Harvard Profs Cook up Low-Cost Battery Storage with ‘Rhubarb’

A Harvard University research team has made a leap in the search for a new class of batteries that can answer the great need for low-cost ways to store energy generated by renewable sources. And it is breaking ground by looking for the solution in non-metallic materials – in this case, a molecule almost identical to one found in rhubarb.

The technology has commercialization potential in the search for solutions to store excess energy produced by solar panels or wind farms. It enjoys backing from Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E) in the form of a $600,000 grant, and has signed up Connecticut-based Sustainable Innovations as a collaborator that aims to build commercially viable demonstration versions of the battery.

The team’s achievement has added to the buzz around the bustling battery storage industry that was palpable at the recent CleanTech Innovation Summit held last month in Newport Beach, Calif.

“They’re demonstrating for the first time that you can actually do these without metal-based systems,” said Cheryl Martin, acting director of ARPA-E, who spoke at the event and whose agency supported the research. “So to me, this is a tip of an iceberg.”

A metal-free flow battery could unlock new ways to store electricity on power grids and address the key issue facing renewable energy generation– turning intermittently producing sources such as wind and solar into more cost-effective and steady options for the market. It is one of many ways scientists are attacking the storage challenge, with research focused on managing the excess energy that renewable generation – whether industrial, commercial, or individual – can put into the grid, making it usable on days when these sources aren’t producing.

Investors are paying close attention, Martin said.

“I think people are trying to figure out exactly what’s true in battery technologies,” she said. “So we have a lot of people playing a lot of different bets. We have venture, a lot of strategic involvement in those companies.”

GE Energized

One of the most focused investors is General Electric, said Colleen Calhoun, senior executive director of its GE Ventures arm, who spoke at the CleanTech conference. “Energy storage? It is the most talked-about subject right now within the halls of GE,” she said.

Calhoun said the first call she got on Jan. 1, 2013 was about what GE was “going to do about solar”, but the first caller this year asked: “What are we going to do about energy storage?”

Noting that the $30 billion energy storage market is likely to grow to $50 billion in the industrial space over the next few years, she said many players now are focused on the key questions: “Who’s going to win? How are we going to do it?”

The research community has put significant emphasis on the challenge, leading to a sense that cost-effective, marketable options are close.

“Grid level storage to me is one of those places we’re finally going to break it open,” ARPA-E’s Martin said. “There’s been a lot of efforts over a long period of time.”

Rhubarb Patch

The work on the rhubarb-like molecule by the Harvard team – led by Michael Aziz, a professor at the Harvard School of Engineering and Applied Sciences – is at the core of ARPA-E’s focus on flow battery technology, Martin said. “We’ve continued to build on the flow battery angle and challenge a lot of the assumptions about what’s possible to the point that we actually started thinking about flow batteries being potentially possible in automotive,” she said.

The key to the “rhubarb” project is relying on the electrochemistry of naturally abundant, cheap, tiny carbon-based molecules called quinones that resemble those found plants and animals and are able to store energy. Flow batteries, which store energy in external tanks using chemical fluids, are useful for application with intermittent renewables, because they can be “decoupled” from the actual battery shell, the researchers say. But the chemicals used in flow batteries to date have been expensive, usually metal-based electrocatalysts. The researchers say that using organic molecules instead opens up “a vast new set of possibilities” because quinones are abundant in crude oil and green plants.

Commercialization Prospects

The Harvard team now plans to further test the system, and is working with Sustainable Innovations to ultimately build a commercial organic flow battery product. The firm, which already designs low cost electrochemical systems for energy storage, is planning on a three-year development period, after which it would deploy demonstration versions of the battery in a unit the size of a horse trailer, a portable system that could connect to a solar array on a commercial building.

The flow battery designed so far in the lab has proven itself through scores of cycles, but needs to go through thousands of them in order to test for commercial applications. The team already has plans that will improve on the current “underlying chemistry” of the battery system and make it a viable option from a cost perspective to succeed in the marketplace, Aziz said in a statement. And its applications could go beyond renewable sources to include avoiding the need for a gas-fired plant built just to handle occasional peak demand or to solve power issues for the 20% of the world’s population that is not connected to a grid.

While the team is characterizing its recent findings, published in Nature, as an early achievement, ARPA-E says the use of organic materials in flow batteries could one day lead to grid-scale storage technology. “The project team’s result is an excellent example of how a small amount of catalytic funding from ARPA-E can help build the foundation to hopefully turn scientific discoveries into low-cost, early-stage energy technologies,” added ARPA-E Program Director John Lemmon in a statement.

Research Bonanza

The Harvard team’s work indeed adds to a parade of research on low-cost battery technologies. ARPA-E’s Martin described another company her agency is backing, Fluidic Energy, that aims to develop rechargeable zinc-air batteries with higher-power applications, and has already sold prototypes into the Asian market for cell phone tower backup power. Fluidic was spun out of Arizona State University and received a $3 million grant from ARPA-E in 2010 and $5 million from the U.S. DOE.  It closed on a $13.8 million round in Feb 2013 and raised $33.4 million in 2011, with inverter manufacturer Satcon and Chevron Energy Solutions having been reported as investors in the company.

Other energy storage research in recent months includes:

•    New techniques to create micro-scale materials in the form of tiny hair-like fibers that can be “grown” – using epoxy and an alternating current – and used in technologies such as batteries that require two surfaces making contact with each other.

•    Advancements in research on how to use the greater energy storage potential of silicon as an alternative to graphitic carbons in rechargeable lithium-ion batteries

•    Development of ways to improve on the low electrochemical performance of metal oxides in lithium-ion batteries by using hollow and yolk-shell iron oxide nanostructures

•    A new generation of “sugar battery” that greatly improves on energy density by using an enzymatic fuel cell based on a synthetic catabolic pathway, which can result in wide application as a green power source, especially for portable electronics.

Even the repurposing of “retired” electric vehicle batteries – which retain 80% of their capacity – may turn out to have significant energy storage potential, said Bill Torre, program director of energy storage at the University of California-San Diego’s Center for Energy Research, who also spoke at the cleantech conference. A team at his center has been working with BMW on a full-scale energy storage system based on the old EV batteries capable of handling 180 KW hours, which Torre says could eventually mimic the utility of photovoltaics used on campus that are down to less than $1 per watt in cost.

Other recent energy storage venture fundings include:

3/14/14 –  Acquion Energy closed a $56.6 million in Series D funding from Bill Gates, KPCB, Tao Invest, and others. Aquion Energy is fundamentally­­ changing the economics of power generation, transmission and distribution by developing and commercializing cost-effective energy storage solutions that are safe, reliable, and sustainable from nontoxic components as simple as saltwater. Based on the research of Carnegie Mellon University Professor Jay Whitacre, Aquion’s proprietary Aqueous Hybrid Ion (AHI™) battery overcomes the pitfalls of conventional energy storage technologies.

3/13/14 – SiNode Systems, founded in Feb 2013, raised seed funding from Energy Foundry, an impact investment fund. SiNode Systems is a materials venture based out of Northwestern University that is commercializing a novel silicon based anode technology for use in lithium ion batteries, developed by research team led by Professor Harold Kung.

3/12/14 – Enchanted Rock, provider of onsite controls for load management and energy storage, received $1.5 million from an undisclosed investor.

3/12/14 – New York City-based Eos Energy Storage, bolstered by a $1 million award from the New York State Energy Research and Development Authority (NYSERDA), plans to ramp up manufacturing of its low-cost zinc hybrid cathode (ZnythTM) battery technology.

3/11/14 – Coda Energy, provider of energy storage for commercial buildings, received $6.4 million from Fortress Investment Group to finance customer-sited energy storage systems at no up-front cost.

2/4/14 –Primus Power, founded in 2009, received $20 million in Series C funding from strategic investor Anglo American Platinum through its Platinum Group Metals Development Fund. Primus’ EnergyPod uses a zinc-based flow battery system and is capable of providing storage for up to six hours, according to company CEO Tom Stepien. Research laboratory Sandia carried out third-party testing on the product. Prior investors include Chrysalix Energy Venture Capital, Kleiner Perkins Caufield & Byers, I2BF, and DBL Investors.




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