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Energy storage research advances
focus:Technology Renewable energy • Technology update From its factory in Marlborough, Massachusetts, Ambri expects to deliver the prototype 1MW hour storage system for Pearl Harbour in 2016.
Energy storage research advances
R
ESEARCHERS AT the prestigious MIT are building a ‘low cost’ battery that promises to provide’ a viable solution for stationary grid storage of energy supplied by renewables. Andrew Mourant reports.
Power generation from wind and sun is one thing; storing it efficiently in a battery able to cope with fluctuating demand and conditions quite another. How best to do it is one of the big questions facing the world — an issue big enough to have set Bill Gates’ antennae twitching. The project that’s drawn him in, rooted in the Massachusetts Institute of Technology (MIT), is among many being worked on globally. Don Sadoway, professor of materials chemistry at MIT, and perhaps on the threshold of a giant step forward, is honest about the bumpy trial-and-error ride his team has undergone. The idea of creating an entirely new type of storage battery, based on two layers of liquid metal sandwiching one of molten salt, was far from being the result of a blinding visionary moment. Its origins, Sadoway notes, lie in the work of a post doc student, David Bradwell — his thesis exploring the
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March/April 2015 | Renewable Energy Focus
possibility of whether it could work at all. A concept with many more questions than answers; slow to take off. Grants were hard to come by at first. Even in a place renowned for forward thinking, MIT had “only a fraction of the funds for wild ideas that it used to,” Sadoway explains. Some concepts “can make people squeamish through fear of them being too radical.” Sadoway’s team came with unfettered minds, but most had no idea of electrochemistry. “They lacked lab skills and experience, so the early days were fraught with failure,” he noted. Obstacles to wrestle with ranged from corrosion issues to developing suitable seals. Plenty went wrong, Sadoway notes, adding: “I could give you a tale of woe.” But that’s how it usually goes with pioneering research. “All the other electrochemistry [relating to power storage batteries] was lithium, done at room temperature,” Sadoway stated.
“It doesn’t involve molten salt and liquid metal — there wasn’t anything like this.” Meanwhile, Sadoway was busy teaching chemistry not only to first year undergraduates but the wider world. “As the Internet became more capable, it was decided to stream lectures from MIT faculties,” Sadoway explains. (Little did he imagine that among his followers was Microsoft co-founder, Bill Gates.) “Then one day I had an e-mail from someone saying she was Gates’ personal assistant, that he was coming to Boston and would like to meet me. I disregarded it — I thought it was a hoax. Then she emailed again.” The outcome was a meeting crucial to the project’s fortunes. “We spent 90 minutes together talking about my chemistry classes, distance learning and on-line advice. Then the conversation migrated to my research, though I had nothing in the way of results; we’d had many frustrating attempts to build cells with liquid metals and molten salts.” It’s hard, Sadoway admits, to wrest academic scientists from the culture of seeking ‘perfect reviews’ – “to stop looking at things with the likelihood of success but, instead, to the degree of innovation, to a perspective of ‘were it to succeed, would it have a profound impact?’ But Bill Gates understood the concept, and said: ‘If you do decide to spin this out in the form of a company, let me know.’ Well, Sadoway did just that, and Gates committed to a project that’s now raised $60 million. Gates’ backing provided a perfect lever for pulling in more money, the catalyst for petrochemical giant Total to invest soon afterwards. Yet, says Ambri CEO Phil Giudice, the chances were always remote of any big business taking on the concept alone. “A commercial enterprise would have looked, and thought ‘could it work?... maybe it won’t…my guys aren’t comfortable at dealing with batteries at high temperatures.’ There was no antecedent research…no one from private industry could fund it.” From being a post doc grappling with the germ of an idea, Bradwell, in 2010, found himself co-founding (along with Sadoway) MIT’s spin-out company
About: Andrew Mourant is a freelance journalist whose areas of expertise include renewable energy education and the rail industry.
Technology
Ambri, created to exploit the commercial possibilities. He’s now a senior vice president and in charge of technology. While this is some way off coming to market, it has found a champion in the US Military. Ambri’s first military pilot will be at Joint Base Cape Cod (JBCC), to be followed by one in Hawaii, the latter currently ‘dumping’ around 30% of its wind energy, according to Giudice. “As a state, Hawaii is probably the most advanced in getting renewables-based energy into the grid by percentage,” he noted. The driver to improve is the price of power; around twice that of the rest of the US because of Hawaii’s heavy reliance on imported diesel.”
Cheaper and greener Theoretically, Ambri storage systems should supply cheaper and greener electricity to Pearl Harbor. “The US Navy is possibly the most enterprising in the world at creating renewable capability,” Giudice explained. “They realise conventional energy source doesn’t make sense.” So how far might an efficient storage system drive down Hawaii’s electricity price by, say, 2020? Giudice, aware that the commercial application remains unproven, won’t be drawn. “We aren’t yet in the marketplace… there’ll be a lot of challenges,” he stated, cautiously. Ambri has filed for more than 30 patents and licensing applications. From its factory in Marlborough, Massachusetts, Ambri expects to deliver the prototype 1MW hour storage system for Pearl Harbour in 2016. Meanwhile, the JBBC military base pilot is due to begin at the end of 2015. Ambri, now in its fifth year, employs 45 people, “mostly technical, working on the transition from lab curiosity to scalable project, with a tiny business development side,” Sadoway notes. One focus is creating a robotic manufacture assembly device; also developing fixed steel containers. Hopes rest on the belief that electrodes will be immune from the common failures of conventional batteries, such as electrode particle cracking. Ambri claims that cycle-to-cycle capacity fades will be averted because the electrodes are reconstituted with each charge.
Behind Ambri: What makes it tick? Ambri’s liquid metal battery is based on the chemistry used in ‘extreme’ electrochemical processes, ranging from aluminium smelting to lithium polymer batteries. The cells operate at high temperature. The battery comprises three liquid layers which, on melting, become segregated. They’re able to float on top of one another because of their different densities and their inability to mix – there’s no need for membranes or separators. On top is low-density magnesium; on the bottom, high-density antimony. In between there’s molten salt (electrolyte). In a charged state (see diagram), potential energy between the magnesium and antimony layers creates a cell voltage. To discharge the battery, this voltage drives electrons from the magnesium electrode and delivers power to an external load – for example, a light bulb. The electrons then return to antimony electrode. Within the cell,
this causes magnesium ions to pass through the salt and form an alloy with the antimony. To recharge, power from an external source — such as a wind turbine — pushes electrons the opposite way. This pulls magnesium from the alloy and sends it back to the top, returning the system to its three distinct liquid layers. While early experiments focused on magnesium and antimony, Ambri is now developing a cheaper, highervoltage chemistry that can operate at a lower temperature, the details of which it’s keeping secret. The active components of Ambri’s cells are housed in steel containers; the cells stacked into 200 kWh systems. Ten are assembled to produce a 2MWh (1MW peak power) storage system, complete with power electronics. For more capacity, systems can be deployed side by side. Ambri claims the cell design is simple, low-cost and reliable.
Figure 1. Current flow and electrochemical make-up of Ambri’s energy storage system.
“We have data indicating that the fade rate will be so low the battery will retain 99% capacity after 10 years,” Sadoway estimated. “If we can get the cost [of a storage system] down to $500 per KW, the market will be large; and if down to $100per KW, then you’re talking about one of a trillion dollars.” Alicia Barton, chief executive of the Massachusetts Clean Energy Center (MassCEC), a public-funded body designed to encourage sustainable technologies, is watching closely. “A lot of companies are working on this around the world — it’s increasingly
competitive and there’s still a long way for all of them to go.” MassCEC has provided funding for a project at JBCC, which is one of the state’s largest consumers of electricity and generators of renewable resources. Its two wind turbines and solar array are a “great testing ground for this type of grid-scale complex where you try to manage intermittent loads,” Barton stated. MassCEC analysis calculates that Ambri technology could cut bills by 25%, saving millions of dollars over 20 years. Barton said it is one of the more “exciting technologies” she has seen.
March/April 2015 | Renewable Energy Focus
29
Energy storage research advances
R
ESEARCHERS AT the prestigious MIT are building a ‘low cost’ battery that promises to provide’ a viable solution for stationary grid storage of energy supplied by renewables. Andrew Mourant reports.
Power generation from wind and sun is one thing; storing it efficiently in a battery able to cope with fluctuating demand and conditions quite another. How best to do it is one of the big questions facing the world — an issue big enough to have set Bill Gates’ antennae twitching. The project that’s drawn him in, rooted in the Massachusetts Institute of Technology (MIT), is among many being worked on globally. Don Sadoway, professor of materials chemistry at MIT, and perhaps on the threshold of a giant step forward, is honest about the bumpy trial-and-error ride his team has undergone. The idea of creating an entirely new type of storage battery, based on two layers of liquid metal sandwiching one of molten salt, was far from being the result of a blinding visionary moment. Its origins, Sadoway notes, lie in the work of a post doc student, David Bradwell — his thesis exploring the
28
March/April 2015 | Renewable Energy Focus
possibility of whether it could work at all. A concept with many more questions than answers; slow to take off. Grants were hard to come by at first. Even in a place renowned for forward thinking, MIT had “only a fraction of the funds for wild ideas that it used to,” Sadoway explains. Some concepts “can make people squeamish through fear of them being too radical.” Sadoway’s team came with unfettered minds, but most had no idea of electrochemistry. “They lacked lab skills and experience, so the early days were fraught with failure,” he noted. Obstacles to wrestle with ranged from corrosion issues to developing suitable seals. Plenty went wrong, Sadoway notes, adding: “I could give you a tale of woe.” But that’s how it usually goes with pioneering research. “All the other electrochemistry [relating to power storage batteries] was lithium, done at room temperature,” Sadoway stated.
“It doesn’t involve molten salt and liquid metal — there wasn’t anything like this.” Meanwhile, Sadoway was busy teaching chemistry not only to first year undergraduates but the wider world. “As the Internet became more capable, it was decided to stream lectures from MIT faculties,” Sadoway explains. (Little did he imagine that among his followers was Microsoft co-founder, Bill Gates.) “Then one day I had an e-mail from someone saying she was Gates’ personal assistant, that he was coming to Boston and would like to meet me. I disregarded it — I thought it was a hoax. Then she emailed again.” The outcome was a meeting crucial to the project’s fortunes. “We spent 90 minutes together talking about my chemistry classes, distance learning and on-line advice. Then the conversation migrated to my research, though I had nothing in the way of results; we’d had many frustrating attempts to build cells with liquid metals and molten salts.” It’s hard, Sadoway admits, to wrest academic scientists from the culture of seeking ‘perfect reviews’ – “to stop looking at things with the likelihood of success but, instead, to the degree of innovation, to a perspective of ‘were it to succeed, would it have a profound impact?’ But Bill Gates understood the concept, and said: ‘If you do decide to spin this out in the form of a company, let me know.’ Well, Sadoway did just that, and Gates committed to a project that’s now raised $60 million. Gates’ backing provided a perfect lever for pulling in more money, the catalyst for petrochemical giant Total to invest soon afterwards. Yet, says Ambri CEO Phil Giudice, the chances were always remote of any big business taking on the concept alone. “A commercial enterprise would have looked, and thought ‘could it work?... maybe it won’t…my guys aren’t comfortable at dealing with batteries at high temperatures.’ There was no antecedent research…no one from private industry could fund it.” From being a post doc grappling with the germ of an idea, Bradwell, in 2010, found himself co-founding (along with Sadoway) MIT’s spin-out company
About: Andrew Mourant is a freelance journalist whose areas of expertise include renewable energy education and the rail industry.
Technology
Ambri, created to exploit the commercial possibilities. He’s now a senior vice president and in charge of technology. While this is some way off coming to market, it has found a champion in the US Military. Ambri’s first military pilot will be at Joint Base Cape Cod (JBCC), to be followed by one in Hawaii, the latter currently ‘dumping’ around 30% of its wind energy, according to Giudice. “As a state, Hawaii is probably the most advanced in getting renewables-based energy into the grid by percentage,” he noted. The driver to improve is the price of power; around twice that of the rest of the US because of Hawaii’s heavy reliance on imported diesel.”
Cheaper and greener Theoretically, Ambri storage systems should supply cheaper and greener electricity to Pearl Harbor. “The US Navy is possibly the most enterprising in the world at creating renewable capability,” Giudice explained. “They realise conventional energy source doesn’t make sense.” So how far might an efficient storage system drive down Hawaii’s electricity price by, say, 2020? Giudice, aware that the commercial application remains unproven, won’t be drawn. “We aren’t yet in the marketplace… there’ll be a lot of challenges,” he stated, cautiously. Ambri has filed for more than 30 patents and licensing applications. From its factory in Marlborough, Massachusetts, Ambri expects to deliver the prototype 1MW hour storage system for Pearl Harbour in 2016. Meanwhile, the JBBC military base pilot is due to begin at the end of 2015. Ambri, now in its fifth year, employs 45 people, “mostly technical, working on the transition from lab curiosity to scalable project, with a tiny business development side,” Sadoway notes. One focus is creating a robotic manufacture assembly device; also developing fixed steel containers. Hopes rest on the belief that electrodes will be immune from the common failures of conventional batteries, such as electrode particle cracking. Ambri claims that cycle-to-cycle capacity fades will be averted because the electrodes are reconstituted with each charge.
Behind Ambri: What makes it tick? Ambri’s liquid metal battery is based on the chemistry used in ‘extreme’ electrochemical processes, ranging from aluminium smelting to lithium polymer batteries. The cells operate at high temperature. The battery comprises three liquid layers which, on melting, become segregated. They’re able to float on top of one another because of their different densities and their inability to mix – there’s no need for membranes or separators. On top is low-density magnesium; on the bottom, high-density antimony. In between there’s molten salt (electrolyte). In a charged state (see diagram), potential energy between the magnesium and antimony layers creates a cell voltage. To discharge the battery, this voltage drives electrons from the magnesium electrode and delivers power to an external load – for example, a light bulb. The electrons then return to antimony electrode. Within the cell,
this causes magnesium ions to pass through the salt and form an alloy with the antimony. To recharge, power from an external source — such as a wind turbine — pushes electrons the opposite way. This pulls magnesium from the alloy and sends it back to the top, returning the system to its three distinct liquid layers. While early experiments focused on magnesium and antimony, Ambri is now developing a cheaper, highervoltage chemistry that can operate at a lower temperature, the details of which it’s keeping secret. The active components of Ambri’s cells are housed in steel containers; the cells stacked into 200 kWh systems. Ten are assembled to produce a 2MWh (1MW peak power) storage system, complete with power electronics. For more capacity, systems can be deployed side by side. Ambri claims the cell design is simple, low-cost and reliable.
Figure 1. Current flow and electrochemical make-up of Ambri’s energy storage system.
“We have data indicating that the fade rate will be so low the battery will retain 99% capacity after 10 years,” Sadoway estimated. “If we can get the cost [of a storage system] down to $500 per KW, the market will be large; and if down to $100per KW, then you’re talking about one of a trillion dollars.” Alicia Barton, chief executive of the Massachusetts Clean Energy Center (MassCEC), a public-funded body designed to encourage sustainable technologies, is watching closely. “A lot of companies are working on this around the world — it’s increasingly
competitive and there’s still a long way for all of them to go.” MassCEC has provided funding for a project at JBCC, which is one of the state’s largest consumers of electricity and generators of renewable resources. Its two wind turbines and solar array are a “great testing ground for this type of grid-scale complex where you try to manage intermittent loads,” Barton stated. MassCEC analysis calculates that Ambri technology could cut bills by 25%, saving millions of dollars over 20 years. Barton said it is one of the more “exciting technologies” she has seen.
March/April 2015 | Renewable Energy Focus
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