Blog: 23 July 2019What is ESS and how does it work?

In our Leeds office, over the last few years, we have seen an increase in the number of renewable energy providers who are diversifying and evolving to respond to the UK’s changing energy demands and advances in technology.  In particular, this includes the provision of Energy Storage Systems (ESS). 

It is helpful to take a step back to understand why ESS is becoming more prevalent throughout the country as the sector grows to a cumulative total of 6,874MW in 2018, from just 2MW of battery storage capacity in 2012 according to Renewable UK.

The National Grid manages the high voltage grid network across the country, and have a responsibility to balance the UK’s electricity transmission system to ensure that supply and demand are matched second by second. They must ensure there is enough back-up power available to cover any potential shortfall, whether due to a power station breakdown, an unexpected event or at times of peak energy demand.  This issue is further complicated by the fact that the National Grid’s infrastructure in the UK is aging and needs modern solutions to enable it to adapt to 21st Century demands.

The advancement of ESS technology is part of the solution to the ‘supply and demand’ issue and is something which The National Grid support, which is evidenced by the fact that they offer incentives for energy storage facilities.

ESS technology works, on the face of it, relatively simply, as it provides a facility where any excess energy which is generated (generally from renewable sources) can be stored, and then released back to the grid in times of peak demand. Many ESS systems take the form of large batteries, which are stored within shipping containers and a key facet of the systems is the speed with which they can charge up and discharge to the grid, within 30 minutes. 

Although ESS do not generate renewable energy, they play an important role in supporting the efficient operation of renewable energy sources and ensuring there is minimal wastage of energy generated.

The important role that ESS currently plays in ensuring The National Grid continues to function effectively is now being recognised through the planning system. Indeed, appeal decisions have made their way through the system which acknowledge that ESS can be classed as renewable / low carbon energy development.  An Inspector recently concluded…“as the appeal proposal is required to provide greater capacity and flexibility in the energy generation network the proposed generators could be described as ‘associated infrastructure’ that would support the move towards low carbon energy supplied increasingly by renewable energy development. It seems to me therefore that on balance it is not unreasonable to conclude that the proposed development would constitute development required for the exploitation of sources of renewable energy.”

Our experience with local planning authorities and how they approach applications for ESS developments is varied, albeit the majority do seem to acknowledge the contribution ESS makes to renewable energy infrastructure and delivery. We are aware of at least one planning authority who are proposing a specific development management policy to deal with future ESS applications.

At a national level the Department for Business, Energy and Industrial Strategy (BEIS) is proposing to amend the Planning Act 2008 to establish a new capacity threshold for co-located projects, for example a combined ESS and solar farm development. Currently, where either element exceeds a capacity of 50MW either individually or cumulatively, it would be classed as a Nationally Significant Infrastructure Project (NSIP). Under the proposed new rules, co-located storage and renewable energy projects will not be classed as NSIPs if the combined capacity exceeds 50MW, providing that neither of the individual elements exceed 50MW. The NSIP threshold for standalone ESS projects will remain at 50MW.

At a time when climate change is high on the political agenda, both nationally and internationally, it will be interesting so see how the role of ESS and similar types of infrastructure develops and is managed through the planning process. The signs are that ESS is becoming increasingly important in the sector and is here to stay.

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Renewable Energy, Energy Storage Systems, NSIP