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How to build a circular economy that recycles carbon

The right way to think about and support carbon capture and utilization.

Concrete being poured onto a rebar grid.
Better with CO2?

This is part four of a four-part series on carbon capture and utilization (CCU), the growing industry dedicated to using carbon dioxide captured from the atmosphere to fight climate change. Part one introduces CCU and its basic forms; part two is about enhanced oil recovery, the largest use of CO2; and part three is about six other industrial uses and their potential.

Right now, humans play a simple role in the Earth’s carbon cycle: We dig carbon out of the ground and put it into the atmosphere, where it accelerates global warming. More specifically, we dig up hydrocarbons, break their bonds to release the stored energy, and then dump the carbon into the air in the form of carbon dioxide, methane, and other greenhouse gases.

To stabilize the planet’s temperature, humanity needs to close that loop, to reach a point where it is taking as much carbon out of the atmosphere as it is adding. That’s what “net-zero carbon emissions” — the global target for 2050, derived from the work of the IPCC — means.

After that, because we have been so slow to reduce emissions, we will likely need to go “carbon negative” for a while, extracting more than we emit. (We are, of course, taking an enormous gamble in assuming large-scale negative emissions are practicable.)

A chart showing carbon neutral and carbon negative scenarios.
Note: Emissions go negative around mid-century.

The main work of closing the carbon loop will involve radically reducing emissions by finding substitutes, ways of powering our devices and manufacturing our products that don’t rely on hydrocarbons and thus don’t emit CO2. Another part of the work will be pulling CO2 out of the air and burying it in geologic reservoirs, so-called carbon capture and sequestration (CCS).

A third idea, which has recently become the subject of intense interest for climate wonks and policymakers, doesn’t quite fit either category, but it overlaps with both. It involves pulling CO2 out of the air and then using it in place of hydrocarbons in energy and industrial processes, effectively recycling it. Rather than finding substitutes for carbon-based processes, it finds a substitute for the carbon used in them — carbon from the air rather than carbon from the ground. It is a small step toward closing the carbon loop.

It is known as carbon capture and utilization (CCU), and depending on who you believe, it either points the way to a new era of carbon abundance or amounts to an expensive distraction.

I explored the various forms and applications of CCU in previous posts in this series. In this fourth and final post, I’ll take a step back and ponder how we ought to think about CCU in the context of the larger climate effort, both in terms of its mitigation potential and in terms of the politics around it. With that in mind, I’ll lay out some policies that experts believe could help get CCU industries off the ground.

How much can CCU help with climate change?

There are plenty of CCU skeptics who think it is largely a distraction.

In this 2017 paper in Nature Climate Change, scholars at Imperial College London tally up the total amount of CO2 that needs to be reduced by 2050 (relative to a business-as-usual scenario) to stay on a trajectory below 2 degrees Celsius of global average temperature rise, the common UN target. The total “mitigation challenge” is roughly 800 gigatons of CO2.

Most models used by the IPCC show CCS accounting for approximately 14 to 20 percent of that challenge. How about CCU? The researchers conclude that, outside of enhanced oil recovery (EOR), other CCU technologies can permanently sequester only 3.86 gigatons of CO2 by 2050 — roughly 0.49 percent of the 800 gigaton mitigation challenge.

A chart showing CCU in carbon context. Nature Climate Change

That’s ... not much. (Their exact estimate could be contested — they might underestimate the growth of CCU concrete, which is close to permanent sequestration — but it’s probably in the right ballpark.)

The researchers conclude that CCU should not be treated as a form of carbon sequestration. Geological storage is likely the only way to bury and sequester the massive amounts of CO2 that will need to be buried and sequestered by 2050. CCU can’t substitute for that; it is a marginal contributor to sequestration at best.

However, as they acknowledge, sequestration isn’t the only way to contribute to the mitigation challenge. CCU might not sequester much carbon, but it can reduce the use of hydrocarbons and thus reduce emissions.

Take synthetic fuels, which are made from captured CO2 and hydrogen (ideally green hydrogen, made from sunlight and water). It is true that captured CO2 is released back into the atmosphere when the fuels are burned. The fuels are not carbon-negative; no carbon is permanently sequestered.

But they are carbon-neutral, introducing no additional CO2 to the atmosphere, and they are substituting for carbon-intensive fuels. They contribute to the mitigation challenge.

Fuels and building materials are not small markets. If their emissions could be reduced by the substitution of captured CO2, it seems an avenue worth pursuing. And there are other forms of CCU, like carbon fibers as strong as steel, that could crack into other large markets if their costs fell enough.

Here are some fairly optimistic projections for both market size and climate mitigation. The graphic is from a recent report by the Center for Climate and Energy Solution (C2ES), but the numbers are drawn from a 2016 roadmap for CCU industries by the Global CO2 Initiative.

A chart showing CCU potential. C2ES

As you can see, the biggest mitigation potential lies in building materials (concrete and aggregates) and fuels (synthetic and algal).

So yes, there is potential in CCU for carbon mitigation, and it is worth exploring. But policymakers should take great care in approaching it because of two features of the politics around it.

The treacherous politics of CCU

The nascent field of CCU is unique, first in that it is policy-dependent, and second in that it is a magnet for fossil fuel fuckery. Let’s unpack those one at a time.

Some clean-energy products, like solar power or electric vehicles, have advantages over their dirty competitors completely outside of climate considerations. Solar power is cheaper than coal and rapidly catching up to natural gas. Electric cars are just better cars — they’re faster, quieter, and require less maintenance.

As costs continue falling, these products are eventually going to dominate the market, even if their climate benefits are never fully monetized. Policy can and should accelerate that shift, but on some time horizon, it is inevitable.

The same is not true of technologies that capture and/or reuse and/or sequester carbon dioxide, including EOR and other CCU tech. They are much more expensive than the alternatives, but that was once true of solar and EVs, too. What sets carbon technologies apart is that they offer no advantages over the alternatives except climate mitigation.

You wouldn’t do any of this stuff — capture CO2, reuse it, or sequester it — if it weren’t for climate change. There’d be no reason. It doesn’t get you any other advantage. It’s like cleaning up the trash. Nobody’s going to make inspiring documentaries about it, but it’s gotta be done.

(There are two exceptions. First, curing concrete with CO2 purportedly produces stronger concrete, so that advantage might be monetized. And second, EOR is profitable on its own. But still, the clean kind, using captured CO2 rather than CO2 pulled from natural reservoirs, and maximizing sequestration, is more expensive. So the larger point stands.)

West Virginia Democrat Joe Manchin is a big fan of CCS and CCU.
Getty Images

This means that most carbon technologies are, and will remain, dependent on policy. They will grow and scale to the extent policy creates incentives and markets for them to do so. Policymakers will have a much more controlling hand in these markets than in other markets, so their decisions will be uniquely important.

There’s no denying that this is a political weakness. It makes these technologies uniquely vulnerable to the ebb and flow of public opinion and policymaker interest, and increases the need for simple, durable policies that can weather political shifts.

The second danger of CCU politics is that the entire policy domain is a magnet for fossil fuel companies to wield their baleful influence.

Think of a Venn diagram. One circle is CO2 policies that benefit fossil fuel companies. One circle is CO2 policies that result in the mitigation or sequestration of CO2.

These circles do overlap somewhat. The area that they overlap basically constitutes Republican climate policy.

But despite a lot of happy talk these days, they don’t overlap completely. Fossil fuel companies want more and higher subsidies for carbon capture, with fewer and weaker monitoring and verification requirements. (See post two for an account of how they are trying to manipulate the regulations around sequestration subsidies in the US tax code.) They want to use CO2 to dig up more oil and methane, whether or not the process reduces CO2 overall. Most of all, they want to stay in business and profit. They see CCS and CCU as ways to have their carbon and eat it, too.

This raises serious political questions. Should climate hawks be supporting policies that enhance the profitability and longevity of fossil fuel companies, even if they reduce emissions? And what confidence can Americans have that their policymakers will keep the focus on carbon reductions rather than on helping favored industries?

There’s no easy answer to these questions, but at the very least they suggest that policymakers (and climate advocates) should proceed with care on CCU. It’s not worth doing for its own sake. And it’s not worth doing just to benefit some big industries. It’s only worth doing if it substantially reduces CO2 emissions.

And even that is not enough. After all, if CCU is competing in the mitigation challenge (rather than on sequestration), then it is competing against other forms of mitigation. If other forms, like electrification, prove enduringly cheaper, there’s no reason to pursue CCU. Its only value is cost-competitive mitigation, even if it takes policy support to get it there.

With that in mind, here are a few policies that could get the CCU ball rolling.

A graphic showing CO2 surrounded by a circle of arrows. Shutterstock

How policymakers can support CCU

There is a growing stack of reports on CCU, and all of them emphasize that these markets will not grow sufficiently on their own, nor with the meager support they now receive. Coordinated policy is needed at every level of government; as of now, there is virtually none.

I won’t go through all the various policy recommendations for CCU from all the various reports, much less the policy recommendations for carbon capture itself, or the policy recommendations for EOR, either of which could be a separate post. (If you want full details, the nonprofit Carbon180 has several reports on policy and innovation in the CCU space.)

We’ll just run through the top suggestions in four broad categories, which I’ve adopted from the C2ES report.

I’ll start with “market enablers,” because it contains an important set of policies that should precede most of the others. To wit: standards, standards, standards. The best way to avoid market manipulation and regulatory capture is to make sure all carbon-related industries are subject to the same transparent standards.

That means some kind of standardized lifecycle analysis (LCA), so that everyone is working with the same numbers regarding how much carbon is embedded in various products and how much is avoided by CCU. And it means clear and consistent industry standards for reporting, monitoring, and verification of carbon flows.

The other big market enabler, a common suggestion in every report or analysis, is government procurement. Federal and state governments wield enormous amounts of capital. They buy enormous amounts of fuel and build an enormous number of buildings and structures. If governments started requiring fuels and building materials to be low-carbon, they could rapidly create substantial markets for alternatives.

(Low-carbon concrete procurement policies have caught on in several places now, including Hawaii; Austin, Texas; Alberta; and New York State. The US Conference of Mayors recent signed a resolution urging its members “to prioritize utilizing post-industrial carbon dioxide mineralized concrete for use in city building and infrastructure projects.”)

The second set of policies needed by CCU industries is “financial enablers,” i.e., funding. That can either be direct subsidies for carbon sequestration and reuse, as in the 45Q tax credit in the US (C2ES has a number of suggestions for improving it), or a variety of other publicly backed financial instruments like private activity bonds and master limited partnerships. More broadly, private capital is not going to flow into this industry unless government policy draws it in, so some form of public financial backing is required.

The third is more and more targeted R&D. In part that just means substantially increasing the currently paltry amount of federal R&D money spent on CCU, ideally without stealing from other federal research. (The whole federal energy R&D budget needs to grow by 10X anyway.)

But it also means coordinating and targeting federal R&D to support products all along the path from basic research to demonstration project to viable commercial product. It makes sense to focus early stage research on longshot products with long-term potential, like carbon fiber and other materials. Other technologies, like electrolysis of hydrogen and chemical CO2 conversions, need applied research, to cut the costs of existing processes.

The costs of carbon conversions, electrolyzed hydrogen, and renewable energy must all fall for, e.g., synthetic fuels, to have a fighting chance. Targeted R&D can help accelerate that.

Important science-type research things happening.

There are bipartisan bills floating around Congress that would seek to do some of this, including the EFFECT Act (Enhancing Fossil Fuel Energy Carbon Technology), sponsored by ranking Democratic member Joe Manchin (VA) and Republican chair Lisa Murkowski (AK) of the Senate Energy and Natural Resources Committee.

Finally, CCU companies need carbon-transportation infrastructure, in the form of CO2 pipelines, and policies that encourage the clustering of CCU projects close to sources of high-quality CO2, to cut down on transportation cots.

Beyond these four broad categories are a whole host of sector-specific policy suggestions — for concrete, fuels, plastics, and more — but I will spare you the details.

Governments could implement carbon taxes, which would encourage all forms of carbon capture, utilization, and storage. A tax would have to be extremely high to get some of these CCU products over the valley of death between lab and market — more targeted, sector-specific policies would also be needed — but even a modest tax would be a universal accelerant.

A future with large-scale CO2 recycling? Maybe.

The notion that humans can create a circular carbon economy — capturing, reusing, and sequestering enough carbon to bring the atmosphere into rough balance — has seized the imaginations of a lot of people, including a lot of people in tech. There is now a Carbon X-Prize, which will offer up to $20 million in prize money to the team with the best idea for carbon utilization.

The finalists are using “artificial photosynthesis” to produce methanol and syngas, converting CO2 and methane into biodegradable plastics, locking CO2 to limestone within concrete, and all sorts of other wild things. It’s a wide-open and exciting area of innovation and it is drawing the attention of a growing, enthusiastic community of researchers and entrepreneurs.

If you want to hear a semi-utopian vision of the circular carbon economy, you can get it from the head of the X-Prize Foundation, Peter Diamandis, in this post. Among other things, he raises the prospect of CCU as the basis for a settlement on Mars, which I confess hadn’t occurred to me.

“Whether for fuel on Mars, smart city infrastructural equipment, or everyday plastic commodities, our atmosphere’s carbon reserves are free for the taking and will fundamentally transform our global energy and materials economy,” Diamandis writes. “Welcome to the age of carbon-derived abundance.”

I don’t know about all that. The atmospheric carbon reserves aren’t really “free for the taking,” they’re quite expensive to mine, and it may turn out that mining them loses out to some other, cheaper set of mitigation technologies in the long run.

But the notion of large-scale CO2 recycling, partially closing the carbon loop, does hold immense appeal, both as climate mitigation and as a challenge to human ingenuity. In what is an increasingly desperate effort to fight against climate change, it is worth a try.

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