Alternate battery technology to chemical energy includes gravity and pressure. What is the probability that these may see commercial reality? Storage of energy as heat, and then used as heat are widely used in heat pumps and direct storage of energy, but these technologies take renewable energy and instead of converting through chemistry, rely on gravity or pressure.

Compressed Air Batteries

Compressed air storage works on a similar theme to pumped hydro, using times of low prices to “charge up” and store significant amounts of energy. Instead of using water, rare in remote areas, it compresses air in suitable caverns, the type that can be found in old mines. One company, Hydrostor’s has A-CAES technology and claims to be able to deliver vast amounts of storage – in the case of the Broken Hill project in Australia up to 1,500MWh – enough to supply the town for days or even weeks.

Hydrostor announced in Jan 2022 it had secured a preferred equity financing commitment of $US250 million from Goldman Sachs for over 1.1GW, 8.7GWh of Advanced Compressed Air Energy Storage (A-CAES) projects in Australia and California.

Heavy Blocks

Energy Vault is the first off the blocks and funded via a SPAC and plan to build made from recycled and locally sourced materials such as waste mining material blocks and use gravity / kinetic energy. Inspired by pumped hydro, but minimal capital cost and automation provides the operation.

Energy Vault completed mechanical construction of the first of its kind, grid-scale unit located in Switzerland (Ticino). This commercial-scale system a 1:4 scale pilot system built and operated in 2018, where all core technology elements were tested and validated. The CDU is connected to the Swiss national utility grid and is being utilized for continued testing and software commissioning.

Warning: Much hype. (See AFR) The potential for Energy Vault’s gravity-based, building block storage technology has attracted some of the world’s biggest participants in the decarbonisation journey – Saudi Aramco, BHP and now Korea Zinc. A potential $US32 billion ($44.6 billion) of projects using the technology could be deployed over the next five-10 years, the Switzerland-based company says.

Pumped Hydro is an alternate battery technology

For a full discussion check out this article on pumped hydro. The key metrics for pumped hydro is the head height (300 m or more) and the volume of water available.