Sand battery 20% global energy claim

Derrick Dao’s May 19 X post described “sand batteries” as a way to supply industrial heat using stored thermal energy rather than direct fossil-fuel combustion. The core claim is directionally grounded in published research and industry analysis, but the 20% figure refers to industrial heating’s share of global energy use — not to sand batteries already supplying that share. RMI said in a February 2025 explainer that industrial heating accounts for roughly 20% of global energy consumption, and that thermal batteries could provide a cheaper, cleaner alternative for some of that demand. MIT Technology Review used the same benchmark in an April 2024 article on thermal batteries. ### What is a sand battery, exactly? Sand batteries are a type of thermal battery that store electricity as heat in a solid material. RMI said thermal batteries typically charge with electricity, often during periods of surplus renewable generation, convert that electricity into heat through resistive heating, and store the heat in insulated media such as crushed rock, bricks or other high-heat-capacity materials for release later to industrial equipment. (rmi.org) Quartz sand is one candidate storage medium because it is abundant, cheap and stable at high temperatures. Academic papers and industry pilots have examined sand beds and quartz sand for sensible heat storage, though the broader thermal-battery field also uses bricks, graphite, concrete and other materials rather than sand alone. That means “sand battery” is best understood as one design within a wider class of thermal storage systems. (rmi.org) ### Where does the “20% of global energy” number come from? RMI’s February 2025 explainer said roughly 20% of global energy consumption goes into industrial heating, usually from fossil fuels. MIT Technology Review wrote in April 2024 that 20% of global energy demand goes to producing heat used in industry, and that most of that heat is generated by burning fossil fuels. Those formulations match the social-media shorthand more closely than a claim about present-day deployment of sand batteries themselves. (sciencedirect.com) IEA data show why that number matters. The agency said in its 2025 industry overview that industry accounts for nearly 40% of total final energy consumption, and that much of energy use in energy-intensive industries is tied to high-temperature heat. In a separate RMI brief, the group said industrial heat processes make up 25% of global final energy demand. The different percentages reflect different accounting frames — global energy consumption, final energy demand and industrial heat processes — but all point to industrial heat as a large decarbonization target. (rmi.org) ### Can sand batteries really cover all of that demand? Thermal batteries can address a meaningful share of industrial heat demand, but published sources do not show sand batteries today covering anything close to 20% of global energy use. The Brattle Group said in a 2023 report for C2ES and the Renewable Thermal Collaborative that commercially available and deployed thermal-battery technologies can support temperatures as high as 750 degrees Celsius, enough to serve nearly 75% of industrial heat demand. (iea.org) RMI said some thermal batteries can deliver heat above 1,000 degrees Celsius, while a separate RMI release said temperatures up to 1,700 degrees Celsius could meet over 90% of industrial heat needs now supplied by combustible fossil fuels. Those are technical coverage estimates, not market-share figures. ### What is commercial reality right now? Rondo Energy has been operating a commercial pilot at a California ethanol plant since March 2023, according to MIT Technology Review, and has announced other industrial projects including facilities for Diageo. RMI’s February 2025 briefing also described thermal batteries as a commercial technology class rather than a laboratory concept. But RMI warned in a separate 2025 report that first-of-a-kind industrial heat projects face execution risks, including site integration, contractor selection and financing hurdles that can delay final investment decisions. (brattle.com) The next evidence to watch is project-level deployment: named industrial customers, operating temperatures, duration, delivered heat output and final investment decisions. RMI, the IEA and companies including Rondo and other thermal-storage developers are publishing those milestones as the sector moves from pilots to larger industrial installations. (rmi.org) (technologyreview.com)