Imagine it is 2050. When you come to a desert, through the sun-baked bushes, there are only a few long-abandoned oil pumps on both sides of the road. Then you see a large, gleaming building rising from the flat ground. The land here is like a giant mirror, and the solar panel array stretches out in all directions like silver-blue waves. In the distance, they surround a huge grey wall, five stories high and nearly a kilometer long. Behind the wall, you can see pipes and racks that meander like a chemical factory.
As you approach, you'll see the wall moving and gleaming; in fact, it's pretty much made up of whirring fans in a steel box that looks like a giant air-conditioning unit, Zoom in to incredible proportions. In a sense, it does. This is a "direct air capture" (DAC) plant, and there are thousands of them all over the world, their job is to "cool" the planet by absorbing carbon dioxide from the air, here The plant works to capture the remains of fossil fuels -- carbon dioxide from the air -- and pump it into underground storage that's been evacuated.
Such a vision may be necessary by the middle of the 21st century if we are to achieve the Paris Agreement target of limiting global warming to 1.5°C by 2100.
Let's go back to 2021 for a moment, though. In Squamish, British Columbia, Canada, a barn-sized, blue tarpaulin-covered facility is in final preparations against the snow-capped skyline. This is Carbon Engineering's direct air capture plant, which will be commissioned in September, starting to remove 1 tonne of carbon dioxide from the air each year. This is just the beginning, there is a slightly larger factory under construction in Texas, but at this stage, the Squamish factory is typical of a DAC factory.
"We have a climate change problem caused by excess carbon dioxide," said Steve Oldham, CEO of Carbon Engineering. "With DAC, you can remove any Emissions. It’s a very powerful tool.”
Most carbon capture focuses on cleaning emissions at the source, that is, preventing harmful gases from entering the atmosphere through scrubbers and filters on the stack. However, this is impractical for the billions of cars on the planet because these sources of emissions are small and numerous. Source cleaning also doesn't address the carbon dioxide already in the air. Thus, direct air capture comes into play.
If the world is to avoid catastrophic climate change, it will not be enough to simply move to a carbon-neutral society. The Intergovernmental Panel on Climate Change (IPCC) has warned that if global warming is to be limited to 1.5°C by 2100, technologies like DAC will be needed to "deploy carbon dioxide abatement on a large scale" - "massive" here Refers to billions of tons per year. Tesla and SpaceX CEO Elon Musk recently pledged to invest $100 million in carbon capture technology, while companies such as Microsoft, United Airlines and Exxon Mobil are also preparing to spend $1 billion in the field level of investment.
Current models suggest that humans will need to remove 10 billion tons of carbon dioxide a year by 2050; that number needs to double to 20 billion tons a year by the end of the 21st century. But right now, we're barely removing any CO2 and have to start from scratch.
Carbon Engineering's Squamish facility is designed to be a testbed for different technologies. At the same time, the company is planning to build a larger carbon capture plant in oil fields in the western United States that will sequester 1 million tons of carbon dioxide a year. After a project is complete, it becomes a replicable model by simply replicating that factory. But the scale of future projects will be incredible, we need to remove 800 billion tons of carbon dioxide from the atmosphere, and this will not happen overnight.
Unrealistic idea?
The science behind "direct air capture" is simple, and there are several ways to do it. Carbon Engineering's system uses a fan to draw air with a carbon dioxide content of 0.04% through a filter into a potassium hydroxide solution. Potassium hydroxide is a caustic chemical, commonly known as caustic potash, which is used to make soap and other potassium-containing chemicals. After potassium hydroxide absorbs carbon dioxide from the air, the solution is piped to another reaction chamber where it is mixed with calcium hydroxide (building lime). These limes absorb dissolved carbon dioxide and form small flakes of limestone. After the limestone flakes are screened off, the remaining material is sent to a third reaction chamber, the calciner, where it is heated until it decomposes to release pure carbon dioxide that can be captured and stored. At each stage, the remaining chemical residues are recycled in the process, forming a closed, repeating reaction that produces no waste.
Without such interventions, it will be extremely difficult to achieve the 1.5°C climate target against the backdrop of rising global carbon emissions. Ajay Gambier, a senior research fellow at Imperial's Grantham Institute for Climate Change and one of the authors of a 2019 paper on how DAC could mitigate climate, said: "Without direct air capture, it is possible to There are all kinds of unforeseen circumstances that will make it very difficult for us to meet the goals of the Paris Agreement.” The
IPCC does propose some models of climate stabilization that do not rely on direct air capture, but these models are critical to energy efficiency improvements and the willingness to change human behavior. Assumptions are too unrealistic. We have passed the stage where we need to reduce emissions and will rely more and more on DAC in the future.
Direct air capture is far from the only way to extract carbon from the atmosphere. We can also remove carbon naturally by changing land use, such as restoring peatlands, or planting forests—and this is the most common practice. But these processes are slow and require a lot of valuable land. It is estimated that if the area of newly planted forests is comparable to that of the United States, food prices will be pushed up fivefold in the process. In the case of trees, their carbon removal effect is limited because trees eventually die and release the carbon they store, unless felling and burning can be done in a closed system.
The challenges are just as great if you don't rely on plants, but instead use technologies such as DAC to remove carbon dioxide. In his paper, Gambier calculated that to keep up with the current pace of global carbon dioxide emissions—36 billion tons per year—it would take the construction of 30,000 large-scale DAC plants, the number of coal-fired power plants operating in the world today. more than 3 times. The construction cost of each DAC factory will be as high as $500 million, and the total cost can be as high as $15 trillion.
Each such carbon capture facility needs to be equipped with a large amount of solvent to absorb carbon dioxide. In a large enough DAC plant, capturing 10 billion tons of carbon dioxide would require about 4 million tons of potassium hydroxide, which is equivalent to 1.5 times the world's annual supply of potassium hydroxide.
When thousands of DAC factories are built, they also require a lot of electricity to operate. If this were a global industry absorbing 10 billion tons of carbon dioxide per year, it would consume 100 exojoules of energy, or about 1/6 of the world's total energy. Most of this energy is used to heat the calciner to about 800°C, which is too much for a single power source, so every DAC plant needs to be equipped with a gas furnace, as well as a readily available source of natural gas.
Cost Issues Estimates for the cost of capturing 1 ton of carbon dioxide
from the air vary widely, ranging from $100 to $1,000 per ton. Most estimates are too pessimistic, pinning their hopes on lower costs once the relevant industrial processes are widely used.
A bigger problem is finding investments. From a business perspective, saving the world is actually a hard sell, which seems unbelievable. However, direct air capture does bring a valuable commodity: thousands of tons of compressed carbon dioxide. This carbon dioxide can be combined with hydrogen to create a synthetic carbon-neutral fuel that can be sold or burned in a gas furnace in a decomposition reaction chamber (where the exhaust gas is captured and recycled).
Surprisingly, one of the biggest customers of compressed carbon dioxide turned out to be the fossil fuel industry. When wells are depleted, the remaining oil can be squeezed out of the ground by means of gas injection or chemical injection, a process known as "enhanced oil recovery". Carbon dioxide is a popular option and has the added benefit of locking the carbon underground, completing the final step in carbon capture and storage. Occidental Petroleum has teamed up with Carbon Engineering to build a full-scale DAC plant in Texas to provide about 50 million tons of carbon dioxide a year for enhanced oil recovery. A tax credit of $225 is available for every ton of carbon dioxide used in the technology.
It might be fitting to end up storing carbon dioxide from the air underground in oil fields, but ironically, the only way to finance this is to get more oil. Occidental and others hope to drastically reduce the impact of oil on carbon emissions by pumping CO2 underground; a typical intensive recovery operation where 1 ton of CO2 is stored while the newly mined oil is released 1.5 tons of carbon dioxide. So while this process reduces oil-related carbon emissions, it doesn't really break even.
There are other uses for compressed carbon dioxide that might make it more commercially viable. Another company working on direct air capture, Climeworks, currently operates 14 smaller installations that store 900 tons of carbon dioxide a year to sell to greenhouses to grow vegetables. Currently, the company is working on a long-term solution: build a plant in Iceland that will mix captured carbon dioxide with water and pump the mixture 500 to 600 meters underground, allowing the carbon dioxide gas to react with the surrounding basalt, eventually become part of the stone. To raise money, the company offers businesses and citizens the ability to buy carbon offsets, starting at just €7 a month. Will this convince the rest of the world to buy it?
"DAC always costs money, and unless someone pays you, there is no financial incentive," Chris Goodall wrote in the book, "Climeworks can sell credit to good people, and Microsoft and Stripe There are contracts to extract a few hundred tons (CO2) from the atmosphere every year, but that needs to be scaled up to a million times, and that requires someone to pay for it.”
Electric cars are heavily subsidized and solar farms are cheaply financed , but you don't see DAC getting that kind of treatment, where there's so much focus on reducing emissions, but not the same level of focus on other issues, like the amount of carbon dioxide in the atmosphere. The biggest obstacle DAC faces is that it is not taken into account when formulating policy.
DAC will follow a similar path to other climate technologies and become more affordable. Researchers are refining the cost curve, showing how quickly technology can bring down costs. Similar hurdles have been overcome in wind and solar. The most important thing is to deploy as many of these facilities as possible. Government support for the commercialization of the technology is important because it is the first customer and a very rich one.
Other researchers have argued for a global carbon tax, which would make it more expensive to emit carbon if carbon offsets are not purchased. But it remains a politically unacceptable option. No one wants to pay higher taxes, especially when many consider the externalities of a high-energy lifestyle—increasing wildfires, droughts, floods, and sea level rise—to be someone else’s burden.
We also need a broader discussion in society about the cost of these technologies. Climate change and the occurrence or exacerbation of natural disasters will impose enormous costs on human beings. We may need to get rid of the idea that DACs should be cheap.
Risks and rewards
Even if the parties agree to build 30,000 industrial-scale DAC factories, and find the chemicals needed to run them, and the money to pay for it all, humanity won't necessarily be out of the woods. In fact, we may end up worse off than before, thanks to a phenomenon called mitigation deterrence.
If you think that DAC will be in the medium to long term future, there will be no reduction in excess emissions in the short term, if the DAC plant cannot be scaled up, such as it is difficult to produce enough sorbent, or the sorbent is very fast would degrade; the technology could become trickier and more expensive than expected, in the sense that the temperature of the planet is destined to rise faster if no effective measures are taken in the short term.
Critics of DAC point out that much of the technology's appeal lies in a hypothetical promise to allow us to continue living carbon-rich lives. But for some industries that are hard to decarbonize (such as aviation), funding DAC through offsets may be the most viable option. If removing carbon from the air is cheaper and easier to do than stopping flying, DACs may be able to make a real difference in carbon emissions control.
But this is not an either-or situation, we need to reduce emissions quickly in the near term, but at the same time, we must also resolutely develop DAC to determine whether it can serve us in the future, DAC is the key to balancing carbon budget Tools, carbon that we cannot remove today, can be removed in the future.
While seeking to scale up DACs, the most important fundamental factor is proving that large-scale DACs are “feasible, affordable and available.” If Carbon Engineering is ultimately successful, the future of Earth's climate may hold promise.
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