Energy Vault has broken ground on two facilities in Texas (USA) and northern Shanghai (China) that will store energy by lifting hundreds of 24-ton blocks made from compressed earth.
Energy Vault’s energy storage facility under construction in Shanghai, China. (Image: Energy Vault).
By lifting these massive blocks to higher levels during periods of excess renewable energy production, the facility’s crane can store a significant amount of electricity and then release it by lowering the blocks when demand is high and supply is limited. This is a simple yet clever idea. If implemented effectively, this system could enhance the resilience and sustainability of the power grid while reducing energy storage costs, Cnet reported on April 23.
Although this is not Energy Vault’s first venture into building a gravity storage system, the company hopes to demonstrate the effectiveness of the concept at a much larger scale. The startup has constructed a small-scale test system near its headquarters in Switzerland, generating 5 megawatts of electricity. However, the new facility in China is significantly larger, standing over 120 meters tall and capable of storing 100 megawatt-hours, enough to power 3,400 households for an entire day. Meanwhile, the facility in Texas is designed to supply nearby power companies with a capacity of 36 megawatt-hours.
The facility in China uses blocks made from 99% compressed earth mixed with water and polymer. By placing them inside a massive rectangular building, Energy Vault aims to use a system of trolleys to transport the blocks in and out of elevators. Each block lowered at a speed of 1.8 m/s can generate one megawatt, with a total efficiency of at least 80%.
Storing energy by lifting and lowering compressed earth blocks may provide a cheaper solution for storing solar and wind energy compared to complex lithium-ion battery systems. The system also allows for greater adaptability to rapidly changing energy production environments and reduces dependence on natural gas, coal, or petroleum. “If we want to cut fossil fuels and replace them with intermittent renewable sources, the only way to address the issue is through storage,” said Robert Piconi, CEO of Energy Vault.
