Our energy system is changing. For example, on windy days as much as 20% of UK electricity is already generated from wind turbines and other renewable sources. Over the next 15 years there is an expectation that the cost of producing renewable electricity will decrease, and its share of supply will increase. But what happens when the wind doesn’t blow and the Sun doesn’t shine?

Variable sources

Unfortunately, many renewable energy sources are variable, and that is one of the reasons why governments talk in terms of a portfolio of electricity generation technologies. The variability in electricity production has to be matched by sources that can fill the gap, virtually at a moment’s notice. Currently, the best way of doing this at scale is to use natural gas-fired turbines that have very fast start-up and shutdown times.

The most efficient gas-fired power stations use a configuration known as combined cycle gas turbines, or CCGTs, and these emit about half of the carbon dioxide (CO2) per unit of electricity of a modern coal-fired power station. So a combination of renewables with low carbon base-load generation such as nuclear and fossil fuels with Carbon Capture and Storage (CCS), along with CCGTs that can ‘load-follow’, is the practical way forward to transition the electricity system over the coming decades in the absence of cost-effective, very large scale electricity storage technologies.

Carbon capture and storage

CCS is an infrastructure chain comprising technologies that remove CO2 from the exhaust gases of power stations and industrial plants (such as steelworks and cement plants), transport it to a storage site, and then pump it more than a kilometre underground into stable geological formations that will keep it there permanently like the oil and natural gas accumulations of the North Sea.

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Source: Pan European Networks