https://unfccc.int/blog/powering-change

When completed in 2026, Dogger Bank will be the world's largest offshore source of power, able to supply the equivalent of 5 per cent of the UK's electricity demand. It will be constructed in three phases (the offshore work on the first phase will start early next year) between 130km and 190km off the North East coast of England, where wind speeds are higher and more consistent than closer to the shore. To put it into perspective, just one turn of a Dogger Bank turbine - each one three times bigger than the London Eye - will be enough to power a British home for two days.

A joint venture between SSE Renewables, Equinor and Eni, SSE Renewables is leading on the construction and delivery of the project, while Equinor will operate it once its completed for its lifetime of up to 35 years.

Work on the project began in 2010, and continues to be challenging given the conditions in the North Sea as well as due to the size of the wind turbines (each turbine blade is 107 metres long). Indeed, a special boat is needed to install the turbines, called the Voltaire turbine installation vessel, which at its highest extended point, is taller than the Eiffel Tower (and can carry fifteen blades and five turbines at one time).

Yet the project is a result of a lot more than technology, according to Steve Wilson, Project Manager, SSE Renewables, who was speaking at the Climate Action Hub at COP26. "There's three key building blocks to this," he said. "You have the regulatory and policy framework which is needed to support corporate investment and sustainable financial solutions; there is the obvious technological innovation which drives the commercial viability of a project such as this; and there is the collaborative supply chain - both global and local - which enables the delivery of large-scale renewable energy projects."

Wind turbines have a surprisingly long history: the first modern commercial wind turbine started operating in Denmark in 1897. Yet, it is only in recent years that growth has exploded, increasing by a factor of 75 in the past two decades alone. Wind electricity production doubled between 2009 and 2013, while wind energy accounted for 16 per cent of renewably generated electricity in 2016.

For an illustration of how far we have come, cast your mind back to 1991, when the world's first offshore windfarm became operational in Vindeby in Denmark, its 11 turbines able to power the equivalent of 2,200 homes for a year. It was also only 2km offshore, a testament to the difficulty of bringing the energy onshore. By contrast Dogger Bank will be 135km-170km offshore, and will power the equivalent of six million homes annually.

As the technology has improved, so the prices of wind-generated electricity have continued to decline, with IRENA's data showing the weighted-average levelised cost of electricity (LCOE) from new capacity additions of onshore wind declined by 13 per cent, compared to 2019, while the LCOE of offshore wind fell by 9 per cent, two massive drops in such a short space of time. The good news is that this means that "New wind projects are increasingly undercutting even the cheapest and least sustainable of existing coal-fired power plants," according to IRENA.

While offshore wind farms are more expensive than those onshore, they are more reliable, due to the simple fact that there are more windy days out at sea. Dogger Bank will be the first offshore wind project in the UK to use HVDC technology to transmit the electricity produced back to shore, ensuring that the electricity is transmitted efficiently over long distances while minimising losses. HDVC stands for high-voltage direct current technology, which is a more efficient way of sending the power back to shore than AC Transmission.

Another issue is the difficulty of constructing anything that far out to sea, where high waves and poor weather conditions add danger - and expense - to any project. "While we are very far offshore, the water is only 15-45 metres deep, but it is surrounded by deep water and there can be waves in excess of ten metres high, so it's a nasty environment to work and build in," Wilson says. Yet the area is obviously not uninhabited, despite its remoteness, something that had to be taken into account during the planning process. "Dogger Bay is in a special conservation area for harbour porpoise, so we had to take that into account, particularly when it came to building the foundation," Wilson adds. "Ultimately you are building what becomes a reef for marine life - other wind farms have been colonised by seals once built - so you have to be a responsible developer."

Another issue has been the expensive cost of maintaining the turbines and their relatively short lifecycle. "The turbines will have a 25-year lifetime, but we believe that can be extended, and so we expect Dogger Bank will have an operational life of at least 35 years, if not longer," Wilson says.

Despite the huge infrastructural challenges, Dogger Bank looks set to be a trailblazer for a new generation of offshore wind technology.