Energy storage executives from global assurance and risk management provider DNV analyse the UK government’s proposal to kickstart investment into long-duration energy storage (LDES).

The case for LDES is arguably straightforward. With the ongoing rapid increase in renewable generation, particularly solar and wind, comes greater intermittency of electricity supply. If Great Britain (GB) and the rest of the world is to meet 2030 and mid-century emissions targets, we cannot continue to fire up combustion plants to meet any shortfall in generation.  

The UK Government’s Department for Energy Security and Net Zero’s (DESNZ) new consultation¹ – which applies to the British mainland – on LDES is a key step in defining a policy to enable the rapid rollout of LDES to meet the 2035 power sector decarbonisation deadline.  

There are two key challenges to a decarbonised energy system, spatial and temporal, and LDES is essential to solving the latter. Storing energy from intermittent renewable sources, primarily wind and solar, during periods of high generation so that it may be dispatched when demand exceeds the renewable generation mix, is a key part of decarbonising the electricity system.

The need for clear objectives and definition of LDES

By defining LDES as storage capable of a six-hour minimum supply duration, the framework also helps set a common understanding of what constitutes long duration in the UK. However, this is lower than the United States Department of Energy (DoE) which applies a 10-hour minimum duration. Different minimum durations between regions could lead to some differences in technology selection, but length is part of the ongoing consultation and it is possible this will change before the policy is finalised.  

The consultation outlines five key objectives:

• Policy Alignment – The policy framework should work alongside and compliment wider energy policy to deliver a resilient, diverse, net zero energy system of the future at least cost to the consumer.  

• Reduce System Costs – The policy framework should ensure that consumers are protected from unnecessary system costs from arising from high operational costs throughout the lifetime of the project.  

• Enable Investment – The policy framework should enable investment in large-scale, long duration electricity storage technologies through reducing uncertainty in revenue projections.  

• System Benefits – Storage projects should be incentivised to respond to market signals and behave flexibly to maximise benefits to the whole system.  

• Delivery – The policy framework should deliver projects in a timeframe that will provide the most benefit to the system, meet public commitments and will help the system to meet net zero targets.

The basis for the consultation is to adapt the ‘cap and floor’ mechanism, which is similar to the approach taken for interconnectors. The cap and floor mechanism has supported six interconnector projects, with a further three pending Final Project Assessment and seven new projects undergoing initial project assessment. The Viking interconnector, which connects the UK to Denmark, started commercial operations in December 2023 and is supported through the cap and floor regime for interconnectors.