HM Insights

The attraction and potential of energy storage

Electricity has historically been expensive to store and the UK national grid spends £1 billion per year on balancing the grid - switching power on and off to keep the lights on.

Electricity storage has the ability to radically change the grid network by taking electricity from the grid or a generator and storing it so that it can be used when it is most needed.

Storage is also important for renewable energy developments because renewable energy is intermittent and storage allows electricity to be time-shifted to when it is needed most and at peak prices maximising the benefits of these developments. Storage is not one single technology but a combination of technologies such as pumped hydro power and batteries which increases the flexibility of the grid network.

Here, we take a look at the benefits and potential of energy storage, as well as an introduction to the two main types of electricity storage systems in the UK, Pumped Hydro Power and Battery Storage, and the contribution they can make to creating a flexible grid network.

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The benefits of Electricity Storage

The grid network has been set up to meet relatively short periods of peak demand. Supply capacity constraints have been managed by either reinforcing the network by building more cables or by preventing sources of demand and supply connecting until the network has been strengthened to meet the level of demand it might face for just a few hours of the day - which is extremely expensive when compared to the benefits it delivers. This is why it is often more cost-effective to pay some power stations or renewable energy developments not to generate for short periods of time.

Having storage connected to the grid network means instead of exporting power onto a network when it is suffering from constraints, generators can instead store the power - for example by charging batteries and this electricity can be released at a later time, meaning the network is then no longer constrained. Storage can therefore offer a cheaper way of ensuring that the grid network both at national and local level is able to deal with the peaks and troughs in the flow of electricity.

A renewable approach to energy storage?

With renewable projects suffering from deep subsidy cuts, opportunities exist for generators and developers to shift their focus and investment to energy storage, which is expected to prove vital in supporting an increasingly clean and intermittent energy mix.

The key behind this will be securing a good market price for power to be exported to the grid and participation in the full range of revenue generating schemes that are available through grid balancing and frequency response services.

The two main types of storage systems that operate in the UK

Pumped Hydro Power

  • The vast majority of electricity storage today, which is about 3,000 megawatts of capacity, is provided by large-scale pumped hydro electric power stations in north Wales and Scotland.
  • Electricity is stored by pumping water up a reservoir to be released when needed, generated through hydro-electric turbines. Large amounts of electricity are capable of being stored - how much is determined by the size of the reservoir.
  • These pumped hydro schemes play a crucial role in the immediate short term to manage sudden spikes of demand and unexpected losses of capacity.

Battery Storage

  • Over the last decade there has been a great deal of innovation in battery storage technology which has been driven mainly by consumer electronics such as mobile phones and investment in electric vehicles. This has driven innovation and reduced costs.
  • The battery storage market is dominated by lithium-ion batteries which are widely seen as reliable technology and able to charge and discharge rapidly over several thousands of cycles.
  • In January 2016, AES UK and Ireland announced the completion of the first UK transmission scale battery storage facility called the Kilroot Battery. Based in Northern Ireland, it offers 10 megawatts of interconnected electricity storage which is comprised of over 53,000 batteries. The battery is able to respond to changes in the grid network in less than a second, providing a very fast response ancillary service to help balance the grid at times of high demand.
  • The UK has now embarked on a battery storage boom that will see around 1GW of storage capacity installed between 2017 and 2020.

Get in touch

If you would like to speak to Harper Macleod about electricity storage systems, we would be delighted to help.