How much power is Scotland's offshore wind set to deliver?

But Seagreen, big as it is, with its 114 turbines, some of them 280m above the waves, almost as tall as the London Shard, will seem like a wind garden compared to the developments we are set to see as the wind revolution gathers speed.

Berwick Bank, a giant fixed wind farm which is planned to host over 300 turbines, at the edge of the Firth of Forth, is set to deliver 4GW of power, enough to supply Scotland’s homes twice over.

Meanwhile, floating wind - turbines tethered to the seabed, but riding the sea’s surface, out in deeper water than these farms - is widely seen as the key wind technology of the future. Its virtue is it is more efficient than fixed sites, though more challenging to develop.

READ MORE: Scotland’s offshore wind farm power and potential visualised

A wind is gathering, as global leaders convene for Cop27 this week, not just in Scotland but globally. If the world is to get on track for 1.5°C, the International Energy Agency has said, annual global wind energy installations must quadruple by 2030. Wind energy must generate more than one-third of global electricity, up from 6% today. It's a shift that has, according to the IEA's recent World Energy Outlook report, already been supercharged by Russia's invation Ukraine, just as oil and gas exploration has also been turbo-boosted. Which, the question is, is tearing ahead in this race?

The offshore wind revolution is well underway and the UK has more installed capacity than any other country in the world. More than a fifth of capacity additions to the global offshore wind market came from the UK in 2021, with, following the ScotWind leasing rounds this year, far more to come. Offshore Energy UK, recently called for a “rapid expansion of offshore wind”. But does it really have the potential to displace oil and gas from our energy supplies? Will we soon talk of Scotland’s wind in the way we once did Scotland’s oil?

The Scottish Government has a target of 11GW of offshore wind power by 2030, but much more is set for development: almost 28GW of offshore wind energy through the ScotWind leasing process.

Last week, Scotwind announced that, making 20 projects with seabed agreements in the pipeline, with investments totalling £28.8 billion and £1billion investment in Scotland per gigawatt of capacity built.

To put that in context, currently there is just over 11 GW of offshore wind capacity in all of British waters, with around 2GW of this, and rising, in Scotland. The speed of change must ramp up. It has taken 16 years, since the first offshore turbine was installed near the Beatrice oilfield, for Scotland to reach that 2GW, but in around half that time we are set to increase it fivefold. The sheer quantity of development in the pipeline is breathtaking, and, since installed offshore wind capacity in the UK is projected to increase from 11GW in 2022 to up to 50GW by 2030, it has been calculated that the UK will need to install the equivalent of four Seagreen projects every single year for the next eight years.

Bear in mind that Seagreen has been 12 years in the making. Berwick Bank has already been in development for ten years. So far wind farms have not been quick fixes.

Right now, according to Professor Keith Bell of the University of Strathclyde, Seagreen, with its capacity of just over 1GW presents a significant addition. However, the wind energy expert noted, “There is a long way to go to the UK Government’s target of a total of 50 GW of offshore wind capacity by 2030. That would be enough to meet roughly 60% of Britain’s annual demand for electricity, if it could all be used.”

Offshore wind has become an important focus of development for several reasons. “Amongst them,” said Bell, “is the fact that economies of scale have been possible with offshore wind in ways that haven’t been possible for onshore wind. In particular the technology has been developed to allow huge wind turbines. For example, the blades on the turbines at Seagreen are around 80m long.”

Among the key questions is whether the full 28 GW allocated in recent Scotwind rounds of seabed leases will all be developed. Prof Bell said: “That depends on what commercial arrangements the developers can access. For example, they may enter one of the auctions for “contracts for difference” (CfDs) backed by the UK Government, in competition with each other and wind farms off the English and Welsh coasts.”

Such contracts for difference effectively guarantee a price for energy – below which the state will pay the difference, and above with the company will pay the Treasury. They have been designed to incentivise investment in renewables.

The 4th such auction was concluded earlier this year and awarded contracts to 7 GW of offshore wind plus 0.6 GW of wind capacity on Scottish islands, all due to start operation in four to five years time. A fifth contract for difference allocation round is expected in December.

Scotland is often said to be ideal for wind energy development. It has often been  said that we are the windiest nation in Europe, or that Scotland has 1% of the population and 25% of the offshore wind potential - though according to a These Islands blog by Sam Taylor, the real figure may be more like 4-6%. 

The sheer power of that wind brings with it a challenge as well as a blessing. Prof Bell said: “Average wind speeds offshore are very good. In contrast, the conditions out there can be quite hostile and present challenges to design and construction of equipment and safe access for maintenance. However, the sector has learned a lot over the years about how to do that.”

The biggest revolution in wind, however, is likely to involve floating wind. The world’s first such development, Hywind, has been operating in Scottish waters, pioneered by Equinor, since 2017, and a second floating project, Kincardine, is almost fully operational. Hywind has repeatedly set records as Scotland’s best performing offshore wind farm, reaching, in the twelve months leading up to March 2021, an average annual capacity factor of 57.1%, significantly higher than the average for fixed foundation projects.

More is likely to come. RenewableUK's Emerging Technologies Policy Analyst Laurie Heyworth, said: “As we build floating projects in the windiest locations further from the shore we expect to see high load factors of 60% or more in the projects now being planned.”

Of the 20 projects that secured option agreements through Scotwind, thirteen included floating wind, including the giant 200 turbine MarramWind, a Shell and Scottish Power project being touted as "a game-changer" in the sector. The chief reason floating wind is attracting such backing, is because it allows access to deeper waters and a richer wind resource, possibly double the capacity of bottom-fixed farms, whose sites are limited to depths of up to 60 metres.

The ambition for floating wind is huge. The UK Government has set the industry a target of installing 5GW of floating wind by 2030 as part of its Energy Security Strategy, but more is needed if we are to decarbonise our electricity system to reach net zero emissions by 2050. According to Heyworth, “Looking further ahead, we'll need to install over 100GW of offshore wind by 2050 (fixed foundation and floating). We expect that more than 50% of this will be floating wind projects.”

There is also, Heyworth said, “a massive economic prize”. “The floating wind sector could support at least 29,000 jobs by 2050 and generate £43.5bn of economic activity (GVA) – particularly in Scotland, Wales and the south west of England, with a supply chain throughout the country.” This is a technology, she said, “in which the UK is a global leader” and has “a first mover advantage”, as well as the potential to "export our floating wind expertise worldwide in the coming years.”

Without an ambitious roll-out of floating wind and large scale windfarms like Berwick Bank there is little chance of Scotland hitting net zero targets. Offshore wind is widely seen as the answer in Scotland and the UK – and the gas crisis is only driving that home.

This article has been corrected to include Sam Taylor's assessment of Scotland's proportion of the offshore wind potential in Europe as 4-6%.