National Nuclear Laboratory (NNL) – Written evidence (LES0033)

This paper presents evidence from the National Nuclear Laboratory (NNL) to the House of Lords Science and Technology Committee inquiry into ‘Long-duration energy storage’

Introduction to NNL

NNL is the UK’s national laboratory for nuclear fission. We are a Public Sector Research Establishment, Government owned (through the Department for Energy Security and Net Zero (DESNZ)) but operationally independent. We have built a distinct identity as the UK’s technical authority on nuclear fission – promoting UK skills and interests whilst tackling global challenges.

We are custodians of a unique set of facilities and capabilities that enable ground-breaking nuclear research and development – including four world-leading laboratories in the North-West of England. Our facilities, valued at £1.5bn, are of national strategic importance and are operated for the benefit of academia (who can arrange access to use our facilities for their own work) and industry. They form a vital part of the UK’s nuclear Research, Development and Innovation ecosystem.

Our purpose is to harness ‘Nuclear Science to Benefit Society’. We channel our work into four strategic areas: Clean Energy, Health & Nuclear Medicine, Environmental Restoration and Security & Non-Proliferation. These four Focus Areas shape what we deliver to our customers, for UK society and how we invest in our future[1].

As the UK’s national laboratory for nuclear fission, we work closely with Government and industry in understanding how new nuclear energy can achieve policy goals for energy security, net zero, and economic growth as part of a future integrated energy system.

Key messages

• The role of nuclear energy, alongside renewables, will make an essential contribution to achieving net zero by 2050 in a way that is secure, flexible, clean and affordable.

• Nuclear cogeneration provides the ability to balance the energy system, where the heat from the nuclear reaction can be directed to different subsystems according to the needs of the wider system. This could mean providing dispatchable power when renewables supply is low, and equally at times of high renewable supply, nuclear can switch to generation of heat required for industrial applications (to produce hydrogen, for example). This enables nuclear to respond to the needs of the system on an hourly, daily, weekly or even seasonal basis, whilst minimising reliance on long-duration energy storage solutions.

• Energy Systems modelling shows that increasing levels of nuclear energy, including cogeneration, lead to significant security of supply and cost savings in a future energy mix compared to scenarios where no nuclear is modelled.

Response to inquiry questions

2. How sensitive is the amount of storage needed to assumptions about the future balance of supply and demand on the grid?

• The energy system is full of interdependencies and subject to uncertainties around energy supply and demand, including future fuel and technology costs, potential technology breakthroughs and societal attitudes and behaviours. Assessing the ideal pathway to net zero is extremely challenging.

• Given these complexities, the Government’s Energy White Paper[2] highlighted the important role of energy systems modelling to support evidence-based policy making. Such models are only as good as the data used to inform them, so they must be regularly updated to capture the latest understanding in terms of social and technological change, including robust engineering assessments of emerging clean energy solutions.

• Energy systems modelling enables sensitivity analysis of various assumptions on demand and supply to help identify high value, low regret technologies as part of a robust net zero strategy. This in turn enables targeted investment through government innovation programmes to bring these technologies to maturity. NNL has worked with Energy Systems Catapult to ensure their Energy Systems Modelling Environment (ESME) represents current understanding of the full range of new nuclear technologies, to assess how these can work alongside renewables and storage as part of an overall least cost approach to net zero. Further details of this modelling work are provided later in this response.

What role could nuclear power, fossil fuel generation with carbon capture and storage, or other energy technologies, play in reducing the need for energy storage on a net zero grid?

• The role of nuclear energy, alongside renewables, will make an essential contribution to achieving net zero by 2050 in a way that is secure, flexible and affordable.

• A future nuclear fleet is anticipated to comprise of current and new technologies, starting with large scale Gigawatt (GW) reactors, such as that under construction at Hinkley Point C and due online around 2027, followed by Small Modular Reactors (SMRs) in the early 2030s, and Advanced Modular Reactors (AMRs) commercially deployed towards the 2040s.

• Each of these technologies can provide different yet complementary roles alongside other clean energy sources in an integrated future energy mix; large scale GW reactors will make a significant contribution to baseload electricity generation, but could be used for other applications such as hydrogen production via electrolysis or Direct Air Capture (DAC). SMRs will contribute to baseload electricity, but also to flexible generation and other applications such as district heating. AMRs will extend beyond electricity generation into provision of heat for difficult to decarbonise industrial process, and for hydrogen and synthetic fuel production, for which few other clean energy technologies are available or likely to be available in the net zero timeframe.

• It is in the role of cogeneration, i.e. application beyond purely provision of electricity the grid, that nuclear energy can provide flexibility to the energy system, enabling further optimisation of the energy mix. Nuclear cogeneration ensures that reactor uptime can be maximised, with the heat from the nuclear reaction being directed to different subsystems according to the needs of the wider system. This could mean providing dispatchable power when renewables supply is low. Equally, at times of high renewable supply, nuclear can switch to generation of heat to produce hydrogen, for example. This enables nuclear to respond to the needs of the system on an hourly, daily, weekly or even seasonal basis, whilst minimising overinvestment in marginal storage and flexibility solutions.

• Nuclear cogeneration demonstrators around the world today are harnessing energy from existing reactors originally deployed for baseload electricity, proving that, once deployed, nuclear reactors can be a versatile, adaptable source of energy for a variety of end use applications as society’s needs evolve. For example, in the UK EDF are investigating using nuclear generated heat and electricity to create hydrogen at its operational Heysham 2 power plant, as part of DESNZ’ funded Industrial Hydrogen Accelerator programme[3].

• The potential value of nuclear cogeneration in the UK has been analysed[4], however many published energy system modelling reports continue to omit the additional value of non-electric applications of nuclear energy. With high anticipated deployment of intermittent renewables and the need for flexible solutions to accommodate this, studies characterising nuclear as baseload electricity-only tend to underplay its potential contribution. More comprehensive whole energy system studies with a complete representation of nuclear cogeneration have revealed significant benefits for flexibility, energy security and affordability on the transition to net zero[5].

• Importantly, the system flexibility provided by nuclear cogeneration is not just within-year, hourly or seasonally, but extends to multi-decadal strategic flexibility as the needs of UK society and industry evolve. The exact quantities of electricity, heat, hydrogen required each year through to 2050 are subject to significant uncertainty, impacted by societal and industrial trends, technology breakthroughs and so on. Nuclear cogeneration facilities can hedge against this uncertainty, responding to market signals to produce different quantities of each energy vector over time to deliver the greatest overall value to the energy system and minimise the risk of stranded single-vector assets.

• NNL has commissioned analysis from Energy Systems Catapult, using their Energy Systems Modelling Environment (ESME) tool4. ESME covers the whole energy system, not just electricity, and offers a probabilistic treatment of uncertainty as well as multi-regional disaggregation of the UK, making it the most comprehensive tool of its kind. Through the analysis NNL commissioned, and building on ESC’s earlier work[6], ESME now includes a range of nuclear cogeneration options in addition to baseload electricity.

• ESC’s analysis shows that there are no silver bullets, and all credible pathways involve the deployment of a diverse basket of technologies requiring an integrated approach to enable full optimisation of supply. At one extreme, when nuclear is deliberately constrained, ESME finds a pathway based largely on offshore wind, supported by a range of alternative sources such as solar and tidal energy, and significant levels of energy storage and other flexibility solutions. This renewables-only solution is expensive though, and the gradual introduction of more and more nuclear technology options results in significant system cost savings as a more balanced technology pathway is adopted. This is true even when the nuclear options are limited to baseload electricity only, while further cost savings are realised as cogeneration applications are introduced into the model.

• Common across all new nuclear and other clean energy technologies will be to ensure they are planned as part of an integrated energy system, and to develop an understanding of how different technologies work together in an energy system as opposed to competing for the same space.

• In summary, nuclear technology (large, small, current and advanced) when integrated with other clean technologies can cost-effectively provide the flexibility needed to balance fluctuations in energy supply and demand, reducing the reliance for long-duration energy storage.

11 September 2023