A new type of battery is coming onto the market that can store multiple days’ worth of energy, that doesn’t degrade, can’t possibly explode and is up to five times cheaper than lithium-ion, claimed its developer as it prepares to pilot the technology in New York state.

The zinc-air hybrid flow battery developed by Canadian company Zinc8 has the potential to disrupt the entire energy-storage market — making wind and solar farms baseload and even replacing the need for transmission grid upgrades in many places.

“For large-scale energy storage, lithium-ion can’t touch us on cost,” says chief executive Ron MacDonald, a former Canadian member of Parliament who now oversees a company that has received $100m of funding.

Zinc-air can beat lithium-ion batteries on price because the latter can generally only hold about four hours’ worth of energy at any one time, so an eight-hour storage system would require two batteries. By contrast, the storage capacity of the Zinc8 system can just be made bigger by increasing the size of the storage tank and the volume of the electrolyte it contains.

The capital cost of an eight-hour Zinc8 storage is about $250/kWh, falling to $100/kWh for a 32-hour system and $60/kWh for 100 hours. By contrast, lithium-ion projects cost about $300/kWh for any duration over eight hours.

“Our market is eight hours [of storage] and above,” MacDonald tells Recharge. “And the reason is that as you increase your storage capacity — the overall cost of the system continues to go down very significantly.”

In terms of levelized cost of storage (LCOS) — ie, the cost of storing each MWh of energy across a project’s lifetime, taking into account all capex and opex — zinc-air blows lithium-ion away for storage capacities higher than eight hours. This is because the LCOS of lithium systems, for long-duration applications that require daily or multi-day full cycling, roughly doubles for every ten hours of storage capacity added, compared to every 70 hours or so for zinc-air.

This means that a 10-hour zinc-air storage system would have an LCOS of about $100/MWh, compared to $125/MWh for lithium-ion. But a 72-hour zinc-air system would have an LCOS of about $180/MWh, compared to more than $600/MWh for lithium.

The cost of the zinc-air battery is expected to fall significantly as manufacturing is stepped up.

The Zinc8 zinc-air hybrid flow battery system. Photo: Zinc8

How the Zinc8 system works

Zinc-air has long been touted as a potentially cheap and powerful form of energy storage, but it always seemed to have a fundamental flaw — the formation of a bumpy coating of zinc on the electrode called a dendrite, which caused short circuits and other problems.

Perversely, Zinc8 found success by embracing this flaw and using it to the company’s advantage.

“Most of the zinc-air battery research was focused on an electrolyte that would eliminate or reduce the dendritic formation,” explained chief technology officer Simon Fan. “We took a totally different approach — we like dendrites.”

Fan’s team invented a process — which remains a trade secret — that easily removes the dendrite from the electrode to “give us beautiful dendritic particles that we can transfer to the storage tank”.

Zinc-air vs vanadium redox

The costs of vanadium redox flow technology — arguably the most advanced eight-hour battery on the market — doesn’t even come close to zinc-air, with capital costs of about $400/kWh and levelized cost of storage more than double that of the Zinc8 technology.

“I love the [vanadium] technology, but it’s cost prohibitive,” says McDonald, who was formerly executive chairman of energy storage company American Vanadium.

Vanadium redox flow batteries requires two tanks, a large membrane and an expensive ultra-pure electrolyte — all of which means that significant cost reductions will be hard to achieve.

The cost of raw materials for zinc-air batteries are about 20 times cheaper than those for vanadium redox, says Zinc8.

In simple terms, the Zinc8 battery uses electricity from the grid to split the chemical zincate (ZnOH4) into zinc, water and oxygen, resulting in charged zinc particles that can store electricity for weeks at a time. When electricity is required, the charged zinc is combined with oxygen from the air (and water), releasing the stored electricity and producing zincate, which is then cycled back to begin the process again.

The battery itself consists of three parts — the “zinc regenerator”, which generates the charged zinc particles; the storage tank, which contains the potassium hydroxide (KOH) electrolyte and holds the charged zinc; and the power stack, a kind of fuel cell that turns the zinc to zincate and delivers its charge back to the grid.

The zinc can be stored for months in the electrolyte — it literally accumulates at the bottom of the storage tank — although it loses about 1% of its stored charge per day. And these particles are then pumped to the power stack when required, via a proprietary pumping mechanism designed and built in-house, where the charge is extracted and delivered to the grid.

The electrolyte — in which the zinc is formed — does not degrade, being identical at the start and finish of each cycle, and there is no net consumption of zinc, oxygen or water. The only parts of the system that degrade are the electrodes and the power stack, which need to be replaced every few years, depending on usage.

The round-trip efficiency of the system — ie, the percentage of inputted energy that is outputted at the end — is about 65%, a far cry from lithium-ion’s 95%, but this is accounted for in the LCOS figures.

Zinc-air vs Baldies

It could be argued that Zinc8’s market competition isn’t really electrochemical batteries, but the emerging range of build-anywhere long-duration intermittent energy storage (Baldies) technologies, such as liquid-air and hot-rock thermal storage, that can also store days' worth of energy.

The most advanced Baldies technology, in terms of commercialisation, is Highview Power’s liquid-air CryoBattery, which has an LCOS of about $100/MWh today for a 100MW system, with chief executive Javier Cavada telling Recharge that this could fall to $50/MWh within ten years. On its heels is Siemens Gamesa’s hot-rock thermal system, which is eyeing an LCOS of about $110/MWh at its commercial-scale pilot project under way in Hamburg.

And unlike the flammable mixture of lithium salts and organic solvents that make up the electrolyte inside lithium-ion batteries, the potassium electrolyte is extremely stable, does not get hot and cannot ignite or explode. This means that some of the additional safety requirements of lithium-ion plants, such as containment buildings, are not needed for zinc-air facilities, further reducing system costs.

Where did Zinc8 spring from?

The zinc-air technology was originally developed by a Silicon Valley company, Metallic Power Inc, which was then acquired by Teck Cominco (later known as Teck Resources), one of Canada’s largest mining companies and one of the world’s biggest producers of zinc. In 2018, MGX Minerals purchased the technology from Teck, and in 2019, and spun it off into a separate company, MGX Renewables, which was listed on the Canadian Securities Exchange last year and later rebranded as Zinc8 Energy Solutions.

Total investment in the technology to date, by Teck, MGX and investors — taking into account last year’s initial public offering and recent funding rounds — adds up to around $52m.

But the firm had largely been under the radar until January this year, when it won the New York Power Authority’s (NYPA) Innovation Challenge, a tender aiming to find innovative eight-hour-plus storage technologies. Zinc8 is now collaborating with NYPA, the largest state utility in the US, on building a 100kW/1MWh (ie, ten-hour) pilot project for a commercial NYPA customer in western New York state by 2022. This will “showcase the long-duration aspect of our battery and also to validate the data so that we can move forward with New York Power Authority on many of their future projects”, Fan explains.

Ron MacDonald, chief executive of Zinc8 Energy Systems. Photo: Zinc8

“This is the thing that's changed our company — going from having some interest, but nobody thinking that zinc-air was ready — to our phones ringing non-stop from big utilities and globally connected companies around the world,” adds MacDonald. “It gave us a level of credibility, of realness with the bigger, broader market that would have taken us a lot of time and a lot of banging on doors [to achieve]”.

Enquiries have been coming in from multinational utilities, transmission system operators, large and small wind and solar developers, EPC (engineering, procurement and construction) companies, technology developers wanting to collaborate on control systems and even lithium-ion battery companies, says MacDonald.

NYPA has been so supportive, he says, that it is providing $2.55m of funding towards the project to help accelerate the development of the technology

Since then, another commercial pilot project has been agreed. Zinc8 has agreed to build a 100kW/1.5MWh (15-hour) zinc-air system in Brooklyn for New York-based clean-energy developer Digital Energy, a project that is being financially supported by the New York State Energy Research and Development Authority (Nyserda).

A third commercial pilot of about 40kW is due to be installed in Surrey, British Columbia, Canada, in the first quarter of 2021.

MacDonald believes that his company’s zinc-air storage systems and their low price means that they could replace the need for expensive upgrades of transmission lines in grid-constrained areas like New York state.

“One of the big opportunities and challenges for the utilities is, how do we reduce the trillions [of dollars] that we will spend on grid upgrades?” he says.

“When you get to around $100/kWh [for an energy-storage system], it changes the economics of laying copper. You can instead put large scale energy storage systems along your grid at the pinch points, and you can almost create a microgrid.”

He points out that such a network would be more reliable than a simple transmission line.

“If you think about all the electricity that’s coming into New York [state] from Quebec, Canada, if there’s a breach somewhere along that line, New York City goes dark. If the copper snaps, there’s nothing below it, there’s no back-up.”

Growth strategy

Zinc8 is now working on building a factory in North America that will be able to produce 40 1MW/10MWh systems per year, which the company acknowledges is unlikely to be enough to meet demand.

“The growth strategy of the company is not to go retail,” says MacDonald, explaining that they are not planning to simply manufacture and sell batteries. And he is adamant that the company is not for sale.

Instead, Zinc8 is focusing on developing collaborations and partnerships with large multinational companies.

“I don't think that they want to run a company like ours. They want the technology. The way that it is normally done is they partner you [and you] come up with various arrangements where they accelerate your commercialization in exchange for a special relationship in a market.”

Zinc8 is still looking into what such collaborations and partnerships might entail, including the possibility of licensing its technology to other manufacturers — including lithium-ion producers

“It’s a little bit surprising for some people that those in the lithium-ion business are talking to us, but it’s not surprising to me — they’re not going to spend 12 years and $100m like we just did to get to where we are,” MacDonald explains.

“We're a very little company with very big promise and there's a lot of larger companies that have opened dialogue with us. It's a David and Goliath thing and you've gotta be very careful how you move that forward. If you become too enamoured with the size of the elephant, they'll sit on you.”