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How ‘mechanical trees’ pull carbon dioxide from the air and lock it away – an inventor of direct air capture tech explains

How ‘mechanical trees’ pull carbon dioxide from the air and lock it away – an inventor of direct air capture tech explains

Two men stand beneath a large structure with fans

Two centuries of burning fossil fuels have emitted more carbon dioxide into the atmosphere than can be removed by nature. As the CO2 builds up, it causes global warming. Heat traps near Earth’s surface, causing global warming. There is so much CO2 in our atmosphere that most scenarios don’t show it. ending emissions alone won’t be enough to stabilize the climate – humanity will also have to remove CO2 from the air.

The U.S. Department of Energy recently launched a new GoalTo scale up direct air captureThis technology uses chemical reactions. Capture CO2 from the air. Although federal funding for carbon capture is often criticised by some because they see it as an excuse for fossil fuel usage, carbon removal in some way will likely occur. Still necessaryAccording to IPCC reports, this is the case. Technology to remove carbon mechanically has been developed and is currently in operation. Very small scaleBecause current methods are expensive and high-energy intensive, this is partly why. But new techniquesThis year, they are being tested to see if they can lower energy demand and costs.

We asked Arizona State University Professors Klaus Lackner, a pioneer in direct air capture and carbon storage, about the state of the technology and where it’s headed.

What is direct carbon reduction and why is it necessary?

My interest in carbon management began in the early 1990s. I was struck by the fact that carbon builds up in the environment. It takes nature It took thousands of years to get rid of that CO2, and we’re on a A trajectory towards much higher CO2Concentrations far surpass anything that humans have ever experienced.

Humanity can’t afford to have increasing amounts of excess carbon floating around in the environment, so we have to get it back out.

Some emissions come from smaller sources, such as the coal industry. Power plants or factoriesThis is where we can capture CO2 directly as it comes out. So we need to deal with the other half of emissions – from cars, planes, taking a hot shower while your gas furnace is putting out CO2. This means that we need to remove CO2 from the air.

How direct air capture works.

Since CO2 mixes quickly in the air, it doesn’t matter where in the world the CO2 is removed – the removal has the same impact. Direct air capture technology can then be used to store or use the CO2.

Important is the way you store CO2. Storing CO2 for just 60 years or 100 years isn’t good enough. If all that carbon is gone 100 years from now, then all we did was take care ourselves. Our grandkids will have to do it again. In the meantime, the world’s energy consumption is growing at about 2% per annum.

One of the complaints about direct air capture, in addition to the cost, is that it’s energy intensive. Can that energy consumption be reduced?

Running fans to draw in air, and heating the CO2 to extract it are two of the largest energy-consuming activities in direct air capture. Both can be reduced by using energy-saving techniques.

For example, we stumbled into a material that attracts CO2 when it’s dry and releases it when wet. We discovered that we could expose this material to wind and it would become CO2. We could then make it wet. Let the CO2 go!It uses far less energy than other systems. The CO2 pressure rises even more when heat is added from renewable energy. This creates a CO2 gas that has water vapor mixed with it, from which we can extract pure CO2.

Two men stand beneath a large structure with fans
Climeworks is a Swiss company that has 15 plants that remove carbon dioxide.

We can save even more energy if the capture is passive – it isn’t necessary to have fans blowing the air around; the air moves on its own.

My lab is developing a method to accomplish this. Mechanical trees. They’re tall vertical columns of discs coated with a chemical resin, about 5 feet in diameter, with the discs about 2 inches apart, like a stack of records. The discs’ surfaces absorb CO2 as the air passes through. After about 20 minutes, the discs have become full and will sink into the barrel below. We then send in water and steam to let the CO2 out into a closed atmosphere. This creates a low-pressure mixture consisting of water vapor, CO2, and steam. We can recover most heat used to heat the box so that heating is not necessary.

We can save about half of our energy by using moisture, and we can use renewable energy for the remainder. This does require water and dry air, so it won’t be ideal everywhere, but there are also other methods.

Is CO2 safe to be stored for long periods of time?

I began working on the concept for mineral sequestration in 1990s as a leader of Los Alamos’ group. The world can actually put CO2 away permanently by taking advantage of the fact that it’s an acid and certain rocks are base. When CO2 reacts in a way that is rich in calcium with minerals, it forms solid carbonates. By Mineralizing the CO2Like this, we Can storeThere is an almost limitless amount of carbon that can be stored permanently.

For example, there’s lots of basalt – volcanic rock – in Iceland reacts to CO2It turns it into solid carbonates in a matter of months. Because Iceland stores CO2 for the rest the world, it could sell carbon sequestration certificates to the rest.

You can also find huge underground reservoirs that are the result of oil production in Texas’ Permian Basin. There are large saline-rich aquifers. Equinor, an energy company, has been collecting CO2 from a gas processing facility and storing it in the North Sea, about a kilometer below sea level. A million tons of CO2 every year since 1996, avoiding Norway’s Tax on CO2 Releases. We will never need more underground storage to do mineral sequestration than we have underground storage. The question is how much can we convert into proven reserve.

Lackner is shown behind a device with a leafy plant being used for testing.
Klaus Lackner tests direct-air capture technologies in his laboratory.
Arizona State University

You can also use direct-air capture To close the carbon loop – meaning CO2 is reused, captured and reused again to avoid producing more. Right now, carbon from fossil fuels is used to extract energy. You can convert CO2 to synthetic fuels – gasoline, diesel or kerosene – that have no carbon in them by mixing the CO2 with green hydrogenCreated with renewable energy. This fuel can be shipped through existing pipelines and stored for years. You can generate heat and electricity in Boston on winter nights using energy from West Texas last summer. A tankful of “synfuel” doesn’t cost much, and it’s more cost-effective than a battery.

The Department of Energy established a new goal to lower the cost of carbon dioxide removal to US$100/ton and scale it up quickly within a decade. What needs to happen to make it a reality.

DOE scares my hell because they seem to think the technology is ready. After neglecting the technology for 30 years, we can’t just say there are companies who know how to do it and all we have to do is push it along. We must assume that this technology is still in its infancy.

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Climeworks, the largest company selling CO2 through direct capture, is the largest. Around $500 to $1,000 per tonne. That’s too expensive. The world could do it at $50 per ton. I believe we can do it.

The U.S. consumes approximately 7,000,000 tons of CO2 each year. merchant CO2 – think fizzy drinks, fire extinguishers, grain silos use it to control grain powder, which is an explosion hazard. The average price is $60-$150. You have a market if your price is below $100

You need a regulatory framework to say that we demand CO2 is stored. The market will then move from capturing thousands of tons of CO2 today, to capturing gigatons.

What do you see this technology going 10 years from now?

I see a world where fossil fuels are gradually phased out, but that has a mandate for long-term capture and storage of all CO2.

Our recommendation is to match carbon with equal removal when it comes out of the ground. You should put away 1 ton of carbon from coal, oil, or gas if you produce 1 ton. It doesn’t have to be the same ton, but there has to be a Certificate of sequestrationThis certifies that it has been disposed of, and must last for more than 100 years. If all carbon is certified from the moment it comes out of the ground, it’s harder to cheat the system.

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It is unknown how hard industry, society, and the government will work to become carbon neutral. It’s encouraging to see companies like MicrosoftAnd Stripe purchasing carbon creditscertificates to remove carbon dioxide and are willing to pay high prices.

It can take a decade to get new technology to work, but if there is an economic incentive, things can move quickly. 1951 was the year that the first commercial jet became available. They were widespread by 1965.

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