UK Government support for nuclear power compared with that of tidal lagoons

In June 2025 the UK Government announced a £14.2bn investment to support building a new nuclear power station, Sizewell C, on the east coast of England as the latest step in its policy to achieve “net zero” greenhouse gas emissions by 2050. It did so despite unresolved questions about the wisdom of commissioning the construction of Sizewell C's forerunner Hinkley Point C (HPC) in 2016. Two years after making the latter decision the Government of Theresa May decided not to provide financial support for the construction of a tidal lagoon on the coast of South Wales as a technology demonstrator, claiming that HPC offered better value-for-money for consumers. These decisions were widely viewed as connected. This article examines the validity of the cost calculations that formed the basis of these decisions, costings which still underpin the policy of successive UK Governments of favouring nuclear power in the technology mix for transitioning the UK to a “net zero” electricity supply by 2050. It is shown from official documents, reports of publicly funded independent bodies and the scientific literature that their policy of favouring nuclear power is based on misinformation and inconsistent application of their costing methodology. It is further shown that correcting these defects and taking into account essential other costs, decommissioning and safe storage of toxic waste results in tidal lagoons providing significantly better value-for-money for consumers and taxpayers.