Advanced resistors in HVDC links could stop the UK wasting clean wind energy and driving up bills, as Mike Torbitt, Managing Director at Cressall, explains.
According to Octopus Energy, the UK turning off wind turbines wasted enough energy in the first nine months of 2024 to power two million homes for a year. Switching off turbines limits the impact of new renewable investments, such as the UK Government’s recent plan to unlock up to 13 major wind projects. Resistor-enabled energy transmission infrastructure can help to tackle this problem.
Deliberately reducing the electricity output of wind turbines – also known as wind curtailment – is becoming increasingly common in the UK. This largely occurs to protect the grid system from being overwhelmed by the power generated during periods of high wind. Between January and the end of October 2024, over 5,000 GWh of wind energy had been wasted.
Worryingly for consumers, wind curtailment comes at a price. Octopus Energy warns that switching off turbines has a knock-on effect on bills, predicting that it will cost consumers £3.7 billion by 2030.
Beyond increased household bills, wind curtailment also limits the UK’s ability to fully transition to clean energy. In order to phase out fossil fuels, the nation must be able to generate sufficient power from renewable sources to plug this gap.
Harnessing wind power is particularly beneficial within the UK, since it is one of the country’s most abundant natural resources. Currently, it is the UK’s largest renewable energy resource, making up 30% of the nation’s energy mix in 2024.
In addition to 44 operational offshore projects, the UK has a large number that are likely to come to fruition in the future. For example, the Government’s Plan for Change, which aims to modernise infrastructure regulations and speed up the construction of new projects, could generate a further 16 GW of electricity.
By giving the Government more power to designate and extend Marine Protected Areas, the new measures intend to prevent the delays that have typically affected offshore projects where sufficient environmental protection could not be agreed.
However, much of the newly harnessed wind energy is likely to be wasted unless the grid system can handle the additional power. So, how can this be achieved?
Distance challenges
One of the main reasons for wind curtailment is the distance between offshore wind farms, the grid and areas of high energy demand.
Offshore farms are often located far from the grid, making it harder to connect them efficiently to the national transmission network. Unlike onshore wind farms, which have more immediate access to the grid, offshore sites have fewer available connection points. When strong winds generate a surplus of power, there are limited options for distributing the energy elsewhere, forcing operators to shut down turbines.
Additionally, offshore wind farms are typically situated in remote locations where energy demand is low. For instance, Scotland has seven operational offshore wind farms, many of which are positioned in the north of the country, where population density is sparse. While Scotland produces vast amounts of renewable energy, the highest demand is further south. Without efficient transmission infrastructure, a significant portion of this power is lost before it reaches consumers.
Managing surplus energy
Energy experts have proposed several strategies to reduce wind curtailment. One suggestion is zonal pricing, where households and businesses located near wind farms pay less for electricity, ensuring more of the power generated is used locally rather than wasted.
According to the Octopus Energy report, companies relocating to energy-abundant areas like Scotland could cut their electricity costs by up to 99%. While this could encourage more businesses to move north, relocation is not a viable option for all industries.
A more widely applicable solution is investing in infrastructure to improve the transmission of power from offshore wind farms to major demand centres. One example is the Eastern Green Link 1 (EGL1), which began construction earlier this year. This HVDC project will transport energy from Torness, Scotland, to Hawthorn Pit in North East England. Once completed, EGL1 will provide enough electricity to power two million homes.
HVDC technology is crucial for long-distance power transmission. Unlike AC systems, HVDC maintains a stable current density, reducing energy loss during transit.
For HVDC to function reliably, resistor technology plays a vital role in managing excess energy. Resistors help protect the grid by absorbing surplus wind power until it can be safely transferred. DC neutral earthing resistors also provide essential safeguarding within HVDC converter transformers, both offshore and onshore.
With the UK Government pushing to reform planning regulations and accelerate wind power expansion through its Plan for Change, progress is underway. However, ensuring that energy transmission systems can keep pace with offshore wind development is just as important as increasing generation capacity.
HVDC networks, supported by advanced resistor technology, are key to unlocking the full potential of the UK’s wind resources. By addressing transmission inefficiencies, the UK can reduce wind curtailment, lower costs for consumers and move closer to a fully renewable grid.
