The UK and parts of Europe have recently experienced a “Dunkelflaute”. This German term translates to a “dark lull” and represents a challenge in the shift to renewable energy. High-pressure weather systems cause the Dunkelflaute phenomenon, which brings a combination of low cloud and fog, limited sunlight, and low wind. These periods often occur in the winter months when energy demand begins to rise. This recent period of gloom has seen entire days with little to no renewable energy generation. As a result, the grid has been forced to rely on fossil-fuel plants to meet demand.
The UK has also turned to subsea grid connections for European energy imports. With new projects like the LionLink and Nautilus interconnectors approved by Ofgem, National Grid aims to link Britain’s power grid to European sources, including wind farms in the Netherlands and Belgium, French nuclear power, and Norwegian hydro-electricity.
Subsea interconnectors play an important role in balancing the international energy market, and are set to be a key element of Britain’s future energy landscape. However, some concerns have been raised about rising demand in European energy markets leading to higher consumer prices here. When the UK experiences these long periods of gloomy weather, often mainland Europe does too. If renewables aren’t generating in the Netherlands and Belgium, these countries will not have surplus energy to export to us.
A reactive approach to stabilising the grid is unsustainable; Despite leaps forward in our renewable generation capacity, we are still seeing a reliance on fossil fuels and energy imports. As we head into winter and begin to see more days with limited sunshine, we need a more robust solution for grid stability.
Dunkelflaute Gloom in the UK and Europe
November has seen much of the UK shrouded in an unusually dense “anticyclonic gloom”, with little sunshine reaching the ground. Many parts of England have recorded nearly no sunshine. The village of Odiham in Hampshire saw as little as 12 minutes of sunlight over an 11-day period. This persistent cloud cover, combined with high-pressure systems, leads to low wind speeds and limited sunlight. As a result, we have seen a near-total reliance on backup energy sources.
During this recent Dunkelflaute, wind farms across the UK were generating only 3-4% of the country’s electricity needs at peak times. Gas-fired plants had to step in and were responsible for meeting around 60% of demand. Solar panels also contributed minimally, with nuclear, biomass, and imported energy via subsea interconnector cables filling the gaps.
Why long-duration energy storage is essential
The Dunkelflaute raises pressing questions about the security and reliability of renewable energy systems. While wind and solar generation are invaluable, they are weather-dependent and thus subject to natural variation. Without sufficient storage capacity, a dark lull like this leave us with few options. Traditionally, we fall back on fossil fuels to balance the grid.
We could instead fall back on energy storage. With a robust energy storage framework in place, surplus renewable energy generated on sunnier, windier days or during periods of low energy demand can be stored and released back into the grid when needed.
Such a framework would mean a massive reduction in emissions, severing our reliance on fossil fuels, and a significantly lowering the risk of blackouts. Long-duration energy storage (LDES) does all of this while also enhancing our energy security and independence. With a comprehensive energy storage infrastructure in place, the UK could rely on stored, homegrown power for energy security during Dunkelflaute events. As such, we’d need less imported energy, ultimately strengthening energy security and stabilising prices.
Storelectric’s role in combating the Dunkelflaute challenge: Compressed air energy storage
Storelectric’s Compressed Air Energy Storage (CAES) technology offers a ready solution to the Dunkelflaute challenge. By using renewable energy to pump compressed air into underground caverns, CAES systems can hold vast amounts of dispatchable, clean energy. We then release the air through a turbine to generate energy when the grid needs it most. Our Green CAES™ and Hydrogen CAES™ models improve on traditional compressed air systems, making them more efficient and adaptable. Storelectric’s Green CAES™ model, for instance, uses thermal energy management to recover heat generated during air compression, enhancing efficiency. Our Hydrogen CAES™ model provides a flexible solution by pumping hydrogen, rather than air, into the cavern. Hydrogen has a higher energy density than air, which allows for more energy storage in the same amount of space.
The UK is in an ideal position to deploy CAES technology. The country has a large network of suitable caverns and suitable geology to support CAES installations across the nation. If these systems were in place, we would be able to store and dispatch green energy effectively during Dunkelflaute events, or other periods of low generation and high demand. This in turn would reduce our dependence on fossil fuels and protect the nation against blackouts.
Building a resilient, renewable energy system with storage
The Dunkelflaute experienced in the UK this November is a reminder of the challenges and complexities involved in managing a renewable energy-powered grid. However, with investments in long-duration storage, we can ensure that low-wind and low-sunlight days do not compromise our energy security. Storelectric’s CAES technology has the potential to enable The UK’s green energy infrastructure to function securely. We could facilitate the nation’s transition away from fossil fuels and towards a more resilient and sustainable system.
As we move towards net zero, long-duration energy storage will undoubtedly be a crucial part of meeting the UK’s climate goals. With LDES, we can store and release renewable energy as needed, ensuring that weather events like Dunkelflaute don’t disrupt our progress. By implementing solutions such as Storelectric’s CAES models, we can start building a secure, green energy future. We can end fossil fuel reliance and empower the nation to thrive on secure renewable power.
