Using a high proportion of solar and wind energy increases the risk of temporary imbalances in the electrical system. As more renewable generation is built, the electricity system becomes less stable, leading to more volatile fluctuations in frequency.
This is why frequency response services, such as pumped storage plants, have been put in place to counter these sudden imbalances. However, these services are only able to respond to frequency fluctuations within 10 seconds at best, which is not fast enough to maintain stability in a national electricity grid.
Going forward, the National Grid, the UK's transmission service operator, will benefit from a new service called Enhanced Frequency Response. This services uses giant lithium-ion batteries that can respond within milliseconds and deliver or absorb electricity to and from the grid for a period of up to 15 minutes.
Vattenfall, which is already involved in various types of battery solutions in other markets, such as Germany, has been selected as one of eight vendors that will deliver a total battery storage capacity of 200 MW. Vattenfall's battery facility, which will be built at the site of its Pen y Cymoedd wind farm in Wales, will provide 22 MW of this total capacity. Together the eight contracts are worth GBP 66 million (EUR 73 million).
The battery facility will be completed in 2018.
How energy storage works