The True Cost of Net Zero: Up to £7.6 Trillion

The official figure is £108 billion. The number buried in the government's own modelling is £7.6 trillion. That gap is not a rounding error — it is a political choice.

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The Number They Don't Want You to Focus On

In December 2025, the National Energy System Operator (NESO) published its Future Energy Scenarios Economics Annex. Buried in the accompanying spreadsheets was a figure that made front pages: the gross cash cost of the Holistic Transition pathway — the one that meets net zero by 2050 — adds up to £7.6 trillion in capital and operating expenditure between 2025 and 2050. Include the modelled carbon costs of residual emissions and the total exceeds £9 trillion.

This is not a fringe estimate. It comes from NESO, the statutory body that runs Britain's energy infrastructure.

To put it in context: the UK government spends roughly £1.2 trillion annually on everything from the NHS to defence. The gross cost of net zero, on NESO's own numbers, is more than six times the entire annual government budget.

NESO and its defenders argue — correctly — that gross system costs are not the same as the marginal cost of choosing net zero over the alternative. The "Falling Behind" scenario, which does not reach net zero by 2050, has its own gross costs of £7.2 trillion. The honest comparison is the gap between the two: roughly £362 billion more for the net-zero path, before carbon costs are applied.

But that framing conceals as much as it reveals. The "Falling Behind" baseline still includes hundreds of billions in green energy spending. NESO does not model a genuine counterfactual — what Britain's energy system would cost if the net zero mandate were removed entirely. As energy analyst David Turver's January 2026 IEA paper notes, the absence of a "stop net zero" scenario makes it impossible to derive a genuine net cost from NESO's published work. The £7.6 trillion gross figure is the most complete number NESO has published, and it is the only one large enough to capture the true scale of the transformation being imposed on the economy.

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How the CCC Got to £108 Billion

The Climate Change Committee's Seventh Carbon Budget, published in February 2025, claims net zero will cost just £108 billion over the 2025–2050 period — equivalent to 0.2% of GDP per year.

This figure is not the result of the transition becoming cheaper. It is the result of the CCC changing what it measures.

In its 2020 Sixth Carbon Budget, the CCC estimated gross capital costs of £1.38 trillion for its Balanced Pathway, netting down to £957 billion after alleged operating savings. By the 2025 Seventh Carbon Budget, that figure has collapsed to £108 billion. The CCC achieved this by switching from reporting gross costs to reporting only the difference between its Balanced Pathway and a notional baseline scenario — a baseline that itself assumes continued heavy spending on low-carbon technologies.

The cost assumptions underlying the £108 billion figure are demonstrably disconnected from reality:

• The CCC assumed offshore wind capacity would cost £1,500/kW for projects delivering in 2030. Hornsea 3, expected online in 2028, is forecast to cost between £10 billion and £11 billion for 2.9GW — a mid-point of £3,682/kW, more than double the CCC's estimate.
• The CCC assumed solar farms would cost £564/kW in 2025. The recently delivered Stokeford and Alfreton solar farms cost £952/kW and £995/kW respectively — nearly double.
• The CCC used a 3.5% discount rate for household and government spending. Current 30-year gilt yields are around 5.3%. Typical car loan APRs run at 5.7–14.9%. Using a below-market discount rate inflates projected savings and deflates the real upfront cost.

The consequence of these assumptions is that the CCC has repeatedly revised down its cost estimates even as the transition has become demonstrably more expensive. The OBR, working from the same CCC data, still arrived at a fiscal cost to the Exchequer alone of £803 billion — nearly eight times the CCC's whole-economy figure. The CCC has not explained the discrepancy.

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The Offshore Wind Reality Check

Offshore wind is the centrepiece of Britain's net zero strategy. It is also the clearest example of official cost forecasting failing in real time.

NESO's current modelling assumes offshore wind will cost £70.10/MWh in 2025, falling to £53.20/MWh by 2035. In May 2025, Ørsted cancelled Hornsea 4 — a 2.4GW project that would have powered a million UK homes — after deciding it was uneconomic even with a government-guaranteed strike price of approximately £85/MWh in 2025 prices. The project had been awarded its contract less than nine months earlier.

The round that followed, Allocation Round 7, is offering £118/MWh in September 2025 prices for index-linked 20-year contracts. That is 121% above NESO's own modelled cost for 2035. For floating offshore wind — the technology intended to unlock deeper waters — AR6 awarded contracts at £202/MWh; AR7 is offering £282/MWh. NESO assumes floating offshore wind will cost £109/MWh by 2035.

Between 2019 and 2024, offshore wind capital costs per megawatt rose by an average of 18% across the UK, Germany, the Netherlands, and Denmark. The weighted average cost of capital for offshore wind projects in Europe rose by 3–4 percentage points over the same period — consistent with a levelised cost of energy increase of around 30%. The IEA paper concludes that NESO's offshore wind cost assumptions alone mean the £7.6 trillion figure is likely a significant underestimate.

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Heat Pumps and Electric Vehicles: Costs That Haven't Fallen

The net zero transition requires replacing virtually every gas boiler in Britain with a heat pump, and every petrol and diesel car with an electric vehicle. Official cost assumptions in both areas have proven optimistic.

Heat pump installation for a typical UK home runs £9,000–£14,000 for air source units, according to current MCS data, with an average actual cost of £12,868 before the £7,500 Boiler Upgrade Scheme grant. Ground source systems cost £20,000–£30,000. The government's grant scheme costs £7,500 per installation — a subsidy that cannot scale to the tens of millions of homes that will eventually need conversion without enormous ongoing public expenditure. Britain currently installs roughly 60,000 heat pumps per year; the CCC wants hundreds of thousands annually.

On electric vehicles, carmakers absorbed an average of £11,000 per EV sold in subsidies and discounts in 2025 to meet the government's Zero Emission Vehicle mandate — a total of more than £5 billion in a single year, according to SMMT data. The SMMT has warned this level of industry support is unsustainable. Battery costs, widely expected to fall, are currently 31% higher than anticipated in the 2021 forecasts that underpin the current mandate. EV market share hit 23.4% in 2025 — 4.6 percentage points below the government's mandated 28% target for 2026, with the gap widening year-on-year. When manufacturers can no longer absorb these losses, the costs pass to consumers.

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What Households Are Already Paying

Green levies on household energy bills raised £5.9 billion in 2024, according to Nesta's analysis. For a typical household, these levies add approximately £140 to the annual electricity bill and £50 to the gas bill — £190 in total, representing 16% of the electricity bill and 5.5% of the gas bill.

These levies are structured regressively. The Resolution Foundation found that more than 99% of the poorest half of British households will not benefit from bill-funded energy efficiency schemes but still pay towards them. Moving these costs from energy bills to general taxation would save the poorest fifth of households around £110 per year. The UK Energy Demand Research Centre confirmed in February 2026 that recovering green costs through electricity bills "produces the least favourable and most regressive economy-wide outcomes" and actively disincentivises the uptake of the decarbonisation technologies the policy requires.

The Autumn Budget 2025 moved some of these costs from bills to general taxation — implicitly acknowledging they were causing harm. But the Chancellor was explicit: the costs are not disappearing, they are being redistributed. Leading energy providers have warned that bills will rise in coming years as policy costs associated with funding decarbonisation — subsidies for new wind farms, levies for grid expansion — continue to increase.

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The Scale in GDP Terms

The OBR's July 2025 Fiscal Risks and Sustainability Report estimates the fiscal cost of net zero mitigation to government at £803 billion — equivalent to 21% of current GDP. That is the cost to the Exchequer alone, averaging £30 billion per year, of which two-thirds reflects lost revenue (primarily fuel duty) and one-third reflects direct public investment.

The whole-economy cost, on any honest accounting, is substantially higher. NESO's gross cost of £7.6 trillion over 25 years implies average annual spending of roughly £304 billion, or around 10–12% of current GDP per year before any savings are netted off. The energy system currently consumes around 10% of GDP. On NESO's modelling, that share rises to 11.4% of GDP in 2029 before falling back — meaning the transition demands a significant short-term increase before any long-run benefits materialise.

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Nobody Voted for This

The net zero target was enshrined in UK law through the Climate Change Act 2008. The original 80% emissions reduction target was upgraded to 100% net zero in June 2019 by statutory instrument — a parliamentary procedure that allows fast-tracking through both Houses without a full vote — in the final weeks of Theresa May's government. No general election has since been fought on the specific net zero commitment and its costs. No referendum has been held.

The BBC reported in May 2025 that the political consensus on climate change has "shattered." Polling consistently shows significant proportions of the public unaware of the scale of the costs involved. A 2022 survey cited in academic research found 44% of Britons supporting a referendum on net zero. Public support for the policy has never been tested against an honest presentation of what it will cost.

The CCC, NESO, and OBR are not elected bodies. They advise governments; governments legislate. But when official bodies consistently produce figures designed to be politically palatable rather than analytically rigorous — when the CCC's cost estimate falls from over £1 trillion to £108 billion not because the transition became cheaper but because the methodology changed — the public is denied the information needed to form a democratic judgement.

Energy analyst David Turver's conclusion in the IEA paper is direct: public bodies responsible for costing net zero "have not been entirely truthful in their analysis. They have made fantasy assumptions about the cost of renewables and low-carbon technologies. The true cost of net zero is much higher than we have been led to believe."

The number NESO's own spreadsheets produce is £7.6 trillion. The number the CCC wants you to focus on is £108 billion. The difference between those two figures is not a debate about methodology. It is a decision about what the public is allowed to know.

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