Sizewell C nuclear power station
The Sizewell C nuclear power station is a project to construct a 3,200MWe nuclear power station with two EPR reactors near the village of Sizewell in Suffolk, England. The project was proposed by a consortium of EDF Energy and China General Nuclear Power Group, who at the time owned 80% and 20% of the project respectively.
In 2022, the UK Government announced a buy-out to allow for the exit of CGN from the project and forming a 50% stake with EDF, though EDF expected this to fall below 20% following anticipated external investment. The final investment decision was made on 22 July 2025, with the UK government taking an initial shareholding of 44.9%, with the remainder consisting of La Caisse, Centrica, EDF, and Amber Infrastructure. The power station is expected to meet up to 7% of the UK's electricity demand.
The project commenced in 2024, with construction taking between nine and twelve years, depending on developments at the Hinkley Point C nuclear power station, which is also being developed by EDF Energy and which shares major similarities with the Sizewell plant. The reactors are expected to have a service lifetime of 60 years.
On 10 June 2025, the government announced that Sizewell C had been allocated government capital investment of £14.2billion., construction is estimated to cost £38billion, equivalent to £11,600 per kW net electric capacity.
History
In 2008, the government decided that new nuclear sites should be constructed on existing sites to replace the UK's ageing fleet of reactors. In 2010 the government revealed that the Sizewell power station site was one of the eight locations at which it intended to allow the development to occur. Following this, EDF Energy put forward proposals for the Sizewell site in November 2012, where it planned to construct two EPR reactors.In 2015, as a part of the government's strategy to open the UK up to China, it was reported that after talks with China agreements had been made to develop three nuclear power plants including Sizewell C, Hinkley Point C and Bradwell B; however, agreements had not yet been made over financing the Sizewell project, with the final agreement likely to be made after the construction of Hinkley Point C had started.
On 21 October 2015, EDF Energy announced that it had 'agreed the Heads of Terms of a wider UK partnership for the joint development of new nuclear power stations at Sizewell in Suffolk and Bradwell in Essex' with China General Nuclear Power Group. At the same time, EDF Energy also announced that it 'will take an 80% share and CGN will take a 20% share' during the development phase of the project.
Following extensive consultation with the local community, on 27 May 2020 EDF Energy announced that it had submitted a development consent order application. EDF stated that 25,000 job opportunities would be created and targeted 70% of the investment to be spent in UK. The plant would largely replicate the Hinkley Point C design to reuse experience and attempt to lower costs.
In June 2020, EDF had yet to organise financing, and could not take on more construction risk in the UK. EDF was looking to the UK government to assist with financing either by offering a Regulated Asset Base model used on less risky infrastructure, though that puts an immediate cost burden on end consumers, or with other approaches such as a government equity stake in the development.
On 30 June 2020, EDF Energy announced that it had applied to the Office for Nuclear Regulation for a licence to build and operate Sizewell C. The ONR is responsible for the safe operation of nuclear sites in the UK and for permitting new nuclear site licencesone of the key regulatory requirements for building and operating a new power station.
On 11 September 2020, Suffolk county council said that it could not support the plans for the construction of Sizewell C in its current form, with the council saying on 23 October 2020 that the plans "do not go far enough" to mitigate the impact on the local community and on the local environment. The council said that a lack of support for the project was not the issue, and that it is that EDF "simply does not appropriately and sensitively address the impacts on our communities and the environment". EDF responded by submitting significant changes to the project which aimed to significantly reduce the number of Heavy Goods Vehicles delivering the materials required for the project by having them delivered by train and sea instead. The plans also proposed to increase the amount of land for the creation of fen meadow to help increase the net gain of biodiversity following the completion of the project. A consultation period began on 16 November 2020, which lasted for 30 days and which will inform all of the stakeholders in the project about the proposals.
On 31 October 2020, the BBC claimed that the government was 'close' to giving the project the green light following intensified talks with EDF, with government officials insisting that it "remains committed to new nuclear" following the withdrawal of Horizon from Wylfa and Oldbury. The BBC also reported that the government had increased its interest in taking a stake in the project following work on the second reactor at Hinkley Point C being completed 30% faster than the first reactor, which 'is thought to have substantially mitigated' the risk in taking a stake in the project.
On 14 December 2020, the UK government published an energy white paper setting out its plans to "transition to net zero", and announced the start of negotiations with EDF, with a view to starting investment on "at least one" new power station before the end of the current parliament in 2024. CGN is thought to be planning to withdraw from the project.
On 20 July 2022, the planning application was approved and a Development Consent Order was issued by the Secretary of State.
On 3 November 2022, the plant was placed under review in the government's effort to cut spending. Chancellor of the Exchequer Jeremy Hunt confirmed on 17 November 2022 that construction would go ahead, with initial contracts to be signed "within weeks". Security concerns about China caused the government to buy CGN out of the development for just over £100million in late 2022, leaving it co-owned by EDF and the UK government.
On 15 January 2024, construction of Sizewell C formally began; Aldeburgh & Leiston Councillor Tom Daly stated that "Sizewell C Ltd confirmed that the construction of Sizewell C new nuclear power station commenced on Monday".
Timeline
Construction
The Sizewell C project is expected to take between nine and twelve years to construct and commission. EDF expects significant time and cost savings compared to the near-identical sister plant, Hinkley Point C. The projected construction cost of £20billion for Sizewell C in the 2020 development consent submission is 25% higher than the £16billion projected for Hinkley Point C during the planning process. Note that the £20billion figure was calculated by inflation adjusting 80% of the cost estimate of Hinkley Point C at that time.Financing history
, the Sizewell C project is expected to cost £38billion. It was originally expected to cost £20billion to £30billion. The project was initially led by EDF Energy and CGN, which in 2020 owned 80% and 20% of the project, respectively.EDF sought UK government assistance with financing either by offering a Regulated Asset Base model, though that puts an immediate cost burden on end consumers, or with other approaches such as a government equity stake in the development, as the company is unwilling to take on further risk within the UK. On 30 June 2020, EDF announced that it had applied to the Office for Nuclear Regulation for a licence to build and operate Sizewell C.
On 14 July 2020, 32 companies and organisations from the UK nuclear supply chain formed a consortium to encourage the government to support the state-guaranteed financing model for Sizewell C, Regulated Asset Base, which the consortium says would reduce the cost of new nuclear projects by having consumers pay the cost upfront through their energy bills.
On 30 September 2020, Jean-Bernard Lévy, EDF's chairman and CEO, demanded that the Treasury provided clarity on the future of nuclear funding following Hitachi's withdrawal from the Wylfa Newydd nuclear power station project which was set to cost £20billion, citing a lack of viable funding.
On 14 December 2020, following the release of the UK government's long-awaited energy white paper, the government announced that it had started consultations with EDF to take a stake in the project following concerns that CGN is backing out of the project, which would leave a financing gap. The government also warned that any stake in the project would be 'subject to approval on areas such as value for money and affordability' with the Secretary of State for Business, Energy and Industrial Strategy, Alok Sharma, saying, "We are starting negotiations with EDF, it is not a green light on the construction".
In January 2022, the UK government invested £100million towards continued development of the project. In March 2022, it was announced that the UK government and EDF would each take a 20% stake in the project, with infrastructure investors and pension funds expected to take up the remaining 60%. Funding was also agreed to improve local activities, courtesy of the Sizewell C and the East Anglia Array projects.
In August 2022, The Guardian reported expected costs were £20billion to be paid with £1.7billion of taxpayer money and a surcharge on customer energy bills through the Regulated Asset Base model. Barclays had been hired to find new financial backing.
In November 2022, the UK government announced that it was taking over a 50% stake in the project for £679million.
In February 2023, EDF confirmed that following anticipated external investment its shareholding in the project will be no more than 19.9%. Project costs estimates vary from £20billion to £35billion.
In September 2023, the UK government issued a pre-qualification questionnaire to prospective investors; successful applicants will be invited to participate in the bidding process. The government have made an additional £511million available for project development and site preparation ahead of the bidding process.
In January 2024, the UK government announced £1.3billion of additional funding for the project for infrastructure work such as roads and rail lines, allowing construction work to progress prior to the final investment decision being made.
In August 2024, the UK government announced up to £5.5billion of additional funding through the Sizewell C Development Expenditure Subsidy Scheme "to enable continued support to the development of the proposed new nuclear power plant Sizewell C to the point of a Final Investment Decision ", "provided subject to relevant approvals, including the upcoming Spending Review". In the subsequent Autumn Budget, the UK government provided "£2.7billion of funding to continue Sizewell C's development through 2025-26", however "HM Treasury has clarified that the £2.7bn is not new funding but rather a sum that would be invested either via the previously announced £5.5bn Devex scheme, or through a separate FID subsidy scheme that would be established at the point of FID."
In December 2024, Sizewell C's joint managing director Nigel Cann stated "We have five investors in the process and potentially more" and are aiming to take the final investment decision in 2025.
In January 2025, it was reported that "one senior government figure and two well-placed industry sources" said the cost of the project was "likely to reach close to £40bn". In response, EDF said the £40billion figure was "not accurate", and it was reported that "the government also said it did not recognise this sum". That month, the French state auditor advised EDF not to proceed with Sizewell C until it had reduced its exposure on Hinkley Point C. That month, The Sunday Times stated that the UK government had already committed £8billion to the project.
On 10 June 2025, the government announced that Sizewell C had been allocated government capital investment of £14.2billion during the 2025 spending review period. The Treasury expects 10,000 jobs to be created and enough power generated to provide electricity for sixmillion homes. The project is still awaiting the Final Investment Decision, when the financial deal with incoming private investors for the remaining capital investment is made, and the cost of the project is disclosed. The Final Investment Decision should take place in summer 2025.
On 22 July 2025, the government signed the final investment decision. The UK government confirmed it would be taking an initial stake of 44.9% in the project, with the remainder consisting of La Caisse, Centrica, EDF, and Amber Infrastructure. There is also a proposed £5 billion debt guarantee from Bpifrance Assurance Export, to back commercial bank loans. The National Wealth Fund is to support the majority of the project's debt finance, alongside Bpifrance.
The equity and debt finance raised will exceed the construction cost to manage potential overruns. The government is using a Regulated Asset Base funding model, introduced in the Nuclear Energy Act 2022. The government claims suppliers are incentivised to reduce costs and investors would lose potential revenue in case of overruns, reducing risk for taxpayers. With an estimated construction cost of £38 billion, this model would limit the effect on monthly consumer bills to a £1 increase. The power station is projected to save the electricity system £2 billion a year, once operational. In November 2025, the financing deal was agreed.