Like many sectors, the offshore wind industry has been hit by rising costs over the past few years.

This is linked to factors like global supply chain pressures, increased steel costs and high interest rates, partly the result of the Russia-Ukraine war.

Last year, energy company Orsted decided to "discontinue" one of the country's biggest wind projects, Hornsea 4, despite it previously being awarded a contract.

In this latest auction, traditional offshore wind projects - those fixed to the seabed - have been awarded an average fixed price of nearly £91 per megawatt-hour of electricity generated, in 2024 prices.

While that is down considerably from the first auction in 2015, it is up from the £82/MWh awarded at the last auction for new-build projects in 2024, also in 2024 prices.

The government acknowledges the rising cost of offshore wind, but argues that it should be compared with the cost of new gas power plants.

Its figures suggest that building and fuelling new gas plants would cost £147/MWh, including a carbon price - a charge for emissions.

"We're confident that the renewables auction as a whole will help bring down bills for consumers," Energy Secretary Ed Miliband told BBC News.

"The truth is, those who say we should stick with fossil fuels are making a massive gamble, and they're gambling with the British people's energy bills," he added, pointing to the rise in gas prices at the onset of the Russia-Ukraine war.

But shadow energy secretary Claire Coutinho said: "They promised the British electorate that they would cut bills by £300. In fact, their bills have gone up by £200 since.

"This is Ed Miliband's new grand plan to lower bills, and he signed up to contracts for offshore wind, which are the highest prices we've seen in a decade," she told BBC News.

Coutinho also suggested offshore wind brought extra costs, such as upgrading the grid.

Reform has also repeatedly attacked the cost of net zero, but the Lib Dems and Greens both support the expansion of renewables to tackle the threat of climate change and boost green jobs.

SNP and Plaid Cymru also support the growth of offshore wind, but argue Scotland and Wales should have control of their energy resources.

The results of the auction have been broadly welcomed by the energy industry and climate groups, although RSPB Scotland raised concerns about the possible impacts of the Berwick Bank farm on seabird populations.