Why the UK can’t rely on renewables...yet

The flaw in renewable energy

13 November 2021

9:00 AM

13 November 2021

9:00 AM

Like a football tournament with an official beer, COP26 had an official energy provider: the Griffin wind farm in Perthshire, operated by SSE. Trouble is that for much of the conference it was not paid to generate electricity. Instead, it received £500,000 in ‘constraint payments’, which are given to owners of wind farms when they are generating too much electricity for the grid to absorb. The payments expose a huge hole in Britain’s renewables-heavy energy policy: we have little means of storing energy when the wind is blowing and the sun is shining so that we can use it on dull, windless days.

In eight years, Boris Johnson has gone from telling us that wind turbines ‘couldn’t pull the skin off a rice pudding’ to boasting that Britain is going to become ‘the Saudi Arabia of wind’. He is wrong on both counts. Give a wind turbine a strong sou’wester and it could pull the roof off the entire Ambrosia factory. As for the Saudi comment, we’ve got a long way to go: as things stand Britain ranks only sixth in the world for installed wind power capacity, behind China, the US, Germany, India and Spain.

The comparison is also inapt because Saudi Arabia doesn’t routinely pour its oil down the drain for want of tanks to store it or tankers to take it away. That is what we are doing with wind energy. According to the Renewable Energy Foundation, 3.7 TWh of wind energy in 2020 — enough to power every home in Wales for the whole year — was wasted because the national grid could not accept it. Wind farm owners were paid a total of £274 million in ‘constraint payments’ to turn off their turbines — which was passed on to consumers’ bills.

The problem is exacerbated because over-generous constraint payments have given wind-farm operators a perverse incentive to build in places where there is little demand for electricity: they get paid more when they are not generating electricity than when they are.

If this is what happens when wind is generating 24 per cent of our electricity, as it did last year, imagine the outcome when we try to meet the PM’s ambition of having all our electricity generated by low-carbon sources by 2035 — when we will no longer have any gas-fired power stations as back-up.

It ought to be obvious that wind and solar power cannot form the backbone of the nation’s electricity supply without vast quantities of storage. Yet our national enthusiasm for wind and solar power has run ahead of solving the storage problem. In spite of a boom in battery installations over the past couple of years, most of Britain’s energy storage capacity is in the form of hydro-electric pumped systems built between the 1950s and 1980s in order to improve the efficiency of nuclear power stations (there is another planned for Loch Lochy in the Great Glen but it will take years to build). This is a disarmingly simple way of storing energy: when electricity is plentiful and cheap, during the night, you pump water uphill to a reservoir. When demand is greater during the day, you release it to run downhill, through turbines.

But Britain’s four pumped storage power stations were designed to iron out diurnal cycles in supply and demand, not to supply electricity for days on end when renewables are not delivering the goods. The battery boom has attracted investors after green assets — two investment trusts which specialise in batteries, Gresham House Energy Storage and Gore Street Energy Storage, are both trading at premiums of 15 per cent to their underlying assets — but it has hardly helped Britain to cope with the regular droughts in wind and solar power. According to National Grid ESO — the demerged bit of National Grid which looks after the actual grid — Britain currently has 25.4 GWh of energy storage. Given that we consumed 346,000 GWh of electricity in 2019, this amounts to just 38 minutes’ worth of supply. Imagine that the nation’s electricity was supplied entirely by wind and solar. If the Cup Final was held on a dull and windless day, we wouldn’t even get to half-time before the TV flickered and died.

Big batteries are not without risk, either. Australia has seen vast battery installations in recent years, one of which, the Victoria Big Battery, burst into flames in July, taking 30 fire engines four days to put it out. While big batteries were credited with helping south Australia get by for 29 days in October on wind and solar power alone, that was an especially windy and sunny month. The state’s massive 129 MWh Hornsdale battery will store just 24 minutes’ worth of energy when the adjoining wind farm is working at full pelt.

When you store energy, you have to pay twice: once to generate it and again to store it. In many cases, the latter costs more than the former. A study last December by the US Department of Energy put the lifetime cost of energy from a 100 MW pumped storage system at around $100 (£75) per MWh and that from a lithium ion battery installation at $300 (£225) per MWh. Prior to this autumn’s spike, the wholesale price of electricity was hovering around £60 per MWh.

We are told that wind and solar power are cheap because the price of turbines and panels has crashed. But you can’t have an electricity grid dominated by wind and solar without supplementing it with massive amounts of storage. The cheapest way of storing energy according to the US Department of Energy, by the way, is by using surplus power to fill an underground chamber with compressed air, then releasing it to drive turbines. There has been such a plant operating in the US since 1991 — although it is not an easy solution because it needs a very particular kind of geology.

Storage technology will no doubt improve, but whether it will do so at the rate and to the extent required to allow the government to close down gas plants by 2035 is an entirely different matter. Saudi Arabians have been richly rewarded by living in a country awash with oil. Filling your tank in Riyadh costs the equivalent of 44p a litre for petrol and 10p for diesel. Keeping yourself warm in the ‘Saudi Arabia of wind’ is not, I’m afraid, going to be so cheap.

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