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Direct CO2 Capture Machines Could Use ‘a Quarter of Global Energy’ in 2100
By Simon Evans
Machines that suck CO2 directly from the air could cut the cost of meeting global climate goals, a new study finds, but they would need as much as a quarter of global energy supplies in 2100.
The research, published Monday in Nature Communications, is the first to explore the use of direct air capture (DAC) in multiple computer models. It shows that a "massive" and energy-intensive rollout of the technology could cut the cost of limiting warming to 1.5 or 2°C above pre-industrial levels.
But the study also highlights the "clear risks" of assuming that DAC will be available at scale, with global temperature goals being breached by up to 0.8°C if the technology then fails to deliver.
This means policymakers should not see DAC as a "panacea" that can replace immediate efforts to cut emissions, one of the study authors tells Carbon Brief, adding: "The risks of that are too high."
DAC should be seen as a "backstop for challenging abatement" where cutting emissions is too complex or too costly, says the chief executive of a startup developing the technology. He tells Carbon Brief that his firm nevertheless will "continuously push back on the 'magic bullet' headlines."
The 2015 Paris agreement set a goal of limiting human-caused warming to "well below" 2°C and an ambition of staying below 1.5°C. Meeting this ambition will require the use of "negative emissions technologies" to remove excess CO2 from the atmosphere, according to the Intergovernmental Panel on Climate Change (IPCC).
This catch-all term covers a wide range of approaches, including planting trees, restoring peatlands and other "natural climate solutions." However, model pathways developed by researchers rely most heavily on bioenergy with carbon capture and storage (BECCS). This is where biomass, such as wood pellets, is burned to generate electricity and the resulting CO2 is captured and stored.
The significant potential role for BECCS raises a number of concerns, with land areas up to five times the size of India devoted to growing the biomass needed in some model pathways.
One alternative is direct air capture, where machines are used to suck CO2 out of the atmosphere. If the CO2 is then buried underground, the process is sometimes referred to as direct air carbon capture and storage (DACCS).
The new study explores how DAC could help meet global climate goals with "lower costs," using two different integrated assessment models (IAMs). Study author Dr. Ajay Gambhir, senior research fellow at the Grantham Institute for Climate Change at Imperial College London, explains to Carbon Brief:
"This is the first inter-model comparison … [and] has the most detailed representation of DAC so far used in IAMs. It includes two DAC technologies, with different energy inputs and cost assumptions, and a range of energy inputs including waste heat. The study uses an extensive sensitivity analysis [to test the impact of varying our assumptions]. It also includes initial analysis of the broader impacts of DAC technology development, in terms of material, land and water use."
The two DAC technologies included in the study are based on different ways to adsorb CO2 from the air, which are being developed by a number of startup companies around the world.
One, typically used in larger industrial-scale facilities such as those being piloted by Canadian firm Carbon Engineering, uses a solution of hydroxide to capture CO2. This mixture must then be heated to high temperatures to release the CO2 so it can be stored and the hydroxide reused. The process uses existing technology and is currently thought to have the lower cost of the two alternatives.
The second technology uses amine adsorbents in small, modular reactors such as those being developed by Swiss firm Climeworks. Costs are currently higher, but the potential for savings is thought to be greater, the paper suggests. This is due to the modular design that could be made on an industrial production line, along with lower temperatures needed to release CO2 for storage, meaning waste heat could be used.
Overall, despite "huge uncertainty" around the cost of DAC, the study suggests its use could allow early cuts in global greenhouse gas emissions to be somewhat delayed, "significantly reduc[ing] climate policy costs" to meet stringent temperature limits.
Using DAC means that global emissions in 2030 could remain at higher levels, the study says, with much larger use of negative emissions later in the century. This is shown in the charts, below, for scenarios staying below 1.5°C (left panel, shades of blue) and 2°C (right, green).
Pathways without DAC are shown in darker shades. For example, the solid dark blue line shows results from the "TIAM" model, with emissions peaking around 2020 and falling rapidly to below zero around 2050.
In contrast, the light blue solid line shows a pathway where DAC allows a more gradual decline, reaching zero in the 2060s and with negative emissions of around 30 billion tonnes per year (Gt/yr) by the 2080s. This is close to today's annual global emissions of around 40GtCO2/yr.
Global CO2 emissions from fossil fuels (Gt/yr) in model pathways consistent with limiting warming this century to 1.5°C (left panel, blue) or 2°C (right panel, green). Results from two different IAMs – TIAM and WITCH – are shown with solid and dashed lines, respectively. The various lines show scenarios that use direct capture ("DAC," darker shades) and those that do not ("NoDAC," lighter), as well as pathways to 2°C without negative emissions of any sort ("NoNET," darkest green). Source: Realmonte et al. (2019).
"The results of both models are surprisingly similar," says Dr. Nico Bauer, a scientist at the Potsdam Institute for Climate Impacts Research (PIK), who was not involved in the study. He tells Carbon Brief: "This increases the credibility about the main conclusions that the DACCS technology can play an important role in a long-term climate change mitigation strategy."
The use of DAC in some of the modeled pathways delays the need to cut emissions in certain areas. The paper explains: "DACCS allows a reduction in near term mitigation effort in some energy-intensive sectors that are difficult to decarbonise, such as transport and industry."
Steve Oldham, chief executive of DAC startup Carbon Engineering says he sees this as the key purpose of CO2 removal technologies, which he likens to other "essential infrastructure" such as waste disposal or sewage treatment.
Oldham tells Carbon Brief that while standard approaches to cutting CO2 remain essential for the majority of global emissions, the challenge and cost may prove too great in some sectors. He says:
"DAC and other negative emissions technologies are the right solution once the cost and feasibility becomes too great … I see us as the backstop for challenging abatement."
Even though DAC may be relatively expensive, the model pathways in the new study still see it as much cheaper than cutting emissions from these hard-to tackle sectors. This means the models deploy large amounts of DAC, even if its costs are at the high end of current estimates.
It also means the models see pathways to meeting climate goals that include DAC as having lower costs overall ("reduce[d]… by between 60 to more than 90%").
Gambhir tells Carbon Brief: "Deploying DAC means less of a steep mitigation pathway in the near-term, and lowers policy costs, according to the modeled scenarios we use in this study."
However, the paper also points to the significant challenges associated with such a large-scale, rapid deployment of DAC, in terms of energy use and the need for raw materials.
The energy needed to run direct air capture machines in 2100 is up to 300 exajoules each year, according to the paper. This is more than half of overall global demand today, from all sources, and despite rising demand this century, it would still be a quarter of expected demand in 2100.
Gambhir tells Carbon Brief:
"Large-scale deployment of DAC in below-2°C scenarios will require a lot of heat and electricity and a major manufacturing effort for production of CO2 sorbent. Although DAC will use less resources such as water and land than other NETs [such as BECCS], a proper full life-cycle assessment needs to be carried out to understand all resource implications."
There are also questions as to whether this new technology could be rolled out at the speed and scale envisaged, with expansion at up to 30% each year and deployment reaching 30GtCO2/yr towards the end of the century. This is a "huge pace and scale," Gambhir says, with the rate of deployment being a "key sensitivity" in the study results.
Professor Jennifer Wilcox, professor of chemical engineering at Worcester Polytechnic Institute, who was not involved with the research, says that this rate of scale-up warrants caution. She tells Carbon Brief:
"Is the rate of scale-up even feasible? Typical rules of thumb are increase by an order of magnitude per decade [growth of around 25-30% per year]. [Solar] PV scale-up was higher than this, but mostly due to government incentives … rather than technological advances."
Reaching 30GtCO2/yr of CO2 capture – a similar scale to current global emissions – would mean building some 30,000 large-scale DAC factories, the paper says. For comparison, there are fewer than 10,000 coal-fired power stations in the world today.
If DAC were to be carried out using small modular systems, then as many as 30m might be needed by 2100, the paper says. It compares this number to the 73m light vehicles that are built each year.
The study argues that expanding DAC at such a rapid rate is comparable to the speed with which newer electricity generation technologies such as nuclear, wind and solar have been deployed.
Climeworks greenhouse © Climeworks / Julia Dunlop
The modeled rate of DAC growth is "breathtaking" but "not in contradiction with the historical experience," Bauer says. This rapid scale-up is also far from the only barrier to DAC adoption.
The paper explains: "[P]olicy instruments and financial incentives supporting negative emission technologies are almost absent at the global scale, though essential to make NET deployment attractive."
Carbon Engineering's Oldham agrees that there is a need for policy to recognize negative emissions as unique and different from standard mitigation. But he tells Carbon Brief that he remains "very very confident" in his company's ability to scale up rapidly.
(The new study includes consideration of the space available to store CO2 underground, finding this not to be a limiting factor for DAC deployment.)
The paper says that the challenges to scale-up and deployment on a huge scale bring significant risks, if DAC does not deliver as anticipated in the models. Committing to ramping up DAC rather than cutting emissions could mean locking the energy system into fossil fuels, the authors warn.
This could risk breaching the Paris temperature limits, the study explains:
"The risk of assuming that DACCS can be deployed at scale, and finding it to be subsequently unavailable, leads to a global temperature overshoot of up to 0.8°C."
Gambhir says the risks of such an approach are "too high":
"Inappropriate interpretations [of our findings] would be that DAC is a panacea and that we should ease near-term mitigation efforts because we can use it later in the century."
"Policymakers should not make the mistake to believe that carbon removals could ever neutralise all future emissions that could be produced from fossil fuels that are still underground. Even under pessimistic assumptions about fossil fuel availability, carbon removal cannot and will not fix the problem. There is simply too much low-cost fossil carbon that we could burn."
Nonetheless, professor Massimo Tavoni, one of the paper's authors and the director of the European Institute on Economics and the Environment (EIEE), tells Carbon Brief that "it is still important to show the potential of DAC – which the models certainly highlight – but also the many challenges of deploying at the scale required."
The global carbon cycle poses one final – and underappreciated – challenge to the large-scale use of negative emissions technologies such as DAC: ocean rebound. This is because the amount of CO2 in the world's oceans and atmosphere is in a dynamic and constantly shifting equilibrium.
This equilibrium means that, at present, oceans absorb a significant proportion of human-caused CO2 emissions each year, reducing the amount staying in the atmosphere. If DAC is used to turn global emissions net-negative, as in the new study, then that equilibrium will also go into reverse.
As a result, the paper says as much as a fifth of the CO2 removed using DAC or other negative emissions technologies could be offset by the oceans releasing CO2 back into the atmosphere, reducing their supposed efficacy.
Reposted with permission from our media associate Carbon Brief.
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By Tara Smith
Fires in the Brazilian Amazon have jumped 84 percent during President Jair Bolsonaro's first year in office and in July 2019 alone, an area of rainforest the size of Manhattan was lost every day. The Amazon fires may seem beyond human control, but they're not beyond human culpability.
Bolsonaro ran for president promising to "integrate the Amazon into the Brazilian economy". Once elected, he slashed the Brazilian environmental protection agency budget by 95 percent and relaxed safeguards for mining projects on indigenous lands. Farmers cited their support for Bolsonaro's approach as they set fires to clear rainforest for cattle grazing.
Bolsonaro's vandalism will be most painful for the indigenous people who call the Amazon home. But destruction of the world's largest rainforest may accelerate climate change and so cause further suffering worldwide. For that reason, Brazil's former environment minister, Marina Silva, called the Amazon fires a crime against humanity.
From a legal perspective, this might be a helpful way of prosecuting environmental destruction. Crimes against humanity are international crimes, like genocide and war crimes, which are considered to harm both the immediate victims and humanity as a whole. As such, all of humankind has an interest in their punishment and deterrence.
Crimes against humanity were first classified as an international crime during the Nuremberg trials that followed World War II. Two German Generals, Alfred Jodl and Lothar Rendulic, were charged with war crimes for implementing scorched earth policies in Finland and Norway. No one was charged with crimes against humanity for causing the unprecedented environmental damage that scarred the post-war landscapes though.
Our understanding of the Earth's ecology has matured since then, yet so has our capacity to pollute and destroy. It's now clear that the consequences of environmental destruction don't stop at national borders. All humanity is placed in jeopardy when burning rainforests flood the atmosphere with CO₂ and exacerbate climate change.
Holding someone like Bolsonaro to account for this by charging him with crimes against humanity would be a world first. If successful, it could set a precedent which might stimulate more aggressive legal action against environmental crimes. But do the Amazon fires fit the criteria?
Prosecuting crimes against humanity requires proof of widespread and systematic attacks against a civilian population. If a specific part of the global population is persecuted, this is an affront to the global conscience. In the same way, domestic crimes are an affront to the population of the state in which they occur.
When prosecuting prominent Nazis in Nuremberg, the US chief prosecutor, Robert Jackson, argued that crimes against humanity are committed by individuals, not abstract entities. Only by holding individuals accountable for their actions can widespread atrocities be deterred in future.
The International Criminal Court's Chief Prosecutor, Fatou Bensouda, has promised to apply the approach first developed in Nuremberg to prosecute individuals for international crimes that result in significant environmental damage. Her recommendations don't create new environmental crimes, such as "ecocide", which would punish severe environmental damage as a crime in itself. They do signal, however, a growing appreciation of the role that environmental damage plays in causing harm and suffering to people.
The International Criminal Court was asked in 2014 to open an investigation into allegations of land-grabbing by the Cambodian government. In Cambodia, large corporations and investment firms were being given prime agricultural land by the government, displacing up to 770,000 Cambodians from 4m hectares of land. Prosecuting these actions as crimes against humanity would be a positive first step towards holding individuals like Bolsonaro accountable.
But given the global consequences of the Amazon fires, could environmental destruction of this nature be legally considered a crime against all humanity? Defining it as such would be unprecedented. The same charge could apply to many politicians and business people. It's been argued that oil and gas executives who've funded disinformation about climate change for decades should be chief among them.
Charging individuals for environmental crimes against humanity could be an effective deterrent. But whether the law will develop in time to prosecute people like Bolsonaro is, as yet, uncertain. Until the International Criminal Court prosecutes individuals for crimes against humanity based on their environmental damage, holding individuals criminally accountable for climate change remains unlikely.
This story originally appeared in The Conversation. It is republished here as part of EcoWatch's partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.
By Natalie Hanman
Why are you publishing this book now?
I still feel that the way that we talk about climate change is too compartmentalised, too siloed from the other crises we face. A really strong theme running through the book is the links between it and the crisis of rising white supremacy, the various forms of nationalism and the fact that so many people are being forced from their homelands, and the war that is waged on our attention spans. These are intersecting and interconnecting crises and so the solutions have to be as well.
The book collects essays from the last decade, have you changed your mind about anything?
When I look back, I don't think I placed enough emphasis on the challenge climate change poses to the left. It's more obvious the way the climate crisis challenges a rightwing dominant worldview, and the cult of serious centrism that never wants to do anything big, that's always looking to split the difference. But this is also a challenge to a left worldview that is essentially only interested in redistributing the spoils of extractivism [the process of extracting natural resources from the earth] and not reckoning with the limits of endless consumption.
What's stopping the left doing this?
In a North American context, it's the greatest taboo of all to actually admit that there are going to be limits. You see that in the way Fox News has gone after the Green New Deal – they are coming after your hamburgers! It cuts to the heart of the American dream – every generation gets more than the last, there is always a new frontier to expand to, the whole idea of settler colonial nations like ours. When somebody comes along and says, actually, there are limits, we've got some tough decisions, we need to figure out how to manage what's left, we've got to share equitably – it is a psychic attack. And so the response [on the left] has been to avoid, and say no, no, we're not coming to take away your stuff, there are going to be all kinds of benefits. And there aregoing to be benefits: we'll have more livable cities, we'll have less polluted air, we'll spend less time stuck in traffic, we can design happier, richer lives in so many ways. But we are going to have to contract on the endless, disposable consumption side.
Do you feel encouraged by talk of the Green New Deal?
I feel a tremendous excitement and a sense of relief, that we are finally talking about solutions on the scale of the crisis we face. That we're not talking about a little carbon tax or a cap and trade scheme as a silver bullet. We're talking about transforming our economy. This system is failing the majority of people anyway, which is why we're in this period of such profound political destabilisation – that is giving us the Trumps and the Brexits, and all of these strongman leaders – so why don't we figure out how to change everything from bottom to top, and do it in a way that addresses all of these other crises at the same time? There is every chance we will miss the mark, but every fraction of a degree warming that we are able to hold off is a victory and every policy that we are able to win that makes our societies more humane, the more we will weather the inevitable shocks and storms to come without slipping into barbarism. Because what really terrifies me is what we are seeing at our borders in Europe and North America and Australia – I don't think it's coincidental that the settler colonial states and the countries that are the engines of that colonialism are at the forefront of this. We are seeing the beginnings of the era of climate barbarism. We saw it in Christchurch, we saw it in El Paso, where you have this marrying of white supremacist violence with vicious anti-immigrant racism.
That is one of the most chilling sections of your book: I think that's a link a lot of people haven't made.
This pattern has been clear for a while. White supremacy emerged not just because people felt like thinking up ideas that were going to get a lot of people killed but because it was useful to protect barbaric but highly profitable actions. The age of scientific racism begins alongside the transatlantic slave trade, it is a rationale for that brutality. If we are going to respond to climate change by fortressing our borders, then of course the theories that would justify that, that create these hierarchies of humanity, will come surging back. There have been signs of that for years, but it is getting harder to deny because you have killers who are screaming it from the rooftops.
One criticism you hear about the environment movement is that it is dominated by white people. How do you address that?
When you have a movement that is overwhelmingly representative of the most privileged sector of society then the approach is going to be much more fearful of change, because people who have a lot to lose tend to be more fearful of change, whereas people who have a lot to gain will tend to fight harder for it. That's the big benefit of having an approach to climate change that links it to those so called bread and butter issues: how are we going to get better paid jobs, affordable housing, a way for people to take care of their families?
I have had many conversations with environmentalists over the years where they seem really to believe that by linking fighting climate change with fighting poverty, or fighting for racial justice, it's going to make the fight harder. We have to get out of this "my crisis is bigger than your crisis: first we save the planet and then we fight poverty and racism, and violence against women". That doesn't work. That alienates the people who would fight hardest for change.
This debate has shifted a huge amount in the U.S. because of the leadership of the climate justice movement and because it is congresswomen of colour who are championing the Green New Deal. Alexandria Ocasio-Cortez, Ilhan Omar, Ayanna Pressley and Rashida Tlaibcome from communities that have gotten such a raw deal under the years of neoliberalism and longer, and are determined to represent, truly represent, the interests of those communities. They're not afraid of deep change because their communities desperately need it.
In the book, you write: "The hard truth is that the answer to the question 'What can I, as an individual, do to stop climate change?' is: nothing." Do you still believe that?
In terms of the carbon, the individual decisions that we make are not going to add up to anything like the kind of scale of change that we need. And I do believe that the fact that for so many people it's so much more comfortable to talk about our own personal consumption, than to talk about systemic change, is a product of neoliberalism, that we have been trained to see ourselves as consumers first. To me that's the benefit of bringing up these historical analogies, like the New Deal or the Marshall Plan – it brings our minds back to a time when we were able to think of change on that scale. Because we've been trained to think very small. It is incredibly significant that Greta Thunberg has turned her life into a living emergency.
Yes, she set sail for the UN climate summit in New York on a zero carbon yacht ...
Exactly. But this isn't about what Greta is doing as an individual. It's about what Greta is broadcasting in the choices that she makes as an activist, and I absolutely respect that. I think it's magnificent. She is using the power that she has to broadcast that this is an emergency, and trying to inspire politicians to treat it as an emergency. I don't think anybody is exempt from scrutinising their own decisions and behaviours but I think it is possible to overemphasise the individual choices. I have made a choice – and this has been true since I wrote No Logo, and I started getting these "what should I buy, where should I shop, what are the ethical clothes?" questions. My answer continues to be that I am not a lifestyle adviser, I am not anyone's shopping guru, and I make these decisions in my own life but I'm under no illusion that these decisions are going to make the difference.
Some people are choosing to go on birth strikes. What do you think about that?
I'm happy these discussions are coming into the public domain as opposed to being furtive issues we're afraid to talk about. It's been very isolating for people. It certainly was for me. One of the reasons I waited as long as I did to try and get pregnant, and I would say this to my partner all the time – what, you want to have a Mad Max water warrior fighting with their friends for food and water? It wasn't until I was part of the climate justice movement and I could see a path forward that I could even imagine having a kid. But I would never tell anybody how to answer this most intimate of questions. As a feminist who knows the brutal history of forced sterilisation and the ways in which women's bodies become battle zones when policymakers decide that they are going to try and control population, I think that the idea that there are regulatory solutions when it comes to whether or not to have kids is catastrophically ahistorical. We need to be struggling with our climate grief together and our climate fears together, through whatever decision we decide to make, but the discussion we need to have is how do we build a world so that those kids can have thriving, zero-carbon lives?
Over the summer, you encouraged people to read Richard Powers's novel, The Overstory. Why?
It's been incredibly important to me and I'm happy that so many people have written to me since. What Powers is writing about trees: that trees live in communities and are in communication, and plan and react together, and we've been completely wrong in the way we conceptualise them. It's the same conversation we're having about whether we are going to solve this as individuals or whether we are going to save the collective organism. It's also rare, in good fiction, to valorise activism, to treat it with real respect, failures and all, to acknowledge the heroism of the people who put their bodies on the line. I thought Powers did that in a really extraordinary way.
What are you views on what Extinction Rebellion has achieved?
One thing they have done so well is break us out of this classic campaign model we have been in for a long time, where you tell someone something scary, you ask them to click on something to do something about it, you skip out the whole phase where we need to grieve together and feel together and process what it is that we just saw. Because what I hear a lot from people is, ok, maybe those people back in the 1930s or 40s could organise neighbourhood by neighbourhood or workplace by workplace but we can't. We believe we've been so downgraded as a species that we are incapable of that. The only thing that is going to change that belief is getting face to face, in community, having experiences, off our screens, with one another on the streets and in nature, and winning some things and feeling that power.
You talk about stamina in the book. How do you keep going? Do you feel hopeful?
I have complicated feelings about the hope question. Not a day goes by that I don't have a moment of sheer panic, raw terror, complete conviction that we are doomed, and then I do pull myself out of it. I'm renewed by this new generation that is so determined, so forceful. I'm inspired by the willingness to engage in electoral politics, because my generation, when we were in our 20s and 30s, there was so much suspicion around getting our hands dirty with electoral politics that we lost a lot of opportunities. What gives me the most hope right now is that we've finally got the vision for what we want instead, or at least the first rough draft of it. This is the first time this has happened in my lifetime. And also, I did decide to have kids. I have a seven year old who is so completely obsessed and in love with the natural world. When I think about him, after we've spent an entire summer talking about the role of salmon in feeding the forests where he was born in British Columbia, and how they are linked to the health of the trees and the soil and the bears and the orcas and this entire magnificent ecosystem, and I think about what it would be like to have to tell him that there are no more salmon, it kills me. So that motivates me. And slays me.
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As the climate crisis takes on more urgency, psychologists around the world are seeing an increase in the number of children sitting in their offices suffering from 'eco-anxiety,' which the American Psychological Association described as a "chronic fear of environmental doom," as EcoWatch reported.
By Ben Jervey
Drivers of electric cars are being unfairly punished by punitive fees in several states, according to a newly published analysis by Consumer Reports. Legislators in 26 states have enacted or proposed special registration fees for electric vehicles (EVs) that the consumer advocacy group found to be more expensive than the gas taxes paid by the driver of an average new gasoline vehicle.
By Oliver Milman
Two-thirds of Americans believe climate change is either a crisis or a serious problem, with a majority wanting immediate action to address global heating and its damaging consequences, major new polling has found.