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These machines scrub greenhouse gases from the air – an inventor of direct air capture technology shows how it works

These machines scrub greenhouse gases from the air – an inventor of direct air capture technology shows how it works

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. Excess heat is trapped near Earth’s surface, causing global warming. The atmosphere is so rich in CO2 that many scenarios do not 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 in the Air. Federal funding for carbon capture is often criticized because some see it as an excuse to continue using fossil fuels. However, carbon removal in some form will likely be possible. Still necessaryIPCC reports confirm this. Technology to remove carbon mechanically in development and operational at Very small scaleThis is partly because current methods are too expensive and require too much energy. 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?

The observation that carbon accumulates in the environment was what drew me to carbon management in the early 90s. It takes nature It would take thousands of years for CO2 to be removed., and we’re on a Trend toward higher CO2Concentrations that are far beyond what 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.

Not all emissions come from large sources. 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. So direct air capture technology can be placed exactly where the CO2 is to be used or stored.

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 this energy use be decreased?

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 in energy consumption.

For example, we stumbled into a material that attracts CO2 when it’s dry and releases it when wet. It was easy to expose the material to wind, and it would fill up with CO2. Then, we could make it moist. Let the CO2 go!It uses far less energy than other systems. The addition of heat from renewable energy increases the CO2 pressure, so we have a mixture of CO2 gas and water vapor, from which we can collect pure carbon2.

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

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. Machine 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 absorb CO2 as the air blows through them. After about 20 minutes, the discs have become full and will sink into a barrel. To let the CO2 out, we send in water and steam. The result is a low-pressure mixture consisting of water vapor & CO2. 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 make use of 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.

Can CO2 be stored safely for long-term storage?

In the 1990s, I was a leader of a Los Alamos group that began to work on the concept. 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 with CO2It turns it into solid carbonates in a matter of months. Because Iceland puts CO2 away for the rest, they could sell certificates of carbon sequestration.

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. One million tonnes of CO2 per year since 1996, avoiding Norway’s Tax on CO2 emissions. We will never need more underground storage to do mineral sequestration than we have underground storage. The question is how much of this underground storage can be converted to 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 lab.
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. People currently use carbon from fossil fuels for energy extraction. 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 has set a new goal: to reduce carbon dioxide removal costs to US$100 per tonne and to quickly scale it up within a ten year. What needs to happen to make it a reality.

DOE scares me because they make it seem like the technology is already available. 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. This technology is still in its infancy.

See Also
Is it possible to heal the damage we have already done to the Earth?

Climeworks is the largest commercial company that does direct capture. It also sells CO2 at 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 really need a regulatory framework that states we demand CO2 be put away. Then the market will shift from capturing kilotons to capturing gigatons.

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

I see a world that does away with fossil fuels gradually but has a mandate long term to capture and store all CO2.

Our recommendation is that carbon should be removed from the ground when it comes out. 1 ton of carbon produced by coal, oil, and gas should be disposed of. 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 will work to become carbon neutral. It’s encouraging to see companies like Microsoft Stripe purchases carbon creditsCertificates to remove carbon dioxide and 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 commonplace by 1965.

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