gravity for energy storage makes sense, via bloomberg

Rather than relying on lithium-ion or other types of chemical batteries, SOM and Energy Vault plan to use gravity. Energy Vault’s systems use electric motors to elevate massive blocks, creating potential energy that can be converted into electricity when they’re lowered to the ground. A rendering of a building designed to store energy. Photographer: SOM The concept is similar to widely used pumped hydroelectric plants. The company completed its first major project this month near Shanghai, a stand-alone storage system that can supply as much as 25 megawatts of power for four hours. Other new types of gravity storage systems are also in the early stages of testing, including ones using abandoned oil wells and mines. Building owners and designers have a growing number of tools to limit carbon emissions from day-to-day operations, from better insulation to heat pumps. However, there are no substitutes for the steel and concrete that are critical components of modern buildings, which together account for more than 10% of the world’s emissions. There are efforts to decarbonize those materials, but they remain far from reaching a meaningful scale. For building owners looking to zero out emissions, turning a skyscraper into a massive battery is one avenue, according to Bill Baker, a consulting partner at Chicago-based SOM. SOM has come up with four prototypes for storage systems based on this concept. Three are standalone storage systems that use either heavy blocks or water, with two that are built into hillsides and a third that’s a tall, cylindrical tower. The last is intended for urban areas, a towering skyscraper that could include residential, retail and office spaces as well as energy storage. Energy Vault’s Shanghai project is about 150 meters (490 feet) high, but SOM’s skyscraper batteries may be much higher, starting at 300 meters. Tall buildings are SOM’s specialty. Baker was the lead designer for the Burj Khalifa, the 828-meter tower in Dubai that’s the world’s tallest building, and he sees significant potential for incorporating energy storage into skyscrapers. That’s because the higher the weights are lifted when there’s a surplus of cheap electricity, the more potential energy they will hold that can be released when electricity is needed. “If I store it twice as high, twice the energy,” said Baker. “High is better.” Once a building gets above about 200 meters, a gravity-storage system could supply more than enough power to cover its operations. That’s when building operators can start to offset the carbon footprint of construction materials, with some of SOM’s designs expected to see that payback in two to four years. Still, Energy Vault has faced hurdles, including fundamentally redesigning its gravity system and offering chemical battery storage systems to customers as a way to generate revenue now. While completing the Shanghai project was an important milestone, and partners in that venture are now planning additional storage systems in China, Energy Vault’s shares have tumbled more than 85% since it went public in 2022 in a deal with a special purpose acquisition company. The idea of adding storage to a major skyscraper is fundamentally sound, according to Thomas Boyes, an analyst with TD Cowen. Planning, permitting and financing for these kinds of developments take years, however. Boyes said it’s more likely that mixed-use towers with Energy Vault technology could appear sometime in the 2030s. “It makes sense on paper,” he said. “There are underlying reasons why buildings will want this technology, but it’s a market that takes a long time.”