CUNY Speeds Up the Race for a Better Battery

Banerjee with some of his team of faculty and student researchers. Lorraine leon and Jude Phillip.
Dastardly dendrites. To researchers at the CUNY Energy Institute, the quest to control these inevitable filaments of crud is what stands between, say, an ordinary zinc battery and one that might someday electrify an entire building or replace a power station with a wind farm.

Zinc is a cheap and widely available metallic element, and for more than a century it has proved an excellent store of electricity when used as a battery's anode, one of its two electrodes. The problem is that after repeated cycles of charging and discharging, zinc has an unfortunate habit of spawning branch-like formations - dendrites - that grow haphazardly, but inexorably, toward the battery's other electrode. Eventually, a dendrite touches that electrode. There is a sudden spike in current. Which causes a short. And a dead battery. Electrochemical engineers describe this phenomenon and its consequences as "catastrophic dendrite formation."

If only the dendrites could be tamed so that the zinc is deposited evenly on the anode during repeated charging and discharging. Chemical engineers have tried to do that for decades, but they have yet to figure out exactly what processes cause the zinc to do what it does.

If they could, the world might be a different place. Cracking the code of zinc dendrites - solving this one problem - could lead to the first battery capable of economically storing enough electrical energy to be part of what energy futurists call a "smart grid." They envision a network that would allow consumers to control the cost and efficiency of their electricity usage and generate some of it locally from the sun and wind, putting it back into the grid when they have an excess.

As scientists at the CUNY Energy Institute see it, this battery of the future would be about the size of a Dumpster. Utilities could scatter them around cities, deferring the need for new power plants and substations. Or perhaps they could be produced in a variety of sizes so that every house could have its own energy storage, allowing homeowners to buy their electricity when rates are low and store it for when they need it. Or homeowners could generate their electricity from wind or solar sources and have an efficient place to store it for times when the wind isn't blowing or the sun isn't shining.

The zinc battery is one of several technologies, along with aluminum batteries and high performance capacitors, that researchers at the CUNY Energy Institute are working to develop. They are part of what, under President Barack Obama, has become a national quest to develop a class of 21st Century super batteries. Forget the Energizer Bunny and the DieHard. The race is on to produce electrochemical packages capable of storing so much energy that they would change the way everything from cars to entire cities is powered.

CUNY Energy Institute Director Sanjoy Banerjee has strived to find new, better and less expensive ways to gather and store energy since CUNY lured him away from the University of California, Santa Barbara, in 2008. Banerjee created the new Energy Institute and has been steadily building it into an ambitious research organization.

Coincidentally, what happened in the two years since Banerjee's arrival was that battery-centered technology became all the rage, a major focal point of the national energy agenda. A month after taking office last year, the Obama administration announced a plan to attack the U.S. dependence on carbon-based energy sources and the ailing economy in one stroke. The Department of Energy made $2.4 billion of the federal stimulus package available to fund research aimed at developing the next generation of batteries. Thus, battery technology became the target of America's decades-old struggle to wean itself from foreign oil.

It's an interesting convergence of circumstances for Banerjee. With the approval of CUNY's Board of Trustees, the CUNY Energy Institute is a reconstituted and reinvigorated version of the Clean Fuels Institute, a research center that had operated at City College since the early 1970s. Started by Arthur M. Squires, a renowned chemical engineer who had been a member of the Manhattan Project, the Clean Fuels Institute had a focused target: coal and how to make it a cleaner energy source.

Nearly 40 years later, the Energy Institute has a far broader mission, as well as a wider reach across the CUNY universe. Like its predecessor, the new institute makes its home at City College's Grove School of Engineering, but it also draws researchers from other CUNY campuses. Thus far, Banerjee has recruited chemists and other scientists from Hunter, Brooklyn and Queens Colleges and the College of Staten Island.

Meanwhile, he has brought in researchers such as Dan Steingart, a young materials scientist who is working on various battery projects and, along with two other new hires - Stephen O'Brien and Masahiro Kawaji - serves as the institute's core faculty. Like several of the institute's scientists, Steingart, an assistant professor of chemical engineering, is working on ways of adapting electrochemical energy storage to cutting-edge uses. Among his goals is to develop a paper battery that could be used, for instance, to power a hospital bracelet which could contain a patient's medical chart.

O'Brien, a chemist recruited from Columbia, is working with Steingart and Banerjee on the next generation of very high performance capacitors, devices that complement batteries by storing less energy while discharging ultra-fast.

Kawaji, meanwhile, came to CUNY from the the University of Toronto, where he developed his expertise in the ways and means of energy flow. Kawaji's earlier work improved the design of power plants and the safety of nuclear reactors, and he was a principal investigator in experiments conducted aboard the space shuttle and the international space station. Banerjee worked with Kawaji years ago at the University of California, Berkeley, and recruited him to the Energy Institute to devise new methods of storing thermal energy. "This is another key problem if energy from sunlight is to be used efficiently for heating and evaporative cooling," says Banerjee.

Born in India, Banerjee is a forceful but charming man appropriately possessed of a thousand-watt smile. He is the rare chemical engineer with both an impeccable academic pedigree and a natural flare for engaging with government and industry leaders and other stakeholders - an essential part of the hunt for research funding, especially in tough economic times.

Some of that outreach actually means reaching inside. "We've got people working on aspects of these programs from all over CUNY," he says. And that's only going to expand: "We're going to open up, take half a million dollars and open it to competition. Anybody in the CUNY system who has a bright idea - a really bright idea - is going to get some seed funding. And we'll encourage them to collaborate and raise more money."

Most of the federal stimulus money is aimed at batteries that would accelerate the nation's transition to plug-in hybrid-electrical vehicles. With the help of a recently announced state grant, which also funds the high-performance capacitor work, the institute's team is working on one such battery. It's a potentially revolutionary version of technology that uses nickel and zinc.

"The problem with batteries for plug-in hybrid electric vehicles is that they are frequently discharged and recharged, which degrades battery life" says Banerjee. By developing a method of controlling the flow and composition of the battery fluid, institute researchers have started to tame the dendrites and already observed much longer battery life - 400 per cent higher than any other nickel-zinc batteries. That's even better than more expensive lithium ion batteries, which typically last two or three times longer than nickel-zinc.

But while the nickel-zinc battery project is showing results that could have a major impact on the growth of hybrid electric vehicles,and the smart grid, it is only one of many energy-storage technologies, with a wide variety of potential applications, that the CUNY researchers are working on. Indeed, the institute is less consumed by the drive to power the Prius generation than by its ambition to use such technologies to make entire cities more energy-efficient - whether with renewable energy sources such as solar and wind, or natural gas, or nuclear power, or even coal and, yes, oil.

As Banerjee never tires of pointing out, he conceives the Energy Institute as "energy agnostic" - a research organization that is ready, willing and able to explore just about any technology that makes sense and might help the United States achieve energy independence. By definition, this means rejecting the herd mentality that has been known to overcome major scientific quests.

"The flavor of the month comes and goes," Banerjee says. He recalls the energy world's infatuation with hydrogen fuel cells, a technology all but proclaimed the solution to the nation's energy problems a few years ago. The idea hasn't quite panned out: The technology is still in the mix, but it's been moved to the back burner.

"When President Nixon declared the war on oil imports, one-third of our oil was imported - now we import two-thirds," Banerjee notes. "If the goal of American energy policy is to reduce or even eliminate our dependence on foreign oil, then no viable alternatives can be ignored. We cannot be consumed by any one technology. We can't put all our belief and devotion into any one approach as if it were religion."

Still, if Banerjee takes an approach that seeks not one Holy Grail but many, the holiest of them would be a battery capable of transforming renewable energy from high-minded concept into game-changing solution.

Solar and wind power are the enduring symbols of cutting-edge eco-friendliness - the embodiment of the green movement - but they still supply less than 4 percent of the nation's energy. The primary reason is that nobody's yet figured out a way around the inevitable paradox of relying on natural resources: They're natural and, by definition, intermittent. It's not always sunny or windy outside, and the energy generated when there is sun or wind can't be saved for when there isn't. It has to be used right away. That's why renewables have never gone mainstream.

"Storage is the Achilles heel of any sort of renewable energy program," Banerjee says. "So if it's ever going to supply more than three or four percent of the national energy requirements, we need ways to collect and store electricity and make it transportable, the way oil and gas are easily collected and stored. That's what we're trying to do: Generate electricity whenever you can and use it whenever and wherever you want. And that means economical and long -life batteries."

To that ambitious end, Banerjee has been steadily building his research staff, recruiting chemical engineers with complementary areas of expertise and focusing on approaches that are a bit off the beaten path. In the Energy Institute's lab stands a battery the size of a trunk; it stores energy gathered from a solar panel on the roof of Steinman Hall. "It's more complex than a standard battery," says Steingart. "It has a lot of plumbing, as we flow the battery fluid to control dendrites,so we can change things as it's running, fix it like open-heart surgery." So far, the researchers have been able to cycle the battery 1,500 times without loss or performance.

Battery performance is one thing. Cost is quite another. In Banerjee's view, it's virtually pointless to develop a long-lasting battery that's so expensive that it wouldn't be widely adopted. "It's one of the most important factors in any new technology," he says. "You can't use the technology you have for your laptop. We need to look in radically new directions."

Those new directions point directly down: to metals such as zinc and aluminum that are abundant and easily extracted from the Earth's crust. Such materials have long proven effective at producing current in batteries, and they do it cheaply. What they haven't done yet is to maintain their performance over daily charge and discharge cycles over many years - because of dendrite formation.

These are research projects of enormous ambition, given that ultimate success would mean developing a large-scale battery that would vastly change the energy picture in two fundamental ways. Besides storing electricity generated by intermittent solar and wind power, such a battery could be used to even out the load of a city's power grid, thus reducing the need for construction of new power plants and substations.

Looking toward the future. From left, Banerjee, Dan Steingart, Yasumasa Ito and Michael Nyce.
Why zinc and not, say, lithium, another material used in batteries? For one thing, lithium would be flammable and possibly explosive in a battery as large as the one the researchers are trying to develop. Zinc, on the other hand, is chemically ideal for the purpose, as well as abundant and cheap - it's less than one-twentieth the cost of lithium.

Of course, there is that problem of those dastardly dendrites, which occur in all high-performance, inexpensive batteries. Institute researcher Joshua Galloway is trying to understand how pumping conductive fluid through the battery and tailoring the charging cycle helps. This seems to reduce the formation of dendrites, though the reasons are not well understood.

Another metal being explored is aluminum. Like zinc, its physical and chemical properties make it ideal for energy storage, and it's cheap and plentiful - the most abundant metal in the Earth's crust, with 20 million tons of reserves in the United States alone. It's 100 percent recyclable to boot.

Practical application - commercialization - is always on Banerjee's mind. Coming to New York after 28 years in California, he has been struck by the difference in the academic cultures of the two states when it comes to bringing scientific discoveries to the marketplace. It's a question with implications that go beyond energy and environment, to issues even more pressing these days: the economy and employment.

Strikingly, there are 20 major technology research centers among New York State's public and private universities, and they spend nearly $4 billion a year. That's second only to California's $6.5 billion. But precious little of New York's investment yields the kind of economic return reaped by California: Just 4 percent of the country's venture capital is invested in New York, while a whopping 47 percent goes to California companies. Massachusetts, meanwhile, spends less than New York on research but incubates many more new start-up tech companies.

Although new to New York, Banerjee has quickly become influential in the state's efforts to bridge the gap. Last spring, he was appointed to a state task force created by Gov. David A. Paterson to explore the issue. The 15-member panel held public hearings, including one at City College's Steinman Hall, three floors below the Energy Institute, and Banerjee emerged as a leading advocate for some of its most audacious proposals.

He argued that a big part of the problem is that New York's academic culture is too stodgy for the times; that universities should promote entrepreneurship by their leading faculty researchers with ideas such as campus-based venture funds and liberal leave policies that would allow professors to take a year or two off to start a company without affecting their tenure.

"New York is living in a world of 30, 40 years ago," Banerjee says. "Universities have to do a lot more to enable collaborations. This is something that California has learned that New York has not. These partnerships are a way of life there."

Banerjee made the case: The task force's final report included those recommendations. It also called for some other policies he championed - most notably that the state give breaks on capital gains taxes to founders and early investors in cutting-edge companies that eventually succeed.

Banerjee certainly practices what he preaches. Meetings and phone conversations with engineers outside his academic world - whether they are employed by large industrial companies or are entrepreneurs with ideas he finds interesting - are always on his calendar. He thinks in eventualities, of not just what the discoveries in the lab might be, but how they could be applied in a practical and perhaps profound way.

And since coming to CUNY, those applications have become more specific. Banerjee is a self described "urbanist" who doesn't drive (although he does have a 1974 Porsche Carrera, which he used to race in California). And when it comes to batteries for hybrid vehicles, he is thinking bigger than a Prius. Lately he's been having conversations with a company in Queens that converts buses to hybrid engine technology.

Banerjee recently invited a senior management group from Consolidated Edison to have a look at the Energy Institute's work and talk about how the utility might use it one day. "What we're looking at is battery technology which could eventually scale up to 10-megawatt size with four to eight-hour storage," he told them. "That, combined with our high-performance capacitor, which also scales. This is what we might be able to do for Con Ed. This would put something within your facilities that would be integrated into your distribution. One of these battery-capacitor combinations could perhaps defer the need for construction of a new substation by two or three years."

This got the Con Edison engineers' attention: Relatively inexpensive batteries instead of new substations.

"Current technology does not exist where you can actually get it at the right price and put it in the middle of Manhattan," Banerjee noted, stating the obvious but raising an intriguing possibility.

One of the Con Edison vice presidents thought Banerjee was actually understating the possibilities. "If you can do 10 megawatts, you can delay a lot of construction," he agreed. "But that's just one use." Con Ed's peak demand periods amount to just 20 hours a year, he explained. "So that's [more than] 8,000 hours a year when we have 2,000-megawatt gas turbines sitting in New York City doing nothing. You move them out and put in your battery-capacitor system? That's a real game-changer."