UK Government announce no U-turn on offshore wind policy - but are less clear on what it means

Toby Maclean, posted 19th October 2020

On 6th October this year Mr Johnson, prime minster for the time being of the UK, announced amongst other things such as the retention of his alleged mojo, that by 2030 in all UK homes:

"Your kettle, your washing machine, your cooker, your heating, your plug-in electric vehicle – the whole lot of them will get their juice cleanly!" [source].

What does this mean?!

It might seem that statement implies in 2030 that offshore wind electricity generation will be greater per annum than domestic electricity use. But it’s more than that! Mr Johnson included heating and most domestic heating in the UK is currently from gas as no doubt he is aware and so he also committed to all non-electrical domestic heating being covered by offshore wind generation as well as the domestic electrical heating and all other domestic electrical use. This is big because energy use from domestic gas is three times energy use from domestic electricity in the UK [source]. And it does not end there; Mr Johnson has included domestic electric vehicles too! Cars (domestic and otherwise) currently account for 60% of fuel use in the UK [source] so we can imagine there is scope for a very large increase in electrical demand if a significant number of cars become electric vehicles.

There were even specifics, with the "target" for offshore wind in order to achieve all this new offshore wind power rising from 30GW to 40GW. His language is a little colloquial but we can probably safely assume that means 40GW capacity and as of 2019 there is about 10GW of installed offshore wind power capacity [source].

Now, it might be said that this was not really a new announcement. 3 months earlier in July this year, Mr Johnson’s "business, energy and clean growth" minister Kwasi Kwarteng announced the aim to increase UK offshore wind power from 10GW to 40GW by 2030 [source]. If it sounds very similar to the words used by Mr Johnson 3 months later it may be because it is the same pledge. But in July it was claimed this capacity "could help power an extra 14 million homes with green energy". There are about 27M homes in the UK [source] so 14M is about half the homes. That’s weird isn’t it as 3 months later Mr Johnson tells us the same offshore wind capacity will power all the homes. Maybe that is what mojo does for you?

And had you read Mr Kwarteng’s announcement in July 2020 and your memory extended another 16 months back to March 2019 you may have remembered his predecessor Claire Perry (at the time it seems business was not included in the brief so Ms Perry was simply "minster for energy and clean growth") announce that "a third of British electricity [is] set to be produced by offshore wind power by 2030" [source]. Now British electricity generation was about 300,000GWh in 2018 [source]. It’s down from a 2008 peak of about 340,000GWh but has plateaued in recent years and will presumably increase with the rise of electric vehicle demand and the uptake of electrical heating with things like heat pumps. So, let’s be generous for now and assume one-third of British electricity in 10 years’ time means only around 100,000GWh and not a higher figure because of higher demand in 10 years’ time.

Now we need to some maths because we’re talking about power capacity in GW and energy generation in GWh we need some way to convert between them. In 2019 the offshore wind power capacity was 10GW and the offshore wind energy generation was 32,000GWh implying about 3,200GWh of energy from every GW of power capacity (this figure fluctuates by no more than about 8% over the preceding 6 years) [source].

So, now we know that to fulfil Ms Perry’s pledge of one-third of all British electricity to be from offshore wind (we’re calling this about 100,000GWh) we’d need 100,000GWh/3200h = 31.25GW power capacity.

And to “power” the 14M homes Mr Kwarteng hoped to we’d need to supply about half all domestic energy from offshore wind. We don’t know if Mr Kwarteng meant energy (ie: including gas and other sources) or electrical energy only when he made this promise but domestic energy use in 2018 was about 480,000GWh and domestic electricity use was about 105,000GWh (the difference is mostly due to gas use) [source] so he either meant 240,000GWh at the top end or 52,500GWh at the lower end. The 40GW of offshore power capacity that Mr Kwarteng referred to is going to get us about 40GW x 3,200h = 126,000GWh of energy generated so is too much to just cover half the domestic electricity but not nearly enough to cover half all domestic energy. The figure of 126,000GWh is in the same ballpark as the implied 100,000GWh from his predecessor Ms Perry though.

And finally we come to Mr Johnson, the latest of the trio to make substantially the same announcement, although we may be beginning to see where the target Mr Johnson referred to of 30GW (similar to the implication of Ms Perry’s promise) has been increased to 40GW (Mr Kwarteng’s promise).

Mr Johnson has gone all out: his extra 30GW of offshore power (from current capacity) will power not just 14M homes but all 27M UK homes. We can see from the above that 40GW of power capacity only delivers about 126,000GWh which covers the current domestic electricity demand of 105,000GWh but is only about a quarter of the total domestic energy use of 480,000GWh. Of course in reality if there is any significant uptake in electric cars or use of heat pumps for domestic heating by 2030, both of which are likely, then domestic electrical use is likely to rise above 126,000GWh by then.

Having written this It occurred to me that I should have first run Mr Johnson’s words through the real-world-translator I have developed that takes any sentence spoken by a member of the current government and parses its actual meaning. When I did this, I found that it translated Mr Johnson’s words:

“Your kettle, your washing machine, your cooker, your heating, your plug-in electric vehicle – the whole lot of them will get their juice cleanly!"

to really mean:

”We will not renege on the announcement we made 3 months ago which is to aim to have offshore wind power capacity by 2030 able to provide equivalent to the current domestic electrical use but not necessarily all domestic electrical use by the time we get to 2030 and certainly barely any of the current domestic gas use which represents three times more energy than domestic electrical use. In short, we’ll probably manage about one quarter domestic energy use from offshore wind if we hit our targets”.

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