Funding flows in for EnerVault

EnerVault has this week landed an additional $3.5m (£2.3m) in funding to help commercialise grid-scale energy storage technologies that could one day resolve the problem of intermittent renewable energy supplies such as wind and solar power.

The US-based company develops flow batteries, which can store the active materials used to generate electricity externally to the battery, enabling them to significantly increase their storage capacity.

Flow batteries use large storage tanks filled with electrolytes. Pumps circulate the electrolyte solution through the tanks, distributing it through an electrochemical cell that converts chemical energy into electricity. The spent material can be re-energised, and electrolyte solution can be added to the electrochemical cell in the same way that fuel is added to a vehicle, making it relatively easy to replenish the energy stored within a battery.

To date, the adoption of flow batteries has been hampered by high costs. However, EnerVault says its flow battery design can provide storage capacity costing about $100 per kilowatt hour, and predicts the cost could come down as it scales up manufacturing. In contrast, Lithium-ion batteries, which are more difficult to scale up to grid-level capacities, cost between $200 and $500 or more per kilowatt hour.

The company is still operating in stealth mode, and is not giving away very much about its technology. However, it has said its flow batteries, marketed under the name Vault-20, are designed to time-shift energy from low-value to high-value periods, provide critical backup power and regulate supply on the grid.

It also revealed this week that it will use the fresh funding to build a prototype storage unit, designed to prove that it can work at the kind of megawatt scale that would be required to support wind farms or solar power stations.

EnerVault was incorporated in 2008, and its chief executive, Craig Horne, is a chemical engineer from UC Berkeley.