What is the role of nuclear in the energy mix and in reducing greenhouse gas emissions?
How much nuclear energy is currently produced worldwide – and in the UK?
At the time of writing (November 2022), there are 437 operable nuclear reactors for electricity generation across 32 countries around the world, according to the World Nuclear Association, with 60 further nuclear reactors being constructed in 18 countries. Together, nuclear plants provided around 10% of the world’s electricity production in 2021. France relies most heavily on nuclear: 69% of its electricity was supplied from nuclear power in 2021. Nuclear power also provided at least a quarter of the electricity supply of a further 12 countries in that year.
The UK has nine operational nuclear reactors across six plants, which in total generated about 15% of its electricity in 2021. Five of these plants are due to retire by the end of the decade, although this will be partly offset by the Hinkley Point C (HPC) project in Somerset, due to come online in 2027. HPC is the first new nuclear power station to be built in the UK since 1987 and is expected to meet an estimated 7% of the UK’s electricity demand once it is running at full capacity. In November 2022, the UK Government announced that it will proceed with the construction of a second new plant at Sizewell C in Suffolk, which will be a replica of HPC.
What role could nuclear power play in reducing emissions?
Nuclear power has a minimal carbon footprint of around 15–50 grams of CO2 per kilowatt hour (gCO2/KWh). In comparison, the average footprint of a gas-powered generator is around 450 gCO2/KWh and for coal it is around 1,050 gCO2/KWh. Nuclear power can therefore contribute to the decarbonisation of the global energy system. Nuclear currently provides almost 30% of the world’s low-carbon electricity, making it the second largest source after hydropower.
According to the International Energy Agency (IEA), nuclear energy enables about 1.5 gigatonnes (Gt) of global emissions and 180 billion cubic metres (bcm) of global gas demand to be avoided each year. According to its roadmap for bringing energy-related CO2 emissions to net zero by 2050, global nuclear capacity would need to almost double from current levels to reach 812 gigawatts (GW) in 2050. The IEA argues that less nuclear power would make global net zero ambitions harder and more expensive to achieve. The UK Climate Change Committee suggests that under a ‘balanced pathway’ to net zero emissions, nuclear capacity in the country would reach 10 GW by 2035 from the current levels of about 6 GW.
But nuclear is unlikely to be the answer on its own. Putting aside concerns about safety and costs, nuclear power is well suited to providing baseload power but is poorly suited to dealing with power fluctuations on the grid (in either supply or demand). Nor are nuclear power plants able to provide backup power to complement intermittent renewable sources such as wind and solar, as they do not have the capability to ramp up and down quickly.
What are current attitudes towards nuclear?
The Fukushima disaster triggered by the Japanese tsunami of March 2011 significantly changed the global outlook for nuclear power. In the immediate aftermath, Japan took almost all of its nuclear power plants offline, leading global nuclear power generation to decline through 2012. Similarly, Germany decided to phase out nuclear power entirely by 2022 (a decision that has since been delayed). Globally, 48 GW equivalent of nuclear capacity is estimated to have been lost since 2011 due to plants that were either permanently shut down or did not have their operational lifetimes extended following Fukushima.
The policy landscape has changed rapidly in the past few years, creating conditions for a potential ‘nuclear comeback’. As of November 2022, around 140 countries had announced, or were considering, net zero targets, representing close to 90% of global emissions, and many of these countries, including China and India, have announced energy strategies that include a substantial role for nuclear.
More recently, the global energy crisis in the wake of Russia’s invasion of Ukraine has made reducing reliance on imported fossil fuels the top energy security priority. The dual challenges of improving energy security and reducing emissions have reinforced the case for nuclear in many places. For example, the EU has included nuclear in its REPowerEU plan; the US has introduced tax credits for existing nuclear plants and support for advanced reactors in its Inflation Reduction Act; and the UK has committed to progressing up to eight new nuclear reactors by 2030 in its Energy Security Strategy. Germany has decided to extend the lifetime of its three remaining nuclear plants beyond 2022, while Belgium and Korea have also scaled back plans to phase out existing nuclear plants.
What are the main controversies surrounding nuclear power?
Public concern over the safety of nuclear power increased after the Fukushima disaster. The accident prompted reviews of safety and pledges to move away from nuclear in some cases. However, countries take different stances on this issue. In the UK, for instance, there is strong political support for and minimal public opposition to civil nuclear industry.
The lack of a permanent solution for nuclear waste raises concerns. Deep geological disposal in the form of purpose-built caves hundreds of metres below ground is widely agreed to be the best solution for the final disposal of high-level nuclear waste. However, there is only one such facility currently in the pipeline, due to open in Finland in 2023. A handful of other countries including France, Sweden, US, UK and Canada are only at the stage of selecting preferred sites for such facilities.
Nuclear power is expensive for a number of reasons. Both developing new safety requirements and building the new Generation III reactors (such as those fuelling the UK’s Hinkley Point C power station) have been costly. Critics argue that as the cost of renewable energy falls, the case for nuclear power weakens. However, some countries are able to deliver nuclear projects at lower costs than others (for instance through standardisation; see evidence from Korea), which suggests that some costs are context-specific and, in theory, avoidable. The World Nuclear Association argues that although nuclear plants are expensive to build, they are relatively cheap to run, making them cost competitive with many other forms of electricity generation. Nuclear is still considered to be the baseload low-carbon technology with the lowest expected global average cost in 2025.
Can innovations in nuclear energy make it a more attractive option?
Advanced nuclear technologies including Small Modular Reactors (SMRs) and Advanced Modular Reactors (AMRs) are smaller than conventional reactors and can be constructed in a modular way (with elements fabricated in a factory environment for assembly onsite), reducing bespoke construction requirements and potentially cutting the upfront capital costs of nuclear projects.
Some AMRs yield much higher outlet temperatures than conventional reactors, which enables nuclear to be used for a range of additional purposes to electricity generation, including the direct provision of high-grade heat for heavy industry (e.g. glass, paper, chemicals) and the efficient production of low-carbon hydrogen. These innovations could diversify the application areas of nuclear energy and unlock a bigger role for it in the global transition to net zero emissions.
Nuclear power is currently derived from fission (splitting the uranium atom), but a major technological advancement that researchers are currently working on is nuclear fusion, which essentially means creating a star on the face of Earth – an unlimited source of low-carbon power. But fusion research is extremely costly. For example, ITER (the international megaproject aiming to bring fusion to life) is now estimated to cost €22 billion, up from an initial estimate of €6 billion. However, private sector investment in fusion is growing rapidly, indicating increasing confidence that it can eventually be commercialised.
This Explainer was updated by Esin Serin in December 2022.