Direct Air Capture

Guest Post: A "Secret Master Plan" for Direct Air Capture?

10 years ago, Tesla announced its plan to radically transform the automotive market by building electric vehicles that were more attractive than conventional combustion-powered cars. While Tesla wasn't the first company to propose such a bold vision, they set out to achieve their goals in an unconventional manner: by producing a high-end performance vehicle as their first foray into the market. Conventional wisdom at the time held that such a plan might succeed at converting some of the Porsche-driving crowd over to electric vehicles, but that it wouldn't help the billions of other drivers around the world that were unable to afford such luxury cars. Tesla saw it differently. As summarized in the company's “Secret Tesla Motors Master Plan,” Tesla planned to use the revenue and experience from niche, high-priced initial markets to build successively more affordable mass-market cars. Amazingly, that plan seems to be working.  

 Above: Tesla's unique approach to transforming the automotive industry to electric vehicles was to start in the luxury segment to gain experience and revenue. Image source: Wikipedia 

Above: Tesla's unique approach to transforming the automotive industry to electric vehicles was to start in the luxury segment to gain experience and revenue. Image source: Wikipedia 

The case study and business strategy of Tesla is highly relevant for another emerging technology with a bold vision, but facing major commercialization challenges: Direct Air Capture (DAC).  DAC technology is basically an industrial sized air filter that can extract CO2 from air and concentrate it to the higher purity needed for utilization or permanent disposal. The reason many see DAC as so important is that, even if Tesla takes over the world and makes all of our energy from renewable sources, we still will have to deal with excess carbon dioxide (CO2) in the air from past industrial activity to prevent climate change. While DAC can provide a promising technological fix to answer this challenge, it has been largely neglected in climate change discussions to date -- cast off as too expensive and something with only niche potential, much like the electric vehicles of only a few decades ago.

So what might a "Secret Master Plan" for DAC to gain market traction and global attention look like?

First Markets

If we want to get good at extracting CO2 in order to sequester billions of tons of past, present, and future emissions, it will be critical to find attractive first markets. For DAC, this is challenging, but not impossible. The biggest challenge for DAC is it's price premium against competing technologies -- much like electric vehicles had to compete against low-cost gasoline alternatives. Estimates for first-of-a-kind DAC costs are all well over $100/ton CO2, which is considerably higher than existing carbon markets and the cost of current low-cost CO2 capture processes from natural sources and/or fuel/chemical manufacturing. Fortunately, CO2 collected from DAC systems can be used to make a number of valuable, and even sexy, products today for which customers are willing to pay a premium.  

 Energy company NRG makes a shoe using recycled CO2 via  Business Insider

Energy company NRG makes a shoe using recycled CO2 via Business Insider

So which of these early markets might give DAC developers a chance to cross the commercialization valley of death, while building the policy support it will need to thrive in the future?

  • Extracting CO2 from buildings: Recent studies have shown that excess indoor CO2 reduces cognitive function. Systems that can solve this pain point can integrate with new technologies that can monitor CO2 concentrations (see FutureAir) and turn on as needed and even provide an on-demand source of CO­2. Skytree is the only DAC start-up that is currently exploring this option. The largest benefit for this application is that by placing DAC units on site, there are no direct competitors (e.g. from flue gas like in other applications).
  • Greenhouses with a passive DAC system: Greenhouses are a lucrative market for providing CO2, because operators pay between $100-200/ton CO2 to enhance plant growth. Because greenhouses do not require pure CO2, companies like Infinitree can take advantage of a passive approach to DAC that uses evaporation to upgrade CO2 to concentrations needed at a much smaller cost-premium. In addition, because DAC systems can be sited directly on site, they can eliminate the costly transportation step often associated with CO2 capture from other industrial sources. Long term cost reductions aside, it also is conceivable that there are customer segments willing to pay extra for “DAC enhanced” food, just as there is a customer segment willing to pay a premium for organically or locally grown food.
 Climeworks entry point into the DAC market is CO2 for enhancing greenhouse yields.

Climeworks entry point into the DAC market is CO2 for enhancing greenhouse yields.

  • Carbon neutral liquid fuels: dispatchable energy for a variable load. Some DAC companies, such as Carbon Engineering, are focused on making synthetic liquid hydrocarbons as their first market. These fuels can decarbonize the transport sector and be used for long-term carbon neutral energy storage. While large quantities of less expensive waste CO2 could also be available for making liquid fuels coming from power plants, by extracting CO2 from the atmosphere, renewably-powered DAC has a clear competitive advantage on the life cycle CO2 balance in niche markets willing to pay for low-carbon fuels. In addition, the modular and dispatchable nature of DAC systems can complement intermittent renewable energy infrastructure nicely.  
  • Remote and distributed niche markets. While both Climeworks and Global Thermostat also aspire to make liquid fuels and feed CO2 to greenhouses, their modularity and active processes also allow them to satisfy remote and niche demands for CO2. This includes delivering CO2 for beverage carbonation, water purification or to algae farms (for use in fuel, feed, and chemical applications). Global Thermostat uniquely can capture CO2 from both air and from power plants.
 A rendering of Carbon Engineering's plant that can be used for producing synthetic hydrocarbon fuels.

A rendering of Carbon Engineering's plant that can be used for producing synthetic hydrocarbon fuels.

Towards a DAC commercialization master plan

The jury is out whether any of the aforementioned companies have a plan that can achieve the escape velocity needed to move DAC from niche markets into mainstream applications. But if a DAC company did have a "secret master plan," I think it might read something like:

  • Find one air-to-end-use for CO2 -- and prove that DAC is a viable business, even if only in niche markets. This step must involve public demonstration and market pull -- transparency is key for showing DAC has an economic, environmental, and social value. DAC companies will need to figure out how to publish credible techno-economic assessments of their technology to prove it works, despite the (understandably) secretive nature of start-ups wishing to protect intellectual property...
  • Work with customers and governments who want to see more of it. Like any new climate solution technology, DAC needs policy and regulatory support. Tesla, after all, got a $465M loan from Uncle Sam back in 2008, and has benefited from consumer tax rebates for electric vehicles at the Federal and state level. Finding champions in government and industry will be critical for DAC to grow into new markets and come down the cost curve. 
  • As DAC becomes cheaper, seek out more mainstream consumer markets, and build on DAC's unique environmental strengths to command a premium from customers. This can help reward the early adopters and inspire new DAC supporters.
  • Act collectively to push for policies that make DAC as a negative emission technology more and more competitive over time as part of the suite of technologies needed to close the carbon cycle.

Christophe Jospe spends his time building networks to enable collective action and amplifying attention and capital to the most promising solutions that can capture, use, and sequester carbon dioxide. Click here to subscribe to his monthly newsletter. 

Socratic Dialogue on Direct Air Capture

Technologies that remove CO2 directly from air offer enormous promise to help fight climate change. Since the world agreed to ambitious long-term climate goals at COP21 that suggest a large role for negative emissions technologies, major media outlets have ramped up their coverage of the direct air capture technologies (e.g. Washington PostWall Street JournalBloomberg Business, and Forbes). But from my recent conversations with industry and government carbon capture experts, much skepticism still remains about the role that direct air capture systems should play in our response to climate change today. Below is a Socratic dialogue about direct air capture between an open-minded skeptic and a reality-based proponent.

Skeptic: I like the idea of direct air capture technology in theory, but isn’t it really expensive in practice?

Proponent: That is a reasonable question to which there is no good answer today. Entrepreneurs in the field will tell you that costs for early pilot projects are expensive (e.g. $250-500/t), but that costs can be competitive (between $50-100/t of compressed CO2) once direct air capture systems are manufactured at scale. Solar PV in the 1980s can provide an analog: costs for PV panels have come down by nearly two orders of magnitude over the past 30 years.

 Direct air capture technologies could follow steep cost reduction curves like solar PV and lithium ion batteries, but only a few projects have been built, and cost data for these projects is scant. Image via  Bloomberg and GTM .

Direct air capture technologies could follow steep cost reduction curves like solar PV and lithium ion batteries, but only a few projects have been built, and cost data for these projects is scant. Image via Bloomberg and GTM.

Unfortunately, entrepreneurs have not yet published auditable cost figures for their initial pilots. And only a few direct air capture projects have been built, so we won’t be able to confirm the slope of the cost reduction curve without further deployment.

If entrepreneurs can bring costs down around $100/t of CO2, it is reasonable to expect these technologies to gain adoption--this price is roughly the price we pay for other climate mitigation policies such as California's Renewable Portfolio Standard and its Low Carbon Fuel Standard.

Skeptic: But won't other alternatives for direct air capture like advanced bioenergy (with CO2 capture from the production process) continue to come down in price, making direct air capture uneconomic even at those long-run cost targets? Direct air capture systems have only received around $3 million in cumulative research and development funding from the U.S. Government compared to the billions spend on next generation biofuels and point-source carbon capture and storage (CCS).

Proponent: We simply don't know whether next generation bioenergy and/or point-source CCS systems will be able to be inexpensive, low-carbon, and land efficient (i.e. not competing for land with food production or ecosystem conservation)--even with billions of dollars of support going into the development of these technologies. For that reason, direct air capture offers an important hedge against sustainable bioenergy systems failing to deliver on their promise, as direct air capture systems are relatively land efficient, and can be cited in agriculturally poor areas. 

 Canadian firm  Carbon Engineering  has a pilot direct air capture facility, and aims to produce synthetic fuel using this technology in the near future.

Canadian firm Carbon Engineering has a pilot direct air capture facility, and aims to produce synthetic fuel using this technology in the near future.

But the question of whether direct air capture can compete against advanced bioenergy production might be the wrong question altogether. Direct air capture systems may prove synergistic with bioenergy production, as biofuel routes such as algae production function best at elevated CO2 levels, which requires a supply of dilute CO2. Direct air capture systems can produce dilute CO2 at much more competitive rates than they can produce more concentrated CO2. And because direct air capture systems can be sited anywhere, they can enable bioenergy facilities to be cited more flexibly and thus operate more cost-effectively.

  Climeworks  is selling developing a direct air capture project to supply CO2 for a greenhouse operation in Germany -- in the future, similar projects could supply CO2 to algae biofuels operations.

Climeworks is selling developing a direct air capture project to supply CO2 for a greenhouse operation in Germany -- in the future, similar projects could supply CO2 to algae biofuels operations.

Skeptic: But in terms of supplying CO2 for use in industrial processes (such as biofuels or even synthetic fuels production), direct air capture has to compete against myriad other industrial sources that produce higher CO2-concentration exhaust streams. For example, the atmosphere is 0.04% CO2 compared to coal power plant exhaust gas streams of 10-15% and natural gas power plant exhaust gas streams of around 5%. Thermodynamic laws dictate that lower concentrations of CO2 require more energy to produce concentrated CO2. This is begs the question: if we can capture CO2 directly from the air, can’t we employ similar processes to capture CO2 from industrial exhausts but at lower costs? Even if CO2 sources are located far from CO2 utilization/sequestration sites, CO2 is fairly inexpensive to transport via pipeline: thousands of miles of CO2 pipelines already exist across the central US, and costs on the order of $10/t.

 Map of CO2 pipeline infrastructure in the US. Via  Steve Melzer and American Oil and Gas Reporter .

Map of CO2 pipeline infrastructure in the US. Via Steve Melzer and American Oil and Gas Reporter.


Proponent: In some cases, CO2 transportation from power plant to a utilization or sequestration source is very expensive—trucking CO2 can cost upwards of $100/t. In these cases, direct air capture systems that can be sited directly at the utilization or sequestration site could make economic sense (assuming there is a source of low-carbon energy nearby). 

And in the long-run, we might need to capture and sequester more CO2 than is emitted from industrial sources to meet negative emissions targets. In this event, direct air capture will be valuable as a complement to other forms of industrial-source CO2 capture.

Skeptic: Even if direct air capture has a long-run option value, we are a long way off from reducing all of the industrial-source CO2 emissions. Why should we focus on developing direct air capture technology today, especially when direct air capture systems require carbon-free energy that could otherwise be used to displace emissions from the electricity sector?

Proponent: Direct air capture technology will likely take decades to reach long-run cost targets. Unless we get started today, we might not have affordable, scalable direct air capture technologies when we may need them in a few decades. In the meantime, some direct air capture technology developers are employing clever approaches to utilize waste heat (which cannot efficiently be converted into electricity) to power their technologies. Direct air capture systems could also serve as a variable load resource that could actually help integrate larger amounts of intermittent renewable energy into the grid (i.e. by turning on direct air capture when there is excess power production, and turning the systems off when other demand for power is high). 

Skeptic: Even if direct air capture systems are using “non-rival” renewable energy and will take decades to reach scale, every dollar spent on direct air capture R&D is a dollar not spent on the development and deployment of other climate strategies (such as solar, wind, industrial point-source CO2 capture, etc.). Isn’t the opportunity cost of investing in direct air capture too high?

Proponent: The best argument for starting the development of direct air capture today is that a diverse portfolio of investments usually performs better over the long run, and direct air capture is largely absent from the climate mitigation solutions portfolio today. There is a real option value for direct air capture as a hedge against advanced bioenergy scalability and as a complement to renewable energy deployment (as a variable load for intermittent renewables and as a CO2 supply for advanced biofuel production), which means that we should be investing some fraction of our clean energy budget in the development of these technologies today. Targeted research and development spending on direct air capture today can answer critical questions about the viability of these technologies, and we can rebalance our portfolio over time to invest more or less in these technologies once we have updated information about their value.

Skeptic: But won’t we need to spend a lot of money on direct air capture research and development to learn whether it can play a large role in the fight against climate change?

Proponent: Again, no great answer to this question exists today, as no direct air technology commercialization roadmap has been published. Professor Klaus Lackner of the Center for Negative Carbon Emissions at Arizona State University has said around $100 million of government funding would go a long way in commercializing direct air capture systems. If this $50 million technology prize for direct air capture that was introduced by Senators Barrasso and Schatz gets passed into law, then the US Department of Energy (DOE) could reach this $100 million target fairly easily with increased funding through the Fossil Energy department’s grant budget for research, the Bioenergy Technology Office’s funding for advanced biofuels utilizing direct air capture as a CO2 source, and the creation of an ARPA-E program dedicated to direct air capture technology innovation.

 The Center for Negative Carbon Emissions team at the 2016 ARPA-E conference in Washington D.C.

The Center for Negative Carbon Emissions team at the 2016 ARPA-E conference in Washington D.C.

Proponent: I hope you will see that I'm not advocating for massive investments in direct air capture instead of investments in other climate mitigation solutions, but rather for targeted research and development into air capture technologies today that enables us to learn how valuable these solutions are without wasting money.

Skeptic: I'm still skeptical of direct air capture ever reaching this potential, but this seems like a reasonable approach to me.

Check out our fact sheet to learn more about direct air capture technologies:

And what other questions do you have about direct air capture systems? Join the conversation in the comment section below or on social media @carbonremoval!

Carbon Removal Dialogue: DAC and Federal Policy

Welcome to the latest "Carbon Removal Dialogue," a feature on the Center For Carbon Removal blog where we ask experts to share their thoughts on important questions related to carbon removal. We've consolidated the responses into a single post (below) -- and please share your thoughts in the comments section as well! 

This time, the question pertains to direct air capture -- i.e. the range of techniques that sequester carbon from the ambient air (check out our fact sheet for more information on these technologies).

Thanks to all of the experts that have responded to our question, and without further ado, our direct air capture dialogue!


What changes to federal policy would have the greatest short-term impacts on the development and deployment of direct air capture systems?


David Keith

Professor - Harvard University

Executive Chairman - Carbon Engineering

A federal low carbon fuel standard with simple technology-neutral rules.

Christophe Jospe

Chief Strategist

The Center For Negative Carbon Emissions at Arizona State University

To provide the greatest short-term impacts on the deployment of direct air capture, the federal government should recognize that carbon management (ie. conventional carbon capture and storage) cannot exclusively benefit coal. This includes removing riders that preclude funding to support other technologies capable of closing the carbon loop. The EPA could extend the clean air act to allow power plants to take credit for sequestration from DAC. This will enable power plants that cannot otherwise decarbonize to explore options that allow them to stay in business. Lastly the government should also incentivize processes that remove and recycle CO2 for commercial processes for DAC.


Adepeju Adeosun


Virgin Earth Challenge

In the near term, federal policy could: i) level the playing field between air captured CO2 and fossil-fuel derived CO2 by providing subsidies or credits for superior carbon lifecycle emissions that account for recovering carbon from the atmosphere; ii) provide additional research funding into air capture R&D initiatives, along with other areas of carbon removal, which have historically been unable to secure grants; and iii) ensure air capture is deployed in a manner that leads to sustainable net-negative emissions pathways in the future, within the framework of near-term national emissions reductions, and securing 2°C-avoiding emissions trajectories.


Peter Eisenberger

Chief Technology Officer

Global Thermostat

It is worth noting that there is essentially no public support for air capture but 10's of billions for flue gas capture. That this is in spite of the fact that both the IPCC in their 2013 assessment and the US National Academy in their recent report on geoengineering both acknowledged that one cannot address the climate change without CDR from the atmosphere. They finally acknowledged the flawed analysis of the climate threat that has been the basis for our policy till now. The flaw being that one thought one could address the climate threat by a combination  emissions reductions , renewable energy use increase,and conservation efforts  because we mistakenly thought the CO2 we emitted would stay in the atmosphere for a relatively short time -under 50-100 years, instead of the 500 and above years we now know a significant portion stays in the atmosphere. The wrong focus of the efforts are accompanied by a flawed Federal Policies. Of course number 1 is no Federal R&D support and no acknowledgement of this change by DOE or the fedral government in a Policy sense. At a more detailed level the Life Cycle Analysis used is focused on Avoided Carbon,reduced emissions from power plants , which does not solve the climate threat. This LCA is used in allocating carbon tax credits and in the carbon markets. To show how distorted this is one can take CO2 out of Federally owned domes of naturally sequestered CO2 , pipeline it to Texas and possible put 1/2 back underground while pushing oil out that when burned with release additional CO2 and get a Tax Credit for the stored CO2 that was stored to begin with. One needs an LCA that is based upon the net removal from the atmosphere , negative carbon. The major other advantage of CDR from fossil fuel plant cleanup is that air capture can be done anywhere and thus where the carbon can be both removed,used , and sequestered  with the use even making the sequestration profitable. This location flexibility  is an important attribute of air capture and needs to be enabled by being able to offset emissions in one place by removal in a different place.  

Thus the three areas for public action are:

  1. Public funding of CDR technology development
  2. Use LCA that is based upon  negative carbon instead of avoided carbon
  3. Allow offsetting in addressing CDR for carbon credits and EPA compliance

Geoff Holmes

Business Development Manager

Carbon Engineering

Any specific indication that the federal government is really starting to tackle economy-wide GHG reductions and go all the way to deep emissions cuts would be hugely beneficial for our field. Even if the initial moves were small, the knowledge that policies will eventually reach a place where they demand deep cuts will encourage investors to think about low-carbon technologies and energy sources. That’s a world where we think direct air capture has an increasingly important role to play.


Noah Deich

Executive Director

Center for Carbon Removal

What the direct air capture field seems to need most urgently is demand for zero-emission concentrated CO2. To address this need, a policy instrument similar to a Renewable Portfolio Standard could work wonders -- if countries/states mandated that an increasing fraction of their emissions be offset through direct air capture, it would create a bankable demand driver that would stimulate further investments in technology research and development.  

The Good, The Bad, and the Ugly of CO2 Utilization

The concept of CO2 utilization goes something like this: instead of releasing CO2 into the atmosphere through industrial processes, we could instead capture CO2 from smokestacks (and/or the ambient atmosphere) and use this CO2 to manufacture carbon-based products -- such as fuels, food, and construction materials. So what role might CO2 utilization play in fighting climate change? The outlook seems mixed, as explained below.

The Good:

Cost-effective CO2 utilization has a number of interesting implications. First, if CO2 capture costs could come down significantly, existing markets for carbon-based products could drive reductions in carbon emission without the need for pesky-to-implement large-scale GHG regulations. Even with today's CO2 capture and utilization technology, a number of companies are successfully turning would-be CO2 emissions into valuable end products.

Above: The Skyonic "Sky Mine" CO2 utilization facility in San Antonio, TX.

Companies like Skyonic, CarbonCure, Solidia, and Newlight Technologies all show the great potential for this field to drive GHG emission reductions without the need to monetize carbon savings through regulatory programs.

Above: Newlight Technologies has created plastic building blocks from waste GHG emissions from landfills.

The Bad:

The main problem with CO2 utilization today is economics. For one, CO2 from naturally occurring underground reservoirs costs about $10-$20/t, where as capturing would-be CO2 emissions from power plants costs 5x-10x that amount. Capturing CO2 from industrial facilities that produce goods like ethanol or ammonia is more cost competitive, but such industrial facilities can only supply a limited amount of CO2 compared to the 10B+t/year of CO2 that the power sector produces. Companies like Inventys are making great innovations to drive down these costs of capture, but technology still has a fairly long way to develop before it is competitive with naturally occurring CO2.

Another factor holding CO2 utilization back is that, even if CO2 was incredibly inexpensive to capture, it still might not be cost-effective to build products out of CO2. For example, right now, fuels remain considerably less expensive to extract from the ground than to synthesize from CO2. As a result, we will have to drive down not only the cost of CO2 capture (and transport), but also that of manufacturing processes that utilize CO2 in order to make CO2 utilization cost effective.

Without cost reductions in CO2 capture technologies, CO2 utilization is only likely to make a small dent in annually GHG emissions. But while these economic challenges are significant, large-scale R&D programs for innovative CO2 capture technologies could change these economic fundamentals in a major way. The field of CO2 utilization seems similar in many way to the field of solar energy back in the 80s: in the 80s, we had solar technologies that worked, but they made poor businesses in most cases. 30 years of aggressive R&D later, solar is now challenging fossil fuels on an unsubsidized basis in many regions -- CCS could follow a similar trajectory with the right investments in R&D and regulatory support.

The Ugly:

Where it just doesn't seem like the numbers will ever truly be in the favor of CO2 utilization is when it comes to carbon dioxide removal (CDR). With CDR growing increasingly necessary, it would be great if CO2 utilization in carbon-sequestering end products (e.g. products that we make with CO2 and then don't turn immediately back into CO2 emissions) could provide significant negative emissions potential.

CO2 utilization venn
CO2 utilization venn

The potential for CDR from such carbon-sequestering end products, however, looks fairly limited today. The markets for three of the major carbon-based products -- cement, plastics, and timber (when sustainably harvested and used for other purposed besides energy production) -- are fairly modest in overall size in comparison to the prodigious ~35B tonnes of CO2 we emit into the atmosphere annually as "waste."

Carbon Mass
Carbon Mass

The above graphic show how much CO2-equivalent is consumed each year with these various end products. The graphic below translates this into the potential for these as a CO2 sink today and in 2100 (assuming 2% annual growth):

Amount of CO2 potential
Amount of CO2 potential

Links to sources: cement, plastics, timber.

The bottom line is that by the end of the century, we will need a lot more than just carbon-sequestering end products to prevent climate change -- we'll also need large scale decarbonization of the economy. Such decarbonization might rely on CO2 utilization for fuel synthesis, but it also means that we will need to pursue other ways to sequester CO2 emissions, such as by storing carbon in soils through farming techniques or fertilizers, or injecting it underground to monetize potential carbon programs.

So while it looks like CO2 utilization will make incremental gains in the fight against climate change, it doesn't look like we will be able to innovate our way entirely out of our GHG emissions problem, and that some form of regulation will likely be needed to contain global warming.

Recap: Theme of the Month - September: Direct Air Capture

This month, the Center for Carbon Removal featured the emerging field of Direct Air Capture (DAC). DAC systems work like artificial trees, using chemicals to pull large volumes of carbon dioxide (CO2) directly from ambient air, and hold significant potential to remove carbon from the atmosphere. 

 Carbon Engineering's pilot DAC plant in Squamish, BC.

Carbon Engineering's pilot DAC plant in Squamish, BC.

DAC can be a complex topic, however, so we did our best to break down the many nuances of the field in our explainer on DAC, and in our fact sheet on DAC. If you're interested in more of the specifics of direct air capture, check out the Science Fridays we posted for this month: 

 Climeworks's DAC system prototype

Climeworks's DAC system prototype

We also were excited to see a number of events on DAC this month, including the Arizona State University / National Grid event for Climate Week NYC 2015... as well as to share exciting news about some of the startups in the DAC field, like:

  • Carbon Engineering is hosting an open house on Oct. 9 in Squamish, BC
  • Climeworks plans to announce its largest project yet in a matter of weeks -- a 1,000 t/year DAC plant to supply CO2 for a greenhouse operation in Germany.

And that's just the beginning of our coverage of DAC. Stay tuned for more updates, and share your thoughts with us about Direct Air Capture as the field continues to grow!

4 non-climate reasons to like Direct Air Capture

Direct air capture (DAC) systems -- essentially artificial trees that extract large volumes of carbon dioxide (CO2) directly from ambient air -- have been touted by a number of experts as a critical-yet-missing piece of the solution to climate change. In the US, however, there are still wide swaths of the population that don't believe in climate change. Do DAC systems have anything to offer to this crowd of climate deniers (disclaimer: we at the Center firmly believe that climate change is real and our response to it should be aggressive)? It turns out, DAC systems have a number of benefits that would appeal to the staunchest climate-deniers and climate-affirmers alike, explained below:

1. Energy security. DAC systems are capable of "mining the air" for raw carbon-based inputs that can then be used for fuel synthesis.* The air is the definition of what economists call a "non-rival" good -- everyone has equal access to this source of raw materials. This means that DAC-driven fuel synthesis can reduce our dependence on foreign oil and gas supplies in a sustainable and non-exploitative manner (as well the dependence of our allies throughout the world). 

2. Jobs. DAC systems offer opportunities to generate large numbers of high-skilled manufacturing jobs. Advanced manufacturing holds the potential to revitalize communities across America, and DAC manufacturing could play a big role in this effort. 

 The Carbon Engineering team on site at their pilot DAC facility -- DAC offers new opportunities for domestic advanced manufacturing jobs.

The Carbon Engineering team on site at their pilot DAC facility -- DAC offers new opportunities for domestic advanced manufacturing jobs.

3. Non-climate environmental benefits. The extraction and transportation of underground hydrocarbons can be messy: Exxon Valdez, BP Deepwater Horizon, and the entire controversy surrounding natural gas fracking, just to name a few. DAC-driven fuel synthesis avoids the messy extraction and transportation steps associated with raw crude and natural gas extraction, making hydrocarbon fuels more environmentally sustainable in a local context.

 Oil spills can be messy -- DAC systems can be sited nearby demand, drastically reducing the likelihood of local environmental disasters. via

Oil spills can be messy -- DAC systems can be sited nearby demand, drastically reducing the likelihood of local environmental disasters. via

4. Reduced government bureaucracy. Energy companies today spend billions of dollars on exploration for new underground oil and gas reserves, and on acquiring the myriad permits and navigating the complex regulations that surround oil and gas extraction and transportation. DAC-driven fuel synthesis eliminates much of this burden -- we just have to look to the sky to find resources -- and there are no permits required to separate CO2 from the air.

*Using DAC for fuel synthesis can provide a carbon neutral recycling technology, but only when the CO2 generated by DAC systems is sequestered do DAC systems generate net-negative carbon emissions (which is the primary focus of the Center). Nevertheless, carbon neutral fuel synthesis is highly beneficial in the fight to curtail climate change, and can help pave the way for carbon-negative DAC systems in the future.

Science Special - Direct Air Capture Economics

After a long week, it's finally (Science) Friday -- which means we share our favorite links on climate change and carbon removal with you.

The American Physics Society put out a great report on the technological feasibility of direct air capture, with special consideration to costs and energy considerations. 

La Follette School of Public Affairs put out this piece on direct air capture titled, "Willingness to Pay for a Climate Backstop: liquid fuel producers and direct CO2 capture" which maps the effect of direct air capture on the fuel industry. 

Finally, this non-scientific article from The Guardian explains the short term revenue constraints to direct air capture technology development. 

Direct Air Capture Explained in 10 Questions

Direct Air Capture ("DAC") systems are an emerging class of technologies capable of separating carbon dioxide (CO2) directly from ambient air at large scale. Want to learn more about how DAC systems work and how they can help fight climate change and create a circular economy? We've got 10 Q's and A's below to get you started: 

1.      How do DAC systems work? DAC systems can be thought of as artificial trees. Where trees extract CO2 from the air using photosynthesis, DAC systems extract CO2 from the air using chemicals that bind to CO2 but not to other atmospheric chemicals (such as nitrogen and oxygen). As air passes over the chemicals used in DAC systems, CO2 "sticks" to these chemicals. When energy is added to the system, the purified CO2 "unsticks" from the chemicals, and the chemicals can then be redeployed to capture more CO2 from the air. Check out the video below explaining how Climeworks's DAC system works:

2.      What type of carbon management technology is DAC? DAC systems can be classified as carbon "recycling" or carbon "removal" technologies, depending on what happens with the purified CO2 that the DAC system produces.

  • Recycling: CO2 produced by DAC can be recycled into fuels or other products that release CO2 back into the atmosphere quickly after their use (such as greenhouses, carbonated beverages, etc.). As a carbon recycling tool, DAC systems can provide an important component of a circular economy, where the sky is mined for the raw inputs used in subsequent manufacturing processes.
  • Removal: CO2 produced by DAC that is sequestered in geologic formations underground or in materials that do not allow CO2 to escape into the atmosphere (such as cements or plastics) can generate negative carbon emissions.
 Above: a visualization of what a commercial-scale DAC plant might look like, via  Carbon Engineering .

Above: a visualization of what a commercial-scale DAC plant might look like, via Carbon Engineering.

3.      Are DAC systems classified as energy- or manufacturing-sector technologies? Unfortunately, DAC systems defy easy industry classification. DAC systems can be used to generate the inputs for manufacturing processes. But DAC systems also can operate in similar fashion to energy-sector carbon capture and storage (CCS) technologies. As a result, DAC systems can be considered an energy-sector technology, a manufacturing-sector technology--or both--depending on how it is used.

4.      What are the pros and cons of DAC as a carbon management technology?

  • Pros: Because DAC systems do not need to be sited directly at power plants, they can be sited close to sequestration/manufacturing sites, eliminating the sometimes costly CO2 transportation step associated. In addition, DAC systems take up a relatively small land footprint. A study by the American Physical Society showed that a square kilometer of DAC machines could generate around 1 million tons of CO2/year (meaning that 3 sq-km of DAC projects could offset the same amount of coal power that the Topaz Solar Field does using over 25 sq-km of land)
 The APS report shows that DAC systems can take up relatively little land compared to other renewable energy technologies such as solar or wind.

The APS report shows that DAC systems can take up relatively little land compared to other renewable energy technologies such as solar or wind.

In addition, DAC systems require no biomass inputs, so there is little competition for agricultural land (as there is with other leading carbon removal approaches).

  • Cons: High costs compared to other greenhouse gas abatement approaches.

5.      What organizations are building DAC systems today? The idea of separating CO2 from air is not new, and has been done on submarines and in space applications for decades (it would be impossible to breathe in these closed environments without CO2 capture from air). That said, large-scale DAC systems used for carbon management purposes are only beginning to emerge today, and there are no commercial-scale deployments of DAC systems as of this writing. Today, there are four leading commercial DAC system development efforts, along with one academic center pursuing DAC research:

a.      Carbon Engineering: Based in BC, Canada, Carbon Engineering is pursuing a liquid potassium hydroxide based system. They have a pilot plant in Squamish, BC set for an October, 2015 launch date.

b.      Climeworks: Based in Zurich, Switzerland, Climeworks is employing a novel sorbent coupled with a temperature swing to release the captured CO2. Climeworks has inked a commercial partnerships for CO2 recycling with Sunfire and Audi, and are building a 1,000 ton-per-year plant in Germany to supply a greenhouse with CO2 for its operations.

c.      Global Thermostat: Based in CA, USA, Global Thermostat is pursuing a DAC technology based on proprietary amine sorbents with a temperature swing for regeneration. Global Thermostat has a pilot plant up and running at the SRI headquarters in Menlo Park, CA.

d.      Infinitree: Based in NY, USA, Infinitree is using a humidity swing process for concentrating CO2. They are targeting the greenhouse market for initial customers. This technology is based on the DAC system developed by now-bankrupt Kilimanjaro Energy (formerly Global Research Technologies).

e.      Center for Negative Carbon Emissions at ASU: based in AZ, USA, this academic group headed by professor Klaus Lackner is developing a DAC technology based on a humidity swing process.

 Global Thermostat's pilot plant in Menlo Park.

Global Thermostat's pilot plant in Menlo Park.

DAC for carbon management purposes is a relatively new pursuit because separating CO2 from air is challenging to do in an economically viable way. The main reason for this is that it takes a significant amount of energy and air to separate and concentrate CO2: CO2 exists in the atmosphere in very dilute concentration compared to other chemical elements (CO2 comprises 0.04% of the atmosphere compared to about 78% for nitrogen, and 21% for oxygen). Finding chemical agents that are sticky enough to bind with the few CO2 molecules that exist in the air—but are also not too sticky so that they will easily release the CO2 in the chemical regeneration step—has proven challenging.

6.      How is DAC related to other carbon capture and storage (CCS) systems? In many ways, DAC systems are quite similar to other CCS systems, especially in regards to the chemicals used to capture CO2. Capturing CO2 from ambient air, however, is thermodynamically more challenging than capture from energy systems, as coal power plants generate exhaust gas with around 15% concentration of CO2, natural gas power plants around 5%, and ambient air has around 0.04%. This relatively dilute stream of CO2 in the air requires DAC systems to deploy novel engineering designs, as traditional CCS systems would require a prohibitive amount of energy to capture CO2 directly from the air.

7.      How much energy is required for DAC? It depends on how efficient the air capture process is, and what ending concentration of CO2 is required. To get 100% pure CO2 stream at the maximum possible efficiency, the American Physical Society report cites that it takes approximately 497 kJ of energy to generate 1 kg of compressed CO2. In other words, for every million tons of compressed CO2 generated from a maximally efficient DAC system, a power plant running at 100% capacity factor of 10 MW is required. To get to the billion ton scale of CO2 capture viewed by many experts as climatically significant, DAC systems would thus require about 10 GW of power, equal to about 3 times the capacity of the largest nuclear plant in the US.

 A visualization of what an "artificial forest" of DAC machines might look like when coupled with renewable energy, via the ASU Center for Negative Carbon Emissions.

A visualization of what an "artificial forest" of DAC machines might look like when coupled with renewable energy, via the ASU Center for Negative Carbon Emissions.

8.      How much does DAC cost? At commercial scale, no one really knows. Estimates range from around $60/ton of captured CO2 at the low end (for only CO2 capture) to $1000/ton of CO2 at the high end (for both capture and regeneration) according to a recent National Research Council study (on page 72). The eventual cost of DAC systems will likely depend on how efficient manufacturing for DAC systems becomes. Because there are no commercial scale deployments of DAC systems, however, it is very difficult to estimate how quickly costs will come down. It is likely that the first commercial-scale DAC projects will cost several hundreds of dollars per ton of concentrated CO2, but as manufacturing improves over time, these costs are likely to come down significantly, especially if DAC is manufactured modularly like many startups are attempting to do. It is also likely that operating costs will come down overtime as novel chemical structures are developed that cost less and/or require less material than existing capture chemicals.

 DAC system costs are likely to come down with larger scale deployments, much like other clean energy technologies such as wind energy have, especially if DAC systems are manufactured modularly. 

DAC system costs are likely to come down with larger scale deployments, much like other clean energy technologies such as wind energy have, especially if DAC systems are manufactured modularly. 

9.      What are the revenue opportunities DAC? In the future, carbon markets or regulations can provide large sources of revenue for DAC system operators. Without carbon prices, DAC systems are likely to find the largest revenue opportunities by providing CO2 for manufacturing fuels, or for use in enhanced oil recovery (as many oil fields are located far from CO2 pipelines, making them ideal candidates for flexibly-sited DAC systems). Smaller, high value markets (such as greenhouses, carbonated beverages, etc.) can provide early revenue opportunities. 

 Audi's "e-diesel" uses Climeworks's DAC system. Transportation fuels can provide an early revenue opportunity for DAC companies.

Audi's "e-diesel" uses Climeworks's DAC system. Transportation fuels can provide an early revenue opportunity for DAC companies.

10.   Are there any policies related to DAC today? Very few. The US Federal government has provided a $3M solicitation from the DOE to support the development of DAC systems, and there is language providing $250k for research and development in the Senate Energy and Water Appropriations Bill report language. In addition, the provincial government of Alberta in Canada has provided grant support for DAC companies through the CCEMC. DAC will benefit from ongoing policy advances around the utilization and geologic storage of CO2, and potentially from the development of carbon markets that are considering traditional CCS as a compliance option. Nevertheless, DAC systems would likely require specific policy treatment in any carbon regulatory system, and so far there has been very little discussion about how to incorporate DAC into any of these existing/potential policy structures.

Bonus question: Want to learn more? Check out our list of links related to DAC, and share your own favorite resources in the comments section!


Thanks to Avi Ringer, Matt Lucas, and Daniel Sanchez for helping to prepare this post.

Science Special - After Capture

Happy (science) Friday! Here we round up our favorite links on climate change and share them with you. This week we are focusing on what happens to CO2 after it is captured via direct air capture or from a point source. There may not be life after death, but there is life for CO2 after capture. Read more below:

This report from the Carbon Sequestration Leadership Forum explains the basics of, the concerns of, the options for CO2 utilization in a condensed, easy to read format. 

This link from the National Energy Technology Laboratory (NETL) maps current markets for CO2 that could help direct air capture (DAC) researchers develop a revenue generating business plan. 

Really interested with the science details of CO2 utilization? Read the latest issue of the CO2 Utilization Journal. 


Science Special - Direct Air Capture pt. 2

It's Science Friday - the weekly blog where we round up scientific articles on carbon removal and share them with you. We're still focusing on the potential of direct air capture, so the following take a policy oriented approached to advancing direct air capture technologies. 

This article from Pielke compares the cost of direct air capture to other stabilization technologies and concludes that direct air capture deserves to be included in international policy debate. 

In turn, this report from David Keith, discusses the effect of developed direct air capture technologies (running two scenarios - one with cost of capture and sequestration at $200/ton and another at $500/ton) on near term abatement pathways. 

This piece is a comment to the previous paper by David Keith explores the ability for direct air capture technology to be integrated to existing political and economic structures. 

See you next week! 

Theme of the Month - September: Direct Air Capture

This month at the Center for Carbon Removal, we will be featuring the work of a number of innovators building direct air capture machines. Direct air capture technologies are capable of separating carbon dioxide directly from ambient air. The concentrated carbon dioxide that these systems produce can then be used to build carbon-based products (such as cements, plastics, and fuels), or buried deep underground to receive carbon credits.

Over the next month, we will be highlighting some of the different approaches direct air capture innovators are pursuing, and highlighting innovative direct air capture companies such as:

We will also be taking a closer look at some of the academic centers pursuing carbon removal solutions, such as the Center for Negative Carbon Emissions at Arizona State University, and we'll be highlighting technical work related to direct air capture all month during our weekly Science Friday blog posts.

So share your thoughts about direct air capture with us, and we look forward to highlighting interesting stories in the field all month long!

"Carbon-removing" gas stations: the future of transportation?

gas stations
gas stations

Over the past several decades, gas stations have remained largely immune to the disruption that has radically altered other industries. But as climate change continues to increase, the imperative for innovation at the pump will start to increase significantly.

Above: A time traveler from the 1970s would recognize today's gas stations. The same could not be said about telephones...

Today, moving people and goods around the planet accounts for nearly 15% of global carbon emissions:

-images-Assessment Reports-AR5 - WG3-Chapter 01-03_figure_1.3 (1)
-images-Assessment Reports-AR5 - WG3-Chapter 01-03_figure_1.3 (1)

Above:IPCC Working Group 3 Chapter 1 Assessment Report 5 Figure 1.3

Scientists, however, are increasinglyconvinced that we will need to not just eliminate those emissions, but also remove and sequester large volumes of excess carbon from our atmosphere and/or oceans to prevent climate change. In effect, the carbon-emitting gas station of today is incompatible with the carbon-removing transportation sector that is required to prevent climate change. As a result, a central challenge for gas stations will be innovation: how can the gas station of the future remove excess carbon from the atmosphere instead of emit underground reserves of carbon into the atmosphere?

Fortunately, a handful of approaches have already started to emerge that offer the prospect of carbon-removing gas stations in the not-too-distant future:

Approach #1: Fill gas pumps with carbon-negative biofuels. Sustainably-grown biomass can be transformed through thermochemical processes into liquid fuels with a low carbon footprint. If some of the emissions associated with the biomass conversion are captured and sequestered underground, the net emissions from these fuels can be negative -- meaning that each gallon of fuel actually sequesters more carbon from the atmosphere than it emits. While biofuels already supply a significant portion of fuel consumed in the UStoday's biofuels are nowhere close to having even a net-zero emissions profile. To achieve net-negative emission profiles, then, biofuel projects will require capture and sequestration of emissions, such as the technology demonstrated at the Midwest Geologic Sequestration Consortium project.

Above: theADM ethanol production facility in Decatur, Illinoiscapturing carbon emissions and sequestering them underground.

Approach #2. Use direct air capture systems to make fuels from excess carbon in the atmosphere.Audi has recently engaged the Swiss startup Climeworks to produce a carbon-neutral gasoline alternative using the Climeworks direct air capture technology. Coupling systems like those Audi is developing with sequestration projects could eventually result in fuels with carbon-negative emission profiles.

Above:Audi makes "e-diesel" using a Climeworks direct air capture system at this plant in Germany.

Of course, the gas station of the future might not actually sell gasoline: we could ditch the internal combustion engine altogether for other types of "engines" that are powered with carbon-negative sources of energy.For example, we could transform our vehicles to run on electricity supplied by a carbon-negative power grid (which could be achieved through utilizing biomass energy with carbon capture and storage, nuclear energy with direct air capture systems, and/or pyrolysis systems that produce electricity and biochar). Another alternative would be to develop carbon-negative sources of hydrogen for fuel-cell-based transportation systems.

But exactly what the carbon-removing gas station of the future looks like is far from certain. For example, the sustainable supply of biomass could be much smaller than is needed to supply carbon-negative biofuel demand. Direct air capture systems likely would add a significant premium to gas prices (even compared to biofuel alternatives), making their widespread adoption politically/economically challenging. And the electrification of heavy-duty transportation (aviation, shipping, etc.) is notoriously difficult to accomplish, making it challenging to generate net-negative emissions across the entire transportation sector if only electrification were pursued.

So in all likelihood, the gas station of the future will look like a combination of all of the above options. But if our society is going to mitigate climate change, one thing is for certain: tomorrow's gas stations will need to be significantly different from today's.

The flawed appeal of unilateral Direct Air Capture programs to prevent climate change

For the past 20 years, UN-led climate change negotiations have failed to produce an accord that halts the rise of global GHG emissions. Given this track record, it's easy to see the appeal of the idea proposed in a recent New Republic article: that the US alone could prevent climate change by investing heavily in large-scale carbon dioxide removal ("CDR") deployments. The idea in the article goes something like this: the US (and/or some of its developed country allies) would fund a "Manhattan Project" for Direct Air Capture ("DAC") systems. DAC systems scrub CO2 from ambient air; the resulting CO2 can then be buried deep underground, where it would be trapped in impermeable rock formations. If DAC system costs fell substantially, the US alone could fund massive "artificial" forests that offset large portions of global GHG emissions.

Unfortunately, there are three major problems with this plan:

Problem #1: The hypothetical costs of the "mature" DAC systems described in the article are likely an order of magnitude too low. The article claims that:

"If $30/ton were indeed possible, the U.S. government could construct huge forests of “artificial trees” in American deserts and absorb 30 percent of 2013’s carbon emissions for about $90 billion per year..."

The problem here is that the author is quoting figures in $/t Carbon (and not $/t CO2) as is done in the rest of the article: 30/t Carbon translates to a price of less than $10/t CO2 (as a CO2 molecule weighs over three times as much as a molecule of pure C). Today, simply injecting CO2 underground and making sure it doesn't come back up -- a relatively mature process thanks to decades of enhanced oil recovery efforts -- costs around $10/t CO2. Even the biggest proponents of the field say that DAC systems are unlikely to cost less than $50-$100/t CO2 even when mass produced. Asking the US to pursue a $0.5-$1T unilateral DAC program seems significantly less feasible than the <$100B program outlined in the article...

Problem #2: The reliance on the "silver bullet" of DAC systems. There are numerous proposals for CDR systems, nearly all of which are expected to cost less than DAC systems:

CDR Supply Curve
CDR Supply Curve

Above: curve assumes midpoints of estimates of costs and supply levels from analysis by: Lomax and Addison (Virgin Earth Challenge), Ciais, et. al. (UN IPCC)

This isn't to say that we shouldn't invest in developing cost-effective DAC systems, but rather that we should invest in a broad portfolio of CDR approaches alongside other GHG mitigation techniques such as renewable energy and energy efficiency. Instead of a Manhattan Project for DAC systems, a better recommendation would be to scale up ARPA-E, SunShot, and other existing applied research programs in a way that incorporates CDR approaches and can find the most cost-effective portfolio of solutions to mitigating climate change. Which all leads to...

Problem #3: The biggest problem of all with the article is the the framing that a CDR research program would be a "hedge" against international climate negotiations not working. Instead, a robust CDR research agenda could serve as a major enabler of the success of international climate negotiations. Unilateral investments in CDR and other GHG mitigation techniques can help parties signal that they are committed to making significant GHG emission reductions, and will not free-ride off of other countries' efforts. The article claims that climate change is not a "repeatable" game, but climate change negotiations are such a repeated game. Signaling individual commitments and building trust are then critical for the players in this "prisoners dilemma" to cooperate, and investments in CDR should be seen as a complement, not a hedge, to enable this cooperation.

Bottom line: the idea of massive "artificial forests" may be an intellectually appealing way of preventing climate change, but the reality of the situation is that a broad portfolio of CDR and other GHG mitigation approaches developed through international collaboration still looks more promising -- even with the disappointing failures of this approach to date.

Direct Air Capture news narrative

E&E Publishing recently posted a story on direct air capture, that I think shows good progress for advancing the dialogue on "DAC" and CDR more generally. I think the narrative of the DAC story could be clarified in several ways:

1. Asking the right key question. The article starts with a quote from Klaus Lackner saying: "It's not a question of if air capture technology will be adopted; it's a question of when." The real question in my mind is "at what scale will DAC be adopted and for what purposes." DAC seems best suited today to provide a valuable tool for decarbonizing sectors of the economy where eliminating carbon emissions is very expensive (today air travel and long haul trucking are good examples of such hard-to-decarbonize sectors). In these sectors, DAC could be used to synthesize liquid fuels out of ambient air, like Audi is trying to do with DAC partner Climeworks, in order to provide a carbon neutral liquid fuel. But whether DAC will ever be used to generate negative emissions on the billion+ tonne scale seems highly uncertain. Today, bio-energy with carbon capture and storage (Bio-CCS) is the leading contender to generate negative emissions cost-effectively and at scale. The article's claim that "the sheer amount of carbon dioxide that has to be taken out of the atmosphere is too much for biomass alone to handle" is unsubstantiated, and flies against scientific literature suggesting that the biomass resource could be adequate for negative emissions so long as we also start abating GHG emissions quickly.

2. Placing DAC in the broader context of CDR. Even if biological sources aren't large enough to achieve all necessary CDR to prevent climate change, DAC isn't the only other option for achieving sustainable atmospheric concentrations of CO2. Mineral carbonization and the creation of carbon negative materials (like cement and plastics) could also play a key role in a portfolio of CDR solutions. Placing DAC in this context gives a more complete picture of where R&D priorities should lie.  

3. Addressing some of the hard questions early on. The article concludes by quoting Lackner again, saying: "In terms of economic viability, I don't know the answer to that; the cost of future technology is completely unpredictable." Completely unpredictable is an overstatement. We might have large confidence intervals around our predictions, but it is important to at least formulate our current understanding of how these costs might evolve over time. This will help us prioritize research and measure the progress of that development over time. Tackling these tough questions early on helps inform the dialogue on CDR to ensure that we develop the most cos-effective and sustainable responses to climate change possible.