Mains electricity: batteries now included

In a small-town in Bedfordshire, Europe’s largest battery supplements local power supply by distributing stored electricity when demand requires it.

The Smarter Network Storage facility in Leighton Buzzard
The Smarter Network Storage facility in Leighton Buzzard
  • Updated: 06 August, 2015
  • Author: Sophie Auton, Earth, Energy and Sustainability BSc at Leiden University College The Hague and ICE Policy Intern

With a growing population, the UK’s demand for electricity is projected to increase in coming years, demanding significant reinforcement of existing supply networks. To mitigate further fossil fuel combustion to generate this extra electricity, we need to increase generation from renewable sources.

These energy sources, including solar and wind power, however, tend to be unreliable and intermittent. As electricity can’t be stored in the network, intermittent energy sources can’t be relied on to supply electricity to homes.

Smarter storage

UK Power Networks’ Smarter Network Storage (SNS) facility is located directly adjacent to Leighton Buzzard’s existing substation. The plant houses over 3,000 ‘trays’ of lithium-ion batteries, of the same variety as an electric car’s. Each tray contains 16 cells, totalling more than 50,000 individual batteries. This provides 10 MW hours, enough energy to power 870 homes for a day when at low to average demand, or make 430,000 cups of tea.

It works by ‘topping up’ the electricity system when other input is unavailable i.e. at times of peak capacity demand. Prior to the SNS facility’s construction, there were two overhead power lines at Leighton Buzzard, each drawing up to 35MW of electrical energy from the national grid when fully functioning. A handful of times a year, however, a power line fails or requires maintenance, and peak capacity demands can’t be met; at these times, extra electricity is required, hence the need for storage.

Extra supply

Conventional reinforcement would construct a third overhead line, allowing for peak demand to be met. However, with the energy storage device, this investment is deferred. When demand increases, the digitally-controlled SNS facility automatically supplies electricity to the substation next door, which is in turn distributed to households, preventing power cuts. The mega-battery can supplement up to 4,750 homes for 90 minutes at peak times, draining the battery entirely. In future, there are plans to enlarge the existing facility from a 10 MWh capacity to 17MWh.

The facility was built as a research project, investigating the potential and cost-effectiveness of this form of energy storage and identifying any legal or practical barriers to its broader usage. The findings are shared with others across the energy industry. Its main goal, reducing the need for capacity installation by bridging the gap between supply and demand, is called peak shaving.

Being able to store intermittent electricity moves the UK one step closer to a ‘smart grid’; an energy system receiving constant information and adapting outputs accordingly to enhance efficiency, while involving more renewable energy sources in electricity production.