The inexpensive zinc air-battery is creating a stir in the energy storage industry. The battery is providing grid-scale energy storage at unprecedentedly low costs - the total cost for a six-hour energy system is US$1,000 per kilowatt, or US$160 per kilowatt-hour of energy storage.
In comparison to flow batteries, costing anywhere between US$400 to US$600 per kilowatt-hour, and Lithium-ion batteries costing US$800 to US$1000 per kilowatt-hour, the saving is huge. While power delivery strengths vary, the price difference remains significant.
Steve Hellman, president of startup Eos Energy Storage predicts that this battery may prove to be competitive with gas-fired generation by mid 2015 -even in the US where prices have fallen dramatically.
Benefits of zinc over lithium
Zinc as a raw material is cheaper than lithium. This is the main reason why zinc air-based battery chemistries are growing in popularity.
Advantages of zinc over lithium-ion are numerous-zinc is a readily available and cheap mineral, with resources totaling 1.9 billion tons worldwide; it costs about a third what lithium costs; it weighs about half what lithium weighs in comparable applications; and while lithium-ion batteries have caught fire under certain trials, zinc is environmentally benign, going to zinc oxide (the main component of baby powder) after playing out in a battery. And zinc oxide is easily recyclable.
Also, like most heavy metals, lithium has limited resources and its extraction involves at least three to five years of planning. The market is also very unpredictable because between the initial investment and the time the actual mining operations commence, prices can plummet, explains Peter Oliver, CEO of Talison Lithium.
What the zinc air battery offers
The battery can do things like assist congested power corridors during grid peaks, or balance out grid voltage fluctuations, to reduce customer costs, defer utility infrastructure upgrades and enhance power quality and reliability.
This capability compares favorably to the lifespan of other batteries on the market, and matches the round-trip efficiencies of most flow batteries currently on the market.
Scientists have been working on using air as the cathode for batteries for close to 50 years. A battery is made up of an anode on one side and a cathode on the other, with an electrolyte in between. Air, of course, is plentiful, lightweight, and doesn’t need a heavy casing to contain it inside a battery cell. Also, theoretically, air can achieve a high energy density, or the amount of energy that it can store.
Eos Energy Storage’s zinc-air battery innovation comes from founder and inventor Steven Amendola, who discovered a breakthrough with his original design of the bi-directional air cathode that could last for 10,000 cycles (or around three decades). The initial battery, costing as little as US$160 per kWh, has the ability to last 30 years and be made up of everyday benign materials. Eos Energy Storage claims that the batteries can achieve 75% round-trip efficiency.
Zinc air battery goes to market
Eos Energy Storage, which has raised about US$12 million in venture capital, has announced that it will soon ramp up manufacturing of its inexpensive zinc-air batteries in conjunction with manufacturing company Incodema Group.
Eos Energy Storage plans to start delivering its first batteries to the market this year, and its first pilot project will be with utility Con Edison in New York.
The batteries are meant to be used on for the power grid to help customers integrate solar and wind power, as well as produce other services like frequency regulation.
Battery market continues to heat up
Eos Energy Storage isn’t the only startup promising groundbreaking advances in batteries. On the rechargeable zinc-air front, contenders include Revolt Technology and PowerAir, PowerGenix and Taiwan’s APET. Venture investors like Vinod Khosla believe that batteries for the grid will involve new chemistries like Pellion's magnesium ion. Kleiner Perkins is betting on sodium-ion batteries from Aquion Energy, and Kleiner Perkins and Khosla Ventures have also invested in battery startup QuantumScape.
New options for low cost power grid batteries used for the power grid are quickly becoming available. This is good news for power companies and utilities as they aim to create a more efficient, resilient and cleaner power grid.