We present what may be the first estimate of the levelised cost of floating offshore wind.
Last year, I wrote a blog post setting out the financial situation of Hywind, the UK’s first commercial floating offshore windfarm, and indeed the first in the world. It was an ugly tale, with a hugely lossmaking operation kept in the black only by a vast transfer of subsidies. However, Hywind has recently published its second set of financial results since it became fully operational, and so we can now start to get a handle on its operational performance and underlying costs, and publish what I believe is the first estimate of the levelised cost of floating offshore wind.
Situated off Peterhead, in what appears to be something of a sweet spot for wind, it is unsurprising that Hywind’s performance is rather better than your typical offshore windfarm. Renewables advocates are keen to point out that its capacity factor (the electricity generated as a percentage of the theoretical maximum) has reached 57%. However, in 2020/2021, that fell back to just 51%, which is only a few points ahead of recent fixed offshore windfarms.
Meanwhile its costs are extraordinarily high. We already knew that its capital cost, at £8.9m/MW. was around three times the that of fixed offshore wind. But its opex costs are also much higher than might be expected. As a rule of thumb, fixed offshore wind opex starts at around £100,000/MW per year, and then rises from there as the turbines age. However, Hywind seems to have started out from a much higher base – its opex costs have averaged over £200,000/MW per year since it became operational.
With only marginally better operational performance than fixed offshore, and costs that are several times higher, there is no hope that Hywind’s overall levelised cost will be anything other than disastrously expensive. I estimate the LCOE figure as £224/MWh, a value that is unchanged since last year, suggesting that the value is reasonably robust. This is approximately double that of fixed offshore wind, and perhaps five to six times what we would expect for electricity from gas turbines. (As always when comparing wind and gas, we should note that the comparison is misleading, since wind should carry a considerable extra cost burden because of its intermittency, which is expensive to correct).
There can therefore be little doubt that Hywind is a failure. Kincardine, the UK’s second floating offshore windfarm, looks as though it will be more expensive still. It seems beyond doubt that floating offshore wind is a financial disaster.
Unsurprisingly, the government is ploughing ahead with it regardless.
Lifespan: 20 years
Output deterioration: 2.1% per annum
Opex increase: 5.7% per annum
The calculations can be seen in the spreadsheet below: