An ESS Energy Warehouse
Image: ESS
The company currently offers two products: the single shipping container Energy Warehouse and a string of warehouse units in an Energy Center. Its Energy Warehouse for C&I customers is a behind-the-meter unit with 400 kWh to 600 kWh of storage capacity. That makes the power rating configurable from 50 kW to 90 kW. The round-trip efficiency is 70% to 75%, DC-DC. Each battery weighs 16,000 kg dry, and as much as 38,000 kg after it’s filled with the electrolyte. Its 3 MW Energy Center for utility-scale applications packs 6 MW/74 MWh per acre footprint.
ESS has already signed customer orders from Enel Green Power in Spain for the delivery of 17 ESS Energy Warehouses iron flow battery systems, providing a combined capacity of 8.5 MWh. They will be used to support a nearby solar farm and provide resilience for the local power grid.
The company’s market expansion in Europe includes the appointment of Alan Greenshields as director of Europe. He told pv magazine the company still hasn’t decided where to set up its European headquarters, but manufacturing locally is part of its strategy.
European insurance policies, however, are already in place. ESS systems are supplied with a 10-year warranty through Munich Re for its flow battery technology and electrolyte management system, supporting system performance guarantees regardless of project size or location. The ESS battery systems have a prescribed design life of 25 years, but their individual components, including battery modules, electrolyte, and plumbing, may well last for decades longer with proper maintenance.
As Greenshields told pv magazine, the company is expanding its production at a fast pace. The US production capacity stood at 250 MWh last year, but is now already topping 2 GWh. “The customer interest is massive,” he added.
The company manufactures its long-duration batteries with abundant materials such as iron, salt and water, which makes them safe, low-cost and sustainable. They do not degrade with cycling and are not prone to the formation of needle-like filaments called dendrites, which can cause battery failure and even fires in lithium-ion technology.
Another advantage they have over lithium-ion batteries is that they do not need any specific environment for their production, such as ultra-low-humidity dry rooms. They can also be assembled on production lines by robots, similar to washing machines, says Greenshields.
And while lithium-ion might have a lower capital cost per kilowatt-hour, ESS’ company’s iron flow system can reportedly claim parity at four hours and win thereafter.
Compared to their technological cousins – vanadium-flow batteries – iron flow claims to win by a large margin. According to Greenshields, the cost of iron-flow stands at around $20/kWh, whereas vanadium-flow costs can be as much as $200/kWh.
www.pv-magazine.com
