Excerpt:

A small company based in Union City is quietly conducting underground field tests of their flywheel energy storage system at Alameda Point. The mechanical device seeks to accomplish the same result as battery storage, only cheaper and with completely recyclable materials. The system is ideally suited for storing electrical energy created by commercial size solar facilities.

Working with the City of Alameda, Amber Kinetics is leasing space on an old tennis court next to the O Club at Alameda Point. The two concrete vaults that they installed in the ground to house their flywheel system go down seven feet. That’s how far they were able to dig before hitting the layer of hydrocarbon residue called the Marsh Crust. Digging into the Marsh Crust would have complicated the testing and created added expense. Since there is no electrical service at the site, they brought in their own generator to perform the tests, which they store in a shipping container.