The Russian invasion of Ukraine has fueled the urgency of energy transition ambitions. For the UK and EU, offshore wind turbines could fuel their advances, but only if innovation on the grid keeps pace.
The UK wants to generate 40 GW of offshore wind power by 2030. ScotWind’s recent seabed lease hovers around a record 25 GW of potential projects, awarded enough to power around 1.5 million homes, placing the country on the way to meet this goal. The EU is targeting at least 60 GW by 2030 and 300 GW by 2050.
But while the costs of offshore wind technology are falling rapidly, grid innovation must be sustained, or we risk missing these goals. Studies show that when offshore wind assets are built at the planned scale, single point-to-point connections from offshore wind farms to the onshore grid (as is the current standard) will be inefficient, more expensive and less environmentally friendly. environment.
What does integration mean? One idea is an offshore mesh network connected to several countries in the North Sea, built with novel technology. This would allow much higher levels of energy to be transported with lower losses. Crucially, supply would be more easily shifted to meet demand in the top five European offshore wind players: the UK, Belgium, the Netherlands, Germany and Denmark.
There is already a growing number of point-to-point interconnectors transporting energy from one European country to another; the UK currently has four. However, a marine mesh network would be like “the main line from London to Brighton,” says Fay Lelliott, global practice leader for power transmission and distribution at Mott MacDonald, a consulting firm.
“It’s not just point to point; it is possible to travel from London to Brighton by many different routes,” he explains.
Dr. Cornelis A. Plet is a principal consultant for DNV and coordinated the PROMOTioN Horizon 2020 project to advance the development of high-voltage direct current (HVDC) meshed marine networks. He explains what integration means in practice. “It’s two lines coming together in the same place, rather than having two separate links with their own converter stations.” Combining them can save hundreds of millions of euros, he says, “and doing it consistently across the North Sea cuts costs significantly.”
UK electricity system operator National Grid ESO has determined that taking an “integrated approach” to wind farms delivered from 2025 could save consumers an estimated £6bn in capital and operating costs between now and 2050, with cables and ground landing points reduced by around 50%. It is developing a holistic network design (HND) that is expected to incorporate some of these learnings and recommend how to facilitate the 2030 target, including 11 GW of ScotWind.
Integration ideas are taking shape. TenneT, Europe’s largest transmission network operator (TSO), advocates an internationally coordinated modular hub-and-spoke concept. This would be created by the North Sea Wind Power Hub, which consists of several European TSOs. The idea would see wind farms connected to multiple countries, as well as hydrogen conversion stations.
Saskia Jaarsma, director of offshore development for TenneT, says this type of expansion is important.
“We will not achieve the Paris climate change agreement with one or two gigawatt systems. It makes sense to combine it internationally, and this [hub-and-spoke plan] it is a sufficient solution,” she says.
While such a concept is years away from materializing, country-level network integration is beginning to take shape. TenneT’s 2GW Program, which has just started the bidding process, will build at least six offshore grid connection platforms, three in Germany and three in the Netherlands, using a new cable system and having a capacity 2GW transmission. The stations will require half as many grid connections and will greatly reduce footprint compared to the combination of two 900MW platforms, as previously proposed. The company is also working with 50Hertz, another German TSO, to deliver 4 GW of power from two offshore wind farms to a multi-terminal hub on land, so only one AC/DC converter station needs to be built, instead of all three. usual.
Denmark’s Energinet has proposed to build two island man-made power centers in the North Sea, where around 200 wind turbines with a combined capacity of 3GW would be installed in the first phase of the project. The hope is that there will eventually be the potential for 10 GW and the ability to connect to other countries.
In the UK, Alice Etheridge, senior manager of offshore coordination at National Grid ESO, says the operator is considering offshore wind farm projects sharing connections with the mainland for the HND, potentially connecting sea cables from projects in Scotland to England and Wales, rather than just directly to Scotland, plus higher capacity connections and potentially multipurpose interconnectors.
A staged approach
Taking a Europe-wide approach “absolutely has its benefits,” says Etheridge, but progress needs to be incremental.
“That is likely something we will build in the future. As we get on a more durable path, we will probably be heading towards increasing levels of integration with Europe. We all have similar decarbonization goals and having a diverse supply is going to be really beneficial,” she explains. “This will also help us with security of supply and really get value out of this low-carbon generation.”
Etheridge doesn’t think Brexit is prohibitive. However, she says it might require some “practical issues” to be clarified. In the short to medium term, the UK-EU Trade Cooperation Agreement should come in handy, she says.
While there appears to be a European consensus to develop a high-voltage grid in the North Sea, creating such an expansive, multi-stakeholder international infrastructure using novel technology, some of which may not be ready until 2030, creates complications. technical, regulatory and political. as well as supply chain challenges.
To accelerate concept, collaborative planning between national stakeholders and countries needs to happen now. “It looks like an empty sea, but it is really teeming with users and stakeholders; this can never be developed without strong government support,” warns Jaarsma.
Working without multi-stakeholder coordination could create challenges later on. For example, HVDC networks with different voltages are very expensive or impossible to connect.
Collaboration between technology providers is also a key challenge. There are only three leading regional manufacturers for the necessary HVDC technology: Siemens, Hitachi Energy and GE, and the manufacturers are not always willing to share information with each other. Costs will also be high: the PROMOTioN project estimated that offshore transmission infrastructure alone would cost approximately €1bn (around £850m) per gigawatt.
And time is running out. Grid construction timelines are typically more than 10 years, with initial integrated connections not expected until 2030. In its assessment, National Grid ESO warns that delaying the development of such infrastructure could risk missing UK targets for 2030.
“The earlier coordination begins, the greater the benefits, but there are practicalities to consider, such as many of the projects to meet the 2030 target are already in progress,” says Etheridge. “But this kind of coordination is going to be really important in helping other projects get their consent and therefore hit the target.”
To encourage the development of a North Sea mesh network by traditionally conservative TSOs, governments will likely need to facilitate more pilot projects to test the technology. This would help increase confidence and reduce costs.
Despite the challenges, however, Plet says a marine grid in the North Sea is “now inevitable”, with the US and China also eyeing the concept to support their own green energy ambitions.