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.
Thousands of Superfund sites exist around the U.S., with toxic substances left open, mismanaged and dumped. Despite the high levels of toxicity at these sites, nearly 21 million people live within a mile of one of them, according to the U.S. Environmental Protection Agency (EPA).
Currently, more than 1,300 Superfund sites pose a serious health risk to nearby communities. Based on a new study, residents living close to these sites could also have a shorter life expectancy.
Published in Nature Communications, the study, led by Hanadi S. Rifai, a professor of civil and environmental engineering at the University of Houston, and a team of researchers, found that living in nearby zip codes to Superfund sites resulted in a decreased life expectancy of more than two months, the University of Houston reported.
"We have ample evidence that contaminant releases from anthropogenic sources (e.g., petrochemicals or hazardous waste sites) could increase the mortality rate in fence-line communities," Rifai told the University of Houston. "Results showed a significant difference in life expectancy among census tracts with at least one Superfund site and their neighboring tracts with no sites."
The study pulled data from 65,000 census tracts – defined geographical regions – within the contiguous U.S., The Guardian reported. With this data, researchers found that for communities that are socioeconomically challenged, this life expectancy could decrease by up to a year.
"It was a bit surprising and concerning," Rifai told The Guardian. "We weren't sure [when we started] if the fact that you are socioeconomically challenged would make [the Superfund's effects] worse."
The research team, for example, found that the presence of a Superfund site in a census tract with a median income of less than $52,580 could reduce life expectancy by seven months, the University of Houston reported.
Many of these toxic sites were once used as manufacturing sites during the Second World War. Common toxic substances that are released from the sites into the air and surface water include lead, trichlorethylene, chromium, benzene and arsenic – all of which can lead to health impacts, such as neurological damage among children, The Union of Concerned Scientists wrote in a blog.
"The EPA has claimed substantial recent progress in Superfund site cleanups, but, contrary to EPA leadership's grandiose declarations, the backlog of unfunded Superfund cleanups is the largest it has been in the last 15 years," the Union wrote.
Delayed cleanup could become increasingly dangerous as climate change welcomes more natural hazards, like wildfires and flooding. According to a Government Accountability Office report, for example, climate change could threaten at least 60 percent of Superfund sites in the U.S., AP News reported.
During the summer of 2018, a major wildfire took over the Iron Mountain Superfund site near Redding, CA, ruining wastewater treatment infrastructure that is responsible for capturing 168 million gallons of acid mine drainage every month, NBC News reported.
"There was this feeling of 'My God. We ought to have better tracking of wildfires at Superfund locations,'" Stephen Hoffman, a former senior environmental scientist at the EPA, told NBC News. "Before that, there wasn't a lot of thought about climate change and fire. That has changed."
In the study, researchers also looked at the impacts of floodings on Superfund sites, which could send toxins flowing into communities and waterways.
"When you add in flooding, there will be ancillary or secondary impacts that can potentially be exacerbated by a changing future climate," Rifai told the University of Houston. "The long-term effect of the flooding and repetitive exposure has an effect that can transcend generations."
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A weather research station on a bluff overlooking the sea is closing down because of the climate crisis.
The National Weather Service (NWS) station in Chatham, Massachusetts was evacuated March 31 over concerns the entire operation would topple into the ocean.
"We had to say goodbye to the site because of where we are located at the Monomoy Wildlife Refuge, we're adjacent to a bluff that overlooks the ocean," Boston NWS meteorologist Andy Nash told WHDH at the time. "We had to close and cease operations there because that bluff has significantly eroded."
Chatham is located on the elbow of Cape Cod, a land mass extending out into the Atlantic Ocean that has been reshaped and eroded by waves and tides over tens of thousands of years, The Guardian explained. However, sea level rise and extreme weather caused by the climate crisis have sped that change along.
"It's an extremely dynamic environment, which is obviously a problem if you are building permanent infrastructure here," Andrew Ashton, an associate scientist at Cape-Cod based Woods Hole Oceanographic Institution, told The Guardian. "We are putting our foot on the accelerator to make the environment even more dynamic."
This was the case with the Chatham weather station. It used to be protected from the drop into the ocean by about 100 feet of land. However, storm action in 2020 alone washed away as much as six feet of land a day.
"We'd know[n] for a long time there was erosion but the pace of it caught everyone by surprise," Nash told The Guardian. "We felt we had maybe another 10 years but then we started losing a foot of a bluff a week and realized we didn't have years, we had just a few months. We were a couple of storms from a very big problem."
The Chatham station was part of a network of 92 NWS stations that monitor temperature, pressure, humidity, wind speed and direction and other data in the upper atmosphere, The Cape Cod Chronicle explained. The stations send up radiosondes attached to weather balloons twice a day to help with weather research and prediction. The Chatham station, which had been observing this ritual for the past half a century, sent up its last balloon the morning of March 31.
"We're going to miss the observations," Nash told The Cape Cod Chronicle. "It gives us a snapshot, a profile of the atmosphere when the balloons go up."
The station was officially decommissioned April 1, and the two buildings on the site will be demolished sometime this month. The NWS is looking for a new location in southeastern New England. In the meantime, forecasters will rely on data from stations in New York and Maine.
Nash said the leavetaking was bittersweet, but inevitable.
"[M]other nature is evicting us," he told The Cape Cod Chronicle.
By Douglas Broom
- If online deliveries continue with fossil-fuel trucks, emissions will increase by a third.
- So cities in the Netherlands will allow only emission-free delivery vehicles after 2025.
- The government is giving delivery firms cash help to buy or lease electric vehicles.
- The bans will save 1 megaton of CO2 every year by 2030.
Cities in the Netherlands want to make their air cleaner by banning fossil fuel delivery vehicles from urban areas from 2025.
"Now that we are spending more time at home, we are noticing the large number of delivery vans and lorries driving through cities," said Netherlands environment minister Stientje van Veldhoven, announcing plans to ban all but zero-emission deliveries in 14 cities.
"The agreements we are setting down will ensure that it will be a matter of course that within a few years, supermarket shelves will be stocked, waste will be collected, and packages will arrive on time, yet without any exhaust fumes and CO2 emissions," she added.
She expects 30 cities to announce zero emission urban logistics by this summer. City councils must give four years' notice before imposing bans as part of government plans for emission-free road traffic by 2050. The city bans aim to save 1 megaton of CO2 each year by 2030.
Help to Change
To encourage transport organizations to go carbon-free, the government is offering grants of more than US$5,900 to help businesses buy or lease electric vehicles. There will be additional measures to help small businesses make the change.
The Netherlands claims it is the first country in the world to give its cities the freedom to implement zero-emission zones. Amsterdam, Rotterdam and Utrecht already have "milieuzones" where some types of vehicles are banned.
Tilburg, one of the first wave of cities imposing the Dutch ban, will not allow fossil-fuelled vehicles on streets within its outer ring road and plans to roll out a network of city-wide electric vehicle charging stations before the ban comes into effect in 2025.
"Such initiatives are imperative to improve air quality. The transport of the future must be emission-free, sustainable, and clean," said Tilburg city alderman Oscar Dusschooten.
Europe Takes Action
Research by Renault shows that many other European cities are heading in the same direction as the Netherlands, starting with Low Emission Zones of which Germany's "Umweltzone" were pioneers. More than 100 communes in Italy have introduced "Zonas a traffico limitato."
Madrid's "zona de baja emisión" bans diesel vehicles built before 2006 and petrol vehicles from before 2000 from central areas of the city. Barcelona has similar restrictions and the law will require all towns of more than 50,000 inhabitants to follow suit.
Perhaps the most stringent restrictions apply in London's Ultra Low Emission Zone (ULEZ), which charges trucks and large vehicles up to US$137 a day to enter the central area if they do not comply with Euro 6 emissions standards. From October, the ULEZ is being expanded.
Cities are responsible for around 75% of CO2 emissions from global final energy use, according to the green thinktank REN21 - and much of these come from transport. Globally, transport accounts for 24% of world CO2 emissions.
The Rise of Online Shopping
Part of the reason for traffic in urban areas is the increase in delivery vehicles, as online shopping continues to grow. Retailer ecommerce sales are expected to pass $5billion in 2022, according to eMarketer.
The World Economic Forum's report The Future of the Last-Mile Ecosystem, published in January 2020, estimates that e-commerce will increase the number of delivery vehicles on the roads of the world's 100 largest cities by 36% by 2030.
If all those vehicles burn fossil fuels, the report says emissions will increase by 32%. But switching to all-electric delivery vehicles would cut emissions by 30% from current levels as well as reducing costs by 25%, the report says.
Other solutions explored in the report include introducing goods trams to handle deliveries alongside their passenger-carrying counterparts and increased use of parcel lockers to reduce the number of doorstep deliveries.
Reposted with permission from the World Economic Forum.
The bill, SB467, would have prohibited fracking and other controversial forms of oil extraction. It would also have banned oil and gas production within 2,500 feet of a home, school, hospital or other residential facility. The bill originally set the fracking ban for 2027, but amended it to 2035, The AP reported.
"Obviously I'm very disappointed," State Sen. Scott Wiener (D-San Francisco), one of the bill's two introducers, told the Los Angeles Times. "California really has not done what it needs to do in terms of addressing the oil problem. We have communities that are suffering right now, and the Legislature has repeatedly failed to act."
The bill was introduced after California Gov. Gavin Newsom said he would sign a fracking ban if it passed the legislature, though his administration has continued to issue permits in the meantime, Forbes reported. Newsom has also spoken in favor of a buffer zone between oil and gas extraction and places where people live and learn, according to the Los Angeles Times. The latter is a major environmental justice issue, as fossil fuel production is more likely to be located near Black and Latinx communities.
Urban lawmakers who want California to lead on the climate crisis supported the bill, while inland lawmakers in oil-rich areas concerned about jobs opposed it. The oil and gas industry and trade unions also opposed the bill.
This opposition meant the bill failed to get the five votes it needed to move beyond the Senate's Natural Resources and Water Committee. Only four senators approved it, while Democrat Sen. Susan Eggman of Stockton joined two Republicans to oppose it, and two other Democrats abstained.
Eggman argued that the bill would have forced California to rely on oil extracted in other states.
"We're still going to use it, but we're going to use it from places that produce it less safely," Eggman told The AP. She also said that she supported the transition away from fossil fuels, but thought the bill jumped the gun. "I don't think we're quite there yet, and this bill assumes that we are," she added.
Historically, California has been a major U.S. oil producer. Its output peaked in 1986 at 1.1 million barrels a day, just below Texas and Alaska, according to Forbes. However, production has declined since then making it the seventh-most oil-producing state.
Still, California's fossil fuel industry is at odds with state attempts to position itself as a climate leader.
"There is a large stain on California's climate record, and that is oil," Wiener said Tuesday, according to The AP.
Wiener and Democrat co-introducer Sen. Monique Limón from Santa Barbara vowed to keep fighting.
"While we saw this effort defeated today, this issue isn't going away," they wrote in a joint statement. "We'll continue to fight for aggressive climate action, against harmful drilling, and for the health of our communities."
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By Brett Wilkins
As world leaders prepare for this November's United Nations Climate Conference in Scotland, a new report from the Cambridge Sustainability Commission reveals that the world's wealthiest 5% were responsible for well over a third of all global emissions growth between 1990 and 2015.
The report, Changing Our Ways: Behavior Change and the Climate Crisis, found that nearly half the growth in absolute global emissions was caused by the world's richest 10%, with the most affluent 5% alone contributing 37%.
"In the year when the UK hosts COP26, and while the government continues to reward some of Britain's biggest polluters through tax credits, the commission report shows why this is precisely the wrong way to meet the UK's climate targets," the report's introduction states.
The authors of the report urge United Kingdom policymakers to focus on this so-called "polluter elite" in an effort to persuade wealthy people to adopt more sustainable behavior, while providing "affordable, available low-carbon alternatives to poorer households."
The report found that the "polluter elite" must make "dramatic" lifestyle changes in order to meet the UK's goal — based on the Paris climate agreement's preferential objective — of limiting global heating to 1.5°C, compared with pre-industrial levels.
In addition to highlighting previous recommendations — including reducing meat consumption, reducing food waste, and switching to electric vehicles and solar power — the report recommends that policymakers take the following steps:
- Implement frequent flyer levies;
- Enact bans on selling and promoting SUVs and other high polluting vehicles;
- Reverse the UK's recent move to cut green grants for homes and electric cars; and
- Build just transitions by supporting electric public transport and community energy schemes.
"We have got to cut over-consumption and the best place to start is over-consumption among the polluting elites who contribute by far more than their share of carbon emissions," Peter Newell, a Sussex University professor and lead author of the report, told the BBC.
"These are people who fly most, drive the biggest cars most, and live in the biggest homes which they can easily afford to heat, so they tend not to worry if they're well insulated or not," said Newell. "They're also the sort of people who could really afford good insulation and solar panels if they wanted to."
Newell said that wealthy people "simply must fly less and drive less. Even if they own an electric SUV, that's still a drain on the energy system and all the emissions created making the vehicle in the first place."
"Rich people who fly a lot may think they can offset their emissions by tree-planting schemes or projects to capture carbon from the air," Newell added. "But these schemes are highly contentious and they're not proven over time."
The report concludes that "we are all on a journey and the final destination is as yet unclear. There are many contradictory road maps about where we might want to get to and how, based on different theories of value and premised on diverse values."
"Promisingly, we have brought about positive change before, and there are at least some positive signs that there is an appetite to do what is necessary to live differently but well on the planet we call home," it states.
The new report follows a September 2020 Oxfam International study that revealed the wealthiest 1% of the world's population is responsible for emitting more than twice as much carbon dioxide as the poorest 50% of humanity combined.
Reposted with permission from Common Dreams.
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