UK report highlights benefits of nuclear cogeneration

The policy briefing - titled Nuclear cogeneration: Civil nuclear energy in a low-carbon future - says 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 the UK's energy mix. Cogeneration - where the heat generated by a nuclear power plant is used not only to generate electricity - could be the answer, according to the Royal Society, the UK's national academy of science.

"When domestic energy demand is being met by wind, solar, or other sources, cogeneration allows a nuclear plant to switch from electricity generation to cogeneration applications," the report says.

While there are no current nuclear cogeneration projects in the UK, a few nuclear cogeneration facilities already exist in several countries, the paper notes.

The introduction of small modular reactors (SMRs) should mean lower investment costs and economies of scale in construction. It also gives greater flexibility in locating plants, and allows them to be tailored to the energy needs of regional or industrial clusters.

A range of options for cogeneration exist, using either low or high-temperature heat, it adds. 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."

The range of cogeneration options from a nuclear power plant (Image: Royal Society)

The UK government has identified district heating as an important way to reduce carbon emissions and heating costs. District heating currently provides just 2% of heat demand in the UK but several countries already use nuclear cogeneration for district heating in colder climates. Analysis suggests there are potentially 50 conurbations in the UK where SMR-powered district heating could work, the paper says. However, "public opinion and acceptance of nuclear reactors being sited close to population centres would need to be examined".

Possible applications for high temperature heat (above 400C) from reactors in the UK include the production of hydrogen and synthetic fuels (such as ammonia). "The development of a cogeneration capability that includes isotope production represents a commercial opportunity due to a global shortage of key radioisotopes."

The economic case to adapt the UK's existing reactor fleet for cogeneration would be challenging, the Royal Society says, but 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."

"This is a real opportunity for nuclear," said Robin Grimes, the report's lead author and a professor of materials physics at Imperial College London. "What cogeneration gives us is options and, frankly, we need options when facing an uncertain future."