(Bloomberg) -- A US company that stores energy by elevating heavy objects is expanding its pipeline in China with five new projects to help provide around-the-clock clean power.

California-based Energy Vault Holdings Inc. and its partners including China Tianying Inc. announced agreements with five local governments to develop 1,160 megawatt-hours worth of storage. The systems are giant buildings that house a system of pulleys and heavy blocks, which are lifted when there’s excess electricity and lowered to generate power in times of need.

The technology is one of many vying to solve the intermittency problem with renewables: how to provide electricity when the sun isn’t shining and wind isn’t blowing. Gravity storage is still relatively untested compared to batteries and pumped hydropower, but the new projects show the potential for the technology to be used at scale, Energy Vault Chief Executive Officer Robert Piconi said in an interview.

“You can build out renewables much more cheaply than fossil fuels now, but you have to store it,” Piconi said. “That’s core to our mission.”

The projects will be built in Hebei, Jiangsu, Gansu, Jilin and Xinjiang. Construction will begin either this year or next, with connection to the grid taking place in 12 to 18 months, Piconi said.

Energy Vault has two other projects in development in China. A 100 megawatt-hour system is in the final stages of commissioning in eastern Zhejiang province, and 2,000 megawatt-hours at industrial parks in Inner Mongolia. Combined with the five new systems, they represent more than $1 billion in project scope, the company said in a press release. 

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