The world needs to get excited about capturing carbon dioxide from the air—and stay that way

Carbon capture at its best.
Carbon capture at its best.
Image: Reuters/Yves Herman
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Donald Trump won the US presidential election by touting a technology that could help Americans combat global warming.

That statement probably sounds pretty weird. But recall the words “clean coal.” Trump used that phrase to rally his fossil-fuel base, but the technology he was talking about really does exist: It’s called carbon capture, and its use is vital in the global fight against climate change.

There’s a widespread consensus about the importance of carbon capture these days among scientists. In the last few months, a large number of very high-profile bodies have published reports that promote the use of carbon-capture and negative-emissions technologies, including the United Nations and the World Resources Institute. The most recent was published yesterday (Oct. 24) by the powerful trio of the US National Academies of Science, Engineering, and Medicine.

The optimism and energy surrounding carbon capture is good news. The problem is that past examples show it’s easy to falter. The technology’s promises look good on paper and it has, from time to time, even gathered the support of politicians and businesspeople. But then, before larger deployments could follow, the momentum has been lost.

How carbon capture works

About the time of Trump’s election, I began to work on an investigative series on the technology behind the “clean coal” marketing slogan. Carbon capture and storage (CCS), as it’s properly known, involves capturing carbon emissions—say from power plants or cement factories—and burying it underground. Much like the oil industry but in reverse. Its use means we can put out fewer greenhouse gases into the atmosphere and slow down climate change.

Climate scientists have known for a long time that, if we are to follow the most cost-effective route to cutting emissions, we will need to deploy CCS at a large scale. Currently, CCS is used to put away about 40 million metric tons of carbon dioxide each year, which is about 1% of annual global emissions.

Until the early 2000s, the use of CCS was promoted to only capture carbon dioxide from already existing sources. However, as governments delayed action to start cutting emissions, climate scientists were forced to consider using CCS and other technologies to pull carbon dioxide from the air— also known as negative emissions.

Carbon capture’s Catch-22

The new 370-page report from the US National Academies of Science, Engineering, and Medicine is aimed at policymakers, setting out the most detailed plans yet to develop and scale up negative-emissions technologies. By 2050, scientists estimate we’ll need to capture about 10 billion metric tons each year—about 25% of current annual global emissions.

The report focused only on land-based negative-emissions technologies. If it had included the use of oceans, which make up 70% of the planet, the report would have been double its length, Stephen Pacala, a climate scientist at Princeton University who led the report, said at the launch event in Washington, DC.

The report classified negative-emissions technologies in two large buckets. One set involves the use of carbon-capture technologies. For example, under the technique known as BECCS, we can grow trees that capture carbon dioxide, burn the wood for energy in power plants, capture the emissions from the gas, and bury it underground. Or we can use large machines that scrub carbon dioxide out from the air, bury it underground, and sometimes turn it into stone (a technique known as DACCS). The other set involves the use of nature-based techniques: planting more trees, for example, or adding charcoal to the soil to stop microbes from degrading organic matter and releasing carbon dioxide.

It’s easy enough to get started with the nature-based technologies, which are both mature and scalable. They are also relatively cheap to deploy, and thus the report concludes that there is absolutely no reason to not get planting those trees right away. More importantly, the report makes it clear that negative emissions are a part of the portfolio of technologies needed to fight climate change—not those to be used after we’ve exhausted the use of current technologies.

The CCS-based technologies are newer, which means there are still some open questions. For example, BECSS is controversial because it’s unclear whether countries have enough land to both grow trees to burn in power plants and grow plants to feed people. In the case of DACCS, there is no worry about running out of space to bury the carbon dioxide captured from the air, but the technology remain expensive.

That said, according to Pacala, with adequate research, scientists believe there is a very good chance to make the technology cheaper. Right now, CCS-based technologies suffer from a Catch-22 problem: It is expensive because it hasn’t been widely deployed, but it hasn’t been deployed because it remains expensive.

The report estimates that, if we are to do the research and develop negative-emissions technologies, the cost to the US would be about $1 billion a year. That’s a small sum, especially when compared with the tens of trillions of dollars of damage that can be avoided if we hit climate goals using these technologies.

After covering these technologies for over two years, I’m noticing a real sense of optimism among the advocates for the technology. Earlier this year, the Trump administration passed a bill that provides tax credits of up to $50 for each ton of carbon dioxide captured using CCS technologies. It’s remarkable that this happened under an administration that is otherwise doing its best to roll back every possible environmental regulation.

But optimism can only go so far. In 2018, the world will likely set a new record high for greenhouse-gas emissions. As a result, the clarion call for negative emissions is getting louder. The more we delay reducing emissions, the more carbon dioxide we will have to pull out from the air in the future.