-pressure air then passes through a gas turbine. In the turbine, the air expands suddenly, gaining kinetic energy. This energy allows the air to perform mechanical work to rotate the turbine.
In a gas turbine power plant, the shaft of turbine, alternator and air compressor are common. The mechanical energy created in the turbine is partly utilised to compress the air.
Gas turbine power plants are mainly used as standby auxiliary power suppliers in hydroelectric power plants. They generate auxiliary power during the startup of a hydroelectric power plant.
Advantages of Gas Turbine Power Plant
- Construction wise a gas turbine power plant is much simpler than a steam turbine power plant.
- The size of a gas turbine power plant is smaller than that of a steam turbine power plant.
- A gas turbine power plant does not have any boiler like component, and hence, the accessories associated with the boiler are absent here.
- It does not deal with steam hence it does not require any condenser hence no cooling tower like structure is needed here.
- As design and construction wise gas turbine power plants are much more straightforward and smaller, the capital cost and running cost are quite less than that of an equivalent steam turbine power plant.
- The constant loss is quite smaller in gas turbine power plant compared to a steam turbine power plant because in the steam turbine power plant boiler has to run continuously even when the system does not supply load to the grid.
- A gas turbine power plant can more instantly be started than an equivalent steam turbine power plant.
Disadvantages of Gas Turbine Power Plant
- The mechanical energy created in the turbine is also used to run the air compressor. Since a large portion of this energy goes to the compressor, the overall efficiency of a gas turbine power plant is lower than that of an equivalent steam turbine power plant.
- Not only have that, the exhaust gases in gas turbine power plant curries significant heat from the furnace. This also causes the efficiency of the system low further.
- To start power plant pre-compressed is required. So before actual starting of the turbine air should be pre-compressed which requires an auxiliary power supply for starting a gas turbine power plant. Once the plant is started there is no more need of supplying external power but at starting point external power is essential.
- The temperature of the furnace is quite high in a gas turbine power plant. This makes the system lifespan smaller than that of an equivalent steam turbine power plant.
- Because of its lower efficiency, a gas turbine power plant cannot be utilised for commercial production of electricity instead it is normally used to supply auxiliary power to other conventional power plants such as hydroelectric power plant.
