Negative carbon emissions


John Deutch of MIT and Arun Majumdar of Stanford University discuss potential technology and policy pathways for negative emissions, and the importance of focusing on gigatonne-scale solutions.

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Francis O'Sullivan: Hi, this is Dr. Frank O’Sullivan, Director of Research with MIT’s Energy Initiative. Welcome to the podcast. I’m delighted to be joined today by John Deutch, Institute professor at MIT, and in Stanford, California by Arun Majumdar, Jay Precourt Professor of Mechanical Engineering at Stanford University. Both Arun and John are long-standing thought leaders in energy here in the United States, having played major roles not just in academia, but, of course, in government. They’re joining us here today to discuss a recent commentary they’ve published in Joule reflecting on research opportunities for carbon dioxide utilization and negative emissions at the gigatonne scale. John, Arun, welcome, and thank you for joining us today. I’d like to begin by hearing from both of you with respect to your motivations for bringing this piece together; the bigger context that you see in terms of today’s energy transition and the carbon challenge. Perhaps we can begin with you, Arun.

Arun Majumdar: Sure. This commentary is a shorter version of a much longer report that the former Secretary of Energy, Secretary Moniz, asked his advisory board to put together. John was the chair of that advisory board, I was the vice chair, and we put together a task force to address this particular issue. The question that he asked is, “What are the research opportunities that we need to focus on today, or in the next five to 10 years, that have the potential to make a gigatonne scale impact on our carbon emissions? Especially that has a commercial impact in the form of some kind of a CO2 utilization and negative emissions?” That was basically the genesis of this whole report. In fact, we had a whole task force that put this together. That report got finalized in December. We thought that, for the sense of brevity, and for people to read it, it may be a good idea to put a commentary together, which is what this commentary is all about.

FO: Turning to you, John, in reading this commentary, one thing that comes out very clearly is the articulation of this need for us to focus on these gigatonne solutions within the context of the carbon challenge and to take a systems approach in doing so. I’m curious just how you and the committee drew out those conclusions. What was the evidence that allowed you to land in those conclusions? Where have we been getting it wrong, if we have been getting it wrong, with respect to our approach to CO2 solutions thus far?

John Deutch: I’d like to step back one moment and point out that here you have a situation which was very prominent in the administration of the Department of Energy by Ernie Moniz, and prior to that by Steve Chu. Both of these secretaries had a broad advisory committee to which they went with questions—technical questions, policy questions—that were of an interest to them and asked for an unvarnished commentary from experts about the questions that they posed to the committee. I underscore this because today the Department of Energy does not have a scientific advisory board in operation, and indeed, the department, as many of the other departments in the executive branch, are not turning to external scientific experts to give them informed judgments about important policy questions that they face. The first point I would like to make to our listeners is how important it is to have activity such as this throughout the federal government. That’s my first point. My second point goes directly to your question, Frank. The charge to the committee from Secretary Moniz certainly presumed that we were going to be unable to reach goals of reducing greenhouse gas emissions to the levels necessary to avoid very, very socially disruptive and expensive to the economy increases in global temperature and climate change. The point was, if we can’t do it by reducing emissions, we have to turn to doing something else. Indeed, that is negative emissions, or some kind of utilization of the carbon dioxide on, eventually, a commercially acceptable manner to help join with the reduction in emissions to avoid the increases in global temperature. That’s a very important point. The study presupposes the need to do much, much better at both CO2 utilization and negative emissions. That’s very important, and I don’t think widely yet internalized by the scientific community, certainly not in the Paris Agreement. It’s unlikely that the globe will be able to manage to avoid deleterious climate change without other measures than just reducing emissions. The third point is exactly what you put your finger on, Frank. If you don’t go to the level of gigatonnes, then you might as well forget about this, because it’s not going to make a difference to the amount of CO2 that’s being emitted per year. Which I believe is about 40 gigatonnes. Is that correct, Arun?

AM: That’s roughly right.

FO: There are a number of elements that I’d like to explore over next few minutes that you’ve brought up there. Before we begin that, perhaps just to step back, this concept of the gigatonne solution, it naturally leads itself to certain sectors. I think we’ve all been very focused, of course, on the electric power system as a major vector for at least the initial tranche of emissions reduction, but there are other sectors with large carbon footprints, though, perhaps, not as many with gigatonne potential footprints for reduction. Within that context, and beyond electricity, where then does the analysis from the committee lead us to, in terms of a focus for that next tranche? Which sectors do we need to really begin to look carefully at, beyond the generation of electricity?

AM: Let me just give your listeners an idea of what gigatonne is. We do emit 40 gigatonnes of greenhouse gas emissions per year. A gigatonne is a billion tons, which is a trillion kilograms. One gigatonne is equivalent to roughly 200 million elephants. One gigatonne. And we produce 40 gigatonnes per year. So this is a big, big number. As John pointed out, this is a gigatonne scale problem, and we need gigatonne scale solutions. Now, what we recommended was not the research be done at the gigatonne scale, but at a much smaller scale, in those topics that have the chance of going to the gigatonne scale. That’s really the premise of the whole report. Let’s not waste time on things that are unlikely to scale to the gigatonne scale, but only focus on those that are relevant. In that, we focused on a few things that we brought out in this report. One was to look at agriculture. We cycle about 120 gigatonnes of carbon per year. We emit back about 118, keeping only about two gigatonnes of carbon in soil. If you could just tweak that a little bit through R&D on plants, crops, or forestation, this could be a very, very big deal. That’s just one option. There are a few other options. When you’re doing things at the gigatonne scale, it’s very important to take a holistic view of what the consequences could be. Because it is engineering at the geo-scale. We recommended that the consequent analysis or understanding of the systems view be part of the R&D. Because it’s very difficult to know a priori what the consequences will be. Some of the effects, in fact, most of the effects, are highly non-linear. They’re not easily predictable. One thing is for sure, if you’re looking at gigatonne scale solutions, then you ask the question, “How many industries today are at the gigatonne scale?” The answer is, not too many. It’s oil, gas, coal, steel, concrete, and agriculture. That’s about it. If you are to solve this problem of climate, these industries ought to be part of the solution and not part of the problem. That’s a very important statement that we make in this report.

JD: It’s a perfect example of what the secretary asked us to do. “Tell us a research area.” We’re not proposing policies, we’re not proposing spending money. But doing research to understand where there might be leverage points to shift that very large flux balance in a way that does take up several gigatonnes.

AM: I think we were a little cautious, but I would say that, exactly as John pointed out, if you want to do something with CO2, you need energy, and that energy better be carbon-free, otherwise you’re back on the same carbon treadmill. We also said that if you want to make chemicals and fuels out of CO2, that cost of energy, we put a number out there. It has to be less than 3 cents/kWh or $30/MWh. By just stroke of luck right now and a huge amount of technology innovation, we do have carbon-free electricity today, whether it’s wind or solar, that is getting cheaper by the day, that is cheaper or approaching $30/MWh in a worldwide sense. At least in the next five years, it will happen. Now, the only problem is that these sources of electricity are intermittent. If we could figure out a way to have electricity delivery at less than $30/MWh, in a continuous way, that could serve a huge purpose on using a decarbonized electricity grid to actually decarbonize the other sector economies, which are much harder to decarbonize. For example, transportation, industrial heat; these are very, very hard. If you want to do something with CO2, you definitely need that very low-cost, carbon-free electricity and energy.

FO: On this theme of the synthetic transformation of CO2, first, the comments that you’ve both just made, I think, reflect the dynamic that we’re seeing today, this increasing convergence of the various elements across the broad energy system, as we see the growth of renewables providing lower carbon and, indeed, very low-cost, albeit perhaps not quite dispatchable, energy yet, and so on. Just to step back a little bit, I think this is very exciting, but on the synthetic chemistry front at least, for as long as you’ve been studying chemistry, John, which as we know is quite a while, people have been exploring these issues. Are there avenues beyond simply lower-cost energy for synthesis? Are there topics that we really need to be focusing on that feel exciting to you today within this space that could benefit from or could yield something exciting if we were able to dedicate that R&D focus to that?

JD: It’s a good question. The two avenues, two pathways which I think have attracted the most attention from serious scientists has been either the water splitting from the sun—splitting water into hydrogen and oxygen—the other one is artificial photosynthesis. Both of those would indeed be a pathway that avoids using energy that has carbon emissions associated. It would be renewable and clean energy. Those have been looked at for a very long time. Quite a few decades. As you pointed out, unkindly, Frank, I’m an old guy, so I’ve spent a lot of time in government, in the university, and elsewhere, arguing for fundamental research in these areas. We’ve had some really great chemists at MIT in the past and in the present who are working on this. But I must say that the results over the decades have not been promising at all in either of these areas. Now, there are strong advocates of both. I know Daniel Nocera, former colleague of mine at MIT and now at Harvard, would vehemently argue against that. But the fact of the matter is, it’s a field that’s been looked at a lot and there’s not been a lot of progress. On the other hand, it’s exactly what our task force was asked to do. Point out some pathways that have potential to do it at the gigatonne scale, and by the way, they have to be cheap.

AM: Can I add to that? Those words of wisdom from John. The cost of electricity, cost of renewable energy that I talked about is a boundary condition. While the boundary condition is necessary, it’s really not sufficient. What we emphasized in our report is there are several pathways to take the cheap energy, carbon-free energy, take water, produce hydrogen. A lot of people think hydrogen is for fuel cells for transportation. Actually, we think that may not be the biggest application of hydrogen, because if you want to do something with CO2 to make a hydrocarbon, whether it’s in a fuel or whether it’s chemicals or plastic, you need hydrogen. The reason we came up with this $30/MWh, because without the $30/MWh, you cannot produce hydrogen at less than $2/kilogram of hydrogen. Unless you produce hydrogen at $2/kilogram, you cannot make fuels, hydrocarbon fuels or chemicals, at the cost-competitive prices. There’s a lot of background in those numbers that we just talked about. But that’s what the report pointed out. That’s where the research is needed. To figure out how to make cost-effective pathways and efficient pathways now that the boundary conditions are there.

FO: I think it’s very interesting, this point about hydrogen, because even within our own work at the Energy Initiative here at MIT, many of our partners are increasingly bringing hydrogen up as a subject that they internally seem to be growing a focus on. Not in terms of simply the traditional applications for transport and so on, but in this broader context about hydrogen being an important vector for a lot of this type of transformation. With that said, the commentary spends a good deal of time reflecting on CCS, or carbon capture and sequestration, and the more contemporaneous flavor of that type of technology. I think that’s very helpful, of course, because today we do have some instances of that technology rolled out. But I think there have clearly been many challenges for that technology in terms of scaling it from the megaton to the gigatonne scale. Both in the separation process and, indeed, in this whole concept about sequestration. I’d love to hear both of you reflect on that particular space. Because whilst, I think, some feel it may not be where it needs to be yet, it still is a proven technology that’s out there. Is there a potential to move that type of technology forward again and to help it begin to gain some momentum?

JD: I think, if you’re talking about carbon capture and sequestration, quite frankly, the issue is the sequestration piece. And the reason that it is, in my mind, the sequestration piece which is so critical, is because of the enormous need for an understood, common, regulatory structure to guide the industry on who will be responsible for choosing the site, who will be responsible for setting the rules for injection at the site, who will be responsible for monitoring and verification of where the CO2 is at the site, who will be responsible for the long-term liability of the CO2 at the site, because it’s going to be there forever, not just a few tens of thousands of years. All of those issues have not really been addressed head on. Even if you get one plant built at great cost in one location, which can’t be done on a commercial basis because there are no benefits for a private company to do this since CO2 emissions are not being charged, but the examples of projects, even at a million-ton-per-year scale of CO2, are very, very small. None of them, as far as I know, are associated with a coal plant. Which is what the original system impetus was, was to have an integrated capture and sequestration system. I think the government, the United States government at least, has been very, very poor at managing those large-scale projects. Many of them have started, a lot of money spent, and have been cancelled. I do say that here is an example of where you need to have government involvement, but it hasn’t been done successfully. One last point, and then I’ll ask Arun to say more about this. The report does talk about trying to use CO2 in enhanced oil recovery in different ways. Right now, the enhanced oil recovery, which occurs in the United States, I think, at the level of about 300 million barrels of oil per year, the people who are doing the EOR, the enhanced oil recovery, must purchase the CO2, maybe at $20/metric ton. These come from pure CO2 sources, of which there’s a limited amount of CO2, I think 70 million tons is about all you can get, a lot of it from places like distilleries where CO2 is a side product. On the other hand, if you use CO2 and inject it and get some oil out, you have a double product. You’ve sequestered the CO2 and you’ve produced more oil. One of our members, Sally Benson, Arun’s colleague at Stanford, is very much an expert in this area and we do call this out as a possible—possible—area where one might be able to get a gigatonne of CO2 storage under acceptable commercial circumstances.

AM: Let me add to that. First of all, I would say that the current policy that we have, the new one on 45Q, is actually a good one. That allows one to use some of the CO2, from pure sources at least. The price is not too high that you can actually do carbon-capture from coal-fired power plants but nevertheless, it actually gets the thing going. I would add, also, in addition to the policy, on the scientific side on the carbon capture, today, most of the capture that is being done is by traditional sorbents like monoethanolamines and a few other amines that are too expensive. The cost of carbon capture has to come down by a factor of two to make it viable to be used, whether it’s coal-fired power plants or other mixed sources. We have a gas mixture coming out. That needs science and engineering. Not only on new chemistries for sorbents that have the right kind of thermodynamics and kinetics, which we don’t have. In fact, there are some very interesting things going on in the chemistry world on metal organic frameworks and a few other kinds of things. We have a different kind of CO2 binding than your traditional MEA, monoethanolamines. That’s the kind of thing that research needs to go into, so that eventually, at scale, we can reduce the cost of carbon capture. Which will help everyone, not just in enhanced oil recovery, but other, for example, CO2 utilizations and the chemicals and fuels. In the report, one of the things that we also focused on was, as John pointed out, enhanced oil recovery. Where, if you use the CO2 for oil recovery, can we do it in a way that will actually store the CO2 and have a net storage? That is, the amount of carbon that is stored is more than the carbon that we get out in the hydrocarbons, so there’s actually net storage from a negative emissions point of view. That’s something that we explored quite a bit, and frankly, most of the work that has been done in enhanced oil recovery has focused on trying to minimize the storage of CO2, because it costs money, and reuse the CO2. As John pointed out, with our colleague, Sally Benson, and Lynn Orr, who’s done some of the work, who was the Under Secretary for Science and Energy during Secretary Moniz’s time, they have done the work in looking at other ways of doing enhanced oil recovery, which we called, for lack of a better name, advanced enhanced oil recovery.

FO: I’d love to hear given the fact that we have some options, what, beyond the science itself, are the key challenges that we now need to also begin to think about?

JD: Let me just give you a personal view. A personal view is that the size of these projects means they’re either going be done by states that have simple governments—by that, I really mean, effectively, China or Russia, maybe a few of the Middle Eastern states—or they’re going to be done by the private sector. To believe that progress can be made on this though OECD governments financing it, and I might say, managing it, in my mind, is really not looking at what the history has told us about such efforts. Now, something like ARPA-E, which is the creation of, basically, Arun, is important because it takes you beyond just a lab or a bench scale, to more of a technology possibility, but is far from technology demonstration of something at the gigatonne scale. I would say that if you need to go to that next step, and we will, then you need to have the involvement of the private sector and really put it in the hands of the private sector. For that you need a stable and understood policy framework, including a cost on carbon.

FO: Perhaps, then, a final question for you both. Given that, and I know this is really soliciting personal opinions, but your opinions matter, both of you. I think for the next decade, obviously, things are not going to change dramatically, but let’s say, in the lifetime of my children, so in the next 60-70 years, do you feel optimistic that we have at least the seeds of a solution for this challenge in what you guys have laid out here? Perhaps a little bit like the revolution that we’ve seen with things like solar, change might actually happen faster than we imagine? Or that in 20 years time we’ll be having a similar conversation? John, perhaps you first.

JD: I must say, again, I think it reflects my age, I’m very unhappy with the progress that the United States is making, and more importantly, that the globe is making on really changing the energy future of the world and the penalties that will come for not dealing with energy in a more responsible way. I’m fairly pessimistic. I would say 20 years from now, very similar to today. If you say, “Well, how is it different today from 20 years in the past?” I don’t believe there’s been a lot of change, if you compare it to 1998.

FO: Arun, do you have a sunnier disposition on the West Coast, perhaps?

AM: I’ll give you a mixed view on this. I think over the last decade, decade and a half, there’s good news stories. That is, as you pointed out, the cost reduction in carbon-free electricity on wind and solar. Which is, now we’re seeing the adoption of that and major investments going on worldwide. It’s still at a very small scale compared to the scale of the whole energy sector, but nevertheless, that’s a good start. Whether that’s adequate or not, I don’t think so. In fact, we point that out. That today we’re talking about penetration of electricity in our grid as 20%, 30%, 40%, but that’s the denominator. The percentage is the current electricity load. What is really needed, if we are to replace the whole transportation sector, or a large fraction of transportation sector, that denominator is much, much bigger. In that sense, we are at a very early stage of this change of our electricity sector with solar and wind, and we haven’t even solved the problem of storage, especially seasonal storage. But in the transportation sector, we are seeing the cost of batteries come down, to the point that in the next five years or so, we are likely to read some cost and range parity in electric vehicles. Now, give it another 20 years and we’ll see some pretty significant penetration. These are all good news things. On energy efficiency, we have seen LED lighting come down in cost to the point that people can now afford it without feeling the pinch. Those are the good things. Now, given the scale of the carbon problem that we have, are we moving fast enough? The answer is definitely no. This commentary is a call to action. To raise the profile so that this is now felt not only by the renewables industry, but, frankly, all the other industries. As I said, if you have a gigatonne scale problem and you need gigatonne scale solutions, it’s a handful of industries that can actually reach that scale, and it’s really a call to action to those industries. I would say, the oil and gas industry has realized that this is a challenge and they ought to be part of the solution. From what we are seeing, I think they have come to that conclusion. They have also been nudged by some of the investors, some of the shareholders and stakeholders, to move in this direction. I think we are starting to see that happen. Again, is this fast enough? Not yet. Can it be done? Can it be fast enough? Absolutely. But certainly, if you align the business incentives, the policies to make the business incentives and the return on investment aligned, then I think we’ll see acceleration. It’s not quite there yet.

FO: Arun, on that note, I think we’ll end. I have to say, both to you and to John, thank you so very much for your perspectives. This was an absolutely fascinating conversation. The commentary in Joule reflects on research opportunities for CO2 utilization and negative emissions at the gigatonne scale. It’s a really engaging read. I think it really does shine a light on the tremendous opportunities at the science level that are out there in this space today. Coupling those with both your perspectives on how we try to take these and move them forward. Let’s hope that in 20 years’ time we will be having a different conversation than we are today. With that, let me thank you all again for listening and ask to please subscribe to the podcast at energy.mit.edu/podcast. Of course, please feel free to tweet @mitenergy with any questions or topics that you’d like to hear us cover in future episodes. Thanks for listening.