Renewables are often touted as the solution to the climate crisis: clean, green energy sources that can replace our dependance on fossil fuels and help save the planet. The reality however is more complex, and there are a huge number of challenges when it comes to wind – particularly offshore – energy.

Global offshore wind capacity continues to rise, largely due to falling costs: overall installation costs declined by 28 per cent between 2015 and 2019 according to the International Renewable Energy Association (IRENA).

Offshore wind generation has a number of advantages over onshore wind. Offshore wind is stronger and more reliable than onshore wind, while it is possible to transport much bigger wind turbines by boat than by road – the bigger the turbine, the more power generated.

There are downsides however: the cost of installation, operation and maintenance is much higher for offshore wind farms than onshore, while the lifespan of offshore wind turbines is also shorter.

This was an issue explored at the Arup: How to Scale Offshore Wind event at the Global Climate Action Hub at COP27. Arup is a professional services firm which provides engineering, architecture, planning, and advisory services across every aspect of the built environment.

Mark Nellor, Arup’s Energy Leader for the UK, Middle East, India and Africa was joined online by the World Bank’s Mark Laban.

“We are thirty years in this industry, we have moved from nothing to a mature industry with 57 GW of offshore wind operating across 19 countries,” Laban said. The two key things the industry has seen in that time are cost reduction and scale, Laban added, as well as the fact that the turbines and the size of the offshore fields have gotten much bigger.

Energy Giants

The world’s first offshore windfarm became operational in Vindeby in Denmark in 1991, its 11 turbines able to power the equivalent of 2,200 homes for a year. Contrast that with just one project, Dogger Bank – which will be fully operational of the English coast by 2026 – which will be able to supply the equivalent of 5 per cent of the UK’s electricity demand.

“Typically, you are looking at building blocks of about 200 sq. km,” Laban says, referring to the size of a modern offshore wind farm. “There is at least 71GW of potential space out there – the International Energy Agency and IRENA have estimated we need about 2000 GW of offshore wind to meet 2050 targets.”

Of course, building these wind farms in marine environments is a complex undertaking. “There are a lot of stakeholders involved,” Laban says. “We want to add technology to these precious marine areas that can coexist with what’s already there – which areas do we need to avoid? Spatial planning therefore is a critical part of this industry.”

This was echoed by Beckie Drake, Arup's Offshore Wind Digital Lead, who introduced SCALE, which, the company claims, will “help government bodies and developers to identify the most favourable sites to locate offshore wind farms, balancing performance, lifetime costs and other environmental and marine economic activities.”

The technology can be used to assess specific sites, Drake says, or be used to assess at a country-wide level. “Given the amount of offshore wind that is needed, we really need to move to data-driven approaches and incorporate marine spatial planning,” she adds.

Environmental Issues

Indeed, there are a number of environmental issues that arise when building an offshore wind farm. Connecting the turbines to the grid usually involves an undersea cable which has a negative impact on marine life, and the installation of turbines – the blades alone can be more than 100 metres long – is also damaging to the sea floor.

The technology takes a number of factors into account, such as how far a potential site is from a port or an onshore grid connection point. “The further a wind farm is a from these, the more expensive it will be,” Drake says.

Yet, with “new wind projects are increasingly undercutting even the cheapest and least sustainable of existing coal-fired power plants,” according to IRENA, it is clear that offshore wind will be a vital part of the sustainable energy mix going forward.