Executive summary
Nuclear power has provided low-carbon electricity for 60 years and today contributes 17% of the UK’s total consumption on an annual basis. It could provide more. There are two key issues that impact on the utility of current nuclear: it is most economic when run at high output, and 65% of the energy generated is lost as waste heat.
Future nuclear power must work with a generating system dominated by intermittent renewable energy. The gap between intermittent generation and electricity demand is currently accommodated using gas fired generation which produces carbon dioxide. The introduction of more intermittent renewable generation coupled with the need to reduce gas fired generation demands greater flexibility from nuclear generation if it is to remain an important part of our energy mix.
This briefing examines how the use of nuclear power could be expanded to improve the overall efficiency and energy system resilience to meet the net-zero 2050 goal. It achieves this by considering cogeneration, where the heat generated by a nuclear power station is used not only to generate electricity, but to address some of the ‘difficult to decarbonise’ energy demands.
A range of options for cogeneration exist, using either low or high temperature heat. For low temperature heat, space heating notably via district heating, holds potential. Desalination of water is also of interest, though not currently in great demand in the UK. High temperature heat from advanced reactors would introduce an interesting set of decarbonising strategies, not least in the production of low-carbon hydrogen. Whilst this would represent an untested approach to hydrogen production, the practicality, synergy and costs appear to be attractive.
For example, hydrogen could be produced at times when electricity demand is low. This would likely be associated with new builds, and users of the high temperature heat would have to be co-located with the power plant.
Other cogeneration interests that should be considered range from the manufacture of synthetic fuels and ammonia to medical isotopes. The development of a cogeneration capability that includes isotope production represents a commercial opportunity due to a global shortage of key radioisotopes. Further, there is potential to use nuclear to power direct air capture of carbon dioxide.
Small modular reactors (SMR (footnote 1)) present a particularly interesting proposition for cogeneration. Their design can be either current type ‘Generation III’ low-temperature reactors or future design ‘Generation IV’ high-temperature reactors (known as advanced modular reactors, AMR, in the UK). SMR designs would enable the thermal output from the reactor to be matched to the thermal/electrical requirements of a single or cluster of industrial processes.
The building of nuclear reactors closer to industrial clusters or areas of the population to utilise the heat available would require support from the public and attention to regulations and licensing.
A few nuclear cogeneration facilities already exist in several countries. Whilst the economic case to adapt the UK’s existing reactor fleet for cogeneration would be challenging, both planned and future UK nuclear reactors could accommodate cogeneration applications. This would help the UK increase the flexibility of its electricity system to support a higher proportion of renewable generation and allow deep decarbonisation of otherwise challenging energy-intensive processes. It also offers the opportunity to create a new industry with export potential.