Offshore wind: the distinction between strike price and subsidy matters

Offshore wind strike price subsidy

On 11 September 2017 the UK government announced that two developers would commit to delivering 2.4GW of offshore wind capacity for a strike price of £57.50 per MWh generated from 2022/23, taking the industry by surprise. Comparisons to the £92.50 MWh required by the planned Hinkley Point C nuclear plant quickly spread on social media.

In reporting the story, these figures were incorrectly described as direct subsidies. This may sound like an unnecessary technicality but what the strike price is (and who ultimately pays) is critical to having a proper debate about the future of UK energy.

The first reason that it is wrong to report the news as a regular subsidy is that the typical news story implied that the support required to make the two offshore wind farms viable is just over half that required by Hinkley Point C when actually the difference is far greater. To understand this, one needs to understand the strike price.

The strike price is a guaranteed price to be paid to wholesale generators of electricity. It is a critical element of UK energy policy with the aim of creating incentives for companies to invest in certain kinds of low-carbon power, like renewables and nuclear. If the wholesale market price is less than the strike price, such generators receive a top-up.

Importantly, if the wholesale price exceeds the strike price, generators pay back the difference to the Low Carbon Contracts Company (the company administering the scheme). For the last six years or so, the monthly average of the wholesale price has fluctuated between around £35 per MWh and £68 per MWh averaging around £45 per MWh according to Ofgem, the energy market regulator. Assuming the average wholesale price stays around £45 per MWh in the future, the top up payment to the offshore wind farms with a strike price of £57.50 per MWh will be just £12.50 per MWh.

In stark contrast, the top up payment to Hinkley Point C will be nearly four times greater at £47.50 per MWh – not double as reported by many commentators. And, as explained above, if the wholesale price should go above £57.50 per MWh, then these two offshore wind sites will not only not require support, they will pay the difference back.

The second problem with reporting the strike price as a regular subsidy is that the funding mechanism (the Levy Control Framework) is different and separate from other government budgetary decisions. To cover the costs of making up any shortfalls from the strike price, the government adds a levy to consumers’ electricity bills. The more electricity you use, the more you contribute to the cost of a strike price. This is not money that comes out of the government’s general pot of funds.

If you still don’t think this distinction matters much consider the difference in the “take-away message” between two readers, one who has been informed about the strike price and one who interprets it as a full subsidy.

The latter comes away with the message: nuclear power and offshore wind still need a big subsidy and to be propped up by the tax payer.

While the informed reader comes away with the message: new offshore wind requires very little support compared to nuclear and, in any case, that support is paid for proportionately by those people consuming the electricity.

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Philip Summerton Chief Executive Officer [email protected]


  • Peter Williams
    13th September 2017 | 6:14 am13/9/2017

    Details do matter!

    Hornsea 2 works on this new lower strike price of ~£57/MW because it relies in part on the existing infrastructure of Hornsea 1 which has a strike price of ~£140/MW.

    A better comparison would be the average strike price of each MW for all electricity supplied by the Hirnsea offshore Windfarm plus the cost of base load power when the wind does not blow with base load Nuclear.

    Put simoly until despatchable grid scale storage is economically developed then we are going to need a combination of Nuckear and renewables for sustainable zero carbon power generation in the UK.

    • Philip Summerton
      13th September 2017 | 5:35 pm13/9/2017

      Thanks Peter, you raise two more important points. On the Hornsea site specifics, as the capacity for the second site is c 1.4GW and the first site 1.2GW you can argue the weighted average is roughly the same as Hinkley. However, DONG is currently consulting on a Hornsea 3, which would presumably be a site between 800MW and 1.5GW (DONG’s preferred site size) and require a strike price similar to Hornsea 2. This would bring the average for all three Hornsea sites to around £80 per MWh. However, a major reason for the cost reduction is turbine size and it is not at all clear how much of the cost saving is down to the shared infrastructure. How might we explain the low cost of Moray East or Triton Knoll?

      The intermittency point matters too. There is a cost to managing intermittency at scale on the grid whereas base load electricity from nuclear is a different ‘thing’. There’s a question as to whether base load should be treated the same was as intermittency at all.

      My point for the blog was not that we don’t need a mix of technologies, nor that intermittently supplied electricity is the same as base load electricity. My point was that the economics related media needs to do more to report these complex issues more clearly without betraying the message.

  • M1cxMk
    1st December 2017 | 6:55 am1/12/2017

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  • Ian Fotheringham
    4th February 2020 | 6:27 pm4/2/2020

    With a mix of strike prices won”t Hornsea’s operators choose to curtail the lower strike price output when requested by the grid to cut back on output?

    Or to put that another way how do curtailment payments work across a wind farm with multiple strike prices?

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