Could carbon capture fix climate change?

A reader writes: “Since it seems unlikely that many of the world’s biggest polluters will fix their emissions problems in the foreseeable future, what are the latest developments in carbon capture and storage?” Capturing carbon seems like an appealing, intuitive way of addressing climate change. If the problem is too much carbon dioxide in the atmosphere, why not snag it before it gets there, or pull it back out of the sky? It turns out, we’re already doing it. According to the US Department of Energy, the US captures 22 million metric tons of carbon dioxide each year. This capacity is poised to grow fivefold by 2030. That potential seems promising — but will it be enough? This reader’s question actually gets at one of the most consequential issues in our fight against climate change. To answer it, let’s first size up the challenge we’re facing: The US currently emits a net total of about 5.5 billion metric tons of carbon dioxide per year. The US would need upward of 80 times the carbon capture capacity it has today in its suite of clean technologies in order to zero out emissions from the economy by 2050, according to the Energy Department — so it has a long way to go. Where are we in the effort to curb climate change? Recently, we’ve actually already seen global greenhouse gas emissions level off and they’re on course to decline, if they haven’t already. This is despite the fact that we’ve seen economies grow, which shows that some of the measures we’re using to address climate change are already having an effect. Tactics like deploying renewable energy, replacing coal with natural gas, and energy efficiency have allowed countries to do more with less emissions. But that pace of change is nowhere near fast enough to meet climate goals of limiting warming this century to less than 3.6 degrees Fahrenheit (2 degrees Celsius) above pre-industrial levels. We’re also starting to hit the limits of these strategies. Natural gas is still a fossil fuel and emits carbon dioxide. Energy storage hasn’t yet matured enough to compensate for all of the intermittency from wind and solar power. Many sectors of the economy, like aviation, don’t have an easy route to decarbonization. Global energy demand is poised to increase further. Without clean options, we’re stuck burning more coal, oil, and natural gas. Meanwhile, the Intergovernmental Panel on Climate Change is banking on some form of negative emissions to materialize in order to meet international climate targets. That’s why carbon capture is so interesting — and particularly appealing for companies that make their money selling fossil fuels. OK, so what exactly is carbon capture and storage? There are two main approaches to consider when it comes to catching carbon from burning fossil fuels. The first and most common strategy is capturing carbon dioxide at the source, like at a coal-fired power plant, and getting rid of it, or putting it to work. It’s typically classified as either carbon capture and storage (CCS) or carbon capture utilization and storage (CCUS). The second is capturing carbon dioxide from the atmosphere — yes, basically sucking it out of the air itself — and is often called direct air capture (DAC). Let’s focus on CCS, systems that scrub carbon dioxide from the mix of gases in an exhaust flue, tailpipe, or chimney. Here’s how it works: The waste gases pass through a reactive chemical — commonly amine-based solutions — that selectively grabs onto the carbon. The carbon-enriched chemical then circulates into a separate chamber where it is heated or undergoes another reaction to release the carbon dioxide. This regenerates the chemical absorber, which then goes back into the exhaust stream to begin the loop again. The advantage of this strategy is that carbon dioxide is at its most concentrated close to where it’s generated and since the scrubbers are installed at power plants and industrial facilities, there’s an energy source right there to power the process. That captured carbon dioxide can then extract oil from aging wells, make concrete, or put bubbles in soda (the “utilization” in CCUS). Or it can be stored permanently in underground caverns as a gas or turned into rock. How has it worked so far? And what’s holding this solution back? The trouble is that carbon dioxide tends to be a fairly stable, non-reactive molecule in most circumstances (remember, we use CO2 to smother fires). Right now, capturing it requires expensive, boutique chemicals that require a lot of energy to recycle. On a power plant, a carbon capture system can impose a parasitic load, devouring up to 30 percent of its energy output. That’s a hard bargain, especially if you’re in the business of selling energy. According to a 2023 report from the Congressional Budget Office, “The main reason CCS is used to such a limited extent is that the cost to implement CCS technology exceeds its value in most potential settings.” Current CCS projects cost anywhere from $15 to $120 per metric ton of captured carbon, with higher prices at larger CO2 sources like power plants and industrial facilities. At the moment, there are 45 commercial CCUS facilities around the world, but just two — just two! — are in the power sector, and they’ve struggled to stay profitable. Carbon capture installations in the US have had trouble getting off the ground, with some falling far behind schedule and going way over budget before being canceled. Storing CO2 underground isn’t simple, either; it requires stable geological formations that have to be monitored over time, or it risks escaping back to the surface. The first major CO2 injection well in the US has already sprung a leak. What would it take to make CCS more popular? To make CCS a more viable decarbonization strategy, it needs to scale up, cost less, use less power, and serve a bigger, more lucrative market. It also needs policy, particularly a price on carbon. Researchers and some startup companies are making some progress on the technical challenges. They are shaving down the price tag of capture systems and developing business models to further offset the costs. There are people who would pay good money for CO2 to make stuff, but those markets are in their infancy and may require additional infrastructure like pipelines to transport CO2, which poses its own challenges. Scientists are also working on alternatives to toxic, expensive amines to capture carbon, like metal-organic frameworks and molten carbonate fuel cells. There’s also work underway to capture carbon prior to combustion. There’s a lot of potential, but these technologies are still in early stages. And who pays that cost for CCS? Right now, probably you, in part. There’s a tax credit for carbon sequestration. With a boost from the Inflation Reduction Act, a developer can claim up to $85 per metric ton of carbon dioxide caught and stored in a rock formation. That’s likely to spur more CCS projects. The Treasury Department estimates that this tax credit will cost $30.3 billion between 2022 and 2032. The Energy Department is aiming to bring the cost of carbon capture from the power sector down to $30 per metric ton. However, the US doesn’t have a national price on carbon emissions, and there’s little political appetite to impose one. Therein lies the biggest hurdle for carbon capture: It’s hard to get someone to pay for something they can do for free. Until CO2 costs too much to emit or becomes too valuable to let go, CCS is going to be a tough sell. This story was featured in the Explain It to Me newsletter. Sign up here. For more from Explain It to Me, check out the podcast. New episodes drop every Wednesday.

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Could carbon capture fix climate change?