Using a high proportion of solar and wind energy increases the risk of temporary imbalances in the electrical system. Therefore, we need flexible production such as hydro power or gas and ways of controlling demand. In addition, various types of energy storage will also be needed.
Batteries are ideal for frequency regulation, as they can alternate from charging to supplying power to the grid as quick as a flash when needed to balance the system.
“Many people are sceptical of the idea of using batteries in the electrical system, as they represent an expensive way of storing energy. However the main factor here is not energy storage, but output regulation. Although the energy capacity of batteries is measured in kilowatt seconds rather than kilowatt hours, their output is large and makes a difference. Many of them together can produce hundreds of megawatts, like a large hydro plant,” says Mikael Nordlander, Head of the Research & Development Portfolio Future of the Energy System at Vattenfall R&D.
District heating can become another key component, simply by complementing boilers with immersion heaters and accumulator tanks. This technology is already of great interest in Germany and Denmark because these countries already have many hours during the year with large electricity surpluses. The potential is enormous – a review shows that the existing district heating system could in theory, balance all generated Swedish wind power for many hours, should it become necessary.
“We are now also looking into the possibility of high-temperature storage of electricity in a medium that is heated up to several hundred degrees. This would allow us to convert electricity to heat and then back again to electricity when there is a shortfall,” says Mikael Nordlander.
See more examples of energy storage technologies: