Britain's Curtailment Problem

Despite the UK’s impressive wind power rollout, a surprising amount of it goes unused. In 2022 alone, more than £900 million was spent curtailing wind energy and replacing it with fossil fuels, while energy bills soared and emissions rose.

A Renewable Energy Paradox

Wind is now the backbone of the UK’s renewable electricity mix, providing roughly 23% of the country’s total generation. But on some of the windiest days, a significant portion of that clean power never reaches homes and businesses.

Instead, wind turbines are deliberately shut down because the grid can’t handle the volume of electricity they produce. This isn’t just a technical glitch – it’s a systemic issue that leads to enormous costs and carbon emissions.

In 2022, the UK paid £215 million to switch off windfarms, then spent a further £717 million to run gas-fired power plants instead. The result? 1.5 million tonnes of avoidable CO₂ emissions.

Mismatch Between Generation and Demand

Most of Britain’s wind capacity is located offshore or in Scotland. This makes sense: those areas have strong, consistent winds and fewer planning barriers. But electricity demand is heavily concentrated in the South East of England.

This imbalance means electricity must travel hundreds of miles from where it’s generated to where it’s consumed. That requires transmission capacity the current grid simply doesn’t have. The biggest pinch point is the B6 boundary, which separates the Scottish and English networks.

When the cables are full, the grid operator steps in. It pays windfarms in the north to power down and activates fossil fuel plants in the south to meet demand, forcing consumers to cover the cost of both.

Why Isn’t This Fixed Yet?

Investing in transmission infrastructure is expensive and time-consuming. The last major cable cost over £1 billion. For years, the logic was that it was cheaper to pay for curtailment than to build new links. But that equation is shifting, especially with volatile gas prices and mounting climate pressures.

On Christmas Day 2022, curtailment costs hit £9.2 million in a single 24-hour period, wasting 76 GWh of wind power, enough to power over 11,000 homes for a year.

What Can Be Done?

1. Expand Grid Capacity

One obvious solution is to add new transmission links. The most advanced plan is the Eastern HVDC, a £3.4 billion project to route electricity from Scotland to England via undersea cables. Once completed, it will provide an extra 4 GW of capacity, enough to eliminate nearly all of 2022’s curtailment.

The catch? It won’t be fully operational until 2029. Meanwhile, wind generation continues to grow faster than grid capacity, so the problem could get worse before it gets better.

2. Build Local Energy Storage

Batteries and other storage technologies can reduce pressure on the grid by absorbing excess wind energy when it’s not needed and releasing it when demand rises. UK battery capacity has already grown to 1.7 GW and is expected to reach 35 GW by 2050.

But batteries are usually operated for short-term trading, not long-term storage. Unless specifically incentivised, they may not prioritise curtailment mitigation.

Pumped hydro, such as the projects planned at Cruachan and Coire Glas, offers long duration storage that’s better suited to this challenge. However, developments of this scale require complex engineering and lengthy timelines, making it unlikely they can be rolled out quickly enough.

Hydrogen could offer flexibility by converting excess electricity into gas, but the economics are still unproven. Electrolyzers are expensive, and running them only during surplus wind events doesn’t currently stack up commercially.

3. Reform Electricity Pricing

A key reason curtailment happens is because UK electricity prices don’t reflect geography. A windfarm in the far north earns the same price for its electricity as one next door to its customers in the south. This lack of locational pricing removes incentives to generate power near demand, or to consume electricity where it’s abundant.

The task of rebalancing the system falls to the Balancing Mechanism, a last-minute market that now intervenes in over half of all electricity generation. It was never designed to operate at this scale and is becoming increasingly expensive.

Introducing locational pricing would shift costs to better reflect the reality of supply and demand. Power would be cheaper in areas with abundant generation and more expensive where it’s scarce. This could stimulate more southern renewables and push energy-intensive businesses to relocate north, aligning with regional development goals.

The National Grid ESO supports this shift, estimating potential savings of £30 billion by 2035. But others are cautious. Past market reforms were painful, and any move that adds uncertainty could deter investment in new wind capacity.

What Lies Ahead

The scale of wind curtailment is projected to grow. By 2030, 15 TWh of wind power could be curtailed annually even under Net Zero-aligned scenarios. The expansion of wind in Scotland, where 78% of new onshore projects are located, risks compounding the issue unless grid and market reforms keep pace.

The UK’s renewable revolution has been a remarkable achievement. But without faster investment in infrastructure and smarter market design, a growing share of our clean energy will go to waste.