Will Carbon Capture Make Local Air Pollution Worse?, with Andrew Waxman

Notable Quotes

• Potential benefits of carbon capture, utilization, and storage for achieving climate goals: “It’s possible to get to net zero without carbon capture, but it’s likely to be very expensive. It may take us a little bit longer to get there—and how much is subject to some debate—but that’s one of the challenges. The International Energy Agency in a 2020 report said that reaching net zero will be virtually impossible without CCUS.” (8:44)
• Carbon-capture impact varies depending on the facility type: “If you were just looking for the one that you could capture the most carbon dioxide from facility by facility, coal facilities are great from that perspective ... If you do the same exercise on a natural gas plant, the challenge is that the emissions—the air pollutants that come off of a natural gas plant—are actually cleaner. The net reduction in pollutants is substantially smaller than the coal plant. One of the things that happens is that the post-combustion technology that you use to capture that carbon dioxide [from natural gas] … emits a small but meaningful amount of ammonia that actually has meaningful air-pollution impacts.” (17:58)
• Health impacts of carbon-capture technology vary depending on demographics: “We find disproportionate impacts on Hispanic and African American communities. Some of that is about location … The pre-existence of the baseline impacts of particulate matter on human health [also] can be larger for some of these groups.” (23:38)

Top of the Stack

• “What Are the Likely Air-Pollution Impacts of Carbon Capture and Storage?” by Andrew Waxman, HR Huber-Rodriquez, and Sheila M. Olmstead
• Special Report on Carbon Capture Utilisation and Storage: CCUS in Clean Energy Transitions from the International Energy Agency
• City Limits: Infrastructure, Inequality, and the Future of America’s Highways by Megan Kimble

The Full Transcript

Daniel Raimi: Hello, and welcome to Resources Radio, a weekly podcast from Resources for the Future. I'm your host, Daniel Raimi. Today, we talk with Andrew Waxman, an assistant professor at the Lyndon B. Johnson School of Public Affairs at the University of Texas at Austin.

Along with colleagues, Andrew recently published a working paper that's been accepted at the Journal of the Association of Environmental and Resource Economists called, “What Are the Likely Air-Pollution Impacts of Carbon Capture and Storage?” It's a really timely and important piece of work.

For years, many environmental justice advocates have argued that deploying carbon capture and storage, or CCS, will exacerbate the pollution that already overburdens many communities of color. This analysis addressed that question head on by looking at the local air-pollution effects of applying carbon capture and storage to coal plants, natural gas plants, and industrial facilities along the US Gulf Coast. What did the authors conclude? To find out, stay with us.

Andrew Waxman from the Lyndon B. Johnson School at the University of Texas at Austin, welcome to Resources Radio.

Andrew Waxman: Thanks so much for having me.

Daniel Raimi: Andrew, we're going to talk today about a really fascinating paper that you've coauthored with a couple of excellent colleagues. The name of the paper, which we'll have a link to in the show notes, is “What Are the Likely Air-Pollution Impacts of Carbon Capture and Storage?” That's what we're going to talk about today. Before we dig into the details, we always ask our guests how they got interested in working on environmental issues—whether it started at a young age through some childhood inspiration, or whether you got interested in this stuff later in life.

Andrew Waxman: I grew up in the Washington, DC, area, and I was fortunate enough to have an outdoor education program in my school. I got to go to the Potomac River right in the heart of DC every day and went on trips, rock climbing and hiking in West Virginia and western Maryland. Through that, I became aware of environmental stewardship through groups like the Potomac Conservancy, which advocates for environmental issues related to that watershed, and I was a raft guide at the Potomac. I think that, combined with my academic interest, created a question about how to think about the environment and climate change as a career.

Daniel Raimi: That's cool. I'm not a DC native or a DC resident. Is rafting on the Potomac a thing? Do people do that a lot?

Andrew Waxman: It's not as big of a thing as other places, but you can hire a guided raft trip down the Potomac, and it's relatively chill and beautiful. The DC area is one of the most biodiverse urban ecosystems in the United States, and most people don't know that about it. It's a fantastic place for all types of outdoor recreation and nature watching.

Daniel Raimi: Wow, that's great. Super cool. Let's dive into the meat of our conversation now, which is about carbon capture, utilization, and storage, which we will call “CCUS” during this conversation. I’m sure most of our listeners have heard of carbon capture, utilization, and storage. They know that it's designed to capture carbon dioxide, but it's not designed to capture other types of pollution. I'm just hoping you can get us started with a thumbnail sketch of what carbon capture, utilization, and storage is, and then also, given the nature of our conversation, can you give us a sense of what is the physical process that happens when carbon dioxide is captured from a smokestack?

Andrew Waxman: Yes, so CCUS—carbon capture, utilization, and storage (sometimes they drop the u and call it “CCS”)—is an umbrella term for a variety of technologies to engage in net-zero or negative-emissions approaches, which the goal of is to reduce greenhouse gas emissions—specifically, carbon dioxide.

There's a lot of things that fall into this. This may include things like direct air capture, where you have a system that's going to pull carbon dioxide directly from the atmosphere, or something called bioenergy with carbon capture and storage, where you're producing some sort of a biofuel. You're going to use that to produce electricity, and you capture the carbon that's produced from that or utilization processes—like green cement—where you're going to produce cement and capture some carbon dioxide that's bonded into that material, or enhanced oil recovery, where you use carbon dioxide to recover oil or gas materials. With any of these, there's a bit of chemical engineering involved.

The basic idea is that you have carbon dioxide; you have a gas that's in a mixture of some sort. If we have a coal or natural gas–fired power plant, there's a flue gas that comes out of the turbine or whatever is combusting those materials. You want to convert that mixed flue gas, which has lots of things in it, including pollutants that harm human health. You want to remove the carbon dioxide gas and produce a pure stream of carbon dioxide.

In the work in this paper, we're focusing on the subset of carbon capture, utilization, and storage that captures carbon dioxide directly from a smokestack—like from a power plant or an industrial combustion source. Some of this is just a research question, but from a kind of climate-policy perspective, that type of technology is going to be more efficient—it's going to use less electricity and energy to remove carbon dioxide, because it's a pure stream.

There's more carbon dioxide in that gas. Depending upon the fuel source and the plant, it could be somewhere between 3 and 14 percent of the gas in there, whereas if it's the atmosphere, it's typically less than half a percent of the volume from air is carbon dioxide. So, it's going to require a lot more electricity or energy to get the carbon dioxide away.

And again, for just kind of a thumbnail sketch, there's a number of ways of doing this capture on a power plant or an industrial facility. You can do what's called pre-combustion, where you have a fuel source like coal and you remove the carbon before you burn anything, and then you get basically a carbon-free fuel. There's also something called oxy-fuel, where you burn fossil fuels in pure oxygen, which produces a high carbon dioxide—a high-purity carbon dioxide stream.

And then what we are principally focused on and what's the most common technology, and I'll qualify that through our discussion probably is post-combustion—where it's the most obvious—you're burning something, there's gas coming off that's got lots of stuff mixed in it, and then you're going to separate that gas into carbon dioxide and other stuff. That technology has been around for decades. It's been used in a number of industrial processes. The large part of what we're studying is how that's applied, although some pre-combustion technologies are used for things like ammonia production, fertilizer production, or hydrogen production. Maybe we'll talk about that a little bit, as well.

Daniel Raimi: Great. To give people a sense of how important this question is, I think it might be useful for us, before we talk about your study and your results, to just get a sense of the scale that CCUS could grow to in the future. If you look at pretty much every US or global energy-system model that shows us getting to net zero by anywhere around midcentury, they all have a very substantial role for carbon capture, utilization, and storage technologies. Can you talk about that a little bit?

Andrew Waxman: Yeah. To say the obvious, it's difficult to predict the future. There are many scenarios, and there's a lot of debate about which ones are most likely to happen, as well as which ones are most desirable from whatever your perspective is—whether it's economic efficiency, or getting to net zero as quickly as possible, or equity. As you said, most conventional net-zero plans for midcentury—so, by 2050 (this includes the Intergovernmental Panel on Climate Change, the UN advisory committee on this, or the International Energy Agency, or even Biden's climate plan)—they're advocating for some proportion of carbon capture to be used. The reason for that is it's possible to get to net zero without carbon capture, but it's likely to be very expensive. It may take us a little bit longer to get there—and how much is subject to some debate—but that's one of the challenges.

The International Energy Agency in a 2020 report said that reaching net zero will be virtually impossible without CCUS, to give you a sense of that perspective. Now, as I mentioned earlier, it depends upon what we mean there, and we're also thinking about how much CCUS we will see. It will make getting to some of these targets easier, if we're able to engage in negative-emissions technology—like direct air capture, where we're sucking carbon dioxide out of the atmosphere. The challenge is, as I mentioned earlier, that's hard, because it's relatively diffuse in the atmosphere, so it's expensive to do. If you want to remove carbon dioxide using renewable energy, which would be the most sensible way to do it, if your goal was to reduce emissions, it's somewhere on the order of $600 to $1,000 per ton, although there's some evidence that some groups are able to do it quite a bit more cheaply. There's some question about how that can happen. That's direct air capture.

It's also likely that a small percentage of the electricity grid will be produced through fossil fuels with carbon capture, but less than 12 percent and potentially quite a large proportion smaller than that—more in the single digits by 2050. Currently, there's one large-scale coal power plant in Texas that has done carbon capture at scale. That's the Petra Nova facility in Texas. It was shut down, and this has been one of the challenges. It was not economically viable, but now it is being brought back online.

And then, the last part of this is classically difficult-to-decarbonize sectors, which are a variety of things that we use that are produced through an industry. The obvious ones here are cement, metals like iron and steel, and chemicals, which use a lot of fossil fuels—and typically natural gas—to produce those things.

There's not a technology where we can electrify them so that they're being used. We're using solar power or wind to produce those things in the future. There are other alternatives. One is, for example, using hydrogen gas, and we can potentially talk about hydrogen and carbon capture, which in some sense go hand in hand, but otherwise, you would need to burn a fossil fuel to produce those things and then capture it and store it underground. For industrial uses … if you look at the US Environmental Protection Agency’s numbers for the United States, industry is a little under one-quarter of US emissions. If you think about the stuff that's happening, electric power has been pretty meaningfully reducing its share of greenhouse gas emissions over time. Transportation—that's probably another podcast about how that's going.

Daniel Raimi: Yes.

Andrew Waxman: But industry has been relatively flat. Part of the challenge is that these are really hard emissions to abate.

Daniel Raimi: Right. We actually did a podcast on industrial-sector emissions mitigation strategies with Jeff Rissman about two months ago.

Let's get into the analysis that you did again with your coauthors, who are HR Huber-Rodriguez and Sheila Olmstead, both from University of Texas at Austin. Although Sheila's moved now—Sheila's at Cornell, is that right?

Andrew Waxman: She will be starting this fall at Cornell. We were very sad to see her go, although Cornell is my alma mater, so she's going to a good place. HR is a recent graduate student from University of Texas, who is going to be—I'm expecting big things—an environmental lawyer.

Daniel Raimi: That's cool. Very cool. Can you describe, again, in a basic way for our listeners, how you and those two coauthors tried to figure out how applying carbon capture and storage to different types of energy or industrial facilities might affect not necessarily just the carbon dioxide emissions, but also local air pollution, which in turn can affect people's health living at or around the plant?

Andrew Waxman: Yes, so when we say air pollution and in the United States, from a legal perspective, we're thinking about the Clean Air Act as the main federal piece of legislation that regulates that. There's two sets of things: one we've been talking about so far is greenhouse gas emissions, which are linked to climate change; the other thing that has a huge impact on human health is local air pollutants. These are things like nitrogen oxides, sulfur dioxide, and ozone.

One of the things we focus on in this paper, which is fine particulate matter—particulate matter 2.5 microns or smaller, and in particular, PM2.5, which is this fine particulate. It has been shown through epidemiological literature, economics, and public health to have the largest human health impacts—those are principally in terms of respiratory and cardiovascular health and particularly on the very young, the very old and those who have respiratory health challenges, and it interacts and leads to respiratory illness in a variety of ways.

There's also been other health challenges like cognitive decline and dementia that have been linked through studies. I'm not an expert on the medical aspect of that. From an economic perspective, when you're thinking about damages from air pollution, these are pretty large. Depending upon the calculation and where we're talking about this happening, they can be comparable to the effects on climate change from the corresponding greenhouse gas emissions that are coming out, as well.

In terms of this study, we were interested in contributing to a broader literature, which is interested in what are called climate cobenefits, or as we document that they're also codamages, which is, essentially … You're interested in a climate policy that's going to reduce greenhouse gas emissions, but there are implications of that policy for other pollutants, other air pollution. In the simplest way, if you shut down a coal power plant and replace it with the equivalent amount of power from, say, a wind farm or an array of solar power cells, which is just a thought experiment, doings that will not only reduce the carbon dioxide emissions from that plant, but also the local air-pollution effects.

So, the human health impacts need to be calculated and considered through part of that process. In our study, what we were trying to do is link a literature that has been looking at low-carbon pathways that include CCUS to this literature about climate cobenefits and get a sense through a thought experiment from what economics call a counterfactual. So, we’re trying to think about what the world would look like under a particular policy scenario. It's a little bit of hypothetical what we're doing here, because what we essentially ask is—if you take within the Gulf region, this set of industrial facilities for which it's possible to do carbon capture in a reasonably economic way, as well as fossil fuel plants, and you just wave a wand and convert them to carbon capture, what would we expect the local air-pollution effects to be, compared to the greenhouse gas–reduction effects? That waving a magic wand is a little bit of the devil in the details in terms of it.

Daniel Raimi: Waving that magic wand is actually extremely data- and time-intensive if you go through the details of the study. We'll let listeners dig into the details themselves with, of course, the paper being linked in the show notes. Let's just jump to the headline conclusions. What are some of your key results?

Andrew Waxman: What we showed, which was in a sense, to some extent, what we had been expecting, is that results are a little bit ambiguous depending upon what the facility you're converting is. Let's take the facility I was describing earlier. You have a coal-fired power plant. Coal is a very polluting fossil fuel. It is also, it turns out, is very energy-intensive and carbon dioxide–intensive. If you were just looking for the one that you could capture the most carbon dioxide from facility by facility, coal facilities are great from that perspective.

Environmental advocates, for a lot of great reasons, and also economists, don't love coal, because it has this history—it has not just environmental implications at the combustion point, but also for mining. It turns out, by doing carbon capture on coal, you have to deal with a lot of the pollutants that affect human health on the front end and a particular one called sulfur dioxide, which, through all the magic wand that we do in the paper, results in a whole lot of particulate matter.

By getting rid of that, you actually substantially reduce the human health impacts of coal. It looks like, on paper, that magic-wand waving, you get a big benefit in terms of, you reduce a bunch of carbon dioxide, you reduce a bunch of human health impacts, and that's great.

If you do the same exercise on a natural gas plant, the challenge is that the emissions—the air pollutants that come off of a natural gas plant—are actually cleaner. The net reduction in pollutants is substantially smaller than the coal plant. One of the things that happens is that the post-combustion technology that you use to capture that carbon dioxide, which is used for most conventional plants and essentially all conventional plants, uses a nitrogen-based solvent to absorb that carbon dioxide out of the flue gas. It emits a small but meaningful amount of ammonia that actually has meaningful air-pollution impacts.

It increases secondary particulate matter, and particularly if you have human populations that are close enough nearby, which you do in the Gulf area for a number of these plants, you can actually get net damages and net deaths, and mortality increases as a result of conversion. So, it produces this kind of mixed result. Doing it on coal reduces the human health impacts, and doing it on natural gas increases the human health impacts. For industrial facilities, for most of the facilities, it's the same as natural gas. It increases the impacts.

We have a lot of caveats associated with that. One thing just to say is that these human health impacts on net are smaller than, say, the total impacts you get from just coal right now, so they're important from a policy perspective. From a broader perspective, there's a larger set of air pollution–regulation concerns, if you're interested in power plants. This is particularly useful when thinking about the impacts of federal policies that incentivize carbon capture. It's going to have these mixed effects, where coal gets, from a local air-pollution perspective, cleaner; natural gas gets a little bit dirtier; and most industrial facilities get a little bit dirtier.

Daniel Raimi: Yeah, that's interesting. Is the industrial facility result in part because a lot of these industrial facilities are primarily burning natural gas to do whatever industrial process they're doing?

Andrew Waxman: Yes. One of the things, just sort of as context for that—we're focusing here on facilities that are in the US Gulf Coast region, so principally in Texas and Louisiana, which is this supercluster of industry, particularly for petrochemicals, but also for refining and gas separation and a bunch of other stuff. Part of the reason that these are located here is they're also located close to natural gas wells, so it's efficient to bring that energy source to them. A lot of these facilities are burning natural gas, and it's concentrating the pollutants in the areas nearby. These areas, the populations who have lived in proximity to these or downwind of them, have been areas which have documented higher local air pollution over time for a long time, as well.

Daniel Raimi: Right. That's exactly what I was just about to ask you about, which is, some parts of the Gulf Coast are epicenters of environmental justice problems due to the clustering of many of these facilities and the variety of emissions that come from them. As you mentioned earlier, a lot of environmental justice advocates have generally opposed CCUS technologies, because they are concerned that it's going to perpetuate this disproportionate exposure. What do your results say to that argument? Does it kind of confirm it? How would you characterize it?

Andrew Waxman: Basically, it confirms it. That’s the short answer. Through our analysis, we're able to track, based upon where people live, what we would expect the differential mortality impacts would be across a very general slice of different demographic groups. We can think about demographics for African Americans, for Hispanic Americans, for white Americans, for Asian and Pacific Islander Americans, and for Native Americans living in this area. We find disproportionate impacts on Hispanic and African American communities. Some of that is about location. Some of that is about … The pre-existence of the baseline impacts of particulate matter on human health can be larger for some of these groups.

It echoes what has been found elsewhere in that literature you're referring to. One thing I will just say: We're only looking at one pollutant, really—this fine particulate matter. There are potentially other pollutants for which environmental justice concerns are relevant, and other work has pointed to that. Particularly for chemical facilities, you get these occasional hazardous releases that can be because of an accident or some other reason. And there, you get, on an isolated basis, quite concerning releases that environmental scientists and health people have pointed to for a while as having disproportionate impact. There are a variety of concerns, some of which we document in the paper here.

Daniel Raimi: Right. To be clear, carbon capture is not designed to handle those types of emissions.

Andrew Waxman: Exactly. In terms of the technologies and regulations to address it, that's, again, another conversation, but an important one for thinking about a disparate impact.

Daniel Raimi: Yeah, for sure. Listeners are probably thinking about some of the policy implications of what you're describing here, but I'm curious—what are some of the big ones that come into your mind? When I was reading the paper, one of the questions that I had was whether there are other types of carbon-capture technologies that could avoid these ammonia emissions that you're describing, or that could reduce some of the other potential negative impacts of deploying carbon capture. What are some of the key policy options that come to your mind?

Andrew Waxman: Yeah, one thing just to say is that there are pollution-abatement technologies available that can deal with a lot of the pollution we're talking about, even for the ammonia pollution. It's possible to run the gas through a felt filter and through water washes that remove a large proportion of the ammonia. There's work from researchers here at University of Texas and elsewhere that has shown how it's possible to bring ammonia levels down to a level that—I'm not qualified to give a definitive answer—but could substantially bring them down to a point at which they may be much less of a concern.

I think the challenge from our perspective is that, in this way, ammonia is not a criteria pollutant as far as the federal government is concerned in terms of the Clean Air Act, which I mentioned earlier. And so, unlike other pollutants like nitrous oxides, particulate matter, and sulfur dioxide, which are criteria pollutants, they traditionally haven't been regulated.

There's kind of a standard of best emissions reduction that the US Environmental Protection Agency tries to encourage or enforce on power plants and other facilities to get them to use these types of technologies. It would be great going forward, if carbon capture is a sizable chunk of our strategy to address carbon reduction, that we also think about ammonia. I think that's the big take-home policy thing.

The other thing I'll just mention, and we can get into it as needed, is that the federal government subsidizes carbon capture, utilization, and storage pretty significantly. These were ratcheted up under the Inflation Reduction Act from President Biden's administration from 2022. For the type of facilities we're talking about, these can be as large as $85 per ton of carbon dioxide. If we're subsidizing this technology so substantially, I think we need to meaningfully also think about addressing potential human health impacts that they could result in.

Daniel Raimi: Yeah, for sure. I think there are a million other questions and policy issues that we could talk about on this topic, but we're running close to the end of our time.

I want to ask you the same question that we ask all of our guests who come on the show, which is to recommend something that you've read, watched, or heard that you think is really great and that our listeners might enjoy. So, Andrew, what's at the top of your literal or your metaphorical reading stack?

Andrew Waxman: At the top of my literal reading stack is a book. My other hat when I'm not doing carbon capture is thinking about the transportation system. There's a book that came out recently from a Texas-based journalist, Megan Kimble, called City Limits: Infrastructure, Inequality, and the Future of America's Highways, which is thinking about why urban infrastructure and transportation systems are designed the way they are, the historical factors at play, the legal factors in play, and the disproportional health impacts of stuff that we've been talking about. It's been sometimes a tough book to read in terms of realizing how much work there is to do, but it’s a great insight into those issues.

Daniel Raimi: Yeah, that sounds fascinating. We'll have a link to it in the show notes so people can check it out. And of course, we'll have a link, as I mentioned, to your paper with HR and Sheila in the show notes, as well, so people can dig into the richness. It really is just a fascinating paper with all sorts of great details laid out, both in the main body and the appendix. I hope people will check it out.

In the meantime, I just want to say thank you, Andrew, for joining us today on Resources Radio. It's been a really fascinating conversation.

Andrew Waxman: Thanks, Daniel. I appreciate it.

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