Klaus Lackner

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.

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

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.
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

(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.

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

…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.
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

Edi­to­ri­al assis­tance: Rebec­ca Cress, Mau­reen Mitra; Thanks to Pame­la Lam­bert and Har­vey Blumm at Stuyvesant High School
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