Harvard's Aziz says emerging battery tech could be game changer for grid storage

Could rhubarb molecules hold the key to cost-effective battery storage for renewable energy in the electricity sector? During today's OnPoint, Michael Aziz, a professor of materials and energy technologies at the Harvard School of Engineering and Applied Sciences, discusses his emerging battery technology and research, funded by the Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E), and talks about the next steps to commercializing the technology.


Monica Trauzzi: Hello and welcome to OnPoint. I'm Monica Trauzzi. Joining me today is Michael Aziz, a Gene and Tracy Sykes professor of materials and energy technologies at Harvard. Michael, thank you so much for coming on the show.

Michael Aziz: My pleasure to be here.

Monica Trauzzi: Michael, battery storage is a critical component to advancing the revolution that's happening in the electricity sector right now, and you've developed a battery technology that could economically store power from renewable sources of energy. What makes your technology unique?

Michael Aziz: That's right. The challenge on storing renewable energy economically is their intermittency is long-term, so you go a long time between making solar energy or wind energy when there're lulls in the wind or a cloudy day or periods of cloudiness, and so I've been working on flow batteries that allow you to optimize for those long periods where you have to deliver energy. There're two important characteristics of a battery, the capabilities of a battery. One is the amount of energy it can store in, it's measured in kilowatt-hours, and the other is the rate at which it can deliver that energy out of storage, and that's in kilowatts, the power of the battery in kilowatts. And those two measures come together in different proportions for different applications. For storing wind and solar, their proportions are pretty extreme, and normal batteries don't give you those proportions readily, so a flow battery allows you to design for extreme proportions of energy to power. And the way you do it is by storing the energy outside the battery container itself in tanks full of fluids. It's a lot like a fuel cell, where you store the energy in tanks full of fluids and you run the fuel cell forward and you're done. But for a battery, you have to be able to run it forward and in reverse. So you take the energy in your high-energy chemicals. Flow them into the battery container. Convert it to electrical energy. Get your electricity out, and if it's a fuel cell, you just exhaust the low-energy chemicals. If it's a flow battery, you've got to contain the chemicals so that when it's time to charge the battery up again, you flow those low-energy chemicals back into the cell, put your electricity back in and restore the original high-energy chemicals. So, with this design, you can choose the power you want based on the size of your cell. The electrodes in your cell give you the power, and then you can store arbitrarily large amounts of energy in these external tanks, as long as the tanks are cheap and the energy storage fluids are cheap.

Monica Trauzzi: And what chemicals are you using, because traditionally those have been expensive.

Michael Aziz: That's what's kept flow batteries out of the normal lexicon is the most commercially advanced flow batteries have to store the energy in vanadium ions, which is a rare and expensive metal. They go into solution in water. So we've developed chemicals that're a fraction of the cost of vanadium. They're organic molecules, which're made of Earth-abundant elements, carbon, hydrogen, oxygen, and they do a terrific job, right? So the cost can go way down, and that can allow, that gives us the prospect of having really low cost in large tanks full of these solutions of organic chemicals in water.

Monica Trauzzi: The creation of this technology resulted from funding in part from ARPA-E. How will you work with the agency moving forward towards commercialization?

Michael Aziz: So, we hope about to sign the contract for the next stage with ARPA-E. We have a small company partner called Sustainable Innovations in Glastonbury, Connecticut. Their job is to commercialize this. We're hoping in a couple of years, or the plan is, I should say, in a couple years to have a system that could store a day's worth of sunshine on a single-family home rooftop in something about the size of a home heating oil tank in the basement, right? And that will be something that's supposed to work really well and be demonstratable and could take orders, and from there it would, I hope that we can move up to storing wind from wind turbines, which is a lot more storage that you need in storage of wind, and at some point storage in just arbitrary places on the grid to help regulate the market price on the grid will become economic as well.

Monica Trauzzi: So this could initially have a really big impact on distributed generation?

Michael Aziz: It really could. In order to do that, it could happen in a couple ways. One is behind the meter, in your basement or in your closet or in your utility owner or a homeowner or a small business or a church or something like that. When you see time-of-day pricing, it becomes important to you to buy the electricity when it's cheap and generate your own or buy it from the grid when it's cheap or generate your own when it's expensive or deliver it out of storage. And the other way is in the utility area, where you have large amounts of solar energy, say, in California and then the sun sets, right? And there's huge oscillations in supply and demand because of that, and so even there at the utility scale, having storage to deal with that, to store the energy from the midafternoon when there's lots of solar and deliver it in the evening when there's lots of demand would be a very useful thing.

Monica Trauzzi: There's a lot of competition in this space. It seems like there's a race to create these advanced battery technologies. In fact, former Energy Secretary Chu has joined the board of an advanced battery technology company. How much room is there for competition in this space, and what do you think about what some of these other companies are doing in advanced battery technology?

Michael Aziz: So there are a lot of companies. There's a lot of development. It's a very exciting time in storage technology and in the storage market. Right now, I don't know of any company that has a commercial product out there that can store the electricity and give it back for a markup on the price of the electricity of less than about 3 cents a kilowatt-hour, right? So if you're paying 11 or something, 3 on top of that is pretty hefty. Our chemicals are cheap enough that if things go the way we plan, the cost of the chemicals themselves would add only a quarter of a penny per kilowatt-hour to the price of storage. Now, that doesn't include the rest of the system, but it leaves a lot of headroom for the pumps and the electrodes and things like that. So we think we have a fighting chance of coming in below a penny a kilowatt-hour.

Monica Trauzzi: Now, I'll note that your paper was published in Nature last month. We're going to end it right there. Thank you so much for coming on the show.

Michael Aziz: Thanks for having me.

Monica Trauzzi: And thanks for watching. We'll see you back here tomorrow.

[End of Audio]



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