Nuclear and Renewables: Playing Complementary Roles in Hybrid Energy Systems

Nuclear power can generate enormous amounts of reliable, carbon free electricity. It works day and night, at all times of the year. This stability is the reason why nuclear power has typically been used as baseload—operating continuously with little if any variation in output.

Some nuclear power plants, however, now contribute to the stability of electricity grids by backing up the intermittent output of renewable sources through flexible operation or load following—adjusting production as electricity demand fluctuates.

“As the share of intermittent renewable energy systems—mostly solar and wind—increases in power grids, more flexible power generation is needed,” noted Denis Janin, Energy Economist at PreussenElektra, GmbH. “This can take several forms: hydropower, gas-fired power plants, advanced batteries, or nuclear power. In France and Germany, nuclear power load following has been a reality for many years already.”

With some 50 small, medium sized or modular reactor (SMR) concepts at various stages of development around the world, SMRs also can play an important role in hybrid energy systems.

They have the potential to meet the needs of a wide range of users and to be low carbon replacement option for ageing fossil fuel fired power plants. They also display enhanced safety features and are suitable for non-electric applications, such as heating and water desalination. With advanced engineered features, SMRs are designed to be built in factories and shipped to utilities for installation, deployable as a single or multi-module plant.

Lenka Kollar, Director of Strategy and External Relations at NuScale, underlined that “SMRs are well-poised to complete an energy system, since they add flexibility and can be easily integrated into a renewables-heavy system. In addition, NuScale plants are ideally suited to provide carbon-free heat and energy for a variety of industrial applications, such as, hydrogen production for clean fuels and desalination to produce clean water”. SMRs can also play a stabilizing role in grids with large shares of renewables and contribute to reducing the overall cost of a low carbon energy system. This kind of combination is expected to reduce rate volatility and system costs for grid management and development, according to panellists at the event, entitled Reactor Technology Innovation to Support Integration of Renewable Energy Systems and Nuclear Installations.

Cogeneration, the deployment of nuclear–renewable hybrid energy systems for non-electric applications, was also discussed. Nuclear power plants produce a large amount of heat which can be both converted into electricity and directly used for other energy purposes. Cogeneration merges the production of usable heat and electricity into a single system that can substantially reduce carbon emissions and increase overall efficiency.

It is a more efficient use of fuel, as what would otherwise be wasted heat from electricity generation is instead put to productive use in district heating, desalination or the production of hydrogen for use in decarbonizing a range of industries including steel manufacturing and transportation.

“Demand for hydrogen has grown threefold since 1975, and this sector is almost entirely supplied from fossil fuels,” noted Fredrik Reitsma, Team Leader for SMR Technology Development at the IAEA. “Especially as more hydrogen-powered fuel cell cars and trains enter the market, SMRs have the potential to replace the fossil fuel power plants that are responsible for around 830 million tonnes of CO2 emissions per year, solely from hydrogen production.”

While considerable experience exists on nuclear desalination, “the high temperatures and operational flexibility of SMRs could position them at the heart of the growing hydrogen market,” Reitsma added.Such hybrid energy systems might be designed for other non-electric, energy-intensive applications, including: chemical feedstocks for fertilizer, polymers, plastics, and textiles; potable water from desalination of seawater and brines; and CO₂ for enhanced oil recovery or as a heat-transport medium. The inclusion of such products can maximize overall energy system performance and profitability.

“Events like this help Member States to share knowledge and experience. They are also very valuable for the Agency as we continue our efforts to foster safe, secure and sustainable nuclear power,” Feruta said.