Energy storage markets are moving toward multiple-hour duration storage to meet the challenges of increased amounts of renewable generated power on the grid, David Bradwell, chief technical officer of liquid metal battery firm Ambri told ESJB.
Deployment of a battery technology that can meet system operator demands for long-duration services such as peak shifting will increase as more wind and solar generated power is deployed, the co-founder of the battery start-up said.
Bradwell sees the large-scale energy storage market heading toward the 3-4 hour duration applications.
“The focus is on multiple hour charge and discharge services that lends itself to the peak shifting markets, which can be on the grid at the right price point as more renewables are integrated onto the grid,” he said.
“We see the need for peak-shifting batteries going up and up and there will be more demand for it.
While Bradwell’s battery has not yet been tested in the field, he believes the technology can straddle both the long and short duration markets.
Liquid metal is so called because all three active components are in liquid form when the battery operates. The two liquid electrodes (magnesium and antimony) are separated by a molten salt electrolyte.
The market for short-duration storage is covered mainly by lithium ion. For example the technology is being used in the majority of projects for the UK’s 201MW enhanced frequency response tender and the record breaking Hornsdale project in South Australia.
Bradwell said that lithium ion was moving toward straddling both short and long-duration storage in terms of coming from higher power to higher energy. “Lithium ion is going to longer and longer durations because the market for 15-minute duration storage is very thin.”
Ambri’s technology was invented in the laboratory of Donald Sadoway, a professor at the Massachusetts Institute of Technology. Bradwell played an instrumental role in advancing the technology while he completed an MEng degree, a PhD degree, and a one-year postdoctoral fellowship.
We speak to Bradwell about his company’s technology and the move toward long-duration storage.
Why are you targeting the long duration markets?
We see the market for multiple hour energy storage system emerging and we’ve got a technology that’s very low cost, a very long life span and can be used for daily, full depth of discharge, four to eight hour duration applications.
There are a variety of applications that grid storage can be used for: ancillary, frequency regulation, voltage support, demand charge reductions.
They can all still be accessed with our battery, but the focus is on multiple hour charge and discharge services that lend itself to the peak demand and peak shifting markets, which can be on the grid at the right price point as more renewables, are integrated onto the grid.
We see the need for peak-shifting batteries going up and up and there will be more demand for it.
Lithium ion is finally getting there in terms of coming from higher power to higher energy. One of the key advantages we have is we are pretty close to the energy density and footprint of lithium ion, and that gives potential customers some comfort.
You can match lithium ion on capacity and size, but what about cost?
We have been tracking prices and looking closely at cost as you would expect. When we started at MIT we wanted to invent a technology that could meet a price point and not just invent a nice new technology.
Lithium ion prices have dropped over the past five years and that will be a significant factor when looking at future cost projections.
We are not engaged in aspirational prices because we are still in the development mode, so cost numbers are based on our own costs analysis based on a 100 different qualities, but we are not releasing a figure for our products because we don’t want to add to the noise of the markets.
What we will say is the capital required for a factory making our batteries at the gigawatt scale is around $30 million to $40 million.
When you factor in equipment, cap ex, operations, and building upgrades that is very low compared to a similar lithium ion factory.
Some lithium buildings have reasonable economics but some are going to cost around a billion dollars in some cases, so ours is very low and we are still making a similar high voltage battery.
How close to commercialization are you?
We are still in the development mode. A little while ago we were ready to ramp up production and preparing to deploy the battery into the field, but we took the decision to take a step back because lithium ion prices were going down.
But we are building toward commercial cells in the next two years when we will start deploying systems.
A year and a half a go we developed an in house prototype system, and the technology works at 500oC. A common question is doesn’t that require a lot of energy to keep hot? But it only needs energy to take it up to that running temperature — about 3MWh to heat a 1MWh scale battery.
The battery runs at 80%-85% efficiency and the rest is turned into heat, and so our thermal insulated containers retain that heat to keep the cells warm.
How does the technology perform?
The chemistry we have worked on reaches 3,000-4,000 cycles with no degradation. A common question is when will it reach 80% capacity? Looking at our data, we would say 360 years, of course that is in laboratory conditions, and it might not last that long in real world conditions as something will degrade, but the fundamentals of the chemistry is extremely long life span.
We are targeting a 10 to 20 year life span but it could be many decades. We haven’t achieved that yet, but the chemistry doesn’t seem to degrade.
Other chemistries suffer, particularly on the electrodes, but our technology just doesn’t have that and doesn’t degrade in the same way as, say, lithium ion or lead acid, so it benefits from extremely stable performance over thousands of cycles, and we project 10-20 years of continuous operations.