ENERGY STORAGE

Gone with the wind: UK curtailment and the storage solution

The £920m annual cost of UK wind curtailment could be cut by 80 per cent with better use of battery storage, according to new analysis, with English-Scottish border the crux of the problem

BEN COOK

April 18, 2024

  • £920m annual cost of UK wind curtailment could be cut by 80% with better use of battery storage
  • Congestion at English-Scottish border is major problem – curtailment costs expected to hit £3.5bn by 2030
  • Batteries should be the solution to this problem, rather than zonal pricing, says storage developer Field 

The £920 million annual cost of wind power curtailment in the UK could be cut by around 80 per cent if existing technologies such a battery storage were used more effectively on the grid. That was the conclusion of a recent analysis conducted by battery storage developer Field.

The Field analysis asserted that increasing the amount of “intertrip services” the National Energy System Operator (previously National Grid ESO) can buy, as well as using “Grid Booster” batteries, would contribute to tackling the problem, with the latter technology already being deployed in continental Europe and Australia. Intertrip services are required by the National Energy System Operator as an automatic control arrangement where generation may be reduced or disconnected following a system fault event.

As Field highlighted, the majority of the cost of wind power curtailment was due to a single pinch point in the UK’s electricity grid on the Scottish/English border called the B6 boundary (see graphic below). The B6 Boundary separates the transmission network at the SP Transmission and National Grid Transmission interface running roughly along the border between Scotland and England. Field estimates this boundary alone could cause up to £2.2 billion of curtailment costs by 2030 as the problem escalates. Overall, UK curtailment costs could reach £3.5 billion by that date, Field said.

Source: nationalgrideso.com

A report by independent financial think tank Carbon Tracker said that, on more than 200 occasions in 2022, bottlenecks in the transmission system meant National Grid ESO had to “pay Scottish wind farms to stop generating zero-carbon power and pay gas power stations in England to increase output to compensate”. This added £800 million to consumer electricity bills and increased greenhouse gas emissions by 1.3 million tonnes.

Scotland has 10GW of wind farms but accounts for only 10 per cent of GB electricity demand, so much of the power they generate is consumed in England, Carbon Tracker said. However, the grid can currently only transmit a maximum of 6GW across the border, so on windy days this generation must be curtailed – due to what the Carbon Tracker report calls “wind congestion” – and gas stations fired up. The wind congestion problem will persist until such time as the transmission bottlenecks are solved, the think tank said.

According to Carbon Tracker, wind generation in Scotland is expected to grow four times faster than the build-out of new transmission capacity required to transmit power across the border. While there are plans to build four new undersea cables between England and Scotland with a combined capacity of 8GW, due to capacity constraints and bottlenecks in the planning process, only two will likely be operational by 2030, Carbon Tracker said. By then Scotland could have an additional 28GW of wind power, based on the current pipeline of onshore and offshore projects. The report notes new undersea cables could generate savings equivalent to half their investment cost in just one year.

Field says that the specific curtailment problem caused by the B6 boundary on the Scottish/English border could be addressed by building 10GW of energy storage in key locations across the UK – this would reduce the estimated £2.2 billion curtailment costs by nearly 90 per cent, the company said.

So what should be the next steps? Field has called on the National Energy System Operator, Ofgem and the Government to establish two priorities:

1. Prioritise available, cost-effective measures like batteries and related services to maximise use of the existing grid.

2. Do this rather than focusing on less practical or new market-based mechanisms such as zonal pricing that will reduce investment certainty, and take a long time to implement.

There is a view in the energy storage industry that the approach to tackling the problem of wind curtailment in the UK is muddled and ill-thought-out. Worse, some argue that billions are being spent as part of a mis-guided strategy for tackling the issue. “In an era where energy bills remain high and carbon emissions keep rising, it’s alarming that we’re wasting clean, cheap, abundant energy on a daily basis,” says Amit Gudka, CEO of Field. “As our analysis suggests, this problem is getting worse, not better”. He continues: “Billions of pounds have been earmarked to upgrade the transmission network, but we think there’s a better route here than overspending on this one approach to upgrading the electricity system. More efficient use of established technologies, such as battery storage, would dramatically reduce curtailment costs and network investment needs. It would also reduce the need for expensive, complex and disruptive market-based mechanisms such as zonal pricing.”

The potential for battery storage to play a critical role in reducing the cost of managing the energy system and reducing household energy bills is being overlooked. Storing cleaner energy for use when and where it is needed most would mean the grid would be managed more efficiently and at a lower cost.