• Climate hub
  • 18 Nov 2021
  • 5 min read

The potential power of metal air batteries

By David Appleyard

Batteries are key to transitioning to a low carbon future

Lithium-ion batteries have found favour, but new options are now coming closer to commercial reality.

Batteries are a vital component of our lives, powering our phones, laptops and electric vehicles. But they’re something of a weak point: often a failing battery is the death knell for a device, and battery concerns like range anxiety and charging times are a major hurdle for EV sales.

While huge strides taken in the lithium-ion battery technology have rapidly accelerated the electricity storage business, there are obstacles to be overcome if renewables are to reach their full potential through electricity storage. Cost is certainly a consideration and though lithium battery costs have plummeted they are still a costly component of any energy system. Lithium-based technologies also face safety concerns, for example thermal runaway problems can cause hard-to-extinguish fires.

Alternatives to lithium batteries

Research in several battery technologies is set to deliver cheaper alternatives to the lithium ion, which should also provide superior performance and safety.

Some of the most promising battery technologies are emerging from far more common elements like iron, zinc and aluminium. So-called ‘metal air batteries’ offer low-cost and easily available primary resources, with the potential for additional safety and scalability benefits over lithium-based cells.

Iron-air – the potential for a fully renewable global power grid

Form Energy is a four-year-old start-up In Massachusetts, backed by Bill Gates and Jeff Bezos, whose work has largely been kept under wraps. It’s been developing iron-air battery technology designed to provide a 100% low-cost renewable electric grid across the world, 365 days a year.

Recently, the company said its first commercial product is a “rechargeable iron-air battery capable of delivering electricity for 100 hours at system costs competitive with conventional power plants and at less than 1/10th the cost of lithium-ion. This battery can be used continuously over a multi-day period and will enable a reliable, secure, and fully renewable electric grid year-round.”

A "reversible rust" battery that could transform energy storage

Iron is one of the safest, cheapest, and most abundant minerals on Earth. The technology is something like a reversible rusting process. Each Form Energy battery is about the size of a washing machine and filled with a water-based, non-flammable electrolyte. These modules are grouped together into utility-scale power blocks of 1 MW. The cost is forecast to be competitive with conventional power generation – and less than 10% of the cost of lithium-ion equivalents. Form Energy expects a commercial grid-scale product to be available by 2025.

Zinc-air – scalable and affordable

Zinc-air batteries have long been used in a variety of devices. They are lightweight, compact, and made of less-flammable materials than other batteries. Researchers have been working on new zinc-air designs that can be used for many applications, including in microgrids, commercial and industrial buildings, and even residential settings.

The Canadian company Zinc8 Energy Solutions uses zinc and air to create a cost-effective clean energy storage option. The zinc-air batteries are scaled up by increasing the size of the electrolyte tank, rather than building new stacks. This is a win for industrial-scale battery use, and the company claims costs as low as US$45/kWh for more than eight hours of storage.

“We’ve got a 15 to 20-year life span and the last charge is as good as the first,” says Ron Macdonald, President and CEO of Zinc8. “With lithium-ion, if you have 10 kWh and you want to go to 100 kWh just on the storage side, you have to buy 100 kW of power stacks. You're buying the most expensive part of the system, which is the power stack. But you don't need it with zinc-air. We have completely decoupled storage capacity and power capacity, so you only pay for what you need.”

A pilot project is already underway, installing a zinc-air energy storage system at the University at Buffalo. The New York Power Authority is hoping this project will demonstrate the feasibility of using the technology more widely. It followed on from the signing of an agreement in principle with Australian engineering firm SmartConsult to explore joint-venture storage projects at aquatic centres, remote mines and similar applications.

Like the iron-air technology, zinc-air uses non-flammable and non-toxic electrolyte which removes the need for costly containment structures.

Zinc8 energy solutions signs deal with New York

Aluminium-air – lightweight long-range driving power

Aluminium is cheap, lightweight and abundant – qualities being tapped into by UK-based Métalectrique Research & Development. The company claims its aluminium-air batteries could power a standard car for around 2400km, before the battery unit is swapped out for recycling (rather than being recharged), at a cost of around 8 pence per mile (NZ$0.25 per kilometre).

High power and scalable, aluminium-air technology is also under development by Israeli company Phinergy, which in March signed a joint venture deal with the Indian Oil Corporation. The two will collaborate with automotive manufacturers Ashok Leyland and Maruti Suzuki to test Phinergy's battery in electric vehicles.

“We hope that the first demo vehicles will drive on Indian roads in the near future, and will subsequently drive millions of passengers in India in an environmental, pollution-free way, with longer driving range compared with lithium batteries of similar size and weight, fast recharging without electric grid dependency, at a competitive price,” said David Mayer, CEO of Phinergy, in a statement.

One key factor in a fully renewable future

With low-cost and safe metal-air storage technologies now emerging, we’re on the verge of having more alternatives for absorbing excess renewable energy and releasing it when we need it. Renewable energy storage opens up a new range of opportunities for a fully renewable electricity and transport system, bringing us one step closer to a 100% sustainable energy future. And your laptop battery might last a lot longer, too.

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