Nuclear (in)flexibility, nearly 100% electricity from solar PV and offshore wind surge!
I keep hearing claims, most recently from the British Government, about how nuclear power can be used flexibly to help balance fluctuating wind and solar. But in reality in most situations around the world nuclear is inflexible and its operation simply pushes wind and solar off the grid. Also, according to a report from Ember, cheaper batteries and proliferating solar can lead to solar on its own cheaply providing all electricity demand for 97-99 per cent of the time in the sunnier parts of the world. Meanwhile back in the UK offshore wind is now surpassing generation from natural gas according to the Energy and Climate Intelligence Unit (ECIU).
Tales of SMRs nuclear (in)flexibility
Looking around the world, it is very difficult to find any examples of nuclear power being flexible. The main example quoted is France. However, France has some close connections with the rest of the European continent. These differ for example, to the connections to the UK and the continent.
Unlike the UK, the French electricity system operator has no choice but to order the scaling down of some French nuclear plant. This is to cope with inflows of wind and solar across its borders that they cannot stop. In Britain where the inflows can be better controlled, as elsewhere, nuclear operators would prefer not to be flexible. Instead, wind and solar power get turned off and the renewable sources are blamed for energy that is really being wasted by inflexible nuclear operations! A study of Scotland, where a lot of wind power is constrained because of a lack of grid capacity, found that most wind power would not have been be wasted if there were no nuclear power station s operating in Scotland (see HERE). And, in practice there is no chance of nuclear power plant being flexible in normal operations, whatever people say!
The current UK Government is struggling to mask the fact that it’s so-called new generation of ‘small modular reactors’ (SMRs) is going to cost even more, MW for MW, than the much-overpriced Hinkley C and Sizewell C Nuclear plant. Rolls Royce is leading the charge here with a proposed 470MW (not small!) nuclear reactor. This will come into operation sometime in the next 20 years or so. According to Rolls Royce this development will be ‘equivalent to more than 150 onshore wind turbines’‘ (See HERE) Ah, so that’s the crack! SMRs are now promised to replace wind turbines! That will please the wideley expected future leader, Nigel Farage! Nigel hates windfarms but loves Rolls Royce and nuclear stuff - so patriotic, he claims!
I must say, it’s pretty small fare. I mean the Rolls Royce ‘SMR’ will only replace 150 onshore wind turbines - and at double or probably triple the price of onshore wind in delivered energy! (currently there are over 11000 wind turbines in the UK). Not much of a bargain really for Nigel, there I’m afraid. But really, as with populists the world round, its the headlines that matter, and never mind the facts!
Of course, as with other policies the Government is struggling to compete in messaging with the far-right. In doing so it feels it has to buy into a lot of myths about nuclear power. As one Government minister was made to say recently (presumably by his pro-nuclear civil servants) in an answer to a Parliamentary Question from a Liberal Democrat MP:
‘The next generation of nuclear, including small modular reactors (SMR), offers new possibilities including faster deployment, lower capital costs, and greater flexibility…..Whilst nuclear energy has a unique role to play in delivering stable, low carbon baseload energy, SMRs may be able to serve the electricity grid more flexibly than traditional nuclear, as well as unlock a range of additional applications in energy sectors beyond grid electricity.’ (See HERE)
What unbelievable nonsense! I would never want to be a government minister and have to spout such rubbish! I’ve already suggested that the SMR(s) will take a long time to emerge at eye-watering cost. But flexibility? Why should this happen? It does not happen now with the PWR plant at Sizewell B. So why should it happen with the Rolls Royce ‘SMR’ which is also a PWR? No reason at all!
In fact the Rolls Royce ‘SMR’ it is even less likely to operate flexibly than Sizewell B (which does not). This is because of the likelihood that, as in the case of Hinkley C, Rolls Royce will be offered a so-called ‘baseload’ contract. This means that the nuclear power plant are paid a set price for every MWh they generate - whenever it is generated. It does not matter whether wholesale prices become negative and wind and solar is forced off the system, nuclear continues to generate.
Rolls Royce will no doubt be given such a contract to ensure that the investors get a virtually guaranteed return. Otherwise it will be virtually impossible to attract private investors to give the required facade of part-private finance to the operation. In reality of course the bulk of the money to finance the equity for the plant will come directly from the taxpayer and the consumers will pick up the bill for the inevitable cost overruns.
To cap it all, the SMR(s) will contribute practically nothing to balancing renewables since that will be done by ‘peak’ gas plant (see my blog post HERE).
Almost 100 per cent 24/7 electricity from solar + batteries
Meanwhile solar PV is advancing around the world at several times the pace of new nuclear and fossil fuel power plant. See my earlier blog post HERE and the Figure below. Now, the energy think tank ‘Ember’ (see HERE) conclude that almost 100 per cent electricity can be delivered cheaply in the sunnier parts of the year using solely solar PV and batteries.
In places like Las Vegas and Oman 97-99 per cent of all electricity demand, 24/7 can be provided solely by solar PV for a cost of $104 per MWh. That is exactly the wholesale power price in the UK. It should be recalled that they are talking about just solar PV and batteries, never mind other renewables.
Source: Ember, see HERE
In Las Vegas, according the Ember: ‘Around 17 kilowatt hours of battery are enough to flatten solar to 1 kilowatt of 24-hour solar generation……A 17 kWh battery is relatively small compared to most electric vehicle (EV) batteries’ (pages 17-18). Too right! My Nissan Leaf EV has a 62 kWh battery!
They say: ‘At the grid level, solar with batteries will be a growing asset — though not a silver bullet. Demand varies hourly and seasonally, and no single resource can meet that variability alone. Batteries play a crucial role in balancing, but must work alongside other renewables like wind, hydro, geothermal, as well as interconnectors and flexible demand.’ (page 35 see HERE).
Note: the green bit is solar PV! Source: IRENA - Renewable Energy Capacity Statistics 2025, see HERE
It has been amusing to see solar-sceptics (on LinkedIn) dissing this report by erecting straw men to distract attention from what the report said. For example, one analyst focuses on how solar PV cannot provide 24/7 coverage of electricity on its own in Germany (see HERE). No **** Sherlock, as they say! Well, that’s not quite the point the report was making about the sunnier parts of the world! Besides which Germany has a lot of wind power to use to balance solar power, which is not mentioned by the detractors.
Offshore wind overtakes power from gas
According to a new analysis by the Energy and Climate Intelligence Unit (ECIU) production of electricity from UK offshore windfarms has overtaken production of electricity from domestic UK natural gas production. This has enabled the UK to save around £1 billion in 2024 alone that would otherwise have been paid for Russian gas (based on historical consumption).
As can be seen in the Chart below UK natural gas production has been declining since the turn of the century as gas fields are exhausted.
Source: Energy Institute Review of World Energy, 2025
The Government is currently holding an ‘auction’, called AR7, that will result in the issue of contracts for difference (CfDs) to offshore windfarms. This involves giving a guaranteed price for generation of units of electricity from the windfarms over 20 years. We shall have to wait to see the contract prices are for these winning bids. But in an earlier report, the ECIU has already ‘calculated that in 2024 UK wholesale electricity prices would have been over 30 per cent higher if there had been no wind power generated in the UK’ (see HERE).
What does seem certain is that if it was not for renewable energy generated in Europe as a whole, the energy costs of the Ukraine War would have been even higher. That is because gas prices would have been even higher. Renewable energy is the only practical way Europe can escape from using Russian gas.
David another thought provoking article. I guess the core of the problem that needs to be addressed, in the UK at least, is however much renewables we build it will never be sufficient at our latitude to cover against wind droughts in mid winter. That situation necessitates c2-3TWh of storage and thats in todays world where gas still drives most space heating. Between PSH & BESS we can muster about 40GWh currently although granted BESS build out is on a steep trajectory currently but DENZ are constraining it in the connections reform to around 300-400GWh so the rest as to come from elsewhere. This is where a 35GW gas standby system is being guided and where SMRs could be an alternative. However, given the way we approach risk and hazard management in the UK now its never going to be competitive on pricing and its going to take decades to realise. That in itself is unbelievable when you consider Calder Hall went from concept to power output in well under a decade without the help (or are they a handicap) of todays computing power.
The other problem yet to be confronted is a NZ energy system isn't going to cost competitive against gas or coal anytime soon in the UK. Yes gas is vulnerable to price shocks as we saw in 2022 but its rebalanced itself extremely rapidly as it has always done. Also its cost is being inflated by carbon taxing which still doesn't allow renewables to be competitive writ the large the upper price limit for AR7.
Then the other issue we have in the UK is the utterly cack handed way we have gone about trying to decarbonise electricity supply. The utter failure to expand the grid commensurate with the build out of both onshore and offshore wind particularly in Scotland is inexcusable. This is largely down to OFGEM frustrating the TO's requests to expand grid capability in advance of this construction for nearly a decade and leaves us in the situation of paying windfarms to switch off and CCGTs to come to the rescue. This of course give easy headlines to discredit wind.
Ive always declared im agnostic about CC but once it was decide it was a problem that had to be solved they've not gone about doing so in a coherent way. The previous government saw it as an opportunity to create money for their friends through ROCs until found out then came up with CfDs which at least have a known cost. NESO have been applying sticking plasters to keep the lights on which also add costs. Milband should have stood back and taken the time to come up with a joined up Transmission & Generation plan which his predecessors tasked the BEA and the CEGB to do back in the 50/60's which gave us good reliable and lowish cost electricity for decades but instead is just doubling down in creating an ever more complicated system.
Quite right that gas is a much better 'partner' technology for variable renewables than nuclear. But isnt part of the argument that we are having to make very long term decisions between various expensive options (since providing security of electricity supply with a largely fossil free renewables dominated network in UK conditions is untried and almost certainly very expensive) we need to back various horses at the moment, and that some level of base load nuclear is helpful. Of course, that is completely dependent on getting nuclear costs down from Hinkley and Sizewell levels. Political factors are important here too. From an environmental and a UK energy perspective, the more we can build on technologies that have cross party support, the better we will do given the very long term investment and delivery profiles. So one thing going in favour of nuclear is that at least both Miliband and Farage support it!