The US has an energy storage problem, and it’s a big one: energy storage might not even exist! The Interior Secretary, for example, doubts that it exists. The Energy Secretary has raised similar existential concerns, and the EPA Administrator reminds everyone that even if they do exist, batteries cost money. Not to worry, though. Unlike unicorns and medbeds, energy storage is a thing that takes up space and time, and new cost-cutting storage solutions are beginning to vault out of the laboratory into commercial application.
Energy Storage Is Coming For Your Fossil Fuels
To be fair, conventional lithium-ion batteries do cost a lot of money, especially as applied to utility-scale energy storage systems. However, conventional coal, oil, and natural gas power plants also cost a lot of money. The public health fallout from air pollution emitted by conventional power plants also costs a lot of money. For that matter, climate change costs a lot of money, too.
In this day and age of modern 21st century technology, the question is not how much money an energy solution costs, but how to focus public policy — and investor dollars — on energy delivery technologies that avoid harmful, costly externalities. From that perspective, lithium-ion battery energy storage systems (BESS) have already solved their own cost problem. Costs have been spiraling steadily downwards for years, partly due to the introduction of the lithium-iron-phosphate (LFP) formula alongside economies of scale as the global energy storage industry expands to meet demand fueled by renewable energy.
“Over the past 30 years, battery costs have fallen by a dramatic 99 percent…. As is the case for many modular technologies, the more batteries we deploy, the cheaper they get, which in turn fuels more deployment,” the nonprofit organization RMI observed last year.
“For every doubling of deployment, battery costs have fallen by 19 percent. Couple these cost declines with density gains of 7 percent for every deployment doubling and batteries are the fastest-improving clean energy technology,” RMI added.
In a report last summer, the International Renewable Energy Agency noted that “91% of newly commissioned utility-scale renewable capacity delivered power at a lower cost than the cheapest new fossil fuel-based alternative,” underscoring the case for more energy storage to support the renewable energy momentum.
Zinc-Air Batteries Are Coming For Your Fossil Fuels
With all this in mind, one might wonder why the familiar lithium-ion battery formula is not sufficient to fill the rising demand for energy storage. That’s a good question. If you have any thoughts about that, drop a note in the comment thread. Before you do, consider that a typical utility-scale Li-ion system provides about four hours of energy storage or less, which is good enough for the diversified grid of today and good enough to be useful in the grid of the future. However, the grid of the future will also need longer duration and lower costs to continue soaking up more wind and solar energy along with other renewables. Eliminating toxic materials, securing a reliable supply chain, and avoiding fire risk is another goal of long duration storage innovators.
Last year, Bloomberg NEF ran the numbers and found that two long duration systems, thermal and compressed air, compare favorably on cost to their lithium-ion counterparts based on BNEF’s 6-hour-plus standard for long duration (for the record, the Energy Department has set a 10-hour standard for long duration).
Other long-duration systems are also bubbling up from the laboratory, with zinc being one focus of attention. Zinc is an abundant, relatively inexpensive material with a 200-year history of use in energy storage systems. The challenge is to apply zinc to scaled up, rechargeable, long-duration systems, and zinc-air technology has emerged as a solution.
Zinc-air batteries began to surface on the CleanTechnica more than 10 years ago, and all that R&D work is beginning to pay off. As recently as 2023 the US Department of Energy issued a state-of-the-research recap of zinc energy storage technology, in which it advised that “air-based systems are complicated by the need to ‘breathe’ oxygen (air), and the oxygen reduction and oxidation reactions at the cathode require catalysts that are either prohibitively expensive (e.g., Pt, Ag, Ir) or are not yet sufficiently efficient or durable (e.g., transition metal catalysts).”
Still, in the same document, DOE noted that “Zn-Air batteries offer potentially high energy density of up to 440 Wh/kg or 1,670 Wh/L and provide a constant, flat voltage discharge profile.”
Zinc-Air Energy Storage: Follow The Money
Although DOE further noted that “few catalysts are capable of performing both oxidation and reduction reactions needed for a rechargeable system,” the agency did allow that the research is ongoing. Apparently, the researchers have not been letting the grass grow under their feet, with the Toronto-based zinc-air energy storage startup e-Zinc providing a good example.
E-Zinc launched in 2012 with the aim of surpassing the Energy Department’s 10-hour goal, to reach up to 24 hours. Along the way it acquired a roster of Series A shareholders including Toyota Ventures, Eni Next, Anzu Partners, BDC, and Graphite Ventures, all of which also participated again to help oversubscribe a new Series A2 round last year. Series A2 was spearheaded by the Canadian firm Evok Innovations with participation from Mitsubishi Heavy Industries, Export Development Canada, and Ultratech Capital Partners, adding another $31 million to e-Zinc’s Series A round of $25 million.
The technology sounds simple enough, though it is the result of decades of experience applied by the company’s late founder and well known zinc electrochemistry expert, Dr. Gregory Zhang.
In e-Zinc’s cell-based architecture, the system charges in an upper section, where zinc pellets form on electrodes. The electrodes are wiped periodically and the pellets fall through a water-based, non-flammable electrolyte to the lower part of the cell, leaving the electrodes free to collect more pellets. As the wiping process repeats, more zinc accumulates in the lower part. There it remains until the battery is discharged.
“When discharging, air is injected into the cell, dissolving the zinc back into the electrolyte, which is then recirculated to the charging section, ready for the next charging cycle,” e-Zinc explains.
With the investor assist, e-Zinc has completed a manufacturing facility in Mississauga, Ontario, designed as a collaboration hub as the company adds demonstration projects to its roster.
The zinc-air formula is just one example in a rising tide of long-duration energy storage solutions, demonstrating yet again that the renewable energy transition is here to stay regardless of any sudden shifts in US energy policy or obfuscation on the part of taxpayer-paid officials who should, and do, know better.
