“Think of a big tanker truck full of gas — that’s approximately your personal budget. Not for today, not this year, but forever.”

Columbia University physicist Klaus Lackner has received quite a lot of attention for his artificial “tree” invention that can suck carbon from the air a thousand times faster than real trees. The idea for the tree was originally inspired by his daughter Claire’s eighth-grade science project a decade ago, which involved extracting carbon dioxide from the air using a fish tank pump and sodium hydroxide. For his invention, Lackner also drew on the natural structure of one of nature’s most successful carbon absorbers — leaves. At Columbia University’s Lenfest Center for Sustainable Energy, where Lackner is director, he and his colleague, Allen Wright, are still finessing elements of the “tree.”

Maria Ioshpa, a senior at Stuyvesant High School, spoke with Lackner and Allen Wright about the potential of this innovation in helping tackle climate change:

Let’s start at the beginning — how do we arrive at a need for air capture technologies like an industrial material that acts as an artificial tree?

Klaus Lackner:

Some people argue about how much CO2 we are really allowed to have in the air: should the limit be 450 parts per million? Some people say no, 350 ppm was already too much. Other people are still saying 450 is all right, maybe 550 is all right. And it doesn’t really matter what you think is all right, because once you’ve gotten to that point, the only way to prevent CO2 levels from going higher is to — for all practical purposes — stop putting CO2 in the air.

Why is that?

Klaus Lackner:

If you want to stop at 450 ppm, how many tons of CO2 are in the personal CO2 budget of the average person on the planet? It turns out, about 30 tons. Think of a big tanker truck full of gasoline or jet fuel which you may have seen in an airport next to an airplane trying to fill that up — that’s approximately your personal budget. Not for today, not this year, but forever — for you, for your children, and for your children’s children. So every time you go somewhere in a car, you fill it up out of that truck. Every time you fly somewhere you pull it out of that truck. Every time you have Thanksgiving and you have a turkey and turn on the gas stove, you have to take it out of that truck — and it turns out the average person in the US goes through a truck like this in five years. So our budget is gone in five years from now. The world’s budget is gone in about 30 years from now because most people don’t consume as much as we do. Some are a little more careful with it. Some are just too poor to consume it. So at the end of the day you have not much time left to stop.

(Klaus Lackner, Director of the Lenfest Center; video by Justin Strauss)

I know this tree creation isn’t magic, although it nearly seems that way. How did you come up with the concept, how does it work, and how much does it cost to operate?

Allen Wright:

The basis is a plastic leaf that has the property of being a vehicle for “air capture.” By air capture, I’m talking about the removal of carbon dioxide from ambient air; from the air outside. If you took all the CO2 out of a block of air roughly the size of a card table, you would just about fill a teacup. Our job is to remove that teacup’s worth of CO2 from any given block of air, concentrate it, and deliver it as a stream of pure CO2. This is different than the removal of CO2 from a concentrated source, such as the exhaust from a power plant or the exhaust pipe on a car.

Consider a situation in which someone is running an old coal power plant somewhere in the world that continues to put CO2 in the air, then what can we do to compensate for the power plant’s emissions? Well, air capture, and this material [holds up artificial pine branch] allows us to take the CO2 out of the air that they have put in.

I think this won’t by itself solve the problem. Scrubbing CO2 from the air is one weapon in the arsenal; by itself it’s not good enough.

Does it matter where the CO2 is being emitted? Do you need to set up these trees in the same location?

Allen Wright:

Actually, one of the reasons we want to remove carbon dioxide from the air is to capture emissions that are occurring in other parts of the world. It turns out that the atmosphere in the world is very well mixed. So if you put CO2 into the air in California, in no time at all that CO2 is very well mixed into the air and you can very effectively take it out of the air in New York City. Now, if you put a ton of CO2 in the air, and you remove a ton of CO2 from the atmosphere somewhere else, you have effectively eliminated the impact of that ton of CO2.

This material has a funny characteristic. In a dry environment (like in the summertime on a hot day, or in the desert), this has a very strong affinity for CO2; CO2 in the air wants to bind with the molecules on the surface of this plastic. In a wet or very humid environment (like it would be here in New York in the summer, or in the tropics), the humidity causes the CO2 to come off of this material and go back into the air.

Well, that’s really neat because that means all the energy we have to use comes from the evaporation of the water off of this as it dries. So, we take this material, which is full of CO2 from being out in the air, and we scrunch it up and put it in a tube, make it wet, and all the CO2 is going to come off of this material and into the gas stream. Then, we can suck that CO2 off and we can deliver it as a stream of carbon dioxide gas. So now we have this material that is wet and empty of CO2, and all we have to do is stick this outside, and if it’s dry outside, the water will evaporate off of this material, and it will revert to the state where CO2 can bind to it again.

And so, in essence, this is a CO2 pump: it takes CO2 from the air and pumps it and delivers it into this stream. This will work over and over for years and years.

(Allen Wright, Senior Staff Associate)

How many of the tree samples that you have shown me would be necessary to reduce significantly the amount of CO2 in the atmosphere?

Klaus Lackner:

Of those little ones, an awful lot. But you have an awful lot of trees too. So we figured out how to package them for a device which can collect one ton per day and that would fit into a big truck, into a shipping container. Such a unit can collect much more CO2 than your car puts out. You don’t put a ton of CO2 out in a day.

And you would need millions of those one-ton-a-day units, but that’s not so bad if you think about it: If you had ten million such units you would take back 3.6 gigatons of CO2 a year, and right there that’s about 10 or 12 percent of the world’s yearly CO2 output. That’s a pretty good start.

If the air capture units last ten years, then each year you have to build a million new ones to replace the old ones, creating a production line of one million units a year. Now the world is producing 70 million cars and trucks a year, so we can do manufacturing on that scale — we do that with automobiles already. So we could make this happen on a scale that is meaningful.

What’s fascinating is that your process and your invention can be seen as a potentially powerful investment if we put a price on carbon.

Klaus Lackner:

I do want to point out that we are working with a private company, Kilimanjaro Energy, which is actually trying to figure out whether there is a market for CO2.

Would the creation of these air capture devices be a sort of magic pill, making people less inclined to stop the production of CO2 because of it?

We have two choices: we make it totally expensive to contribute to the problem, so that people opt not to, or we pay for whatever it takes to avoid the problem in the first place.

Klaus Lackner:

It’s a complicated question. Will this tempt you to not deal with the problem? Let me turn this around: What other options do you have?

Furthermore, I think this won’t by itself solve the problem. Scrubbing CO2 from the air is one weapon in the arsenal; by itself it’s not good enough. Clearly there are other places where other strategies are more economical. If you had a power plant and you were to scrub the CO2 out of the power plant that would be much smarter. If you had power which didn’t make CO2 in the first place that would be very useful. But you do end up with some fraction of power that for a long time will emit CO2 because we have that infrastructure, and because it’s actually very difficult to get rid of liquid fuels.

So to come back to your question regarding whether this will encourage people to ignore the problem for a while: The answer is, maybe for some people it does. But the flip side of the problem is: you may not have a choice anymore but to take back CO2. You need some way of pulling the CO2 out of the air, and forests are not quite fast enough.

How much of a role do people’s choices play in this discussion?

Klaus Lackner:

I’m not particularly an advocate for the idea that we have to give up liquid fuels. What I am arguing is that if you successfully remove the problem that liquid fuels create, and you pay for removing that problem, then there’s nothing wrong with using liquid fuels. If you can’t fix the problem or it is too expensive, then you have to find another solution. And in the long run, we cannot let CO2 pile up in the atmosphere. So we have to find answers.

Now, with individual choices it’s always easy to say, ‘I’m such a little bit that it doesn’t matter so I’m ok.’ I’m always amused when I go to a conference and we all talk about how much CO2 everybody emits, and then I proceed to ask a “dumb” question: “How did you all get here?” And the participants all came on long intercontinental airplane trips. When I follow up by asking how much CO2 each participant caused to be emitted on that flight, I am often met with a response to the effect that, since the trip was taken for a good cause, the output in that case doesn’t count. That may well be true, but if we all think that way, we’ll never fix the problem.

So we have two choices: we make it totally expensive to contribute to the problem, such that people opt not to, or we pay for whatever it takes to avoid the problem in the first place. And of course it’s not just one — there are many problems associated with fossil fuel. The first and immediately most important one is that it puts greenhouse gases in the atmosphere. But there are other issues as well. Mining is hazardous and often environmentally difficult business, so you have to figure out how to fix that too. You have work on all of these pieces, but currently the most pressing is CO2.

…if you are worried about the planet, there are still many ways to get involved. It is not one size fits all, and I can’t even tell you which one is more important.

What can the younger generation do to fix this problem? What careers can they enter to help solve it?

Klaus Lackner:

I think it’s not just one career — there are very many different paths. I would argue that what we at the Earth Institute call “sustainable development” has many different pieces to it that are so central to the problem. We’re being challenged environmentally. We have technologies to address energy and transportation issues; we have technologies for a lot of things. Where we run into trouble rather routinely right now is the environmental footprint of the things we do.

So we have to figure out how to make those footprints smaller, and that involves people from different facets of our entire society. You can decide that you want to be a political scientist, and there are plenty of relevant policy questions to address there. You can decide to become an engineer and solve the problems by looking at the engineering issues. You can become a scientist, and a lot more of science today is focused on how, precisely, the planet works and on what the environmental issues are that come with it. You can also become an astrophysicist and you would not be particularly concerned with this planet, but if you are worried about the planet, there are still many ways to get involved. It is not one size fits all, and I can’t even tell you which one is more important. Adding to that, politicians are perfectly willing to find a good solution if they feel like there is a solution, but as long as the engineers don’t provide anything, nothing much will happen. And if the engineers aren’t focused on these problems, nothing will happen either. So you have to get all of the various fields and disciplines together, and push in the right direction in whatever field you end up in.

Do you have any general advice for environmentally-conscious people?

Klaus Lackner:

That is a very difficult question. In my opinion, you have to combine realism with optimism because if you can’t do that, you feel like the problems are all so daunting and you’re not coming out of the other side. Realism means that you look at the issues and recognize that there are real problems that require real solutions and then start working on solutions. Don’t start from the premise the world is coming to an end; be an optimist, but be a cautious optimist and make this optimism real.

What can initiatives like City Atlas do to help your cause?

Klaus Lackner:

By making carbon footprints and other environmental impacts more visible, by getting people excited, you’re getting the message out there. The issue right now is that nothing happens, because there’s no political will to make it happen, and the political will can only come from informing the public. I think there are a lot of messages out there that are saying we’re all doomed, and that’s there’s nothing we can do. And that message doesn’t rally people to do something. I think it’s better to say that here’s a problem, and here’s a solution. It may not be the only solution, it may not be the best solution, but at least it means there’s a way out. This creates hope, which leads to the assurance to start asking questions like, “Can’t we do better?” And if you come up with something better, I’ll take it.

About Klaus Lackner:

Klaus Lackner is the Ewing Worzel Professor of Geophysics at Columbia University, where he is also the Director of the Lenfest Center for Sustainable Energy, the Chair of the Department of Earth and Environmental Engineering, and a member of the Earth Institute faculty. Lackner’s current research interests include carbon capture and sequestration, air capture, energy systems and scaling properties (including synthetic fuels and wind energy), energy and environmental policy, lifecycle analysis, and zero emission modeling for coal and cement plants.

Lackner earned his degrees from Heidelberg University, Germany: the Vordiplom, (equivalent to a B.S.) in 1975; the Diplom (or M.S.) in 1976; and his Ph.D. in theoretical particle physics, summa cum laude, in 1978. He was awarded the Clemm-Haas Prize for his outstanding Ph.D. thesis at Heidelberg University. Lackner held postdoctoral positions at the California Institute of Technology and the Stanford Linear Accelerator Center before beginning his professional career, and he attended Cold Spring Harbor Summer School for Computational Neuroscience in 1985. Lackner was also awarded the Weapons Recognition of Excellence Award in 1991 and the National Laboratory Consortium Award for Technology in 2001.

About the Lenfest Center:

The Lenfest Center for Sustainable Energy focuses primarily on developing the next generation of carbon capture and storage technologies, as well as technologies that will improve energy efficiency and thus reduce carbon emissions. The center, part of The Earth Institute, Columbia University, is also engaged in policy research and outreach on a variety of energy topics, with a common emphasis on sustainability and climate change.

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Photography by Justin Strauss