As we prepare for a decarbonized grid with more wind and solar, it’s critical to prepare a way to balance energy supply, which varies over the course of the day, with demand. Demand varies too, but on a different schedule.
Balancing supply with demand has always been essential to ensuring a reliable grid. Energy use varies from minute to minute, driven by people’s use of air conditioning, heating, lighting and other devices. Today, the energy system meets those changes by shifting how much fossil fuel it is burning.
In solar intensive locations like California, copious energy from the sun at midday leads utilities to shut down their fossil-fired generation. As the sun goes down, people come home from work and turn on air conditioning and TVs and start using appliances like microwaves for dinner. As demand increases, solar disappears.
Plain and simple, demand threatens to rise faster than the fossil-fueled system can accommodate.
The solution is to store energy for when it’s needed most, and that’s where advanced nuclear technologies have a strong role to play. These nuclear innovations must be developed in parallel with increased deployment of wind and solar, building a foundation of always-on, carbon-free energy that can also help maintain the instantaneous balance between supply and demand.
Four of the newest advanced nuclear designs are being prepared to store energy, using innovative ways to run a nuclear reactor continuously while varying the electricity output. When the reactor’s production of heat exceeds the demand for electricity, the excess energy is stored as heat. When demand for electricity is higher than what the reactor is producing, the extra heat is drawn from the storage tank and turned into electricity.
An example of this design is the Natrium project, a partnership between Bill Gates’s TerraPower and GEHitachi that is backed by the United States Department of Energy. Natrium is choosing among four sites of soon-to-be-retired coal plants in Wyoming for a plant that can vary its output from 100 megawatts to 500 megawatts.
TerraPower also has a design for a molten chloride reactor that would store energy as heat. Moltex Energy and Terrestrial Energy also have reactors in design that would use a giant tank filled with salt or rocks as a bank for depositing or withdrawing heat. The concept keeps the reactor running at full output almost all the time, while creating heat storage and saving the energy for when it’s most valuable and needed.
While other options exist to store energy, advanced nuclear technologies are critical to this effort as they offer both an efficient and environmentally friendly energy storage option. When compared to batteries for example, heat storage is cheaper and doesn’t require scarce minerals.
Policymakers and developers are smartly investing in new innovative nuclear designs. Their investments have the potential to offer tremendous returns with new designs churning out the reliable, carbon-free energy necessary to reach our climate goals, while also helping match production with demand by efficiently storing energy as heat.
Advanced reactors will be essential in multiple ways to our future energy grid, offering unique capabilities to complement wind and solar technologies and demonstrating vital innovation to match our energy needs.
