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Waste not want not: why energy storage is vital to prevent winter blackouts

In the UK, the National Grid has recently warned the government that its capacity to supply electricity is at a seven-year low due to recent generator closures, fires and outages. The margin of capacity over demand is expected to be just 4% this winter. Experts suggest blackouts are unlikely as long we take steps to curb electricity usage and don’t experience any more serious breakdowns or a harsh winter. The Confederation of British Industries (CBI) has reacted angrily to suggestions that industry should shut down at times of peak demand, jeopardizing an already fragile economic recovery.

The situation is only going to get worse. Next year capacity could slump to less than 2% as yet more of the UK’s ageing fleet of plants are retired. Since 2012, 15 power plants have been fully or partially closed. The country will lose a fifth of its generating capacity in coming years as additional ones are retired. However, energy companies are wary of committing to build new plants until they understand the impact of market reforms currently being introduced. Once agreed, construction projects – including protracted planning permission negotiations with local communities – will take many years and come at a high cost.

This highlights the urgency of investments in affordable and fast energy storage to enable the UK to use wind and solar power that is currently going to waste. The wind blows most consistently at night and it’s often sunniest in winter during periods of the lowest energy demand. Energy storage captures this “wrong time” renewable energy and avoids the need for governments to make constraint payments to generators to switch off capacity.

Currently, expensive coal-fired “peaking power” stations, which sit idle for the majority of the time, are used to address energy shortfalls. This costs around £15-20/MWh (US$24 to US$32/MWh) and £0.7m-£5m/MW according to industry reports. In contrast, power from proven and safe battery systems cost between £0.5m and £1.8m/MW – a saving of up to 50%. They can also play a vital dual-use role of regulating the frequency on the grid to reduce the risk of outages.

Spare electricity capacity in the UK National Grid during winter. Image: National Grid.
Energy storage is the most reliable demand-supply balancing technology class with a 97.38% rating according to the National Grid – much higher than coal or Combined Cycle Gas Turbines (CCGT), hydro, oil or nuclear power, which can also be used as peaker plants.  Whilst most of the ancillary services are provided today by generation resources, isn’t it better to free this vital generation capacity to produce much-needed energy – and use energy storage instead? Ideally suited to provide balancing, and already doing so in many places around the world including the US and Chile, energy storage can release trapped capacity held in reserve for balancing purposes.

Energy storage in substations can also reduce the need and costs transformers and cabling upgrades on the distribution network.  Energy storage is already in use in the UK to a degree and more extensively around the world. The batteries fit into standard shipping containers and can be easily and quickly slotted into wind and solar parks or substations, providing greater utilisation of renewable generation capacity, and more effective, higher performance balancing services.

Demand-Side Response (DSR) will also be important to manage energy usage over the long time. Equipment used by heavy energy users, ranging from fridges to furnaces, is Internet-enabled and switched on and off to free up capacity in the grid without affecting production output by manufacturing plants or food producers.  Energy storage can also help to increase the efficacy of DSR resources by enabling greater levels of participation without inconveniencing the end-user. 

The UK needs to invest £110 billion in modernising its electricity infrastructure over the next decade. It’s vital that investments in energy storage are accelerated to help us decarbonise energy, whilst maintaining security of supply and keeping costs down.

Containerised energy storage from NEC Energy Solutions. Image: NEC Energy Solutions.

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