Traditional gas turbine technology could help to solve renewables’ intermittency headaches, writes European Energy Centre’s Cora Moran
Renewable energy technologies need to be adopted fast, and on a wide scale, to reduce global carbon emissions.
However, while solar and wind technologies have the greatest potential for growth, it isn’t always daytime or windy. Hydroelectricity, geothermal, biomass and nuclear fission can provide baseload power to a grid, but they are variously restricted by geography, cost, scalability and levels of societal acceptance.
To date, fossil fuel power stations still produce the majority of power globally. Even nations such as Germany, which use high proportions of renewable energy, still use fossil fuels to provide the majority of its baseload power.
Potential solutions for the future include more refined demand management and interconnecting power grids between nations on the same continent. Arguably, the two most substantive proposals are:
- To provide baseload for the grid by using fossil fuel plants kitted out with carbon capture and storage technologies, in cases where low carbon alternatives are not viable
- The use a range of energy storage technologies
However, both of these solutions have limitations at present. Carbon capture and storage (CCS) technologies are technologically complex and expensive. The proven energy storage technologies – such as pumped-storage hydroelectricity, battery banks and flywheels – still face issues of scalability, cost and a lack of suitable locations.
Ironically, it may be gas turbines – a staple technology of the fossil fuel era – which could provide the most cost-effective methods of CCS and energy storage.
Ironically, it may be gas turbines – a staple technology of the fossil fuel era – which could provide the most cost-effective methods of CCS and energy storage
Turbines are available in two main types: steam turbines and gas turbines. Steam turbines are used to generate electricity from sources such as coal, nuclear, biomass, solar and geothermal. Gas turbines are typically used in natural gas power plants for several niche applications. The two are sometimes combined in cogeneration facilities for greater efficiency; the gas turbine produces electricity and waste heat, which is then used by the steam turbine to generate additional electricity.
A conventional fossil fuel power plant burns hydrocarbons to generate steam that drives a turbine and emits CO2 as a by-product. However, an American company, ‘Net Power’ has developed a novel system where high temperature, high pressure CO2 is used in place of steam. Natural gas, ignited with pure oxygen, will heat up and then act as a source feed for CO2 in the system, with excess gas being siphoned out to maintain a pressure balance in the system. This gas can then be piped away without entering the atmosphere and then be sold on for a profit as a feedstock for industrial processes or safely stored in geological deposits.
If Net Power is successful in developing the technology commercially, the company claims it will be able to produce electricity as cheaply and efficiently as a conventional modern gas-fired power plant. If they achieve this it will mark a record industrial achievement.
‘Highway Power’ is another company with promise. The northern England-based firm is using off-peak electricity to pressurise and cool air to -196C so it becomes liquid, which can be stored for as long as required. When needed, this air can be converted back into a gas to turn a turbine and generate electricity. This technology offers long-term energy storage that can scale up to hundreds of megawatts.
While Highway Power still requires subsidy assistance to achieve profitability, its technology is currently a more reliable method for evening out grid variability on a larger scale than today’s battery technology.
If these technologies are proven to be commercially viable, these pilot innovations have the potential to make a substantive impact on energy generation and help make the rapid adoption of renewables more technically feasible and cost-effective.
Cora Moran is an experienced researcher who has worked in the Built Environment and Renewable Energy sectors for a number of years and writes for the European Energy Centre about a range of environmental issues.