Mains Batteries: Not Just Lithium Batteries

As utilities and industrial companies seek to use more renewable energy, the market for grid batteries is growing rapidly. Alternatives to lithium-ion technology could offer environmental, labor and safety benefits. And these new chemistries could work in markets, such as the electric grid and industrial applications, where lithium doesn’t work well.

“I think the longer-term storage market is just beginning to form,” said Mark Higgins, Redflow’s chief commercial officer and president of North America. “We’re seeing a lot of… very rapid scaling in the types of projects we’re working on and the size of the projects we’re working on. We’ve deployed about 270 projects worldwide. Most of them are small off-grid systems or remote grid systems. What we’re seeing today is a lot more of the types of projects that are connected to the grid.”

“The demand… seems to be growing every day,” said Giovanni Damato, CEO of CMBlu Energy. The media’s predictions of growth in this space are huge. “We’re really excited about the opportunity… to just play in this space and provide as much capacity as possible.”

New industrial markets are also becoming active. Chemical plants, steel mills and metal processing plants have not been able to deploy renewable energy well so far because of the fire hazards of batteries, said Mukesh Chatter, co-founder and CEO of Alsym Energy. “Once you’re generating a lot of heat in those plants and there’s a risk of fire, you don’t want to deploy any batteries that are flammable.”

Chatter said the definition of long-term energy storage is not agreed upon by industry organizations. Despite this, there are many potential competitors developing storage for this market. Here, we look at Redflow, CMBlu Energy and BASF Stationary Energy Storage.

Zinc-bromine batteries

Redflow has been making zinc-bromine flow batteries since 2010, Higgins said. These batteries don’t require the critical minerals that lithium-ion batteries need, which sometimes come from parts of the world with unsafe work practices or geopolitical threats. The minerals for these zinc-bromine batteries are inexpensive and easy to obtain.

According to the International Flow Battery Forum website, flow batteries contain a liquid or gas electrolyte that flows through the cells from reservoirs:

The interconversion of energy between electrical energy and stored chemical energy takes place in an electrochemical cell. It consists of two half-cells separated by a porous or ion-exchange membrane. The battery can be made from inexpensive and readily available materials such as thermoplastics and carbon-based materials. Many parts of the battery can be recycled. The electrolytes can be recovered and reused, leading to a low cost of ownership.

Building them could be very different from building other batteries. “I would say our manufacturing process is much more similar to … the manufacturing process of cars than it is to the manufacturing process of electronics … like (a) lithium-ion battery,” Higgins said. “It’s basically putting together batteries made of plastic tanks, pumps, fans (and) tubing. It’s a flow battery, so it’s a liquid that flows through a system that goes through an electrical stack, which is where the cells are, which is where most of Redflow’s intellectual property is. The rest of the battery is … parts that we can get pretty much anywhere.”

Charging and discharging takes place inside an electrical pile. In the pile, zinc is applied to the surface of the carbon during the charging process. It then dissolves into the liquid during the discharging process, Higgins said.

Zinc-bromine electrolyte is made from a chemical that has long been used in the oil and gas sector, Higgins added.

This battery cannot catch fire, and all of its parts are recyclable, Higgins told Ars. “There are none of the toxic materials that are in a lithium-ion battery.” The liquid electrolyte can be reused in other batteries. If it is contaminated, it can be used by the oil and gas industry. If the battery leaks, the contents can be quickly neutralized and are not hazardous.

“We currently manufacture our batteries in Thailand,” Higgins said. “The process and wages are fair wages, and we comply with all relevant environmental and labor standards.” The largest sources of bromine come from the Dead Sea or the United States. Zinc comes from Northern Europe, the United States or Canada.

Batteries typically use an annual maintenance program to replace components that wear out or break, something that can’t be done with many other battery types. Higgins estimated that in two to four years, the technology will be “completely competitive with lithium-ion” in terms of cost. Some government subsidies have helped the commercialization process.