Natural gas and electricity: a closer relationship than you might realise
Around 11% of Germany’s electricity was generated in gas-fired power stations in 2012. This is more environmentally friendly than using coal, as natural gas emits much less CO2 because of the low carbon content in methane. Moreover, gas-fired power stations attain very high efficiency rates thanks to sophisticated technology, converting a larger proportion of the energy in natural gas into electrical energy. For example, the power station Irsching 4 near Ingolstadt achieved an efficiency rate of 60.75% shortly after it was commissioned in 2011, which was a world record! In comparison, coal-fired power stations can reach an efficiency rate of 50% at best.
Gas-fired power stations are increasingly efficient due to improvements made to turbines in the last few decades. They are powered by burning natural gas, which heats the incoming air and sets the turbines in motion, in a similar process to a jet aircraft. The rotary movement is transferred via a shaft to the electrical generator, which generates electricity, like a bicycle dynamo.
Making electricity green: CCGT power stations and CHP stations
Engineers took a huge leap in efficiency when they began putting the waste heat from gas turbines to use for electricity production. The heat is used to boil water and drive a steam turbine, setting an additional generator in motion to generate electricity. This innovation increases the yield substantially and was the technology that enabled the power station Irsching 4 to achieve its world record. Additionally, CCGT power stations are much cheaper than some other methods of electricity generation. They cost around 50% less than a comparable coal-fired power plant and can be built in a short space of time.
There are some other possible uses for the waste heat. Rather than being used to drive a turbine, in combined heat and power (CHP) stations, it is used either directly on site for industrial processes or put on a local heating network for residential areas.
This model is also available on a small scale, with so-called micro-CHP plants in that can be used in residential basements or cellars to generate electricity and heating. CHP plants achieve an 80-90% rate of efficiency, but to achieve this figure there must be a user for the energy in the immediate vicinity of the plant.
Flexibility with Gas-fired Power Stations
Gas-fired power stations are environmentally friendly because of their high efficiency rates and low CO2 emissions, which is why they will play an important role in the future of green energy. Wind turbines and solar power facilities do not generate a guaranteed and reliable output, so other power stations often have to stand in at short notice. Gas-fired power stations are ideally suited to this purpose as they can easily be fired up in just a few minutes, and subsequently shut down, far more quickly than coal-fired power plants. Gas-fired power stations, in combination with new electricity storage systems, will make sure that we have a secure electricity supply in the renewable energy age.
Using Electricity to Produce Gas: A milestone in the energy future?
As well as generating electricity from gas, innovative techniques mean that we are also able to do the reverse! When renewable energy techniques generate more electricity than can be used at that moment in time, artificial gas can be created with the excess electricity. First, the electricity is used to split water into its individual elements, hydrogen and oxygen, by electrolysis. Then the hydrogen is converted into methane by adding carbon dioxide in a process known as methanation. The natural gas created can be transported using the existing German gas pipelines and storage facilities, and can be used for heating or as a vehicle fuel. Although this ground-breaking technology, which we call “power to gas”, is still in its infancy, it could be a way to link up the power and gas highways intelligently and effectively to minimise any energy waste.
Decentralised Energy: electricity and heat production at home in your cellar
The close links between natural gas and electricity continue at micro level. Environmentally friendly electricity and heat can be generated with natural gas in fuel cells at home, perhaps in the cellar or basement. In the fuel cell heating systems, a “reformer” converts natural gas into hydrogen, which produces electricity by a chemical process. The heat generated by the process is not wasted, but used to heat the rest of the homes and provide hot water. This initiative will give individual homeowners the opportunity to make a real difference to the environment, as the fuel cells only emit around half the CO2 emissions of traditional solutions with the same output.