Eos Energy Storage, the startup that says its zinc-air battery chemistry can provide grid-scale energy storage at unprecedentedly low costs, has just landed its first utility pilot partner to test it out.
That’s Consolidated Edison, which announced Wednesday that it’s using a $250,000 NYSERDA state grant to deploy one of Eos’ batteries somewhere on New York City’s grid. From there, the partners intend to test the battery’s ability to 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,” according to Wednesday’s release.
It’s the first public display of the New York-based startup’s potentially disruptive energy storage technology, but it won’t be the last. Eos has five other unnamed partners now testing smaller-scale versions of its battery, and expects to announce some more big utility partners this summer, Philippe Bouchard, business development manager at Eos, said in a Wednesday interview.
All of these early pilot tests, in their turn, are aimed at supporting the eventual commercial launch of a 1-megawatt, 6-megawatt-hour battery called the Eos Aurora. Think of it as a cargo-container-sized box, filled with a complex of air and aqueous electrolyte solution battery “cells,” stacked 50 cells high per module, that absorb and discharge electricity via the interaction of air and Eos’ proprietary zinc hybrid cathode technology.
The company, which has raised about $12 million in venture capital, claims its batteries can achieve 75 percent round-trip efficiency, along with a 10,000-cycle, or 30-year, lifetime. That compares favorably to the lifespan of other batteries on the market, and matches the round-trip efficiencies of flow batteries now on the market, though not those of the latest lithium-ion battery chemistries now in deployment on the grid.
But it’s the low price Eos is offering that has utilities and competitors most interested. Eos is targeting a total system cost of $1,000 per kilowatt, or $160 per kilowatt-hour of energy storage for its six-hour system, Bouchard said. Today’s flow batteries are being priced anywhere from $400 to $600 per kilowatt-hour, but at lower efficiencies. Lithium-ion batteries, on the other hand, while offering certain power delivery strengths that Eos doesn’t match, cost $800 to $1,000 per kilowatt-hour and up, he said -- although some Chinese Li-ion manufacturers are targeting $500 per kilowatt-hour.
Part of what makes it so cheap is its use of zinc, Bouchard noted. Zinc is much cheaper than lithium, at approximately $2 a kilogram, with global reserves of 1.9 billion tons and 30 million tons a year in production. That’s made zinc air-based battery chemistries popular, and indeed, many are on the market today -- but almost all in non-rechargeable formats. Getting them to recharge is much tougher, for various complex technical reasons having to do with the way air affects the anodes and cathodes of the batteries.
Eos says it has fixed those cycling issues by using what’s essentially salt water as an aqueous electrolyte in its battery cells, with the ability to amend or refill the system with more liquid as needed, he said. That’s gotten it to 6,000 cycles in lab tests, way beyond other zinc-air-based rechargeable batteries, and on a par with lithium-ion batteries, giving the startup optimizm that it will reach its 10,000-cycle goal for its commercial-scale units, he said.
Eos isn’t the only startup promising groundbreaking advances in batteries, of course. On the rechargeable zinc-air front, contenders include Revolt Technology and PowerAir, PowerGenix and Taiwan’s APET. On the more esoteric front, 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, and Kleiner Perkins and Khosla Ventures have also invested in battery startup QuantumScape.
Eos is just in the early stages of real-world testing, Bouchard stressed. The ConEd project won’t actually get underway until 2014, and while Eos expects to unveil other utility partners in the coming months, they’ll also be running on similar timeframes.
That may seem to put it behind competing energy storage vendors like NGK, A123 or Xtreme Power, which collectively have installed hundreds of megawatts of grid batteries to date. At the same time, Eos is taking a slow and steady approach that befits an as-yet-unproven technology, Bouchard said.
“We’ve built this fully transparent relationship with major utilities that are themselves going to be trendsetters for the industry,” he said. “They know exactly what we’re doing -- we’ve given them an in-depth perspective on the technology and how it operates, so there are no surprises.”
At the same time, Eos is still perfecting various parts of its grid-ready storage system, including developing a new generation of its current battery management software (BMS), which monitors the state of each liquid-filled cell within the battery arrays that Eos stacks together for power and energy data, as well as safety, he said. But unlike lithium-ion, which must be carefully managed to avoid thermal runaway, Eos’ aqueous-based, electrolyte-filled cells power themselves down in high-temperature extremes, presenting no fire hazard, he said.
As for what ConEd plans to use Eos’ first battery for, the partners are still looking into various options, Bouchard said. But the utility certainly has a lot of challenges in keeping its mostly underground, highly stressed metropolitan grid balanced, both in delivering power to certain congested corridors during peak demand times, or in keeping power quality stable amidst new intermittent generation sources like rooftop solar, he said.
Indeed, ConEd is also working on a broad range of energy storage projects as part of its $181 million in smart grid stimulus grants, including an $18 million project with Brooklyn-based Green Charge Networks to install batteries at 7-Eleven stores and airport EV charging stations to help balance end-use power for grid purposes. With 2012 grid upgrade plans that added up to $1.2 billion (PDF), the utility certainly has a lot of opportunities to look for places where batteries could help it avoid replacing or augmenting the 86 percent of its 130,000 miles of power lines that lie underground, for instance.
The grant Eos and ConEd are using for their pilot is also just part of millions of dollars in energy storage grants given out by the New York State Energy and Research Development Authority (NYSERDA). The state agency has backed everything from flywheel maker Beacon Power’s 20-megawatt energy storage facility in upstate New York (the company went bankrupt, but the facility is still providing frequency regulation to the grid), to startups like Eos and Albany, N.Y.-based BESS Technologies in more recent grants.