SoftBank subsidiary participates in $30 million Series C funding round for ESS, a maker of “all-iron” flow batteries

SB Energy's large-scale solar PV project in northern Japan. Image: SB Energy

SB Energy, a subsidiary of Softbank Group, is one of the investors in ESS, which recently successfully completed a $30 million Series C round of financing. ESS, headquartered in the United States, is a manufacturer of "all-iron" flow batteries using a specialized salt water electrolyte.

As previously reported, ESS is also backed by chemical giant BASF, which is in the process of launching an energy business and invested again in this round. Other early backers and new investors include Evergy Ventures and PTT Global Chemical.

Several flow battery manufacturers, including ESS, were profiled in a mid-2018 feature article, also published in the technical journal PV Tech Power. All of these manufacturers are at various stages of commercialization, striving for market acceptance, and using a variety of materials and electrolytes. ESS has patented and makes the only "all-iron" flow battery that uses a saltwater electrolyte. At the time, ESS CEO Craig Evans said that in addition to the non-toxic, non-flammable composition, the battery's durability and long life are among its strengths.

20,000 cycles won’t be a problem. “A lot of PPAs, particularly solar ones, those will be typical 20-year lifetimes. If you’re going to do all the installation work, you’ll want the battery to last as long as the solar cell so that you don’t incur multiple costs over the life of the project. So you want a battery that can cycle tens of thousands of times: 20,000 cycles won’t be a problem, and we can do that with zero capacity fade,” Evans said.

ESS recently achieved an industry milestone when Munich RE agreed to a plan to cover its products in the field, while the $30 million it just raised will be used to expand and automate the production process for its second generation of flow batteries.

The new battery module design is included in the company’s branded Energy Warehouse containerized energy storage product and can also be installed as part of the company’s new utility-scale solution, Energy Center.

ESS claims the technology is suitable for “projects of virtually any size with up to 10 hours of storage duration” and that it can support “large-scale renewable energy projects, as well as transmission and distribution level services, with no cycling restrictions.”

“As a global leader in renewable energy, we are very interested in long-duration energy storage technologies and see great potential in applying ESS’s iron flow battery technology,” said Rich Hossfeld, senior vice president of SB Energy.

“This investment reflects our belief that ESS’s technology will be a clean, secure and low-cost storage solution that can be deployed at scale to complement renewable energy resources.”

“ESS is remarkable for using low-cost, safe, and effective materials – iron and water – to provide long-term storage solutions across multiple applications, even in high-temperature environments where significant off-grid energy is needed. We are excited about the near-term opportunities for large-scale deployment of ESS technology,” said Carmichael Roberts, founder and managing partner of Breakthrough Energy Ventures.

SB Energy recently joined the growing virtual power plant (VPP) behind the scenes in Japan, announcing a 102.3MW solar PV project in Japan and a 27MWh battery energy storage facility in Hokkaido, northern Japan. Meanwhile, a solar farm developed by SoftBank sits near a 60MW vanadium redox flow battery system, also in Hokkaido, designed and built by Sumitomo Electric Industries and launched as a pilot project in 2015.

In addition, earlier this year, the SoftBank Vision Fund, set up by the group to invest in a number of early-stage technologies, including Uber, Slack and WeWork, committed $110 million to Swiss startup Energy Vault, whose technology involves lowering 35-metric-ton concrete blocks down a tower to store and release energy.

ESS all-iron flow battery schematic. Image: ESS Inc.

(Original source: Energy Storage News New Energy Network Comprehensive)