23 Feb 2012

Rethinking Carbon Dioxide: From a Pollutant to an Asset

Three startup companies led by prominent scientists are working on new technologies to remove carbon dioxide from the atmosphere. The scientific community is skeptical, but these entrepreneurs believe the process of CO2 removal can eventually be profitable and help cool an overheating planet.
By marc gunther

With global greenhouse gas emissions still on the rise, despite decades of talk about curbing them, maybe the time has come to think differently about the climate crisis. Yes, we need to burn less coal, oil and natural gas, but clearly fossil fuels are going to be around for awhile. So why not try to clean up the mess they make?

That’s what a handful of prominent scientists are trying to do by developing technologies to remove carbon dioxide from the air. These scientists have launched start-up companies and attracted well-to-do investors — most notably Bill Gates — along with venture capital and, most recently, the attention of Wall Street. They say their technology does not need government support, though it would help. What it needs, above all, is a mindset that regards CO2 not simply as a pollutant but as a valuable commodity.

Nathaniel “Ned” David, the chief executive of a startup called Kilimanjaro Energy, puts it this way: “The single largest waste product made by humanity is CO2. Thirty gigatons a year. It’s immensely valuable, and today we just blow it out the tail pipe. What if there were some way to actually capture it, use it, and make money?”

Carbon dioxide removal, or CDR, is sometimes seen as a subset of geoengineering — deliberate, planetary-scale actions to cool the Earth — but it’s actually quite different. Geoengineering strategies are risky, imperfect,
Carbon dioxide removal is more akin to recycling waste than to playing God with nature.
controversial, and difficult to govern. The most-discussed geoengineering technology, solar radiation management, alleviates a symptom of the climate problem (warmer temperatures) but does nothing to address the cause (rising atmospheric concentrations of CO2). What’s more, geoengineering as a climate response is stuck because governments have declined to provide more than token funds for research, and there’s no business model to support it.

Carbon dioxide removal, by contrast, targets the root cause of global warming. It doesn’t create global risks. It’s being financed by the private market, and it’s more akin to recycling waste than to playing God with the weather.

Despite widespread skepticism in the scientific community, three startup companies are betting that they can make money by recycling CO2, and thereby cool an overheating planet. Kilimanjaro Energy is the pioneer. The company was launched in 2004 by Klaus Lackner, a Columbia University physicist who first wrote about air capture of CO2 in a 1999 paper. It was initially financed with $8 million from Gary Comer, the founder of Land’s End, who grew concerned about climate change after he sailed a yacht through the normally ice-bound Northwest Passage with relative ease. (Comer died in 2006.) Last year, Kilimanjaro raised another $3.5 million from a venture firm called Arch Venture Partners.

Global Thermostat, a second startup, also took root at Columbia. Its founders are Peter Eisenberger, a former head of research for Exxon who started Columbia’s Earth Institute, and Graciela Chichilnisky, who holds dual Ph.Ds in economics and math. Edgar Bronfman Jr., the former Warner Music CEO and heir to the Seagram’s fortune, has put $15 million into the
Most scientists believe removing CO2 from the air is expensive and impractical to do on a global scale.
venture, and a big private equity firm is in talks with the founders about taking a major stake in Global Thermostat. (Eisenberger and Chichilnisky wouldn’t identify the investor.)

Global Thermostat has built a small demonstration plant at SRI International in Menlo Park, Calif., that today is sucking carbon dioxide from the air. About the size of a two-story elevator shaft, the pilot module sucks air past porous ceramic blocks known as monoliths, where amines bind with the carbon dioxide; the blocks are then lowered into a chamber where they are flooded with steam that releases the CO2, and the process then repeats itself.

Finally, there’s Carbon Engineering, a startup run by David Keith out of Calgary, Alberta, the nerve center of Canada’s oil and gas industry. Bill Gates is an investor, as is his friend Jabe Blumenthal, a former Microsoft executive who is passionate about climate issues. So is N. Murray Edwards, an oil and gas billionaire. Keith, a physicist and climate scientist, has a joint appointment at the University of Calgary and at Harvard’s Kennedy School.

There’s no doubt that CO2 can be removed from the air using chemical processes. That’s how people can breathe on submarines or in spaceships. But the conventional wisdom among scientists is that it’s expensive and therefore impractical to do air capture on a global scale. Last year, a committee of the the American Physical Society produced a 100-page technology assessment, called Direct Air Capture of CO2 with Chemicals, which estimated that the cost of an air capture system would be “of the order of $600 or more per metric ton of CO2.” The report concluded: “Direct air capture is not currently an economically viable approach to mitigating climate change.”

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Carbon Engineering Air Contactor

Carbon Engineering
Carbon Engineering is developing a technology (shown in this rendering), which uses a water-based solution to “scrub” CO2 from the air.
Howard Herzog, an MIT professor, argues that it makes more sense to capture CO2 from the flue gas of power plants, where concentrations are higher — about 12 percent for coal plants or 4 percent for natural gas plants. (In the air, CO2 levels remain under 400 parts per million, which means that less than 0.04 percent of the air is CO2.) Herzog says anyone who claims that they can capture CO2 from the air at a low cost is “either not being totally honest or they’re deluding themselves.” He co-authored a peer-reviewed study in the Proceedings of the National Academy of Sciences that estimated the cost of air capture at “on the order of $1,000 per ton of CO2.”

“I am absolutely sure that’s wrong,” replies Carbon Engineering’s David Keith. In an FAQ on its website, Carbon Engineering offers a “conservative estimate” of the cost of air capture at “less than $250 per ton” of CO2 and says that it will drive costs lower. In his 1999 paper, Lackner estimated the cost of air capture as “on the order of $10 to $15 per ton,” a target that now appears wildly optimistic. This argument about about costs is crucial to the future of air capture, but it is unlikely to be settled until one of the startups begins to build industrial-scale plants.

Costs matter — a lot — because there’s substantial demand for CO2, at prices that can top $100 a ton. Most of it comes from oil companies that want to
There’s a substantial demand for CO2 at prices that can top $100 a ton.
inject liquefied CO2 into reservoirs to squeeze out stranded oil, a proven technology called enhanced oil recovery (EOR). The U.S. government estimates that state-of-the-art EOR using CO2 could add 89 billion barrels of oil to the recoverable resources of the U.S. That’s more than four times current proven reserves.

“The single largest deterrent to expanding production from EOR today is the lack of large volumes of reliable and affordable CO2,” says Tracy Evans, the former president of Denbury Resources, which specializes in enhanced oil recovery.

Each air-capture startup is pursuing its own technology and plant design. Global Thermostat plans to use residual waste heat from power plants to run its machines, while Carbon Engineering is betting on a technology known as “wet scrubbing” in which a water-based solution absorbs CO2 from air that is passed through devices known as air contactors. Each machine will require massive amounts of hardware, and thousands of machines would need to be built to have a meaningful climate impact.

All three startups intend to get their businesses rolling by selling CO2 to the oil industry. Farthest along is Global Thermostat, which has had serious conversations with a Seattle-based energy firm called Summit Power about building a demonstration plant to capture CO2 and extract stranded oil, as part of Summit’s massive, government-backed Texas Clean Energy Project. Liquid CO2 used for EOR would be sequestered underground, offsetting emissions generated when the oil is later burned. By some estimates, oil recovered that way would have roughly half the carbon footprint of conventional petroleum. This oil, the theory goes, could be made into lower-carbon transportation fuels with special appeal to customers — airlines, most obviously — that face regulatory pressure to reduce emissions.

Over time, if costs come down, air capture technology could serve CO2 markets beyond the oil industry. At least two startups have been talking to algae companies that would like to enrich air with CO2 to feed algae to
The startup companies intend to get their businesses rolling by selling CO2 to the oil industry.
produce biofuels. “Algae is the most efficient creature for making fuels, and it can’t on its own harvest enough CO2 from the atmosphere,” says Ned David of Kilimanjaro, who previously worked at Sapphire Energy, an algae firm. Capturing carbon from the air to feed algae makes possible a carbon-neutral, closed-cycle fuel — that is, one in which the CO2 released when the fuel is burned is offset by the CO2 absorbed when it is produced.

At Global Thermostat, Eisenberger and Chichilnisky talk about making transportation fuels by combining CO2 with hydrogen extracted from water. (They have formed a joint venture with an unnamed startup that they say can produce hydrogen from water at a lower cost than previously possible.) If the process could be powered by solar energy, it could produce renewable, carbon-neutral hydrocarbons for cars, trucks, ships and planes. “This has always been for me the holy grail, even back when I was at Exxon in the last energy crisis,” Eisenberger told me. “It solves the energy security issue since everyone has water and CO2 from air.” Any nation could become an oil producer.

Because greenhouse gases are dispersed around the globe, air capture can be done anywhere. This fact is key to the business plans of all three startups. Carbon Engineering’s business model, for example, revolves around what Keith calls “physical carbon arbitrage.” The company plans to build its first carbon-capture plants in places with cheap labor, cheap land, cheap construction costs, cheap natural gas to operate them and, ideally, strong demand for CO2. “If we can find all those at once,” he says, “we’re printing money.”

What this means for the environment is that carbon pollution need not be cleaned up at its source. CO2 spewing from a tailpipe in Sao Paulo or a coal plant in China can be captured by machines in Iceland or the Middle East because the atmosphere functions as a conveyor belt, moving CO2 to any sink. Air capture may prove to be the only way to absorb dispersed emissions from cars, trucks, trains, ships or planes.


CO2 Capture and Storage
Gains a Growing Foothold

CO2 Capture and Storage
Gains a Growing Foothold
In 2010, David Biello reported that the drive to extract and store CO2 from coal-fired power plants was gaining momentum. But two questions loomed: Will carbon capture and storage be affordable? And will it be safe?
It’s an exciting prospect, at least in theory. But remember — the scientific establishment says this is all pie in the sky. What’s more, for air capture to do what we’ve failed to do so far — reduce emissions on a scale that matters to climate — these tiny startups would have to spawn a giant, global industry, employing thousands of engineers and requiring many billions of dollars of investment. “If air capture is going to succeed, it’s going to take industrial might,” says Keith. To reduce atmospheric concentrations of CO2 by one part per million — they’re now at about 390 ppm, which some scientists think is too high — would require the removal of about 8 gigatons, or 8 billion tons, of CO2.

Given the obstacles ahead, most everyone who has looked at carbon dioxide removal warns that the technology cannot be seen as a license to keep burning fossil fuels. As Steve Hamburg, chief scientist at the Environmental Defense Fund, puts it, “We’ve got to mitigate emissions — that’s first, second, third and tenth.” But until we do, coming up with a backup plan can’t hurt.


Marc Gunther is a contributing editor at Fortune, a senior writer at and a blogger at His book, Suck It Up: How Capturing Carbon From the Air Can Help Solve the Climate Crisis, is available as an Amazon Kindle Single.

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Sounds like it may become, possibly, a profitable, but rather small, business?

Or could it just become another pseudo-solution that turns up having various bad side effects? Like chopping down tropical forests to plant oil palms to produce bio-diesel? While driving up food prices in poor countries?

Let them try by all means .. but if the scientific community says it is pie in the sky, and some people say it can be a good business. Hmm.

Posted by Nichol on 23 Feb 2012

"All three startups intend to get their businesses rolling by selling CO2 to the oil industry."
"What this means for the environment is that carbon pollution need not be cleaned up at its source."

It's astounding that these air capture technologies all have their hands in the continuation of one of the extractive energy industries most responsible for emissions! How is that not contradictory? Here's an idea that makes economic sense, and doesn't support palliative attempts at keeping 'extreme energy' extraction afloat for as long as possible:


Closed-loop or carbon-neutral cycles involving algae biofuels won't make a deep impact on current levels of atmospheric CO2 -- no carbon-*neutral* approach will. Carbon-negative strategies with an emphasis on drawing down carbon into soils and agriculture, as with deep-rooting perennials and biochar production, increase their capacity to store carbon the more widely they're implemented, and directly impact increased food production and local economic security. And they don't require the natural gas industry, struggling to squeeze out its final drops, in order to be deployed.

Posted by Sam S on 23 Feb 2012

While it is great to see these new technologies being considered, what appears to be entirely missing from this particular discussion of CO2 "air capture" is reforestation. Trees have a long and proven track record as global carbon sinks while also providing numerous other ecosystem services.

Some will say that trees have limited life spans and ultimately will give back their CO2 and become carbon neutral or even positive. However, entrepreneur Sir Richard Branson and others have concluded that waste biomass can be converted into "biochar" and put back into the soil where it will perform many valuable functions while sequestering the CO2 indefinitely.

Sustainable Land Development Initiative Goes Carbon Negative -

Posted by Terry Mock on 23 Feb 2012

What about the CO2 required to build and power the carbon capture equipment???? - alternatively plant quick growing trees use the wood for fuel (instead of fossil fuel) and/or construction timber instead of energy consuming steel or concrete - and its a double plus - quite simple really.

Look at the Mckinsey Carbon dioxide cost abatement curve - available in this report - carbon capture is waste of time and money:

Posted by Andrew on 23 Feb 2012

Carbon dioxide injection has been used for decades by the energy industry to enhance recovery from aging reservoirs. However, it seems unlikely this mechanism can achieve the magnitude of CO2 reduction needed to ever partially offset emissions. In addition, as I understand it, the injected CO2 serves two purposes in enhancing recovery: it pressurizes the reservoir so oil flow is restored and some of the CO2 dissolves in the oil to lower its viscosity. However, as this oil is produced, what happens to the CO2? Matter is neither created nor destroyed. If it leaks out with the product (and much of it actually does), then it isn't sequestered but merely re-emitted to the atmosphere. So in addition to re-emitted CO2, the newly produced petroleum will be burned for an overall net gain in atmospheric CO2.

Posted by Steve Boss on 23 Feb 2012

CO2 Removal fails to address the root cause of global warming as Gunther claims. It is addressing the problem only at the end of the pipe. The root causes stem from over-consumption of energy and the subsequent production of greenhouse gases as waste. To address the root causes - we need to be looking at the front end of that equation, which means reducing fossil fuel consumption and CO2/Methane production.

Geo-Engineering will play a small role in the overall carbon equation, as reflected by its absence in Stephen Pacala's nine stabilization wedges. Natural carbon sinks: soils, forests, oceans, etc, will play a much larger role. Utilizing soil and forests as sinks will go much further and will ultimately be much more cost-effective, with many other potential benefits to communities and ecosystems.

Posted by Ross Geredien on 23 Feb 2012

I just want to emphasize what a couple other posters have said:

Sequester carbon in trees/soil.

Putting money into CCS is dumb when forests sequester carbon for a fraction of the cost with a number of co-benefits. CCS is a waste of time/money/energy.

Posted by Duncan Gromko on 23 Feb 2012

Thanks for these comments.

Sequestering carbon in soil in the form of biochar is another promising "negative emissions" technology. Several biochar companies are finalists in Branson's Virgin Prize, as are the three companies written about here. It's not an either/or. We will probably need all these approaches, and more. Unfortunately, growing more trees (reforestation) won't capture enough CO2 sequester it for long enough to have a meaningful climate impact, I'm told by scientists.

It's important to understand that air capture of carbon is NOT a substitute for mitigation or for CCS at power plants. But mitigation isn't working and even if we do replace coal and natural gas plants with cleaner sources of electricity, removing CO2 from the air may be the best way to capture emissions from dispersed sources, i.e., cars, trucks, planes, etc., until clean forms of transportation fuels are developed.

These arguments will be addressed at greater length in my ebook which would be out in early March.

Posted by Marc Gunther on 24 Feb 2012

Yes, reforestation is a far simpler, more elegant and more cost-effective way to sequester CO2. Biochar can make a significant contribution to reducing global methane emissions, along with methane capture in our landfills, the use of "conservation tillage," feeding our cattle on grass rather than "cattle feed," etc. However, during the period of transition to the creation of a fully renewable global energy system, it is the achievement of significantly higher energy efficiency that will be the most cost-effective way to reduce overall CO2 emissions, and, hence, to "sequester" carbon in the most elegant way possible: by not burning it in the first place.

Our existing electric power plants are currently 30 to 34\% efficient. This exceedingly low efficiency can be more or less doubled if the waste heat from burning coal and natural gas is either used to heat nearby buildings or to heat water so that this water can be then be flashed into steam to spin a turbine and to create more electricity. This should be required by law ASAP. The same can be done with the waste heat from our industrial processes: steel-making, aluminum smelting, etc. Meanwhile, our transportation fleet can be lightweighted----made of carbon fiber, aluminum, magnesium, and superplastics----and run on a more and more renewable electrical supply, while existing buildings can be retrofitted at a comparatively low cost to significantly improve efficiency, etc.

The best way to "sequester" carbon is leave coal, oil, and natural gas in the ground and as we move toward a fully renewable global energy economy, higher efficiency will be the least expensive way to do this and thereby to radically reduce CO2 emissions, thereby eliminating the need for risible carbon sequestration schemes that have been conceived in order to benefit global oil drilling firms.

Posted by Victor Provenzano on 24 Feb 2012

$1,000, $600, $250 per ton? That's expensive! It's MUCH cheaper to not burn the fossil fuels and therefore avoid emitting the CO2 in the first place.

There are plenty of options for increasing energy efficiency and reducing CO2 emissions that will have a net benefit per ton of CO2. See

Posted by Steve Roof on 24 Feb 2012

Because most CO2 is the result of burning fossil fuels for energy, the major question for these projects is their energy cost. If they require more energy to run than the energy produced when the fuel was burned they provide a positive environmental impact only if powered by nuclear or solar energy.

Using such nuclear or solar energy directly in the economy seems likely to produce larger environmental benefits than using it to produce CO2 for use in enhanced oil recovery.

Posted by Sam Carmalt on 25 Feb 2012

Whatever happened to the work of Wallace Broecker at Columbia University and that Tuscon, Arizona company Global Research Technologies (GRT) that said they could have a greenhouse gas technology by 2010 that could economically capture a tonne of CO2 a day from the air?

Posted by Burnet on 25 Feb 2012

Excellent article. If this can be done even to a limited extent it is a giant step forward towards controlling Global Warming.

Dr.A.Jagadeesh Nellore(AP),India

Posted by Dr.A.Jagadeesh on 26 Feb 2012

Far simpler and more COST effective than CDR would be:

"Irrigated afforestation of the Sahara and Australian Outback to end global warming"


"Replacing coal with wood: sustainable, eco-neutral, conservation harvest of natural tree-fall in old-growth forests."

Combined, these could sustainably sequester more than 8 gigatonnes of carbon per year – sufficient to draw down, in less than a century, the entire excess of CO2 added to the atmosphere – from the burning of fossil fuel and from deforestation – since the beginning of the industrial revolution.

Simultaneously a valuable, low-CO2-footprint supply of wood, for use as fuel, for construction and as an input to the synthetic organic industries (plastics, etc,) would be provided.

This would be cheaper than CDR. The product (wood) would be much more valuable than the product of CDR (high pressure CO2). And the wood would be much safer to store than enormous quantities of high pressure CO2.

And, in contrast to CDR, the development of little, if any, new technology would be required!

Posted by Leonard Ornstein on 27 Feb 2012

Most estimates of percentage of CO2 emitted by deforestation and destruction of grassland ecosystems ranges from 15\%-25\%. That accounts for approximately 18-30 ppm of CO2 now in the atmosphere above perindustrial CO2 concentrations of 280 ppm.

Even if these ecosystems could be restored and 18-30 ppm removed from the atmosphere,, it would not significantly counteract all of the CO2 emitted by burning fossil fuels over the past two hundred years.

Given a growing population of 7 billion people to feed, the possibility of using large scale reforestation or conversion of ag systems to deep-rooted prairie plants is not going to happen unless we have a global pandemic.

The only way to avert runaway global warming if it is still possible is the immediate drastic reduction of fossil fuel use. I only see evidence for increased fossil fuel use. Let's face it, runaway global warming is very likely upon us.

Posted by John Schwarzmann on 29 Feb 2012

The CO2 will be taken out of the atmosphere and then either used to extract more fossil fuels (releasing CO2 back into the atmosphere), or converted into a fuel which will be burned releasing CO2 back into the atmosphere?

Has someone invented a perpetual motion machine? It sounds more like a sop to ease through the recovery of even more oil (three years worth at current rates of global consumption).

The only answer is that we completely change the focus of our societies and embrace our place in nature rather than constantly try to prove our dominance over it. Technology can't save us alone, we have to change as well.

Posted by Steve Russell on 07 Mar 2012

To me this seems like a very cool prospect with a lot of potential. What especially occurred to me in reading this article is the fact that Wall Street seems to be backing up this idea. I think a joint effort from finance experts and scientific experts makes this idea very appealing. Generally the scientific community meets the most of its opposition in attempting to mitigate the effects of global warming because their ideas generally involve losing money or foregoing the opportunity to make money. However in this case, if they really can find a way to make this a global practice at a price that is economically feasible then you are almost solving that problem in and of itself. The amount of jobs that can be created would help to stimulate the economy while at the same time combatting global warming would be killing two birds with one stone. Obviously there is a long way to go between the ideal situation and where the project is at now, but at the very least this seems like a very exciting prospect for the future.

Posted by Ann on 13 Mar 2012

Before spending vast sums of money attempting to reduce atmospheric CO2, it would pay to consider the following facts.

1. CO2 is not a pollutant, it is vital for all plant and biota life.
2. Increasing atmospheric CO2 increases plant and biological productivity.
3. There is not one piece of empirical evidence linking increased atmospheric CO2 with the warming that has occurred. (Circumstantial evidence and unverified computer models are not evidence).
4. There are multiple proofs that CO2 is not the cause of this warming.
5. Conversely there is a growing body of evidence and observation that the warming is the result of natural and normal phenomena.

Basing policy and actions on false assumptions is a recipe for disaster. Therefore it would be prudent to comprehensively check your facts first.

Posted by Ian McClintock on 09 Jun 2012

I agree with everything that Ian says. I will add that there is substantial evidence in ice core samples that shows that an increase in temperature is followed by an increase in CO2. The lag is about 800 years. The last warming that ended about 10 years ago coincides with the Medieval Warm Period about 800 years ago.

Posted by Bruce on 15 Jun 2012



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Solar Geoengineering: Weighing Costs of Blocking the Sun’s Rays
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Black Carbon and Warming: It’s Worse than We Thought
A new study indicates soot, known as black carbon, plays a far greater role in global warming than previously believed and is second only to CO2 in the amount of heat it traps in the atmosphere. Reducing some forms of soot emissions — such as from diesel fuel and coal burning — could prove effective in slowing down the planet’s warming.


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