Nuclear power drive obsesses over baseload. Do we need it?

The Herald Scotland

29-07-2025

Lately there has been a mounting noise on behalf of more nuclear power in Scotland, pleas for John Swinney to do a u-turn on his ruling out of new nuclear reactors.
For the Herald's recent Torness series, I covered the calls by campaign group Britain Remade for a new small modular reactor to be built on the site of Scotland's only working power station which is set to be shut down in five years.
'Scotland, a country with a proud nuclear heritage, 'said Britain Remade founder Sam Richards, a former Boris Johnson advisor, ' should be looking to build a next generation of reactors.'
Calls for Scotland to embrace nuclear have been greeted with a certain amount of enthusiasm in some quarters, including many SNP voters. But what troubles me, in the current debate, is that all too often it feels like we are stuck in an old vision of the grid – and one of the terms that suggests this is 'baseload'.
Baseload is defined as the minimum amount of electricity required by a grid to meet the continuous demand for power over a day. Currently, it's mostly used to refer to the generating capacity that we need to always be there if the wind stops and the sun doesn't shine.
Britain Remade, for instance, talks about nuclear in terms of 'clean, reliable baseload power'.
But what if nuclear is actually a technology that does not suit a modern renewable grid? What if wind and nuclear are not good bedfellows and, as a baseload, new plants will only make our electricity more expensive?
In a recent Substack, David Toke, author of Energy Revolutions: Profiteering versus Democracy, described the 'accepted truth' in the media that new nuclear power is needed because there is no other practical or cheaper way to balance fluctuating wind and solar power, as 'demonstrably false'.
He said it 'runs counter to the way that the UK electricity grid is going to be balanced anyway' – which, he noted, is by gas engines and turbines 'that are hardly ever used'. Simple gas fired power plants, he said, are many times cheaper per MW compared to nuclear power plant.
Toke advocated for a system balanced by more batteries and other storage as well as gas turbines or engines which will proved 'capacity' rather than generate much energy.
He has a strong point. Of course, the problem with gas, is that it is, famously, a fossil fuel and produces greenhouse gas emissions. However, if, as Toke says, that gas is an increasingly small percentage of electricity generation, about handling the moments when demand is not met by wind and solar, the 5% predicted by the UK Government's Clean Power 2030 Action Plan, to be what we require, perhaps that's no big deal.
It's a bigger deal, though, if the gas power station emissions required to balance the grid are, as another Substack write calculated recently more like 19 percent.
Interestingly, Toke, whose main criticisms of nuclear are its high cost of electricity generation and lack of grid balancing flexibility, also noted that if we are thinking about the financial costs of reducing emissions we might be better off spending our money in other ways. For instance: 'setting up a scheme to pay £15000 each to 500,000 residents not on the gas grid to switch to heat pumps will likely save as much carbon as Sizewell C is likely to save'.
One of the problems with the nuclear and renewable energy debate is that it plays into the idea of energy production as an ideological issue.
But it seems to me the question is not whether nuclear power is simply right or wrong, but what its place is within the kind of modern grid we are developing, a grid which faces transmission challenges between Scotland, already producing more energy than it uses, and elsewhere, and whether the costs are worth it.
It's hard to get clear answers on this. The problem in part is the sheer complexity of the grid and the absence of any clear map for how that is really going to be done. NESO itself doesn't give any kind of guidance on what the grid actually needs. It is technology agnostic, and simply has to work with whatever the politicians and the market dictate.
Too often those that argue for nuclear sell it via the concept 'baseload'. But you only have to do a quick scan of the internet to see it is brimming also with articles about how baseload is extinct or outdated. These critics point out that what the grid actually needs is more flexible sources, both of storage and power.
One of the problems is that traditional nuclear power stations tend to be all on or all off. Torness, for instance, has either one or both of its reactors, either at full or zero capacity. That kind of inflexibility in nuclear plants has already led to constraint payments being made to wind farms, which have been switched off because there was too little demand even as the nuclear power stations kept producing.
In 2020 energy consultants Cornwall Insight estimated the quantity in MWh of constraints that could have been avoided had nuclear power plants in Scotland been shut during two recent years. It found that, in 2017, 94 per cent worth of windfarm output that had been turned off (constrained) could have been generated had nuclear power plant not been operating.
But a new nuclear power station wouldn't have to be like Torness. Ideally, it would be flexible, of what's called 'load-following', reacting quickly to changes in demand on the grid. France, for instance, does have some load-following flexibility in its nuclear system, So, is that what we in the UK are developing?
Not if we look at the two nuclear power stations in the pipeline, Hinkley Point C or the £17 billion Sizewell C, which is not due to generate electricity till after 2040.
Hinkley Point C, though it is set to have some load-following capabilities, is not designed to be a load-following reactor. As written evidence to the UK Parliament from the Nuclear Industry Association in 2023 put it: 'Load-following is not the intended method of operation for the EPRs at Hinkley Point C and Sizewell C because the ratio of nuclear capacity to grid demand will only shrink in the medium term and because in a net zero grid, nuclear could be used for instance to power hydrogen production at times of excess power on the system rather than reducing output….
'This would avoid sacrificing clean energy production and would produce a clean[1]burning fuel for hard-to-decarbonise sectors such as heavy industries that need high temperatures for production.'
As the statement shows, Sizewell C, which got the green light only last week, will be a near replica of Hinkley Point C, in order to reduce production costs – and will therefore also not be load-following.
Winds of Change on nuclear power (Image: Derek McArthur) The good news is that the UK government has a 44.9% stake – but this is only good news if it's the right technology for the right purpose and doesn't go ludicrously over budget. This is a project with estimated costs of £38 billion, which, it has been calculated, could see the public exposed to up to £54.6bn of costs.
So, if neither Hinkley Point C, nor Sizewell C, are set to be load-following, what about the new generation of Rolls Royce Small Modular reactors which the UK Government are backing. These new SMRs are more flexible – but are they even, in any case, what Scotland needs?
But balancing capacity in a grid that requires flexibility is not the only potential use of nuclear – as the Nuclear Industry Association statement shows, it may also be used for hydrogen production.
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Nuclear has been touted as an answer in some of the harder to abate industries, like steel and cement. Sam Richards from Britain Remade raised with me its potential as a source of energy for AI firms.
Gillian Martin recently responded to calls to end the moratorium on new nuclear in Scotland by saying, "We think the investment is much better placed in areas of renewable energy, which is cheaper to produce and is also cheaper for consumers.
"We already have in Scotland more renewable electricity than can often fit onto the grid. We also have hydro power stations which are a way of filling in any gaps in the generation of power."
When people start arguing their case by saying things like 'because baseload' without ever discussing how the grid works, or what that means, it's clear there is a problem.
When the lights went out in Spain, many, including myself speculated over whether the problem could have been lack of inertia, or even inadequate baseload in a grid that was over-reliant on renewables, but the problem turned out to be a flaw, according to the most recent report, in the rules governing what renewables and battery storage are required to do in terms of voltage regulation.
I suspect that when we look back in the future we will consider baseload a security blanket and an unnecessary cost, incompatible with the kind of grid we have in Scotland. But, who doesn't need that blanket?
Meanwhile, our evolving energy system is such a complex thing that what we need is more debate and discussion rather than kneejerk answers. The one thing we can be sure of is that it will be different from the grid of the past.