Hywind, low economics: the cost of floating offshore wind power

Posted: October 18, 2020 by tallbloke in Big Green, government, turbines, waves, weather, wind
Image credit: Equinor, Via GWPF

Guest reblog of a post written by Andrew Montford at the GWPF

Yesterday, I wrote about the financial travails of the Kincardine Floating Windfarm and the eye watering bill that is going to have to be paid for its construction. The cost of floating offshore wind power is, it seems, going to be high.

I thought it might be interesting to look at Hywind, the UK’s first operational floating windfarm, which started production back in 2017. Floating windfarms are thought to be a good idea for two main reasons. Firstly you can park them where-ever the wind is best; that means you should maximise production. It is also argued that operating and maintenance costs should be lower; instead of having to deliver crew and parts by boat or helicopter, you simply tow a broken turbine back to port and fix it there.

Let’s see how Hywind is doing. The windfarm is aptly named, because, parked 20 miles off Peterhead, it has been delivering load factors (that is, the percentage of theoretical capacity) of over 50%. That’s better than even the best fixed windfarms, for which you might expect a figure of around 45%.

Unfortunately, according to Hywind’s most recent accounts, this improved performance comes at a cost. At £264 million, its paltry 30MW of capacity cost its backers £8.8m per megawatt. This compares to £3.5m for fixed offshore wind (which operates at much lower load factor) , and £0.6 million for gas turbines (which can operate at much higher ones). So the projects backers are paying three times the price of fixed offshore wind, for marginally higher output.

Meanwhile, the operating costs are either disappointing or disastrous, depending on your view of the world. A fixed offshore windfarm like Rampion – of similar vintage to Hywind – has operating costs of around £150,000/MW. On that basis, Hywind’s £200,000 per megawatt is very disappointing. On the other hand, renewables advocates claim that the true operating costs of fixed offshore wind are well below £100,000/MW. If that’s the case, and floating offshore is supposed to be cheaper to maintain, then Hywind’s performance could be seen as a disaster.

All this means that the underlying economics of the project are appalling. Hywind only managed to clock up £5 million of electricity sales, and its underlying position is a loss of £15 million or so. Still, the developers will not be overly worried; subsidies from the government brought in another £29 million of income, and so they are sitting pretty on a profit of £13 million.

Why would they care about their operating costs?

  1. oldbrew says:

    This might save a bit on costs…

    Drone inspection of wind turbines – on- and offshore

    Robots doing servicing from remotely controlled unmanned boats has also been talked up. Not so good for the ‘green jobs’ hype though.

    Any kind of structure at sea is going to lead to high costs, ask the oil and gas industries. At least they generate(d) massive profits, so didn’t need vast subsidies.

  2. It doesn't add up... says:

    With the 3.5 ROC subsidy, worth £175/MWh, they are not in danger of going broke, even if the market value of their output is only worth about £30/MWh. However, this is only the beginning…

    From FES 2020:

    Deep Water sites – Dolphyn project:
    Environmental Resources Management (ERM) has developed a design for
    Dolphyn (Deepwater Offshore Local Production of HYdrogeN) to produce green hydrogen
    at scale from offshore floating wind. Earlier this year, the UK government allocated £3.12m
    for the second phase of this programme, initially established under the BEIS Energy
    Innovation Programme.
    The concept involves floating semi-submersible wind turbines integrated with electrolysis
    and desalination facilities. The electrolysers will split desalinated seawater into hydrogen
    and oxygen, with the hydrogen being piped ashore. The use of floating turbines will give
    access to the most favourable UK offshore wind resources in deep water several hundred
    kilometres from land.
    The initial stage will involve a 2MW prototype, aimed to begin operations off the coast of
    Scotland in 2024, with a 10MW full scale pre-commercial facility three years later. This
    could produce up to 800 tonnes of hydrogen per year – enough to heat around 2,500
    homes, fuel up to 240 buses or run 8 to 12 trains.
    Over the long term the project aims to roll out 400 turbines in the 2030s, with a capacity of
    4GW and producing over 320,000 tonnes of hydrogen per year – enough to heat 1.5 million
    UK homes.

    Water for electrolysis and desalination:
    Where electrolysis takes place offshore, we have assumed that it would
    not make sense to pipe fresh water from the mainland so instead propose that some
    input energy is required to power co-located desalinisation equipment. This reduces the
    conversion efficiency of the process in energy terms which is reflected in our analysis
    where we have assumed a 70% efficiency.

    So that’s several hundred km of subsea hydrogen pipeline, likely subject to HIC in a few years, coupled to the most expensive form of offshore wind, with desalination built in as well as the optimistic assumptions. At least the Ancient Mariner might not be faced with water, water everywhere Nor any drop to drink. But the rest of us will be landed with the most extravagant method for producing hydrogen devised by man or beast, with a cost that probably exceeds the highest FiT ever paid. They really are taking the Mickey now.

  3. Dave Ward says:

    “You simply tow a broken turbine back to port and fix it there”

    I doubt it is quite that simple. For a start, is the electrical connection made by a waterproof* plug & socket? And what about the tethering cables? They must either be (temporarily) secured to floating buoys, or lowered to the seabed. In both cases this will need divers or some sort of ROV to do the job.

    * I’d love to see one capable of handling 2MW+, at tens of kilovolts, AND robust enough to withstand salt water for years…

  4. Chaswarnertoo says:

    ‘Green’ insanity.

  5. Coeur de Lion says:

    “You can park them wherever the wind is best….”
    Where’s that exactly? A phrase written by somebody whose depth of ignorance about, say, North Sea meteorology is unplumbable. And move them about, eh? I love the miles of undersea hydrogen pipework. Are the leaking bubbles detectable? How deep, where to dive, use a robot, how commanded? Acoustically?

  6. oldbrew says:

    GWPF article: Unfortunately, the cost has risen further still. First to £350 million, and it is now reported that the management think the final bill could end up at £500 million. That would amount to £10 million per megawatt, or nearly seventeen times what a megawatt of gas capacity would cost.
    – – –
    The work is mainly going to Spain and the Netherlands. The Real Madrid chairman has a stake…

    ‘World’s largest’ floating wind farm off Aberdeenshire delayed by six months

    Gary Smith, GMB’s Scotland secretary, said the decision by Spanish fabrication firm Naviantia to create up to 350 jobs at its yards in Spain was part of a “long political failure” in Scotland.

    He added the situation threatened to “sink” Scotland’s renewable energy supply chain ambitions before they had “even got started”.


    *World’s largest*= six turbines = £500 million? Insanity.

  7. gbaikie says:

    –Dave Ward says:
    October 18, 2020 at 8:28 pm
    “You simply tow a broken turbine back to port and fix it there”

    I doubt it is quite that simple.–

    I would lower it, remove broken component, replace with “new” one, take just broken component
    to place to repair/refurnish it.

    I would use what call a pipelauncher. A pipelauncher is pipe with one end capped and open end
    of pipe is underwater. By adding air, or removing air, pipelauncher goes up and down.
    And would use liquid air to add air. Liquid air by the ton is fairly cheap.

    The basic idea of pipelauncher is to launch rockets {go up fast by adding liquid air}. So such pipelauncher would be quite big and acceleration 1000 ton rocket to about 100 mph.
    For wind mills the pipelauncher part of it, would be smaller- maybe, it could be retro fitted to such floating platforms.