This week's Long Read

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Will carbon dioxide removal tech help or hinder climate targets?

Billions of dollars are pouring into the carbon dioxide removal industry, which aims to clean up emissions and slow global warming, but few companies have delivered results. Is the technology a planetary saviour or a risky bet?

By James Dinneen

29 November 2023

 

 

 

A direct air capture plant operated by Heirloom in California

Heirloom Carbon/Handout via REUTERS

 

What do Microsoft, Ikea and Shopify have in common? All have promised to become “carbon negative” companies, aiming to not only cut their emissions, but go beyond that to remove carbon dioxide from the air. With such pledges becoming increasingly popular as boardrooms flex their green credentials, the carbon dioxide removal (CDR) industry is seeing an investment boom.

At the moment, around 2 billion additional tonnes of CO₂ are taken out of the atmosphere each year, over and above existing carbon sinks, but this is almost entirely due to efforts to expand forests or other nature-based approaches. To keep emissions in line with the Paris Agreement goal of staying below 1.5°C of warming, the Intergovernmental Panel on Climate Change (IPCC) estimates we need to be removing between another 5 to 16 gigatonnes a year by 2050, depending on emissions reductions elsewhere.

 

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CDR technologies, which can store CO₂ for longer periods and may be able to scale up more quickly than nature-based approaches, have the potential to close that gap. But to date, they have removed only around 115,000 tonnes of CO₂ (see “A slow start”, below).

As nations assemble this week for the COP28 climate summit in Dubai, United Arab Emirates, any steps towards net-zero emissions should be welcomed. But the question remains whether big bets on CDR technology will pay off in time – and will do so without detracting from efforts to directly slash emissions by transitioning away from fossil fuels. Gregory Nemet at the University of Wisconsin-Madison calls this the “formative phase” for CDR, where ideas that worked in the lab are put to the test in the real world. “Inevitably, it’s a messy period.”

There are a slew of CDR technologies, but two are likely to dominate: bioenergy with carbon capture and storage (BECCS) and direct air capture (DAC). The former involves growing plants to absorb CO₂ from the atmosphere, and then burning them for energy while capturing the resulting CO₂ emissions. The latter sees air blown over materials that absorb CO₂, then release it when heated. The stream of CO₂ from either approach can then be stored underground, turned into rock or locked away by using it in any number of products, from concrete to condoms.

Other engineered approaches use chemicals to remove CO₂ from seawater, which naturally absorbs the gas from the atmosphere. Yet others involve grinding up rocks to spread on fields to absorb CO₂, or removing carbon taken in by plants by using them to make charcoal and adding this to soil, or sinking wood and seaweed to the bottom of the ocean. There are variations on all of these themes. California-based company Charm Industrial, for instance, uses heat to turn agricultural waste into oil that it then pumps underground.

None of these methods has yet been used to remove more than a few thousand tonnes of CO₂, but all have their sights set on billions. Proponents, however, are less clear on the downsides, such as cost, steep energy and land-use requirements and potential consequences for people and ecosystems. Much of the hype around these technologies fails to recognise “how difficult CDR is and how ineffectual it’s been”, says David Ho at the University of Hawai’i at Mānoa. “We haven’t shown that we can do this.”

Ho reflects a widely-held view that sees CDR as a false solution, promising a way to keep emitting without the consequences, all while diverting financial and energy resources that could go directly to reducing emissions. He sees the need for large-scale CDR eventually, but says removals now, when the world continues to emit so much CO₂, are futile. “Right now, the most valuable thing about CDR is greenwashing,” he says.

 

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But others, including Nemet, argue that we have to begin aggressively scaling up CDR now to ensure there is sufficient capacity to meet net-zero targets come mid-century. While many people say relying on removals to hit these targets is a gamble, Nemet sees it the other way. “I find it a little bit risky to hang our hat on people just stopping emissions,” he says.

Either way, it is now the consensus view that a substantial amount of CDR will be needed to meet climate targets. According to the IPCC, CDR is “unavoidable” if we are to reach net-zero emissions. But it says those removals are primarily needed to “counterbalance” the residual emissions left in sectors that are difficult to decarbonise, like steel-making or long-distance aviation, and to address any overshoot of our dwindling carbon budget. They shouldn’t be seen as a general solution for every industry or as an excuse to keep emitting, says the IPCC.

“We can’t be relying too heavily on this because we don’t really know today how much we can be removing,” says Eli Mitchell-Larson at the think tank Carbon Gap, emphasising the importance of cutting emissions before resorting to the much more difficult task of removing them.

Even in an optimistic scenario where efficiency gains lower demand for energy, the IPCC says a total of 20 gigatonnes of CO₂ must be removed by the end of the century to meet climate targets. In a more pessimistic scenario, 660 gigatonnes of removals are required. In a middle scenario, we would need a 540-fold increase in removals from new CDR technologies by 2030, and a 1300-fold increase by the middle of the century, according to modelling by Nemet and his colleagues.

 

Whether this scale is achievable is a question for the future. Today, CDR projects are only just getting started. In November, the first commercial DAC plant in the US started operations in California. Heirloom, the firm behind it, says it will remove 1000 tonnes of CO₂ a year, equivalent to the annual emissions from around 200 cars. Meanwhile, a giant DAC plant being built in Texas is supposed to be able to remove half a million tonnes of CO₂ a year.

Record amounts of money are also flowing. A consortium of tech giants called Frontier has pledged to buy more than a billion dollars worth of such carbon dioxide removal and recently made its first purchase. Firms that want to green themselves pay CDR outfits per tonne of carbon removed, a bit like carbon offsetting. Leading bank J.P. Morgan has said it would invest $200 million in CDR technology. The US Department of Energy too announced a programme to pay firms tens of millions of dollars in return for carbon removals, and has billions of dollars of support to develop regional DAC hubs. All this amounts to a more than four-fold jump in purchases of new CDR since 2022, which would equate to 5 million tonnes of removals, according to the website CDR.fyi.

But this rush of money is no guarantee that CO₂ actually leaves the atmosphere. Only about 2.3 per cent of tonnes purchased so far have been removed. The rest may be delayed or never happen, either because the technologies involved don’t work as planned or upstart companies fold. Mitchell-Larson says the problem is exacerbated by an “inadequate” system to monitor and track removals. He says the system is a bit like “students marking their own homework”.

 

But Mitchell-Larson and others also say potentially risky purchases are needed to spur innovation. “There will be failures in the years ahead,” says Harris Cohn at Charm Industrial. “But there should be if the market is experimenting as aggressively as we need [in order] to grow.” According to its website, Charm has delivered 6417 tonnes of the more than 165,000 tonnes of removals it has sold so far.

Despite concerns over delivery, demand for long-lasting removals doesn’t seem to be flagging. A report from consulting firm BCG, also a buyer of carbon removals, forecasts demand outpacing supply at least to 2030, with the former reaching as much as 900 million tonnes of CO₂ per year by 2040 as cost falls and governments do more to support CDR. However, even if CDR firms deliver this, it would leave removals billions of tonnes short of what the IPCC says is needed by 2050.

Mitchell-Larson says closing that gap will require governments to buy removals themselves or force companies to pay for CDR, perhaps via a carbon tax, rather than leaving it to the generosity of climate-conscious firms with lots of extra cash. “The question that everyone is asking is: ‘Where is the next billion dollars?’ ” he says.

Such issues are set to be discussed at COP28, where CDR is likely to get more attention than before. Currently, the technologies don’t play a big role in any nation’s formal climate commitments, but that could change, says Mitchell-Larson. The summit may also lead to a deal enabling states to trade removals between themselves.

“I think the CDR community is looking for a sense of legitimacy,” says Nemet, to be seen alongside other key climate industries like wind and solar, which also once looked impossibly expensive to build at scale, he says. “We have gone that fast before.”