Steve Mirsky:    Welcome to Scientific American's Science Talk posted on February 25, 2016. I am Steve Mirsky. On this episode:

Bill Gates:          People say, "Oh, there's a water shortage." Well, another way to say that is that energy is too expensive, because converting this thing we have called ocean into clean water anywhere, that's all a matter of pay for the desalination and pay for the pumping.

Mirsky:               That's Bill Gates on February 22nd. Scientific American energy and environment reporter met with Gates here in New York City. Gates was in town to publicize his foundation's annual letter. This year's edition focuses in part on coming up with ways to tackle carbon emissions while at the same time making necessary energy available to evermore of the globe's growing population.

                           Now the conversation does get a little bit jargony at times, so let me tell you a few things to look out for. When you hear Dave and Bill Gates talk about CCS, that's carbon capture and storage; TerraPower is a nuclear reactor design company. TerraPower also refers to a class of nuclear fast reactors that they are designing. You'll also hear the expression "peakers". Peakers are power plants usually using natural gas, that generally run only when there's a high demand or peak demand for electricity. Late in the conversation you'll hear a reference to the Anthropocene; the Anthropocene refers to this geological time period that we're all living in, and it means that it's been human-influenced, it's anthropogenic. The fact that humans have altered the very atmosphere, geology, hydrology, and other Earth systems that we all are living in.

                           And finally you're going to hear them talk about "the equation." The equation is something that Gates discusses in the letter; it's an equation that he came up with, and basically all it is is PSEC=CO2. Okay, PSEC is PxSxExC, and again, that equals carbon dioxide, 36 billion tons of which we put into the atmosphere last year, we being everybody on the planet. PxSxExC, P is the number of people on the planet, S is the services per person, E is the energy per service, and C is the carbon per unit energy. So PxSxExC last year equaled 36 billion tons of carbon dioxide. And the objective is to get CO2 down to zero. So each of those terms on the left side of the equation is a candidate for going to zero in order to get CO2 on the right side of the equation to go to zero. P, the number of people on the planet, well, that ain't going to zero; that's getting bigger. S, the services per person, that's also growing. E, the energy per service, that's the—basically the efficiency, that is actually getting better, but it's not going to zero. And finally, the carbon per unit energy. If you want to get the right side of the equation, the CO2, to zero, that's what you have to get to zero on the left side of the equation, the C, the carbon per unit energy. In other words, you can't burn fossil fuels, you can't burn substances with carbon in them, and the only way around that is alternative energy, nuclear energy, wind energy, solar energy.

                           So now you have all that you need to know to listen to the conversation between David Biello and Bill Gates.

David Biello:      What do you mean by an energy miracle? Miracle is a tough term for Scientific American.

Gates:                Yeah, I may have used that term. People may have a stronger definition of that term than I do. I mean, I consider the computer-on-a chip a miracle. The Internet is a miracle. The cell phone is a miracle. So, you know, big scientific advances, you know, unanticipated, broad-impact, they're coming and coming at a faster rate than ever. And if we can get something that's measurably less expensive than hydrocarbons, completely clean, and providing the same reliability, which is a very key constraint for energy systems, that I will consider a miracle.

                           And I, you know, I predict that in the next 15 years we have a high probability of achieving it. Not because any individual path, do I rate it say greater than 50 percent, but when you have about a dozen paths, all which at least to mea appear to have better than 20 percent chance independently, that if you get the R&D up, if you do things on the demand side that include great things we've done, like production tax credit, investment tax credit, Renewable Portfolio Standard, many, many tens of billions of money just in the U.S. alone, so we push the demand side, and now with the commitment to raise R&D and 2016 being the first year that actually did get appropriated, then you're very much tilting the odds to have a very positive surprise.

Biello:So we've heard about your efforts in fission and the like, but one of the things that stood out in the letter was you mentioning solar fuels and what we call at Sci Am "reverse combustion." Why does that stand out to you as a possibility? The energetics don't seem so great.

Gates:                Well, no, the photons have energy.

Biello:                 Well, yeah, that's for sure.

Gates:                Lots of energy. And, you know, biological photosynthesis, you know, which is this miraculous, incredible thing that we're still—there was this great book, was called Eating the Sun, talked about current understanding. But actually since that book came out we understand it more. And actually in ten years we may really understand, you know, that there's quantum effects in terms of how all that stuff gets the chemical whim that it gets.

                           So nature shows that it can be done. The reason I like that one in particular—well, partly I like—Professor Nate Lewis works on that stuff and he, you know, showed me that he's within a factor of 100, which is a long, long ways. But they can make tiny, tiny amounts. It doesn't guarantee that they can get there, but it certainly, you know, if you want an example of something I think should get double or triple—I can easily say triple the amount of R&D it gets today, I'd say that's it. Not just the one lab, but several labs taking hopefully slightly different and competitive approaches.

                           The beauty of it, though, is that it reminds people that hydrocarbon—liquid hydrocarbons, you know, say gasoline, is really a magic energy carrier. You put it in a steel tank, it sits there for arbitrary periods of time, you put it in a pipe, it goes down the pipe, it doesn't mess up the pipe at all. It's the infrastructure that we have today, it's got a density that's still an order of magnitude better than the best battery that we can make. So, you know, it's incredible.

                           You know, whenever we talk about batteries we always talk about their energy rating and their power rating. But the energy rating of gasoline tanks is just build a bigger tank and you get the energy rating up. Just like a natural gas peaker, you know, natural gas isn't as easy as the liquid stuff to store, but we can store it pretty darn well, either in liquid or gaseous form. So that's why when you look at those battery charts, natural gas peakers, if you don't have a carbon constraint, they're really kind of miraculous. Yes, you have to spend a little bit of capital to get your power rating, but to get your energy, your per marginal unit of additional energy, those things are really, really cheap. And only sort of, you know, if compressed air or flow batteries were super, super successful can they even be in that order of magnitude of that regime of super, super-high amounts of energy.

                           Which when we talk about grid storage, where you say, okay, there's, you know, five days with no wind or sun and yet we're still not supposed to freeze people in their houses, you know, then you're going to pick the technology that really, really can deliver. And as people have simulated this stuff, you know, unless there's an extremely high price on CO2 and natural gas CCS doesn't come along, most battery technologies have a hard time playing a grid role. Which is different than saying a role in consumer transport, where another factor of two or three probably would get you into the mainstream product profile.

Biello:                 So didn't the energy miracle already happen with the fracking revolution? And if we just get CCS then we're done?

Gates:                Well, CCS is hard to do. The one thing you can never say about CCS is it won't make energy cheaper than it is today. And remember that my initial entry into the energy problem isn't so much climate, although I think that's super, super important and I absolutely put it out there equal, but I start out with let's make energy cheaper, because when I say I want more fertilizer for Africa, I want more light at night, I want vaccines to stay cold for Africa, that's all about the price of energy.

                           You know, people say, "Oh, there's a water shortage." Well, another way to say that is that energy's too expensive, because converting this thing we have called ocean into clean water anywhere, that's all a matter of pay for the desalination and paying for the pumping. You know, they're actually—so in a certain sense there isn't a water shortage; it's just the price of water, given a certain price of energy, means that doing agriculture in the Middle East, in Northern China, is becoming increasingly uneconomic. You know, that—of course, the government has to decide, okay, what are you doing relative to the farming and the income that have come out of those areas, or even food security for some countries.

                           So, yes, fracking is an incredible thing. You know, it's some mix of government R&D, entrepreneurial attitude—and the digital revolution, of course, is playing a nice role in all these things. That ability to take seismic data or magnetometer, all this different data, and create an understanding of the various geological layers, and therefore say, "Okay, I think this 25th deposit probably extends out to there" and, you know, control all the things to be very precise. The IT part of it is never to be underestimated. People kind of take that for granted, but the oil industry didn't have the magic of big data, machine-learning type stuff in the past, and now they do. And the sensors that let you impute all that stuff get dramatically better as well.

                           But, you know, in CCS I absolutely think we should pursue it. But how much—it's not a question—it does not make energy cheaper. You definitely, to take the CO2 out of the flue gas, it's a separation problem, it has an energetic minimum. To liquefy it it's got an energy minimum. And to guarantee it stays in the ground, which probably only a governmental entity can take on that multi-century liability, that they're going to be around and ensure the quality of that. So you have to have the right regulation, you have to find the right geological structures, and then you have to understand what the capital and energetic costs are for CCS. And it is fair to say that if you had asked 20 or 30 years ago would we be further along in understanding that, you'd have to be very disappointed at what the U.S. has done, what everyone, all the countries, you know, somebody should've done a large-scale CCS project, both with a high percentage recovery against coal and with a high percentage recovery against natural gas.

                           So understanding is it 70 percent premium or 20 percent premium, which are still nobody's even done for high recovery rates even a 70 percent thing. It's not impossible that it would be like 20 percent, which in which case as a backup plan to say, "Okay, at least the rich countries should pay that price premium." It's not clear what you would do with India at that point. India's a big enough energy consumer over the next 40 years that you can't give them a free pass. Sub-Saharan Africa, who in the worst-case over the next 40 years would be 4 percent of greenhouse gas emissions, you can give them a pass and say, "Hey, any way that you guys can get energy, if it's natural gas, coal, gasoline, you know, whatever you want. Hey, you are such a small percentage and your per-person emissions are essentially zero," putting aside land use and livestock, which is a complicated area. And even then you wouldn't get to our greenhouse gas level per person till the end of the century if they went full speed ahead with their current coal-based plans. But unless there's some sort of negative CO2 capture coming out of rich countries, which, you know, we should not assume that such a thing becomes economic. There are people, including some I fund, who are working on that, but the cost per ton recovered is in the $100.00-plus regime, and you need to get down into the, you know, probably $20.00 to $30.00 regime before you can start to say, "Okay, let's multiply that by 36 billion, and start thinking about whether or not we should do this or not."

                           Anyway, so, you know, India to me is kind of paradigmatic because the imperative in terms of women not breathing smoke and people being able to have fertilizer, the imperatives of giving them what we take for granted is that they will live, A, far more energy, probably five times more energy-intensive life, which would still leave them less than a third of U.S. energy-intensive, even somewhat below European. You know, so they should more energy. So in my equation the first three terms, PxSxE, that probably is going to be about 1.5 times bigger than it is today. So in other words, you know, P is going to be about 1.2, S is going to be about 2, and E, say we do super-well in efficiency, it's a 0.5, because there's a mix of things like lighting that you can do super-well, and things like making fertilizer, where you're literally, unless there's something we're not seeing, we're close to the, you know, taking atmospheric N2 and making fertilizer's got an energy cost that—actually, those processes are so amazing, they're within like 20 percent of what we think that minimum looks like.

                           So without changing C, if C stays the same, you go from 36 billion tons a year to 48 billion tons a year. And where your assignment was to go from 36 billion tons a year to essentially zero, you know, now you can have a footnote and say, "Okay, poor countries are still allowed to emit" and the livestock land use era deserves its own footnote because, you know, short of something like artificial meat, which is a whole other topic, we actually don't have—mostly we talk about energy: household, factory, office, transport. We talk about energy usage. It's not the only net source of CO2; land use in livestock is a meaningful part of it. And when you're trying to get 36 billion down to zero, you know, every 5, 10 percent, you know, is still a net warming fraction.

Biello:Cars, coal, and cattle is how we put it at Scientific American. The three Cs.

Gates:                Yeah, factories—I don't know if you saw this book, what's it called, Sustainable Energy-

Biello:David Mackay? I don't know how to pronounce his last name.

Gates:                Well, he is Sustainable Energy Without-

Biello:                 Without the Hot Air.

Gates:                Without the Hot Air. Then there's the—I'm forgetting the name of it. The materials book.

Male:Yeah, I'll get it. We [Inaudible].

Biello:Okay. Yeah.

Gates:                Mackay is the one who told me about it, but it's not Mackay; it's some fellow professors of his at Cambridge.

Male:Right, it's his colleagues at Cambridge.

Gates:                Yeah, it's materials—anyway, I'll think of it in a second. But it just goes through steel, wood, plastic, paper, and aluminum, and how much are we likely to need in the future, and what sort of process improvements would reduce the energy intensity. Basically it's a study of E in the materials space, and it says that if you just look at it in a straightforward way you've got a problem. They assume you can't do something magic to C, so they're just trying to look at big changes in E, and they end up having to saying, "Okay, you've got to start reusing stuff." So it was a great book, because it teaches you—like when a refrigerator is "obsolete," it's actually the plastic parts that have gotten messy and ugly and need to be replaced. The metal parts are not fatigued in any way.

Biello:Mm-hmm. So it could be reused is basically what you're saying?

Gates:                Reused. And one thing—

Biello:                 Or repurposed.

Gates:                The key point the book makes is that reuse is a stronger benefit energy-wise than recycle, because in recycle you, in the case of the metals, you molt it again, and so you're actually using almost as much energy—aluminum say half as much—but almost as much energy—actually, it's less than half. But it's using a fair bit of energy, particularly in the case of steel, which if you reuse it. And in the digital world being able to label everything; who made it, what alloys does it have, when was it made, and even maybe someday putting sensors in that will understand the degree of fatigue. It's big—the book is With Both Eyes Open is part of the title, that both eyes open means you can't just take the metal manufacturing process and optimize that; you have to look at the whole design and reuse as a societal materials thing in order to get to these drastic reductions.

                           But if you can play with C then their whole thing doesn't matter. Honestly. Which to me, that's why I don't minimize E, the energy efficiency thing at all. It's wonderful, but I'm afraid that you can only get there by C approaching—greenhouse gas per unit of energy has to approach zero.

Biello:                 Yeah. So what gives you hope besides reverse combustion and Nate Lewis? What are some of the other pathways to zero?

Gates:                Well, I have a ton of money in a company called TerraPower, which is a fourth-generation nuclear. And to me, what's cool about that, you know, it may specifically be a solution; it's a great, great company, but the reason we're so amazing is because of computer simulation. You know, we built a piece of software which, with today's supercomputers, shouldn't be too surprising, where we sit and simulate the material's fatigue, you know, and we can throw a tidal wave at it, we can throw a Richter 10 earthquake at it, a volcano at it. And we've tried out more designs, more nuclear powered designs in this one company than in all of the history of mankind put together, because we just happen to be out in front on, "Oh, change the fuel rod this way." "Okay, shall we have the core burn through linearly or shall we shuffle the things?" Okay, if we're going to shuffle these rods around what's the best shuffling pattern? What's the size? Okay, how about the burn at the top? The burn at the bottom? And, you know, the distortion over time as our steel gets very high DPA.

Biello:                 Yeah, brittlement.

Gates:                Yeah. The software is amazing. And then, you know, we do all these tests to make sure—in fact, you know, we have materials out of the last U.S. fast reactor and FFT, and they had some neutron bombardment, but then we put those _____ reactor or 60, and we do additional radiation. Then we sit there and look at these things and see, okay, what's happened to the crystal structure. So we think we really understand how to make steel that doesn't-

Biello:                 Do what inconel did?

Gates:                Yeah, doesn't expand in this bad way.

Biello:                 So the knock on nuclear has always been Rickover's comment that best reactors are always paper reactors, and we might update that to say like even better reactors are the computer reactors and then everything changes when you get them in actual working experience. Do you anticipate that you'll be able to overcome those challenges, particularly with regulators? It seems too slow.

Gates:                We wouldn't want to count on TerraPower. We need, you know, 12 paths, 5 companies per paths. We need at least 60 TerraPowers. I'll stick up for TerraPower because the assignment was inherent safety based on physics; no humans, no buttons, no training; superior economics; more than a factor of 10 waste reduction; strong proliferation—anti-proliferation. Sorry. And that you don't run out of uranium, that is you don' peak your fuel price, so if you say to the whole world, "Hey, let's all use these things you don't mess up your economics 'cause of a uranium shortage. And on paper they have met their assignment, and so the idea of through a partnership with China or some other country, can you get the pilot plant built, get that built by, if everything went well, by 2024? And then have six years of operating experience, where by 2030 you would say to the world, "Hey, build as many of these as you want." You know, all new nuclear starts should be this and nuclear starts as a percentage of new or replacement energy should be very high. That's the possibility there, but we've got to get the pilot plant built, we've got to get it approved, it has to work super-well, the timeframes can't slip too dramatically. So it's a serious entrant, and from my potentially biased point of view in the nuclear fission category, I don't know many other entrants that you look and say, "Okay, if you go from paper to real then this is a meaningful contribution to cheap energy/global warming as an incredible problem."

Biello:                 I can see that working for India, but it doesn't seem like that would necessarily work for many of the countries in Africa that you're worried about getting cheap energy to, 'cause they don't have the grid to go with that TerraPower.

Gates:                Okay, well, there's always been this thing called ship-based nuclear.

Biello:                 Ah yeah, the Russians.

Gates:                Now my credibility will drop even more.

Biello:                 No, no, I like it. I love ship-based nuclear.

Gates:                But the ocean is pretty magical.

Biello:                 What about Chad? What about Chad? I mean it's, you know-

Gates:                You're right. We're going to have to fly that baby into Lake Chad. No, landlocked countries are always tough. And one of the interesting simulations we're doing nowadays, this is kind of a new topic, is if you build high-voltage DC grids, this work needs to be done at even more precision and more carefully. But in places that use a lot of energy, i.e. Europe, North America, and China, if you build a high-voltage DC grid, which isn't free and has all sorts of regulatory problems, but it's not—it wouldn't make your cost of your energy super-high. If you assume you have that I'll call it magic grid, and if you optimize your renewable sources to be as diverse as possible, so you're taking weather maps and basically making your wind not set inside the correlated feature size of windfronts, i.e. don't build it all in the Midwest. Build a lot in the Midwest, you know, build some a little more north than you would otherwise, some way down in Texas to cut the correlation. Sun; you would put more sun on the coasts than you might otherwise, because you're going for 11 hours of sun instead of 8 hours of sun.

                           So if you diversify your sources, which like California wind, Washington wind, various things would win out in that model, you can get up to 80 percent, which I was always skeptical about and doesn't seem intuitively right to me, but the models are pretty clear, you can use—get up to 80 percent. And so then you have this 20 percent is unsolved. So assuming the price of wind and solar come way down, which, you know, if you can extend the learning curve on solar, that gets to be pretty good, although that may not be predictive. But you want to get rid of the subsidization piece.

                           And then that works—it doesn't work for Africa. It doesn't work for Japan, assuming they don't want to take a dependency on China. So anyway, one part of this solution I think will be if sovereigns are willing and able at large geographic scale to build these kind of networks. And one thing that's cool about it that I like is you do get about 25 percent of the time where your peakers are turned to zero and you have more energy than you need. So you need a new type of customer that's called the "I can use intermittent energy" customer. So you need a profile where their capital cost is very low and the cost of energy in their equation is very, very high, so that they're competitive with plants that are getting—they outcompete plants that get 24-hour energy. And so things like probably voluminous melting doesn't work, because they don't like going solid.

Biello:                 Yeah. [Laughs]Crazy.

Gates:                Although maybe somebody will create some standby heat solution or something, but it would be interesting, 'cause then you would have two prices; you'd have the price of 24-hour energy, and then you'd have this significantly lower specialized price, which with the magic grid you could deliver to essentially any parts of the geography. And so people would bid, is it fertilizer, steel, aluminum, making hydrogen, you know, whatever thing you like, making hydrocarbons, I mean electrofuels. You know, when you get the price low enough and you can do—and, you know, who knows what kind of breakthroughs will be there, then you do electrofuels. But anyway.

Biello:                 And then we export those to Africa to solve their problem?

Gates:                Exactly. The fungibility of energy is a very—the more fungibility you can get, it makes these problems a lot easier, because you still have like planes, where energy density, you know, it's hard to beat liquid hydrocarbons for flying airplanes. Not even flow batteries are in the regime, but it's a percentage of all energy usage that's small enough that some biofuels/electrofuel-type approach or some expensive per-ton free-air capture thing can offset that piece.

                           The land use and livestock one is tricky, and there's less going into that than you might like.

Biello:                 Well, so the energy miracle based on this discussion that it seems like we need is on the deployment side. So we have all these options: TerraPower might be one, there are the solar panels that are going up across the U.S. but maybe not in the rest of the world, we need more batteries out there so they can get the experience with the new chemistries. Is deployment the miracle that we're looking for? No?

Gates:                No, no. Well, just do the equation of how much we put into the demand side for clean energy, and look at Germany and Japan and the U.S. and say, "Okay" and then look at how much incrementally we put into the supply side. Did Germany increase their R&D budget when they bought some of the solar that's in the strangest place in the world to put solar? Not the strangest place in the word, but one of the stranger places in the world to put solar. You know, and what did they end up with? So in my view there's been an imbalance towards funding the demand side versus—I love all of it, and of course you need to do both. And there are deployments challenges, but high-wind is not a deployment challenge. If there's some fusion path, if there's some solar fuels path in a—Nate Lewis's problem is not a deployment problem; his problem is a basic research, generosity, materials understanding.

                           And we are on the verge—you know, you can put aside energy—understanding alloys on a rational basis. Understanding catalysts on a rational basis. Sure, there's a few people who have gotten ahead of themselves on saying that they can simulate those things, but not—I claim not more than a decade ahead of themselves. And so when you talk about an energy R&D budget, it's not just, "Okay, this is only useful for an energy-type thing." This is really basic materials science that, you know, why do we have to keep repairing roads and bridges? Come on, let's create something that takes away that ongoing cost or at least reduces it.

Biello:                 But it's a great way to get rid of bitumen that we're making at our refineries.

Gates:                True.

Biello:                 I mean that's why we do it that way.

Gates:                I don't know that the equation there very well.

Biello:                 It's kind of like gasoline was a waste byproduct for many years and then they decided, "Hey, let's put it in cars."

Gates:                But there is this huge—and I've never audited the figures—this claim of this huge liability for the—that we're not accounting for the maintenance we need there. Anyway, I think the science will have more than pay for itself by its non-energy benefits, particularly if we're tasteful.

Biello:                 I have to ask you, have you heard this term, the "Anthropocene"?

Gates:                Yeah.

Biello:                 Yeah. You think we're in it?

Gates:                I think it's probably appropriate to use that term. I mean when you look at the biomass of livestock, you know, what's the biggest thing in the plant world? Human stuff. What's the biggest thing in the animal world? Human stuff. I mean it, you know, how much cement have we laid. It's pretty incredible. Now as man will say, "there are mountains bigger than all the cement we've laid," but still, the surface areas are significant.

Biello:                 That's true.

Mirsky:               That's it for this episode. Check out our series of e-books; they're available via the Scientific American Web site. That's www.ScientificAmerican.com, where you can also find all the latest in breaking science news. And follow us on Twitter, where you get a tweet whenever a new item hits the Web site. Our Twitter name is @sciam. For Scientific American Science Talk I'm Steve Mirsky. Thanks for clicking on us.