Facility stores energy with 24-ton brick lift system

Energy Vault, a Swiss startup, has begun building two facilities in Texas and near Shanghai to test energy storage using 24-metric-ton bricks made of compressed dirt.

The concept behind Energy Vault's energy storage system is elegantly simple. During periods of excess renewable energy production, the facility's cranes lift massive bricks to its upper levels for storage. When demand for energy is high and the supply is low, the cranes lower the bricks to release stored energy. If successful, this technology could improve the resilience and sustainability of the electric grid, while reducing energy storage costs.

Although Energy Vault has built similar gravity storage systems before, it is now attempting to prove its concept on a larger scale. The company has already constructed a five-megawatt pilot system in Switzerland, and its new facility in China is even bigger, standing at 400 feet tall and capable of storing 100 megawatt-hours of energy. This is enough to power 3,400 homes for a day. In Texas, Energy Vault is building a facility that will provide a nearby power company with 36 megawatt-hours of capacity.

The Chinese facility uses bricks made of 99 percent compressed dirt, mixed with water and polymer. These bricks are transported to and from the elevator using a trolley system. According to Energy Vault, each brick being lowered at six feet per second can generate a megawatt of power, with an overall efficiency of at least 80 percent.

This method of storing energy using giant blocks of compressed dirt could be a far cheaper solution than complex lithium-ion-based systems for storing solar and wind energy. It also allows utilities to adjust to rapidly changing energy production environments and reduces reliance on fossil fuels like natural gas, coal, and oil.