As utilities and industrial companies look to use more renewable energy, the market for grid-scale batteries is growing rapidly. Alternatives to lithium-ion technology can offer environmental, labor and safety benefits. And these new chemistries can work in markets like the electric grid and industrial applications that lithium doesn’t address well.
“I think the longer duration storage market is just now emerging,” said Mark Higgins, Chief Commercial Officer and President of North America at Redflow. “We’ve had 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 around the world. Most of those were small off-grid or remote-grid systems. What we’re seeing today are a lot more grid-connected types of projects.”
“The demand… seems to be increasing every day,” said Giovanni Damato, president of CMBlu Energy. Media projections of growth in this space are huge. “We're very excited about the opportunity to… just play in that space and provide as much capacity as possible.”
New industrial markets are also emerging. Chemical plants, steel mills and metal fabrication plants have been unable to successfully deploy renewable energy because of the fire hazards of batteries, said Mukesh Chatter, co-founder and CEO of Alsym Energy. “If you’re already generating a lot of heat in these plants and there’s a fire hazard anyway, you don’t want to deploy batteries that are flammable.”
Chatter said that the definition of long-term energy storage is not agreed upon by industry bodies. However, there are a number of potential contenders developing storage for this market. Here we look at Redflow, CMBlu Energy and BASF Stationary Energy Storage.
Zinc-bromine batteries
Redflow has been producing zinc-bromine flow batteries since 2010, Higgins said. These batteries do not require the critical minerals that lithium-ion batteries require, which sometimes come from parts of the world with unsafe labor practices or geopolitical risks. The minerals for these zinc-bromine batteries are affordable and readily available.
According to the International Flow Battery Forum website, flow batteries contain liquid or gaseous electrolytes that flow from tanks through the cells:
The interconversion of energy between electrical and stored chemical energy takes place in the electrochemical cell. It consists of two half cells separated by a porous or ion exchange membrane. The battery can be made of cheap and readily available materials, such as thermoplastics and carbon-based materials. Many components of the battery can be recycled. Electrolytes can be recovered and reused, resulting in a low cost of ownership.
Building this can be quite different from other batteries. “I would say our manufacturing process is much more like… a car manufacturing process than it is like [an] electronics production process…such as [a] lithium-ion battery,” Higgins said. “Essentially it's assembling batteries that are made from plastic tanks, pumps, fans, [and] tubes. It’s a flow battery, so it’s a fluid that flows through the system and goes through an electrical stack with cells in it, where most of Redflow’s intellectual property is. The rest of the battery is all… components that we can source almost anywhere.”
Charging and discharging occurs in an electrical stack. In the stack, zinc is plated onto a carbon surface during the charging process. It is then dissolved in the liquid during the discharging process, Higgins said.
The zinc-bromine electrolyte comes from an industrial chemical that has long been used in the oil and gas sector, Higgins added.
This battery can’t catch fire, and all of its components are recyclable, Higgins told Ars. “You don’t have any of the toxic materials that you have in a lithium-ion battery.” The electrolyte fluid can be reused in other batteries. If it’s contaminated, it can be used by the oil and gas industry. If the battery leaks, the contents can be quickly neutralized and are then non-hazardous.
“Right now we're manufacturing our batteries in Thailand,” Higgins said. “The process and wages are all fair wages and we follow all the relevant environmental and labor standards.” The largest sources of bromine come from the Dead Sea or within the United States. The zinc comes from Northern Europe, the United States or Canada.
The batteries typically use an annual maintenance program to replace parts that wear out or fail, something that isn’t possible with many other battery types. Higgins estimated that in two to four years, the technology will be “fully cost-competitive with lithium-ion.” Some government subsidies have helped with the commercialization process.
