Small modular reactors (SMRs): the key to net zero

SMRs are advanced nuclear reactors with a power capacity of up to 300 MW(e) – megawatts electric – per unit, around a third of the generating capacity of traditional reactors. Because SMRs are so much smaller, simpler, cheaper and quicker to assemble, prefabricated SMRs can be built in places unsuitable for larger nuclear power plants.

“One of the challenges to accelerating access to energy is infrastructure – limited grid coverage in rural areas – and the costs of grid connection for rural electrification”, notes the IAEA. “In areas lacking sufficient lines of transmission and grid capacity, SMRs can be installed into an existing grid or remotely, off-grid.”

“This is particularly relevant for microreactors, a subset of SMRs designed to generate electrical power typically up to 10 MW(e). Microreactors [are] better suited for regions inaccessible to clean, reliable and affordable energy [and] could serve as a backup power supply in emergency situations, or replace power generators that are often fuelled by diesel, for example, in rural communities or remote businesses.”

SMR designs are generally simpler because they rely more on passive systems and inherent safety characteristics, such as low power and operating pressure. Passive systems rely on physical phenomena such as natural circulation, convection, gravity and self-pressurisation, meaning that human intervention isn’t needed to shut down SMR systems, making them safer.

“Power plants based on SMRs may require less frequent refuelling, every three to seven years, compared with between one and two years for conventional plants,” says the IAEA... “[the aim is to bring] SMR technology to fruition within this decade.”

SMRs are under construction or in the licensing stage in Argentina, Canada, China, Russia, South Korea and the US. According to a new report by consultants Wood Mackenzie, there has been a 65% surge in demand for SMR projects since 2021.

The study found that the SMR project pipeline reached 22 gigawatts (GW) in the first quarter of 2024, requiring an investment of close to $266bn. “The nuclear-power market has been gaining momentum as a key strategy to achieving net zero,” says David Brown, Wood Mackenzie’s director of energy transition.

“While the sector has faced a range of challenges over the last 12 months... multiple markets across the world are expanding their focus on nuclear SMRs,” he adds. Five countries (the US, Poland, Canada, the UK and South Korea) account for 58% of the SMR project pipeline.

“In Wood Mackenzie’s net-zero scenario, SMRs would account for 30% of the nuclear fleet”.