10% of UK Renewable Energy Wasted Due to Grid Constraints

February 27, 2025

A growing share of the UK’s wind and solar energy is being wasted due to grid limitations, underscoring the need for better energy storage and transmission. Aurora Energy Research estimates nearly 10% of Britain’s planned wind power output was curtailed in 2023, with Northern Ireland seeing even higher rates at 30%.

The issue arises from a mismatch between the rapid expansion of renewables and slower grid infrastructure upgrades. Surplus energy is often wasted due to insufficient storage capacity or transmission bottlenecks, contributing to volatile electricity prices. In 2024, Europe saw a record 4,838 hours of negative electricity prices, while Great Britain recorded 176 hours.

Scotland, home to most of Britain’s onshore wind farms, is particularly affected, as limited transmission capacity prevents efficient energy distribution. Grid operators frequently pay generators to shut down while increasing output from gas-fired plants elsewhere to balance the system.

Battery Energy Storage Systems (BESS) provide a key solution, storing excess electricity and releasing it when needed. Companies such as Fluence Energy Inc (FLNC:NSQ), Gresham House Energy Storage Fund PLC, and Harmony Energy Income Trust PLC are investing in large-scale battery projects to improve grid stability and reduce curtailment.

Harmony Energy Income Trust PLC recently reported a 57% revenue growth, reflecting the growing role of battery storage in balancing supply and demand. Its portfolio, including the Pillswood and Bumpers facilities, now totals 790.8 MWh/395.4 MW. Long-duration BESS assets like these are essential for ensuring grid reliability and minimising renewable energy waste.

Vanadium Flow Batteries (VFBs), championed by Invinity Energy Systems PLC, offer a high-capacity, long-life alternative to lithium-ion storage. Siemens Energy AG is advancing energy storage technology, while ITM Power PLC is pioneering green hydrogen electrolysis as another solution for storing excess renewable electricity.

The UK’s National Energy System Operator (NESO) plays a vital role in managing grid stability. Recent updates to the Open Balancing Platform allow more flexibility for energy providers to bid into the balancing market, improving real-time energy management and reducing waste. These measures, alongside expanded storage capacity, will help mitigate curtailment and enhance renewable energy utilisation.

NESO estimates curtailment and balancing actions added around £4 per month to consumer electricity bills in 2023-24, with costs expected to rise. Globally, curtailment is an increasing issue, with China losing 58.7TWh of wind and solar energy in 2024—enough to power 24 million households.

To address these challenges, the UK must prioritise grid expansion, accelerate BESS deployment, and implement smarter energy management systems to maximise renewable energy efficiency.

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