The grid-scale battery market is expanding rapidly as utilities and industrial companies look to expand their use of renewable energy. Alternatives to lithium-ion technology could offer environmental, labor and safety benefits. These new chemistries could also work in markets such as power grids and industrial applications that lithium cannot adequately address.
“I think the market for long-term storage is really just emerging,” says Mark Higgins, Redflow’s chief commercial officer and North American president. “The type and size of projects we’re working on is expanding very quickly. We’ve deployed about 270 projects around the world, most of which are small off-grid or remote grid systems. Now we’re seeing more grid-tied projects.”
“Demand seems to be increasing every day,” said Giovanni D’Amato, president of CMBlu Energy, with the media predicting much growth in the sector. “We’re very excited about the opportunity to be in this space and provide as much capacity as we can.”
New industrial markets are also thriving: Chemical plants, steel mills and metal processing factories have so far been unable to successfully adopt renewable energy because of the risk of battery fires, says Mukesh Chattar, co-founder and CEO of Alsim Energy. “These factories are already generating a lot of heat and are a fire hazard to begin with, so they shouldn’t be putting flammable batteries in there.”
Chatter said the definition of long-duration energy storage hasn’t been agreed upon among industry groups. Still, there are a number of potential competitors developing storage for this market. Here we look at Redflow, CMBlu Energy, and BASF Stationary Energy Storage.
Zinc-bromine battery
Higgins said Redflow has been making zinc-bromine flow batteries since 2010. These batteries do not require the critical minerals required for lithium-ion batteries, which can sometimes be sourced from areas with unsafe labor practices or geopolitical risk. The minerals for these zinc-bromine batteries are affordable and readily available.
Flow batteries contain a liquid or gaseous electrolyte that flows from a tank to a cell. International Flow Battery Forum website:
The interconversion of energy between electrical energy and stored chemical energy takes place in an electrochemical cell, which consists of two half-cells separated by a porous or ion-exchange membrane. Batteries can be constructed from low-cost, readily available materials such as thermoplastics and carbon-based materials. Many parts of batteries are recyclable. The electrolyte can be recovered and reused, resulting in a low cost of ownership.
Manufacturing these is quite different to other batteries: “I would say our manufacturing process is very similar to the car manufacturing process. [an] Electronic device manufacturing process: for example [a] “A lithium-ion battery,” Higgins says, “is basically a battery that you put together made of a plastic tank, a pump and a fan. [and] “It’s a flow battery, which means that the liquid flowing through the system passes through an electrical stack that contains the cells. This is where most of Redflow’s intellectual property resides. The rest of the battery is all… components that you can get anywhere.”
Charging and discharging take place in an electrical stack, where zinc is plated onto the carbon surface during the charging process, and then dissolved into a liquid during the discharging process, Higgins said.
Higgins added that the zinc bromine electrolyte is made from an industrial chemical that has been used for many years in the oil and gas industry.
The battery won’t catch fire, and all of its components are recyclable, Higgins told Ars. “It doesn’t contain any of the toxic materials that lithium-ion batteries contain.” The electrolyte can be reused in other batteries. If it’s contaminated, it could be used in the oil and gas industry. If the battery leaks, the contents are quickly neutralized and aren’t dangerous afterward.
“Right now we manufacture our batteries in Thailand,” Higgins says. “The processes and wages are all fair wages and comply with all relevant environmental and labor standards.” The largest sources of bromine are the Dead Sea or within the U.S. Zinc comes from Scandinavia, the U.S., or Canada.
Batteries typically have an annual maintenance program to replace worn or failed parts, something not possible with many other types of batteries. Higgins predicts that in two to four years, the technology will be “fully competitive with lithium-ion” on cost. Government subsidies are helping aid the commercialization process.
