PolicySeed UK

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[PolicySeed UK @policyseed]

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[PolicySeed UK @policyseed]

What if domestic electricity pricing were simple?

⚡ 15p/kWh daytime electricity
🌙 7.5p/kWh overnight
🔌 A transparent network subscription
📉 No traditional standing charge

That’s the idea behind our National Domestic Electricity Tariff.

https://t.co/nnvqMIwOk6

@Miatsf @mgshanks @energygovuk

[PolicySeed UK @policyseed]

This misses something rather important about the RO.

Renewable Obligation support isn’t permanent. As individual RO accreditations reach the end of their support periods, the ROC support ends.

The wind farm doesn’t disappear. The hydro station doesn’t disappear. The biomass plant doesn’t disappear.

The generating asset can continue producing electricity and selling it into the market — but consumers no longer have to fund its ROC support.

The scale matters. Ofgem estimates the entire RO scheme at around £8.7bn for 2025/26.

And it currently covers an enormous amount of generation: in 2024/25, RO-accredited stations produced 74.8 TWh, equivalent to around 30% of UK electricity supply.

So simply looking at today’s RO cost and assuming that cost continues indefinitely gives a misleading picture of the economics of the existing renewable fleet.

These are largely already-built assets. As their support expires, Britain retains the generating capacity while the historic subsidy progressively falls away.

That’s precisely why comparing the remaining lifetime cost of existing renewables with a hypothetical all-gas system is more interesting than simply quoting today’s subsidy bill.

Gas has the opposite characteristic: the fuel bill never expires.

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[PolicySeed UK @policyseed]

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[PolicySeed UK @policyseed]

What is Britain making this week? Quite a lot...

https://t.co/U1N7zRHIKf

[PolicySeed UK @policyseed]

https://t.co/hg7XsWkjWO

[PolicySeed UK @policyseed]

Indeed. Our analysis shows a huge gap between overnight and daytime electricity demand — which is hardly surprising, but the scale is interesting when you actually look at the numbers.

We also don’t think millions more EVs automatically mean exhausting that spare overnight capacity. The important bit is smart charging. Cars don’t all need to start charging at 11:30pm at full power; charging can be spread across the night according to when capacity and electricity are available.

NESO itself sees smart EV charging as an important part of managing future electricity demand. In fact, flexibility increasingly works both ways: consumers can shift demand away from constrained periods and increase consumption when electricity is abundant.

That’s part of our argument for making cheap overnight electricity available to everyone, not just EV owners.

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[PolicySeed UK @policyseed]

We’re now getting quite a long way from the point of the original post.

Our analysis wasn’t arguing that renewables have no additional system costs. It asked a much simpler question: if Britain didn’t have renewable generation and instead generated that electricity from gas, what would the fuel alone have cost?

That’s why comparisons with highly gas-dependent systems are useful. Singapore, for example, currently generates around 94–95% of its electricity from natural gas. Even Singapore is actively pursuing solar, electricity imports and other low-carbon sources to diversify its system.

Whether Britain should have built Kingsnorth D instead of BritNed is an interesting historical debate, but it doesn’t answer the cost question in our original post.

And arguments about Blair, the EU and centralised control take us even further away from the engineering and economics we were discussing.

Britain’s electricity system is complicated. There isn’t a single technology that solves everything.

What interests us is the practical question: what generation mix and market design delivers secure electricity at the lowest sustainable cost to consumers?

We’ve published our own proposal for reforming the retail electricity market. What we’d genuinely like to see from alternative proposals is the same thing: show how they actually reduce the price households pay.

Otherwise we end up having an ideological argument about wind vs nuclear vs gas instead of addressing the electricity bill.

That’s probably a sensible point for us to leave this discussion.

[PolicySeed UK @policyseed]

Anyone driving a lot of miles can see the financial benefit of an EV quite quickly.

Unlike petrol or diesel, home charging also gives drivers the option of locking in a cheap overnight electricity rate for 12–18 months or more, giving much greater certainty over the cost of those miles.

But we recognise the obvious problem: not everyone can simply swap their petrol or diesel car for an EV.

At the bottom of the used market, particularly below £5,000, the choice still isn’t great. You’ll find plenty of older Renault Zoes and first-generation Nissan Leafs, often with higher mileage and relatively small batteries. They can make perfectly good town cars or second cars, but they’re not necessarily practical replacements for someone who regularly needs to travel long distances.

That’s why the transition has to be about making EVs genuinely affordable and practical, not simply telling people to buy one.

As more current-generation EVs enter the used market, that equation should improve significantly.

[PolicySeed UK @policyseed]

Oh well, this is awkward.

It isn’t for us to explain why another country should supply Britain. Electricity is traded across interconnected markets — Britain can import when it is economically useful and export when the reverse is true.

But if your objection is dependence on foreign-owned energy, be careful with the nuclear argument.

Britain’s existing operating nuclear fleet is 80% owned by EDF and 20% by Centrica. EDF is owned by the French state.

Perhaps we’ve actually found something we agree on: decades of privatisation have left substantial parts of Britain’s energy infrastructure and generation in overseas ownership.

We think Britain should own more of its critical energy infrastructure and generation — which is precisely why we’ve started mapping who owns some of the largest generators in the GB electricity system.

And interconnection isn’t a one-way dependency. GB also exports electricity. Ireland is connected to GB through interconnectors, including links serving the all-island electricity market.

Energy security doesn’t require Britain to generate every MWh domestically at every moment. It requires a resilient mix of domestic generation, storage, dispatchable capacity, demand flexibility and interconnection.

https://t.co/je34k2p3Nl

[PolicySeed UK @policyseed]

Great — finally some data we can actually look at. 👍

And yes, you’re right that 16/17 July 2025 was a period of exceptionally low wind generation.

We’ve downloaded NESO’s operationally metered wind data and checked it.

Wind remained below 500 MW for around 7 continuous hours, reaching a low of approximately 214 MW.

But let’s put that into context by looking across the NESO dataset rather than selecting one event.

From April 2018 to September 2026, NESO’s half-hourly operational wind data contain:

67 occasions below 500 MW lasting 6+ hours
34 lasting 12+ hours
4 lasting 24+ hours
0 lasting 48+ hours

The longest continuous period below 500 MW was approximately 30 hours.

At the less extreme threshold of 1 GW, longer wind droughts are more common:

39 periods lasted 24+ hours
6 lasted 48+ hours
2 lasted 72+ hours

The longest was approximately 101 hours.

So we have never disputed that low-wind periods occur. They clearly do, and the electricity system has to be engineered to remain secure through them.

Where we disagree is the assumption that every GW of renewable generation therefore requires another GW of permanently duplicated generation sitting behind it.

That’s not the only way an electricity system can provide resilience.

It can use a mixture of dispatchable generation, interconnectors, storage and flexible demand.

Indeed, during the 16/17 July 2025 event you’ve highlighted, while wind was below 500 MW and solar was zero overnight, our analysis of the NESO data shows GB was averaging approximately 4.6 GW of net electricity imports.

That’s precisely why interconnection matters.

Grid batteries are another part of the system. They can cover some shorter periods while also providing frequency response, balancing and other grid services. Longer events require other sources of flexibility and firm capacity.

The engineering question therefore isn’t:

“Can wind generation fall close to zero?”

We already know it can.

The question is:

What is the most economical combination of generation, storage, interconnection and demand flexibility needed to maintain security during the relatively small number of extreme periods?

We still don’t know what alternative generation mix David is putting his name to.

We’re very happy to analyse it when we do.

But we have yet to see a credible alternative GB electricity mix that excludes wind and solar while demonstrating that it would deliver reliable electricity at a lower overall system cost.

Source: NESO Monthly Operational Metered Wind Output, 148,113 half-hour settlement periods analysed, April 2018–September 2026.

[PolicySeed UK @policyseed]

With all due respect, you’ve repeatedly refused to provide evidence to support your claims.

We’re happy to engage with evidence-based arguments and to correct our analysis where the evidence supports doing so.

What we won’t engage with are unfounded accusations about our motives.

You don’t have to agree with us, and we don’t have to agree with you. But if you want to challenge our analysis, bring the evidence and we’ll discuss it.

[PolicySeed UK @policyseed]

You haven’t shown that at all. You’ve shown that wind and solar can sometimes have very low output. We agree.

What you haven’t demonstrated is your claim that this means Britain requires a 100% parallel domestic generation grid.

Britain is connected to neighbouring electricity systems. Interconnectors already contribute to GB’s capacity adequacy — including access to French nuclear and Norwegian hydro — alongside domestic nuclear, gas, storage and demand flexibility.

So why, for example, must we build a dedicated gas station to duplicate every MW of wind capacity in Kent if, during a period of low wind, the wider interconnected system has spare generation available?

That’s precisely why system modelling matters. Security of supply is about whether the whole system can meet demand during stress events, not whether every wind turbine has its own gas turbine sitting beside it.

[PolicySeed UK @policyseed]

We didn’t claim that. We challenged the claim that renewables require a 100% parallel backup grid.

So show us the evidence and system modelling that demonstrates this requirement.

Low wind and solar output clearly requires firm, dispatchable or flexible capacity. But that capacity can include gas, nuclear, storage, interconnectors, demand flexibility and other dispatchable generation. A period of very low wind does not itself prove that every GW of renewable capacity requires a corresponding GW of dedicated backup generation.

NESO’s modelling is a useful place to start: its 2030 scenarios combine wind and solar with firm generation, storage, interconnectors, demand flexibility and around 35 GW of retained gas capacity. Gas provides security during low-renewable periods, but is modelled to generate only around 4% of annual electricity.

That’s the distinction we’re making: capacity required for security of supply is not the same thing as operating a second parallel electricity system.

If there’s modelling demonstrating that Britain needs a complete GW-for-GW parallel grid alongside renewables, please link it. We’d genuinely like to examine it.

[PolicySeed UK @policyseed]

We’re not actually aware which alternative energy policy David is backing — do link to it if you know.

Nuclear? We’ve been looking at that too.

Hinkley Point C: £35bn (2015 prices).
Sizewell C: ~£38bn (2024 prices).

And before we hear “but France” — France’s Flamanville EPR went from €3.3bn to €13.2bn, excluding financing costs.

Finland’s EPR suffered major delays and overruns too.

Nuclear can provide firm generation. But new nuclear being “cheap” is a claim that needs evidence.

[PolicySeed UK @policyseed]

Standing charges are unpopular, but let’s not invent the reason they’re high.

They weren’t increased to claw back payments to people with solar panels.

Standing charges recover costs including maintaining the electricity and gas networks, metering, supplier operations, debt and other system costs.

Solar export payments are a separate arrangement under the Smart Export Guarantee.

The legitimate debate isn’t whether standing charges are a “solar scam”. It’s which costs should be fixed, which should be charged per kWh, and whether some should be removed from energy bills altogether.

[PolicySeed UK @policyseed]

@TiceRichard https://t.co/U1N7zRHIKf

[PolicySeed UK @policyseed]

https://t.co/hg7XsWkjWO

[PolicySeed UK @policyseed]

We’d challenge that every GW of renewable generation requires an exact GW-for-GW replacement of gas capacity.

The question isn’t whether wind and solar are variable — they are. It’s how often combined renewable generation across Britain and NW Europe falls sufficiently low, for sufficiently long, to require the entire system to be supplied by firm generation.

But there’s another side to this comparison.

Suppose we replaced renewable generation with gas.

How many additional TWh of gas would we burn every year? What would that fuel cost? What additional gas import, pipeline and storage capacity would be required — and where are those costs included in the comparison?

Britain currently has only 3.2 bcm of gas storage capacity. Gas security already depends on North Sea production, Norway, LNG, European pipelines and storage.

Renewables have system costs. So does the alternative. We should compare the whole systems.

[PolicySeed UK @policyseed]

@energygovuk @Miatsf @MartinSLewis https://t.co/ALcWcsFKMH

[PolicySeed UK @policyseed]

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[PolicySeed UK @policyseed]

@energygovuk @Miatsf @MartinSLewis https://t.co/ALcWcsFKMH

[PolicySeed UK @policyseed]

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[PolicySeed UK @policyseed]

@energygovuk @Miatsf @itvMLshow https://t.co/ALcWcsFKMH

[PolicySeed UK @policyseed]

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