This summer, we asked readers to send us their climate change questions. And they did. We received many, many, many climate change questions. So many, in fact, that we’re doing several different projects around them. You’ve already seen the first of our columns on Who’s Winning Climate Change? Today, we’ll dive into the mailbag for the first Climate Question from an Adult – a series that will explore the business, culture and chemistry behind your most pressing questions about global warming. Have a question? Send it to us!

Q: One of the few things that has given me hope about our ability to avoid climate disaster is reading about companies that are capturing carbon from the air and finding ways to monetize it. Are there limitations to our ability to do this? Is there a reason why this couldn’t become a rapidly expanding industry in the next decade or so? — Andrew Janet, Maryland

There are worse reasons to invest in a nascent industry than that a Nobel prize-winning body heavily implied it would be a good idea. Since at least 2005, the Intergovernmental Panel on Climate Change has been drawing attention to the benefits of “carbon capture and storage,” the technologies that allow us to suck carbon dioxide from the air and trap it where it can’t do any harm. Just last year, a special IPCC report on keeping warming below 1.5 degrees Celsius found that some kind of carbon capture technology would be essentially required to maintain any hope of hitting that goal.

That should be good news for CCS as a commercial industry. But despite that, and despite the way several other climate and energy-related industries have grown over the last decade, carbon capture and storage is still more of a gamble than a clear success story.

The problem lies in a behavioral economics problem that differentiates this industry from solar power, electric cars and other profitable tech sectors, said Gregory Nemet, professor of public affairs at the University of Wisconsin-Madison. Namely: There’s not really any reason to pay for CCS other than combating climate change. Turns out that saving the world, on its own, isn’t necessarily a good enough reason to save the world.

Carbon capture and storage works, essentially, because chemistry is nifty. There are many different ways to pull carbon dioxide out of the air or a column of factory smoke, but all methods are based on the principle that CO2 sticks to certain chemicals. So, for example, a coal-fired power plant in Saskatchewan, Canada, uses a system that you can kind of imagine as a giant bong. The plant takes the mixture of water vapor and gas left over after coal is burned and bubbles it up through a liquid that contains several chemicals related to ammonia. The CO2 clings to the liquid solution and the rest of the gases keep on rising up and out of the power plant smokestack. Heating the solution frees the CO2 molecules, which are then trapped and compressed in tanks. The liquid can be reused.

This process takes a lot of equipment. It takes energy to heat the liquid and compress the CO2, and that means the power plant has to burn more coal and produce more power than it did before. But while those facts mean carbon capture isn’t cheap, it’s also a pretty well-understood technology. The scrubbing process used at that Canadian power plant is cutting edge, in terms of reducing CO2 emissions, but it’s old tech. The fossil fuel industry has been using the same process since the 1930s to improve the quality of natural gas. The main difference between the older process and the modern application is that the captured CO2 t is meant to be squirreled away indefinitely, where it can’t ever reach the atmosphere.

Today, there are 19 large-scale commercial carbon capture and sequestration facilities operating around the world, 10 of which are in the United States, according to the Global CCS Institute. All of them are pulling carbon dioxide out of the emissions from an associated factory or power plant. Systems that pull CO2 out of the ambient air, like the ones Andrew referenced in his question, do exist. They’re just harder and more expensive to operate because the concentration of CO2 in the air is so much lower, Nemet said. “At a power plant, 10 to 20 percent of what goes up the smokestack is CO2, compared to .04 percent in the air,” he said.

So generally speaking, the technology of carbon capture is ready to go. The problem with CCS is that it doesn’t really have a destination, said Dan Lashof, U.S. director of the nonprofit World Resources Institute.

Other climate-adjacent industries, such as electric vehicles and solar photovoltaics, have grown rapidly in the past decade. But Lashof pointed out the other industries offer benefits outside of their climate impact. “Solar is generating electricity you can sell. Electric cars are really fun and fast and you don’t have to go to the gas station. There’s a market for that independent of climate benefits,” he said.

In a world where trapped carbon emissions are essentially worthless, there’s not much reason for companies to invest in a technology that does nothing but reduce carbon emissions, experts told me. Wind, solar and electric cars were all able to start small and build on niche demand. But CCS hasn’t really been able to do either of those things, said Howard Herzog, senior research engineer at the MIT Energy Initiative.

This in part explains why CCS boosters have so much enthusiasm for the idea of finding ways to monetize captured CO2. It’s not just about winning at business. Barring the miraculous passage of a carbon tax, it might also be about the only way to get crucial climate tech off the ground.

There have been some successes. In Switzerland, for example, a company called Climeworks is sucking CO2 directly out of the air and selling it to soda companies and agricultural interests. “They pump it into greenhouses to increase the yield on tomatoes,” Nemet said. But even those applications have to compete with naturally occurring CO2 extracted from the ground. In other cases, companies can just buy CO2 as a cheap byproduct from chemical manufacturing, he told me.

Awkwardly, the most successful market for captured CO2 has been … extracting more fossil fuels, experts told me. Oil and gas companies buy CO2 extracted from the emissions of coal-fired power plants and pump it into depleted wells to help loosen more trapped hydrocarbons. It makes sense as a way to store CO2 — if you know the geology could reliably hold the oil and gas, then you know it can hold the CO2 as well. But the practice “comes with some baggage,” as Nemet put it. Enabling the further burning of fossil fuels probably isn’t what people like Andrew had in mind when they look at CCS as a reason for hope.

There are some policies that will likely help CCS solve its market problems. In 2018, Congress passed a tax credit that rewards companies for each metric ton of carbon dioxide they lock away. That, combined with new California laws that also reward companies for carbon sequestration, might make CCS truly profitable for the first time, said Geoff Holmes, head of business development at Carbon Engineering, a Canadian carbon management company.

Again, he’s talking about CO2 used to pump more oil and gas out of the ground. But if these policies help a few additional CCS projects succeed, Holmes and Lashof think that could convince politicians to pass more laws that make sequestering CO2 valuable. And hopefully all of that would happen fast enough to get the direct-air capture industry off the ground in time to save the world. It’s kind of a high-stakes game of chicken-or-egg, played in the middle of the interstate.

This has all gone in a bit of a “let’s undermine Andrew Janet’s faith in humanity” direction, and I apologize for that. But there is some reason to maintain hope, even if CCS never makes it to the other side of the road.

If you’re willing to accept that we won’t keep global warming under 1.5 degrees, it might not matter much whether CCS becomes a winner or not, Nemet said. That’s because so many other emissions-reducing technologies are winning. If you lump them all together, he said, the combination of solar, wind, electric vehicles, advanced batteries, liquid biofuels and other technologies could make enough of a dent that it doesn’t matter whether CCS ever becomes cheap. “It’s a really good thing we have these other possibilities that are emerging,” he said. “Potentially it eats away at the case for the necessity of CCS.”