At NARUC’s February winter policy summit, amid conversations about grid reliability and steep increases in energy demand, over 40 regulators and staff attended a breakfast hosted by the Renewable Thermal Collaborative (RTC) and the Long Duration Energy Storage (LDES) Council to discuss how thermal energy storage can address some of these issues.

Thermal energy storage (TES) units, also called thermal batteries, use grid or onsite electricity to generate and store heat in a medium or in chemical bonds. They can charge when low-cost electricity is available during off-peak times to store heat for later consumption, up to multiple days later. The technology is flexible and efficient because it decouples the availability of low-cost clean electricity from when energy users actively need the heat. For example, energy generated by wind turbines at night can be used to store heat for use during the day, when higher demand for electricity would otherwise drive prices higher. Thermal energy storage can also capture heat and store it directly, including from waste heat from a facility or heat-generating technologies like solar thermal.

The breakfast event opened with introductory remarks and scene-setting presentations from Melissa Hulting of C2ES/RTC and Julia Souder, CEO of the LDES Council, who both noted that TES is commercially available and in operation today. Noah Long of Antora Energy provided a TES manufacturer’s perspective, discussing the technology’s potential to decarbonize large portions of U.S. industrial processes at lower costs, including utilizing otherwise wasted energy from curtailed renewables and waste heat. Finally, a panel including previous presenters and Katie Sieben, a Minnesota PUC Commissioner, discussed the importance of including TES in resource planning for utilities, how TES compares to other forms of energy storage, industry’s demand for thermal energy, and key barriers such as current rate structures.

This electrification technology is an exciting option for end-users and grid operators alike; it can utilize excess renewables that would otherwise be curtailed, increasing flexible use of existing grid assets and addressing load growth without contributing to peak demand, and would allow end-users to take advantage of lower-cost electricity pricing. Electricity demand is expected to grow by about 4% annually through 2027, primarily due to unprecedented electricity use for industry and data centers. Meeting this demand will be challenging and will require a full suite of energy technologies, including energy storage.

Thermal energy storage is versatile. In addition to providing heat for 24/7 operations, it can be configured to convert stored heat back to electricity, increasing resilience capability. Commercially available thermal energy storage technologies can reach temperatures of 1500°C or even higher, and are capable of satisfying the majority of industrial thermal process heating demand. The heat generated can fulfill the role of a boiler, oven, dryer, or similar heat process.

So, why aren’t we using thermal energy storage across industrial facilities? One key barrier is current rate structures, which do not grant thermal energy storage access to wholesale or near-wholesale power system prices. Reforming these rate structures will level the playing field and enable TES to better compete in the marketplace with existing fossil fuel technologies and lower costs for end users.

What can utilities and Public Utility Commissions (PUC) do to increase deployment of this Long Duration Energy Storage (LDES) resource?

• Consider thermal energy storage in outreach, programs, and planning. At the breakfast event, Commissioner Sieben shared that the PUC had recently approved Xcel Energy’s Integrated Resource Plan that includes a pilot project with RTC and LDES Council member Rondo Energy. This forward-looking document sets out a plan to meet energy customers’ forecasted demand, analyzing how energy conservation, power generation, and infrastructure changes will factor into meeting anticipated demand for the next 15 years. Incorporating energy storage into these plans will put utilities on a path to reinforce the grid’s resiliency and efficiency and meet increasing energy needs while minimizing strain to the grid’s infrastructure.
• Consider Rate Design Reforms that would make TES more competitive. outlined tariff design recommendations, including energy charges that reflect wholesale or marginal pricing to and other rate components that reflect the benefits TES provides to the grid (less infrastructure buildout, reliability enhancements, etc.

Learn more about thermal energy storage on the RTC website, in the RTC Thermal Batteries Report, and in the LDES Council’s Net-Zero Heat report.