Dr. Howard Herzog is a pioneer of carbon capture and storage research, having studied it since 1989 in what is now called MIT's Energy Initiative. He was also a Coordinating Lead Author for the IPCC's 2005 Special Report on Carbon Dioxide Capture and Storage, and he is author of the 2018 book Carbon Capture.
Bertie talked to Dr. Herzog about the different forms of CCS, issues around direct air capture's cost, why enhanced oil recovery and CCUS are not the way forward, and what policies need to be put in place to incentivise CCS deployment.
Hello and welcome to the Economy, Land and Climate podcast. My name is Bertie Harrison-Broninski. I'm an assistant editor here at ELCI, and today I'm talking to Dr. Howard Herzog, Senior Research Engineer at MIT's Energy Initiative, about carbon capture and storage technology, also known as CCS. CCS actually describes a group of technologies that can be used to either capture carbon dioxide emissions from smokestacks in power plants or industrial facilities, or even to create so called negative emissions by removing CO2 directly from the atmosphere. Dr. Herzog is a pioneer of CCS research. He's worked on it since 1989, and he was a coordinating lead author on the Intergovernmental Panel on Climate Change as 2005 special report on CCS.Howard:
You know, if the models say I've got to hit this target, it's going to put in technologies no matter how much they cost, to meet their targets.Bertie Harrison-Broninski:
I began by asking Dr. Herzog to tell us a little bit about the different types of technology involved in CCS and how they work.Howard:
There's lots of ways to do it. And one reason is there's lots of different of sources of CO2. As I said, originally, we looked at coal fired power plants, so you have exhaust going up the chimney and that CO2 concentration there, is say somewhere between 10 and 20%, or maybe 10, to 15%, I should say. You have industrial processes like cement, maybe even 20% in the exhaust. We have some processes like ammonia and ethanol, which have pure pretty pure CO2. So that's a pretty easy capture process, you have other things like natural gas turbines, and that's fairly low at, say, 5%. And as I say, some people are looking out of the air, which is 0.04%. So very dilute, about 300 times less than a power plant. So you have different technologies for that. The most common one used right now is called chemical scrubbing, where you have a chemical that reacts with the flue gas and reacts with the CO2 in the flue gas and pulls that out of the gas and into the solution. You do this in big towers. So where you contact that flue gas with a solvent that contains the chemical, in general, the chemical's an amine. The way it works is the amine's a base, CO2 is an acid and they form a bond, and you can regenerate the solvent to reuse. In general, there's several ways to do it. But the most common way is called a temperature swing, you heat it up and drives off the CO2, and then you can reuse the solvent and you have fairly pure CO2 there that you can do something with. What do you do with it? You need to transport it so you can transport it in pipelines is the most common way. In Europe and the North Sea, they're looking at trying to do it with a network of ships. That's a little more expensive than pipeline transport. And the most common thing to do with it now is put it into geologic formations under the Earth, these formations are below 800 metres, I'd say about half a mile down. That way, you keep the CO2 in a liquid form, so it's dense. When it goes in the ground. It's also below say, usable water aquifers, so you don't get that type of contamination. The types of formations are the same type of formations, we take oil and gas out we can use depleted oil and gas wells, but also there's a lot of things called deep saline formations. And these are in rock that similar to the oil and gas thing, sedimentary rock. They're porous, but instead of containing hydrocarbons, they just contain brines, which is basically salty water, and you can put the CO2 in there. So that's sort of the broad concept of how it works all the components, basically, at least, some components, there are technologies for each of these components that are commercial today. And we have maybe a couple of dozen demonstration plants or commercial plants around the world. There's other technologies under development, people are trying to maybe use what they call cryogenic and freeze out the CO2. Sometimes they want to burn it in oxygen, as opposed to air and that eliminates the nitrogen in the combustion process at the end of the process which makes the capture higher so it makes the process easier. You also can change the process to try to have the process itself put out higher, higher concentrations of CO2 to make it easier to capture. So all of those things are being looked at a long list of people looking at technologies and different stages of development. Obviously, they all won't come to fruition. But if a couple do that sort of could really move the technology forward and cut the price down.Bertie Harrison-Broninski:
You talked about injecting liquid CO2 into oil and gas reservoirs. At the moment. I think I'm right in saying that the vast majority of active CCS projects are being used for oil recovery. I wondered if maybe you could explain quickly kind of what that was. And also in your book, you talked about it as a stepping stone to developing CCS, even if it's not great in climate terms at the moment. So I was interested to hear whether you think kind of three, four years later, do you see that happening? Do you see us kind of stepping off that stone? Or is it a bit of a roadblock to doing the processes that we want to be doing?Howard:
So first, let me explain what CO2 injection into oil fields are, that's a lot of time called enhanced oil recovery or EOR for short. Basically, when you tap an oil field, you get some oil out, but most of it stays in the ground, and you have to use advanced recovery techniques. Sometimes, the next thing they may do is put a water flood in there, keep the pressure up, to mobilise it. But a lot of times the oil is stuck in the rock itself. And if you inject CO2 down, it what's called mobilises. It actually changes the chemistry a little so this CO2 lowers its viscosity, and you can get it out. So you know, I don't have the exact numbers of what percent but maybe as much as 20% of the original oil in place can be, you know, retrieved using these techniques. So the industry likes it. They don't like paying for the CO2. So it's really developed in the United States where there were cheap supplies the CO2, basically, there are reservoirs of CO2, just like we have gas reservoirs in the United States, we have reservoirs that contain gas, but that gas is mostly CO2. And that's how the industry developed in the US and why the US has by far the most enhanced oil recovery operations. The reason I call it a stepping stone is for two reasons. One, why are people using that, to put the CO2 away? Today, that's probably the cheapest way because you may have to get paid a little money for your CO2 and help overall project economics and where there's not a lot of incentives in terms of climate for reducing CO2 emissions, this helps project economics. It is only a stepping stone, because A, the amount of CO2 you can put it in oil wells is fairly limited. The there's a lot more room in gas reservoirs. And then there's a lot lot more room in these deep saline formations. If you just kept doing it in these oil reservoirs, you know, as you put the CO2 in you're producing more carbon. So your overall carbon reduction isn't as great as when you just put it into formations where you don't produce additional hydrocarbons. So eventually, if this is going to be used on a large scale, you have to move well beyond enhanced oil recovery.Bertie Harrison-Broninski:
And just briefly, the only thing you mentioned that I think people might not know what he meant was water flooding, what's water flooding?Howard:
It is just injection of water into the oil fields. And a lot of times when they inject CO2 they will do it along with water flooding, they'll call it water alternating gas, so they'll put some CO2 in then they'll put some water in, more CO2. And this helps move it along through the reservoir in terms of the flow, because the CO2 is less dense in the water so the water can push them along in slugs.Bertie Harrison-Broninski:
And you mentioned how enhanced oil recovery is partly popular in America because there are CO2 reservoirs. So you don't need to capture that CO2 necessarily. And I think that leads into a question I was going to ask you to talk about in terms of enhanced oil recovery is not a new process, right, that predates CCS. And am I right in saying that actually, quite a lot of the parts of the CCS process are old technologies that are not as novel as people might expect?Howard:
The core technologies. And of course, as you know, as you use it, things evolve. So it's a little different today than when first invented. But I believe enhanced oil recovery started I think the first fields of CO2 injection were back I think about 1970. So that's about 50 years ago, and it was used with the one thing in mind, let's get more oil out of the ground. And of course, we had the oil shocks of the '70s where were we thought we were going to be running out of oil, were going to really need these techniques. So that's where that came from. Capture, the chemical scrubbing process I described was originally patented in the 1930s that was used, or one of the main uses was for natural gas processing. A lot of natural gas came up with too much CO2 in it. So that had to be removed. And they they did that so it could be pipeline quality. The amount of CO2 in a natural gas reservoir will vary greatly from some with very little to others as I say there's almost pure CO2. So that was another area. In fact, some of the first CCS projects were taking that CO2 which was captured from natural gas and putting it back down into the Earth. The first one they did, that was Sleipner in 1996, started up in 1996, still running today in the North Sea off of Norway. Last there is in terms of pipelines. With the advent of CO2 enhanced oil recovery, a pipeline network grew up and I think today we have about 5000 miles of CO2 pipeline here in the US. So the cores of those technologies were here. But like the capture technology today, it was originally invented, used on natural gas, there was very limited oxygen in natural gas, the technique did not work well. So it's been adapted. And today can handle flue gas streams out of power plants which contain oxygen, you know, some excess oxygen in there, because they added things like inhibitors to stop the oxygen from degrading the solutions. So as I say, things are moving on and becoming more energy efficient in the process, and as they say, technology doesn't stop, but it will keep growing and changing. It changes the quickest when there's a market for it. So R&D is important understand the basics, but what really generates I think innovation is the marketplace in the needs of the marketplace and how you adapt the technology to that.Bertie Harrison-Broninski:
You mentioned Sleipner and I wanted to bring that up, because from what I've read, it seems like quite an unusual example in terms of A) just how long it's been running, since 97, and B) in terms of how successful it's been. It hasn't had that many hiccups. I read a study from September last year that reviewed several 100. Pretty much all of the major CCS projects that have happened and found that 78% of them, the large ones had either been suspended or cancelled before they were meant to be. What has gone wrong with CCS to date in terms of these projects not being as successful as they should have been, and what makes Sleipner different.Howard:
There's lies, damned lies and statistics. So yeah, maybe 70% of that project list never made it. But a lot of those projects were never more than a press release from a company saying we're going to do this project. These aren't projects that were started and stopped, most of them never reached the financial decision, you know, the financial investment decision. There are a couple of projects that did get under construction and never completed. But most of the ones that got a financial decision, were completed and were successful. That's the real reason here, it's economics. So people have aspirations, they want to reduce the CO2 emissions, let's look at this project. And then they look at the real world and said, there's no economics, I can put it in the atmosphere for free. Why am I capturing this? So you know, they just couldn't monetise it. What made Sleipner different? There has been a lot of activity in Norway. One is the government there was very supportive, and they put a lot of money behind these projects to do it. It's a little complicated. Sometimes people talk about a carbon tax in the North Sea, and that was contributed to Sleipner but my talks with the Norwegians was the government wanted this done, and therefore it was going to get done. I think the government at that time was a major stockholder in Statoil, their economics were a little different than say, economics in other places. So where we've seen projects succeed, or where there's been government programs to help subsidise or now they move to tax credits with what's called the 45Q tax credits. So that's what's going to drive it but we really even today, do not have the type of markets needed for large scale deployment of carbon capture and storage. So I'll turn your question around and say it's pretty amazing 22% of those projects made it given the circumstances that, you know, we're under in terms of policy. So I think if we have the policy, you'll see projects come online and be successful.Bertie Harrison-Broninski:
Yeah, it's funny, isn't it? Because on one hand, you have the kind of IPCC integrated assessment models including a lot of CCS, particularly around negative emissions, because they find them more economically feasible than nature based solutions a lot of the time. So in theory, they should be economically better than other alternatives. And yet, we also have people saying CCS hasn't worked because of economics. So I mean, I don't know if you feel like you've already answered that. But well, how do we kind of bridge thatHoward:
I think there's no argument that capturing CO2 out gap? of a power plant exhaust to 10% is going to be a lot cheaper the capturing out of the atmosphere at 0.04%. Why all the interest in things like direct air capture? A number of reasons. One, I work with modelers at MIT, and I know a lot of the other modeling groups out there, you know, when you have to hit a 1.5C target or 2C target, you know, we're at the point, now we're so far along, we're going to need negative emissions to get there in any practical sense. And so the models use them and it fills up, you know, if the models say I've got to hit this target, it's going to put in technologies, no matter how much they cost to meet that target. That's part of what's happening. I also think there's a naive view of how much direct air capture is going to cost. You read the literature, there's a lot of hope in the one to $300 range, I've done some analysis, and my best guess, is $600 to $1,000 per tonne of CO2 by 2030. And I may be biased, because, you know, there's a bias to go along with the crowd. So you know, I'm way out there. And, you know, I think my, if I look at my $600 to $1,000 range, I still think that may be still optimistic. But that's, that's where I'm at today. And I you know, as I say, I've written about it on why this is so expensive, because it takes a lot of energy to take it out of the air, and you have to process a lot of air to do it. Because there's so little CO2 in the air, if you want to get a ton of CO2, you've got a lot of air to process, and that takes big machines, and big fans and lots of energy. And you can't get around that.Bertie Harrison-Broninski:
Another thing I was interested to ask you about that I think people have a very vague understanding of including myself, but not in detail is about CCUS, which is carbon capture, utilisation and storage. So instead of maybe injecting underground using that carbon dioxide for something else, I was interested to ask you what forms of CCUS you think are good in climate terms, or which ones are less so and which ones maybe are more feasible and which ones are less so because I know there are a lot of options for what you can do with that carbon dioxide.Howard:
Well, I mean, that's it's only natural that people says, Well, why should I stick the CO2 way underground? Why can't I find a use for it? And there's a number of significant challenges in using CO2, the market for CO2 itself is fairly limited. We're maybe talking 10s of millions of tonnes per year here in the US, compared to 6 billion tons of CO2 being produced, you know, out of our smokestacks and other places. So that's a big disconnect there. And most of the uses, the CO2 end up in the atmosphere anyways. If you want to look at new uses, like turning CO2 into fuels, the problem there is CO2 is spent fuel, so I burned fuel to get CO2. To turn it back into fuel, I had to put all that energy back in. Not only do I have to put all that energy back in, I have to put maybe 50% even 50% over that, because I have losses and conversion. Unless you have really cheap, carbon free energy to do the conversion, it's going to make no sense whatsoever to do that. But people they're talking about all sorts of fuels you can make with direct air capture, get the CO2 react it with green hydrogen and make fuels. Well, green hydrogen is probably the most expensive form of hydrogen we have today, CO2 from there is the most expensive form of CO2 we have today. And then you add more money to that by conversion process. People are complaining about gas prices today. They haven't seen anything yet. You got to be a little realistic.Bertie Harrison-Broninski:
I don't think we talked much at the beginning about some of the other forms of storage like mineralisation or mineral carbonation is something people often talk about as well. And I know people are talking about like injecting biofuels and all sorts of other types of storage now too. Do you think is geologic formation just the way to go?Howard:
I think geologic formation's the way to go today and I think if we can expand the types of formations it would be even better. There's there's quite a lot of space in there. Probably, you know, space for a couple of hundred years of the world's CO2 emissions at this point. But they're not totally accessible from everybody. And that's one of the problems. I mean, they're spread around the lot, but not everywhere. And so that becomes an issue. Mineralisation has been looked at, it's a really nice way to do it. The CO2 turns into a rock, basically, it's about one those stablest forms you can do it. And then nature does this. But nature takes hundreds of thousands of years to turn CO2 into rock, so we need to speed it up. And in trying to speed it up, it costs money, you have a lot of rock to mine. And therefore it's very hard. The Department of Energy had a program back in the 1990s on this. And they concluded that what they call ex situ, which is doing it out of the mine, and everything is going to be very difficult, but they saw ways that may be in situ, you could do it. One thing, there's a project in Iceland called Carbfix, where they're injecting CO2 into a volcanic rocks, and it's reacting within two years. And so that concept looks promising how widespread we can make that we don't know and how it will cost be versus other things is still not clear.Bertie Harrison-Broninski:
Some researchers and campaigners have always warned that CCS could disincentivise companies from reducing emissions, if they have the option of capturing them or offsetting them using technology. What would you say to that kind of concern and what policy type solutions could be put in place to prevent that happening?Howard:
So I'd like to make a distinction between carbon capture what we call CCS, carbon capture and storage. And on the offsets, a lot of people call it CDR, carbon dioxide removal. And I see carbon capture and storage, the same way I see energy efficiency, I see renewables, I see nuclear, it reduces the amount of CO2 we put into the atmosphere. And if I can do it of all of those ways, the cheapest way to do it is what we should do. It's a challenge to do it, we want to do it in the most cost effective way. And the more options we have, the better. And there's plenty of room for all the other options. CCS you know, there's no silver bullet, nothing's gonna dominate the scene. So you know, I think that argument for CCS is totally off base. For carbon dioxide removal? Fundamentally, that's not an issue. But the way it starts getting applied is that that you're right, people will not look at their own operations or they will say, we're going to offset everything. And everybody wants to offset and there's not enough offsets to go around. And I think it also gives this unrealistic exuberance toward how cheap this may become, I think, in reality not there. But carbon dioxide removal has a really important position. So even if it costs, say $500 per ton of CO2, maybe 10, or 20% of our CO2 sources or greenhouse gas sources may cost a lot more than that. So if those are going to cost more, once again, that's the most cost effective. To decarbonise our electricity system, we probably get 95% of the way there or maybe 98% of the way there without offsets. Let's do that. If the last 2% need offsets, okay. You know, and we look at that in other industries. So I think there's a way to look at it. It's a big world out there, people will spin things their ways, a lot of money coming from the tech companies these days, the tech companies say I want to be carbon neutral, not just today or in the future. But since my past, this is one way I can say that. And you know, so if they spend say $1,000 a ton on capturing CO2 from the atmosphere, you know, and buy those negative emissions, if they took that $1,000 a tonne, and started a program for insulating houses for low income people, they can do A) a lot more CO2 for the same price and B) do a real social good. But of course, this doesn't sound so sexy on their website that I'm carbon neutral since birth. So you know, it's their money, you can't control it. But that's why you see the greenwashing type of things come out and another reason of the greenwashing is, if you don't do the carbon accounting right, you can really take a lot of credit for a lot more carbon offsets than you've really done because you got to do a real cradle to grave on that. So there is danger. Carbon dioxide removal is a good idea. It's how people apply it so any good idea can be misapplied, and that's what we got to be vigilant about.Bertie Harrison-Broninski:
My thanks to Howard Herzog for coming on the show. If you'd like to learn more about CCS, we've recently published my series of long reads on the topic that go into everything from what CCS is and how it works to what facilities are planned what our already operational, CCS's place in the modeling, and why we've come to rely on it so much, to the issues that we're going to have rolling it out at scale. I'll link it below or you can find the articles and many others at www.elc-insight.org. If you enjoyed this episode and would like to listen to future ones, please follow or subscribe on your favorite podcast platform. And we'll be back soon with more interesting interviews with climate experts. Thanks for listening.