The ability to store energy promises to revolutionize the way we generate, transmit and use electricity: making renewable sources such as wind and solar cheaper and more dependable.
Massachusetts is one of just three states requiring electric utilities to build battery facilities in the future. Ambri – a company in Marlborough believes it literally has the next hot technology in energy storage: liquid molten metals.
Their first storage cells were made of magnesium and antimony, but in order for the prototypes to operate, the metals had to be melted into liquids by getting heated to 700 degrees Celsius.
The The researchers began churning out new chemistry options, using such metals as tin, lithium and calcium. Today, the new and improved molten metal batteries produced at Ambri’s factory operate at a cool 480 degrees Celcius.
“Well, there’s a secret sauce on the specific materials that we’re using,” David Bradwell of Ambri says. “It’s not magnesium and antimony, but it’s similar type materials.”
The liquid metal storage cells look like stainless steel shoe boxes. They’re filled with raw materials and vacuum sealed.
It’s a very straightforward process,” Bradwell says. “Low-cost capital equipment, high-capacity throughput to allow us to scale to manufacturing with relatively low capital investments.”
Five investors including Bill Gates and the giant French energy company Total have pumped $50 million into Ambri, attracted by the company’s low-tech approach.
Ambri’s molten metal technology is at the cutting edge of the emerging energy storage industry. The company plans to begin commercial production within two years. There are competing battery designs, but the revolution in the way we use, generate and transmit electricity has already begun.
“The electrochemistry of the battery involves three liquid components,” Bradwell says as he explains the inner workings of the molten metal battery: A liquid metal as the bottom positive electrode which pools on the bottom of one of those stainless steel cans; a layer of molten salt, which floats on top of that; and then a third liquid layer, a second metal, which floats on top of the salt, allowing the battery to establish a potential.
That energy potential produces a flow of electrons; electricity. On discharge, the top electrode metal dissolves into the electrolyte as an ion, shedding electrons which goes through an external circuit delivering power.
Reverse the flow and the electrons return to the positive electrode, charging the battery. The molten metals have different densities and don’t mix. Like oil and water, they separate into layers. No pumps, no moving parts.
And the system essentially runs itself. At the factory Ambri has built a beta prototype battery: 432 storage cells strung together and placed into a small insulated shipping container. A commercial version the same size could supply a day’s worth of electricity to 30 average Massachusetts homes. The model to scale up is simple, add more containers!
