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For over two thousands years, scientists have experimented with ways to capture the energy of the sun. Archimedes in 212 BC, for instance, famously rigged a system of mirrors that was used to spark fires aboard enemy ships—sort of like an ancient heat ray. Over time, the methods of capturing solar energy have obviously evolved (and perhaps become a bit less dramatic) but there are persisting questions for scientists: How do you best store the energy from the sun, and how do you distribute it cheaply and efficiently at scale?

From my perspective, as a person who cares deeply about the environment and the future of our planet, those questions are among society’s most pressing concerns. Global warming is an existential threat to humanity, and we must reduce our dependence on fossil fuels. But I’m also an investor who embraces the belief that fossil fuels and carbon emissions will eventually be phased out entirely. I’ve been calling it the “clean energy revolution,” and to get there, we must cultivate new ideas, start anew, and listen to the boldest visionaries who are addressing these problems at a global scale.

Recently I had the chance to speak with one of those visionaries: A scientist who has spent an entire career working on (and inventing) grid-level renewable energy storage mechanisms. Professor Donald Sadoway is a current MIT professor, an inventor with over a dozen patents, and a 2012 TIME “Most Influential Person of the Year” for his pioneering research. He has even been called the “Mick Jagger” of battery science researchers, a qualification I asked him about in our conversation.  “I’m not sure I’d want to turn Mick loose in my laboratory,” Professor Sadoway told me. “But maybe metaphorically speaking they’re saying that I do dare to do things differently.”

And what does he do differently? Professor Sadoway is a bit of a renegade amongst battery researchers. Most industry executives and researchers argue that lithium-ion batteries will pave the pathway to the future of solar storage. Tesla’s Powerwall, for instance, uses rechargeable lithium-ion batteries for stationary energy storage that can power your home through the sun’s rays. The lithium-ion market is projected to be worth $93.1 billion by 2025, according to Grand View research, but Sadoway believes that lithium-ion has limitations that should not be underplayed.

“Nobody in the in the modern world is going to settle for green electricity only part of the time,” he says. “We expect electricity on demand all the time. Wind doesn’t blow all the time and sun doesn’t shine all the time. The missing piece is storage. Lithium-ion batteries are out there and it works in your phone and in your computer, but no one has ever installed lithium-ion batteries at grid scale unless it was part of some demonstration. The costs are still way too high. I see everything pivoting on the availability of reliable grid-level storage.” (For more on that, watch Sadoway’s TED talk, “The missing link to renewable energy.”

Earlier this year, Professor Sadoway published results of his new battery technology, using liquid metal, in Nature, the world’s preeminent science journal. “The battery, based on electrodes made of sodium and nickel chloride and using a new type of metal mesh membrane, could be used for grid-scale installations to make intermittent power sources such as wind and solar capable of delivering reliable baseload electricity,” MIT’s press release noted. It’s certainly an innovative idea, and one that Sadoway believes could lead us into a new era of sustainable energy storage.

“I consider this a breakthrough,” Sadoway said in the release, “because for the first time in five decades, this type of battery — whose advantages include cheap, abundant raw materials, very safe operational characteristics, and an ability to go through many charge-discharge cycles without degradation —could finally become practical.”

Professor Sadoway has over four decades of experience, and his breakthroughs are coming at a critical juncture for the path to a renewable future. As a global society, we simply need to find better ways to cultivate and store wind and solar energy—before it’s too late.

Read on for our edited Q&A with Professor Sadoway, where he talks about sustainable energy solutions and the future of battery design.

Arne Alsin: In your view, what will it take to wean our society off of fossil fuels, leading to more renewable energy technologies?

Donald Sadoway: What I’ve learned is that no one is going to embrace any of this clean technology unless it’s going to give you a product that is comparable to what we have now, or even superior to what we have now, and at a price that’s comparable to what we have now.

The notion that if I show up and I say look, ‘I can sell you steel that is made with zero greenhouse gas emissions, but it’s a little bit inferior to steel that you can buy otherwise, and it’s going to it’s going to cost a little bit more…’ People won’t buy it. And so I’ve set cost as a factor in the early discovery stage. That’s the sort of the weakness of university-based research when when people are just inventing the coolest chemistry… But if what you want to do is to radically disrupt something like the world steel industry or the world aluminum industry, you better think about cost on day one—not on day one thousand.

That’s really changed the way I go about conducting even the most early stage research on campus.

Alsin: Would you tell me how your battery differs from lithium—and why it’s potentially better?

Sadoway: The thing that makes this thing so compelling to me and blows the doors off of lithium-ion is that unlike lithium-ion, our data, not only from campus, but from [my startup] Ambri, is that we have battery cells that have been running for over four years with 100% depth of discharge. They’ve logged over five thousand cycles, and those cells are retaining 99-plus percent of their initial capacity. That means this has the the features that would make it suitable for grid-level storage. Lithium-ion doesn’t.

So all we have to do is match lithium-ion for the installation cost and then anybody would be a fool not to choose liquid metal over lithium-ion.

Alsin: How does it work?

Sadoway: The liquid metal battery operates because it’s got electrodes made of liquid metal as opposed to lithium-ion, which has electrodes that are made of solid. Classical batteries have typically solid electrodes and a liquid electrolyte. In our case, we have both liquid electrodes and a molten salt, which is also a liquid electrolyte. 

The way the battery operates is that there’s density differences, and one of the metals is high density and it lies on the bottom of the cell, and then above that is the molten salt which is the electrolyte.  And then on top of the molten salt lies a low density liquid metal… The three layers just self segregate, kind of like oil and vinegar. So that’s that’s the basic premise behind it, and at MIT we’ve invented a plurality of chemistries that can serve as the electrode choice for the top layer and the electrode choice for the bottom layer.

Alsin: What do lithium-ion researchers say about your research? Does that make you a controversial person in this field?

Sadoway: I think that people look at it and they’ll say, ‘Well, it’s fine for Professor Sadoway to publish in the leading journals of the world. Nature’s arguably the premier scientific journal on the planet. Some people call it the

“gateway to the Nobel Prize.” But they’ll say this just isn’t practical.

I accept the criticism. In the end, the market is the arbiter. If you want to find someone who’s Debbie Downer, talk to a battery guy. Battery guys are pessimists, they’re skeptical, and they’re very tribal. So lithium-ion guys have lithium-ion war paint on, and they see me as wearing liquid metal war paint and so therefore they say condemnatory things.

But I don’t care about that. It doesn’t matter what the battery guys say. It’s what the market says. If we get a product and it performs the way I believe it will perform with no capacity fade and round trip efficiency, giving you electricity that is cheaper than what we have right now, the stuff will fly off the shelves.  Because the market doesn’t care.

The moral of the story is that innovation in batteries will not come from the battery industry. In fact, the battery industry might stand in the roadway to block the advance of new battery technology.

Alsin: What do you mean by that? Is this a sort of innovator’s dilemma type of situation of who will create the next generation of energy-efficient batteries?

Sadoway: Right, the incumbents aren’t going to point the way to the future.

Disruption in the big industries is going to come from outside the industry. We see that over and over again. Be prepared to see disruption coming from the most unlikely places.

Alsin: When you think about CO2 emissions, do you envision an accelerating interest around battery science?

Sadoway: Yes, but the problem is that just as there are incumbents in battery production, there are incumbents in battery research. And 99% of the battery research on lithium-ion is incremental improvements. You can’t just wave a magic wand and say, “Innovate!” They’re incapable. So it goes back to who funds it. Government? Private enterprise? We definitely have to be bolder in our innovation when it comes to what goes beyond lithium-ion. We have to apply the criterion “If successful, how big is the impact?” And we have to have the courage to fail.

Alsin: As investors, we believe we’re going through a renewable energy revolution—or disruption, if you like. How do you think the next 50 years of energy disruption plays out?

Sadoway: Well, I think that there are efforts at disruption. I think there’s a lot of interest in substituting fossil fuels with renewables—wind and solar—but I think the truth be told we’re not seeing the disruption at a large enough scale. And all the forecasting is, in my mind, off base. You can take a semi-log plot and get a coefficient and project into 2030 and 2050.

But basically all you’re doing is grabbing what’s happening with respect to early adopters and trying to make it mainstream. In my judgment, the reason that renewables are not taking over is that without storage they stall, because if you go 100% solar, close down all of your fossil fuel burning plants, what are you going to do after dark?

Alsin: So what has to happen for us to get to grid-level storage capabilities?

Sadoway: You have to have all of the pieces in the puzzle. And while the cost of PV solar has dropped dramatically in the last 15 years, the prices still have come way, way down. But now, as I said earlier, what do you do after dark? People people have been allowing certain aspects of the system to get far out in front, while the other aspects are lagging so far behind. The chain is as strong as its weakest link. So if I gave you solar for free, you still can’t do it right now because you don’t have storage, and if you don’t have storage for solar, it’s useless.

If you give people the option, “Would you rather have green electricity or dirty electricity?” They’ll say green. Now if you say the green electricity is going to cost a lot more than the dirty electricity, how much you want to pay more per month on your bill? $5? $10? $100? You’ll find they’re not willing to pay much of a premium for all green electricity.

Alsin: What do you think of Tesla’s Powerwall and their solar energy innovations?

Sadoway: I applaud Tesla for raising our sights on this, but I’m not sure that we’ve got data that show that you can take the Powerwall and use it to 100% depth of discharge every day to allow you to get through the evening after the sun has gone down. My understanding of the use patterns that are prescribed for Powerwall is infrequent use.

It’s a step in the right direction, but obviously I don’t believe in lithium-ion for this application, otherwise I’d be working on it. That’s why I’ve worked so hard on liquid metal battery because I dismiss lithium as a bad fit for grid-level storage. It works well in a in a phone or in a computer, but I even question its utility in a 70 kilowatt-hour automobile.

Alsin: You said in a recent NYTimes editorial that without requisite research, we can’t expect commercialization. What does that look like to you?

Sadoway: I think in the pre-competitive stages it’s going to have to come from government agencies where they fund radical innovation. They have planning horizons that can go five to 15 years. They don’t worry about the likelihood of success—instead they think about the potential impact if successful. They realize that they might give a dozen grants and the majority of them are going to fail, but the few that succeed are going to be game changers. That’s the that’s the way we have to proceed.

Alsin: Tell me about Ambri—your startup—and what sort of goals and challenges you’re looking at?

Sadoway: It’s been seven years and I was hoping we’d already have product to market by now, so it’s been a long journey. The reason is that the electrochemistry, as as was invented here at MIT, has worked beautifully. We’ve never had any hiccups with the electrochemistry.

But it’s all about the conversion to a marketable product at scale, and that means the battery’s going to have thousands of cells. And how do you manufacture this? We’re not manufacturing it to a price point that will compete with fossil fuels. So, you know, you’re going to have to build this thing out of cheap, earth-abundant materials. It’s going to have to be a cheap ceramic that doesn’t crack, and can withstand all sorts of thermal excursions.

Alsin: One clean energy journalist characterized you and your work as the Mick Jagger of battery researchers. What do you make that comparison?

Sadoway: I don’t know! I mean, you don’t want to hear me sing. And I’m not sure I’d want to turn Mick loose in my laboratory. But maybe metaphorically speaking they’re saying that I do dare to do things differently. The Rolling Stones hit the scene when I was a teenager, along with the Beatles, and I always preferred the rougher musicians. So I don’t know where this guy got the idea of comparing me to Mick Jagger as opposed to Paul McCartney, but he made the right choice!