Post from old blog

Exciting blog news: Everything and the Carbon Sink is Moving to the Center for Carbon Removal!

It is with great pleasure that I announce that this blog will be moving to the Center for Carbon Removal at:! The Center for Carbon Removal is a new environmental NGO dedicated to accelerating the development of carbon removal solutions (many of which have been featured here on this blog!). Carbon-removing farms, energy systemsbuildings, and manufacturing facilities -- among many others -- hold enormous potential to transform the global economy to be more sustainable. The Center for Carbon Removal is a first-of-its-kind effort to unlock this potential through research and analysis, event organization, and information/communication campaigns focusing on carbon removal solutions.

My posting frequency has been slower than I'd like over the past few months as I've worked with an amazing team of advisers and partners to get the Center ready for launch, but our team at the Center plans to post content with greater frequency on the new site. What's more, out website ( aims to provide our community with a growing range of tools to continue the dialogue on carbon removal, discover new information about promising carbon removal solutions, and share information with other communities that are passionate about sustainability, fighting climate change, and cleantech entrepreneurship.

So please check out our new site, give us feedback and engage in conversation, share resources you think are useful, and help us grow our community by spreading the word on carbon removal via Twitter (@CarbonRemoval) and Facebook!

12 things I believe about carbon removal: June 2015

Next month marks the one year anniversary of Everything and the Carbon Sink. Having watched the carbon removal field develop over the last year, I've decided its time to synthesize my views on the topic, in hopes of revisiting and updating these beliefs as I get new information to strengthen/disabuse me of these notions. Without further ado, 12 things I believe about carbon removal:

  1. Preventing catastrophic climate change is a moral and economic imperative.
  2. Preventing catastrophic climate change requires that we limit the global mean temperature increase to 2 degrees C from pre-industrial levels.
  3. A portfolio of traditional greenhouse gas mitigation measures (renewable energy, energy efficiency, avoided deforestation, etc.) and a portfolio of gigatonne-scale carbon removal solutions (both biological and chemical) are necessary to limit temperature increases to 2 degrees C if we also want to avoid geoengineering.
  4. In the future, the portfolio of large-scale carbon removal solutions will include: re/afforestation, ecosystem restoration, carbon sequestering agriculture, biochar, bioenergy with carbon capture and sequestration, direct air/seawater capture and sequestration, mineral weatherization, "blue carbon" strategies, and likely other techniques not yet proposed/published.
  5. Geoengineering is worth avoiding, as its risks outweigh its potential benefits.
  6. Developing sustainable and economically-viable carbon removal solutions will require significant investments in research and development.
  7. Once developed, commercializing promising carbon removal solutions will require the development of markets that demand carbon removal -- carbon removal as a co-benefit alone will not be enough to reach gigatonne scale removal levels.
  8. In order to catalyze development of carbon removal technologies and markets, leaders from industry, policy, NGOs, philanthropies and the general public need to engage in dialogues about the best ways to develop carbon removal solutions -- information and discussion is needed before effective action occurs.
  9. Armed with information about the opportunities and challenges of carbon removal, a broad coalition of business and environmental interests will emerge to support the development of carbon removal solutions -- no entrenched interest gains from keeping carbon in the air, so no entrenched interests have an economic incentive to fight the development of carbon removal solutions.
  10. Opponents to carbon removal will mostly object to the specifics of how carbon removal is accomplished/implemented, not to the overall need for carbon removal to fight climate change.
  11. The few opponents that do object to carbon removal writ large will do so on grounds that A) carbon removal will lead to a moral hazard that delays action to reduce emissions and/or B) carbon removal solutions are too expensive and slow working to implement at scale.
  12. Carbon removal solutions will not lead to moral hazard around reducing emissions, as carbon removal solutions will not develop quickly enough for companies to continue emissions at large scale so long as they remove more than they emit, rendering the moral hazard argument largely a distraction.

“Pre-pay” carbon policy: how carbon removal enables regulatory alternatives

Today, there is growing bipartisan support for governments across the world to price carbon emissions. Moving from theory to practice, however, has proven challenging, as the two leading approaches to pricing carbon, carbon taxes and cap-and-trade programs, only cover about 12% of all carbon emissions globally today.

Above: the World Bank State & Trends Report Charts Global Growth of Carbon Pricing -- many jurisdictions are considering carbon pricing programs, but only a fraction of all emissions are currently covered under existing regulations.

Besides carbon taxes and cap-and-trade programs, few other approaches to carbon pricing have been proposed. But the development of carbon removal solutions – i.e. processes that remove and sequester carbon from the atmosphere – could provide an opportunity for a new type of “pre-pay” carbon pricing system that avoids many of the pitfalls of today’s carbon pricing proposals.

A “pre-pay” carbon policy might work something like this: before a company extracts a ton of carbon from the ground (be it in the form of oil, natural gas, coal, trees, soil, etc.), it would have to “pre-pay” for a credit demonstrating that the organization (or a third-party) had already removed and sequestered an equivalent ton of carbon from the atmosphere. Accompanied by an open commodity market for such “carbon removal credits,” companies would be able to comply with this policy in an economically efficient manner.

A “pre-pay” carbon pricing policy would have many benefits compared to carbon taxes and cap-and-trade policies. For one, “pre-pay” systems are intuitively fair. If a company removes an equal quantity of a pollutant that it intends to emit before it actually creates that pollution, then the company can make a strong case it is doing no harm to the environment on net. Second, a “pre-pay” policy would be administratively simple. Unlike existing cap-and-trade program designs, a “pre-pay” system has no need for setting rules about allocating emission allowances, banking/borrowing of allowances, and the use of offsets. Third, a “pre-pay” system provides a political middle ground that enables both fossil energy and environmental advocates to achieve their goals, as a “pre-pay” policy would neither kill fossil energy nor enable business-as-usual when it comes to carbon emissions. Instead, a “pre-pay” carbon policy would let the market decide whether it is more economically efficient to transition to non-fossil sources of energy or to pay for removal credits needed to continue using fossil fuels. In this way, a “pre-pay” system would look similar to both an upstream carbon tax and a cap-and-trade system. Finally and best of all, this system would lead to an immediate decarbonization of the economy on net.

A “pre-pay” carbon pricing system would have a number of significant challenges to implement. For one, it would require complex border adjustments to imported goods to ensure carbon emissions aren’t simply shuffled internationally. Second, this program would need to be coupled with strong conservation policies to ensure that ecosystems were not purposefully degraded for the purpose of then “restoring” them for carbon removal credits. Third, removal credits – be they biological or geological – would have to be stringently verified for their permanence and sustainability, requiring significant and potentially complex administration (and potentially additional scientific analyses).

But the biggest challenge and reason that a “pre-pay” carbon policy will remain purely hypothetical for the near future is the cost of carbon removal approaches. Today, many carbon removal approaches are estimated to cost over $100/ton of carbon removed, which is an order of magnitude greater than other major carbon pricing programs across the world (including the EU and California). What’s more, many carbon removal systems have not been built at commercial scale yet, so it is possible that a “pre-pay” carbon policy would even be technically infeasible to achieve in the near-term.

Carbon Removal Costs and Scale
Carbon Removal Costs and Scale

Above: while the estimated scale potential for carbon removal solutions is large, so too are the estimated costs of carbon removal systems.

If carbon taxes and cap-and-trade programs continue to languish as politically infeasible, however, we will need some way to efficiently reduce net carbon emission levels. And even if other carbon pricing systems do take off, a complementary “pre-pay” policy could prove beneficial for stimulating early commercial demand for carbon removal solutions. As such, investing today in research and development to lower the cost of carbon removal approaches and to improve the efficiency of monitoring and verification efforts would have an enormous payoff if it led to a politically feasible “pre-pay” carbon policy.

How today's "low-carbon" investors are charting a course for financing tomorrow's "negative-carbon" investments

IEA investment
IEA investment

In 2014, investors allocated $310B in capital to clean energy projects according to Bloomberg New Energy Finance, making up a significant portion of the ~$1.5T in total global investment in energy supply as estimated by the International Energy Association ("IEA"). What's more, the IEA predicts we will need over $40T in cumulative energy investment by 2035 to meet energy needs, suggesting that the amount of capital needed to be deployed annually for clean energy projects will have to increase by an order of magnitude over the coming decades to meet the dual goals of preventing climate change and powering the world's economy.

Above: The IEA's 2014 World Energy Outlook projections for necessary clean energy investment.

As the clean energy finance community grows, it also pioneers new ways to finance low-carbon energy projects. The past few years are no exception: publicly-traded yieldcos have flourished, asset-backed securitization has helped reduce cost of capital for distributed generation companies, and public-private partnerships have helped increase clean energy deal flow.

These financial innovations that enable low-carbon projects have enormous implications for "negative-carbon" projects that scientists increasingly project we will need but that have only just begun to develop. Low-carbon technologies like energy efficiency and renewable energy have had several decades to de-risk technical, regulatory, and financial barriers, and sit well poised to expand rapidly. Negative-carbon approaches must leverage as much of the experience of low-carbon projects as possible if they are to develop to appropriate scale quickly enough to prevent climate change.

Later this month, many low-carbon financial success stories will be on display at the Low Carbon Energy Investor Forum 2015 in downtown San Francisco. I'm excited to be speaking at the event, as the agenda includes conversations on emerging financial innovations, technology developments, and policy support needed to scale low-carbon developments.

What is particularly interesting to me about this, however, is that for an event with the words "low carbon" in the title, the word "climate" appears only once on the agenda -- for a session titled "Climate Change – The new factor becoming mainstream among investors." This shows that, with or without an explicit mandate to fight climate change, the financial sector is committing hundreds of billions of dollars to technologies that are pivotal for fighting climate change. And as much as any financial lesson, negative-carbon solutions can learn from low-carbon solutions the power of strong financial business cases in helping to catalyze the growth of negative-carbon solutions, and make these nascent investments today the "mainstream" investments of the future.

Want to join the Low Carbon Energy Investor Forum? Use the code "lcei15" for a 15% registration discount.

Weekend Links

Pathways to carbon-removing energy:

Agriculture and Forestry:


Throwing the Carbon Capture Baby out with the Coal Bath Water

The environmental advocacy group Greenpeace recently released a report lambasting carbon capture and storage (or "CCS") as "a false climate solution" that "[i]n no uncertain terms...hurts the climate." The Greenpeace analysis, however, made a number of assumptions that fit the conventional wisdom surrounding CCS, but when analyzed with greater scrutiny turn out to be deceptively misleading. Misleading Assumption 1: CCS requires that we prolong coal use. Can we have CCS without coal? From a technical point of view, of course. The California Energy Commission just held a workshop on natural gas power generation and CCS, a handful of companies and researchers are working on direct air capture systems that can pull carbon from ambient air, and researchers across the globe have begun thinking about carbon-negative bio-energy and CCS projects. It may be politically infeasible to start developing CCS on these non-coal resources, but a compromise could be to ensure that we phase out coal CCS in favor of non-coal CCS. Regardless, it's too early to say whether these non-coal (and even renewable!) CCS systems can play a large role in fighting climate change, because we simply have not done enough research and development to have good data on these systems. Throwing out renewable CCS today as the unrealistic dreams of "techno-optimists" is analogous to stopping the development of solar energy back in the 1970s because it was over 100 times more expensive than it is today.

(Update: presentations from CEC workshop on natural gas + CCS available here.)

Solar PV chart
Solar PV chart

Above: Data from Bloomberg New Energy Finance

Misleading Assumption 2: It is inevitable that CCS will lead to increased EOR. Can we do CCS without EOR? Yes. There are a number of demonstration plants across the world injecting CO2 underground that involve no EOR. If we don't want EOR, we simply need to regulate CCS so that it can be cost-effective without additional fuel production. Such a pathway will increase the cost of CCS, and there is a much more valid and nuanced debate than what the Greenpeace analysis provides on whether we should pursue EOR in combination with CCS that focuses on using EOR as a pathway to net-negative emissions. But if we wanted to assume that EOR was entirely undesirable, we could still have CCS -- it would just cost more than it would in conjunction with EOR.

Misleading Assumption 3: Underground storage of carbon is required for sequestration. Does carbon have to be stored underground? No. We can turn it into cement, plastics, or any number of other solid products. Will there be issues with storing large volumes of solid carbon above ground? Probably. But we can get around the geologic sequestration problem if we wanted to accomplish this goal.

So can CCS hurt the climate if done wrong? Certainly. But is Greenpeace justified in saying that "in no uncertain terms" CCS "hurts the environment?" Certainly not.

As a result, I remain unconvinced that we should throw out CCS as a climate solution today. Instead, environmental advocates should strive to make clear all of the potential pitfalls of CCS, and ensure that its development balances these environmental and social concerns with the economic considerations of the companies and regulators responsible for deploying these solutions. If you think coal is bad, fight coal. If you think EOR is bad, fight EOR. If you think geologic sequestration is bad, fight geologic sequestration. But we can make a world where coal, EOR, and geologic sequestration do not exist but where large-scale CCS still flourishes if we so choose. While this world might seem far from reality today, it might be the only world where we can prevent catastrophic climate change, as most renewable energy solutions (like wind, solar, geothermal, etc.) are not capable of generating the net-negative emissions we likely need to prevent climate change.

Carbon removal wedges
Carbon removal wedges

Above: adapted from the Climate Institute "Moving Below Zero" report 

So let's stop entangling CCS inappropriately with arguments against related energy systems, because we can decouple CCS from these system is we choose. If we keep conflating CCS with these other arguments, we risk throwing out the CCS baby with the coal bathwater.

"Legacy" Emissions and Beyond-Neutrality Corporate Emission Reduction Targets


  • Corporations need not only to stop emitting greenhouse gases ("GHGs") to prevent climate change, but they also need remove and sequester "legacy" emissions from the atmosphere.
  • Corporate GHG emission reduction targets set at levels above 100% create new challenges for corporations around measuring their past emissions, setting appropriate targets, and deploying strategies to remove carbon from the atmosphere.
  • Despite the challenges, the new opportunities for value creation from carbon removal for corporations are significant.



A number of large companies have recently introduced pledges to eliminate carbon emissions entirely in their efforts to fight climate change and grow in a sustainable manner. While eliminating future emissions is an important first step on the pathway to stabilizing our climate, few companies are talking about how they can deal with the fact that a significant percentage of their emissions from previous decades of doing business still remain in the atmosphere, contribute to climate change, and affect the sustainability of their operations going forward.

Scientific context. Carbon dioxide is considered a "long-lived" pollutant, meaning that it resides in the atmosphere for centuries (on average). This leads to a pesky problem -- we could decarbonize our economy entirely, and we still could face the consequences of climate change caused by pollution from decades past. As a result, it is increasingly likely that we will need to employ carbon removal solutions -- i.e. processes capable of removing and sequestering carbon from the atmosphere. While there is increasing activity to develop such carbon removal solutions, proven and scaleable carbon removal solutions have yet to emerge.

Challenges for corporations. Carbon removal creates a number of challenges for corporations seeking to set meaningful GHG emission reduction targets.

  • Measurement. It is frequently difficult for companies to asses their historic contributions to carbon emissions. Companies can usually get a rough order-of-magnitude estimate of historical emissions, but it is very difficult to tell using legacy systems that might not have captured necessary data to get a more precise estimate.
  • Targeting. Even if companies have a good sense of their total historical emissions, it can be difficult to set reduction timelines. New science-based methodologies are being developed to help inform forward looking targets, but it is unclear whether they will incorporate negative emissions.  A more fundamental question is how companies might deal with legacy emissions not directly attributable to them, but that still affect how they do business in the future.
  • Action: Given the current state of development of many carbon removal approaches, companies could face challenges around generating scalable and verifiable net-negative emission levels. Many carbon removal approaches today are expensive to deploy and/or measure, so companies are unlikely to deploy these such technologies at scale without further development.

Opportunities for corporations. Despite the challenges associated with adopting greater than 100% emission reduction targets, corporations that strive for such targets stand to seize valuable business opportunities -- even in the sort-term.

CDP 2012 data
CDP 2012 data

Above: data from the CDP 2012 disclosure scores, with my own analysis of carbon removal potential. 

For one, carbon removal offers new growth opportunities for companies thinking about providing carbon-negative products and services. Today, startups like Newlight Technologies are developing carbon-negative plastics that can substitute directly for carbon-emitting products -- similar carbon-removing products could provide a great way for companies in commoditized industries for differentiating their offerings.

Above: AirCarbon packaging used by Dell. Source:

In addition, carbon removal solutions can help improve operational and supply chain efficiency. For example, agricultural carbon removal solutions such as restorative farming approaches hold the potential for increasing crop resilience, reducing water and fertilizer needs, and even enhancing yields.

Columbia Field Trials

Above: biochar field trials. Source: International Biochar Initiative.


Lastly, corporations that move early to set net-negative emission reduction goals stand to generate large brand leadership benefits. Consumers are hungry for innovative climate solutions, and are likely to reward corporations for their leadership in enabling consumers to vote with their wallets for carbon-removing products and services. With strong corporate leadership and academic partnerships, we could start seeing carbon-negative products across numerous industries, including: foods, cements, fertilizers, and even gasoline.

Moving forward. It is clear that companies still have a long way to go just to get to carbon neutrality. But it is important for corporate managers to think about how the long-term pathway to sustainability might involve net-negative emission reduction targets, and how early movers can start generating value through carbon removal today. Right now, little changes in reporting standards and protocols could go a long way to achieving this potential. For one, the CDP could update its Leadership Index and the GRI could update its reporting guidelines to encourage companies to employ net-negative emission strategies. In addition, the LEED green building rating system could encourage the use of more carbon-removing materials. But most importantly, early corporate leaders will have to stand up and commit to a "beyond-neutrality" goal, and show that it is possible to make steady progress towards that goal with a combination of the mitigation technologies of today and the carbon removal solutions that hold promise for our future.

Carbon-as-a-service Businesses?

The Cleantech Group's annual San Francisco Forum wrapped up earlier this week. The event's theme was "Cleantech-as-a-service," and featured parallel tracks named "Cloud" and "Connect." Overall, this focus on technology-enabled business model innovation shows how mature the cleantech field has become, as the event felt very much like a "standard" tech conference in the Bay Area.

Above: Sheeraz Haji kicking off the Cleantech Forum SF 2015 event.

The growing emphasis on the "tech" portion of "cleantech," however, has not caught on for all clean technologies. For example, carbon sequestration businesses were conspicuously absent from this year's Forum. Economic fundamentals can help explain this lack of carbon sequestration businesses on display. Most of the discussion at the Cleantech Forum focused on the left-hand side of the McKinsey GHG abatement curve (below), which makes perfect sense: no amount of clever business model or financial product innovation will help uneconomic businesses (like many carbon sequestration businesses today) flourish.

mck ghg abatement
mck ghg abatement

Above: McKinsey GHG Abatement Cost Curve

The big exception to the above, however, is solar PV -- which many would call the poster child of the cleantech-as-a-service revolution. What has set solar apart from other high dollar-per-ton GHG abatement schemes is non-carbon-focused regulations (be it some combination of net-metering, renewable portfolio standards, PACE financing, etc. designed to specifically support renewables).

What is so striking is how little acknowledgement such policies now get in the cleantech conversation. Business model innovation is highly complementary to environmental policies, yet so few of the leaders on stage at the Forum advocated for additional/ongoing policy support. I worry that the focus on business model / financial innovation will only take the cleantech field so far (or will delay its development considerably), preventing us from achieving the rates of decarbonization necessary to prevent climate change.

When former EPA Administrator Lisa Jackson came to speak at Berkeley on March 12th, she remarked that her job at Apple today is still to make good policy, it is just to do it from inside of business instead of inside government. I am eager to see if this philosophy will gain broader acceptance, and I look forward to the discussion at future Cleantech Forums to track how this dialogue unfolds.

How weight loss can put carbon removal in perspective

Six years ago, then U.S. Secretary of State Hillary Clinton compared climate change to weight loss:

"You know, oftentimes when you face such an overwhelming challenge as global climate change is, it can be somewhat daunting,"


"If we keep in mind the big goal, but we break it down into baby steps - those doable, achievable objectives - we can do so much together."

Clinton's analogy comparing fighting climate change to weight loss can be extended to help put carbon removal in context. In this analogy:

  • Conservation and mitigation: analogous to going on a diet. The no-brainer strategy for starting to lose weight is to eat fewer calories, just like the no-brainer strategy for preventing climate change is to reduce carbon emissions from activities such as burning fossil fuels, deforestation, and intensive industrial agriculture.
  • Removing carbon from the atmosphere: analogous to exercising. Sometimes diet alone isn't enough to lose weight, exercise is needed too. In the same way, simply stopping carbon emissions might not be enough to prevent climate change -- we might also need to remove excess carbon from the atmosphere and/or oceans. And even if we could prevent climate change without carbon removal, pursuing carbon removal strategies slowly and in moderation is likely to be beneficial regardless, much in the same way that moderate exercise is healthy regardless of whether it is necessary for weight loss.
  • Adapting to changes in the climate: analogous to buying new clothes. Buying new clothes does nothing to help you lose weight -- but it does make like more comfortable while you are overweight. No doctor has ever said, "it's OK to be obese -- you can adapt to this condition by planning what new clothes you should buy as you grow larger..." just like scientists largely agree that climate adaptation is no substitute for preventing climate change in the first place.
  • Albedo modification geoengineering techniques: analogous getting lap-band surgery. Lap-band surgery can have devastating side effects and so is only recommended in extreme circumstances. What's more, the procedure only works in conjunction with diet and exercise. In the same way, albedo modification geoengineering techniques are viewed as highly risky and uncertain, and require dramatic emission reductions and carbon removal for them to be phased out.

"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.

A busy week in Carbon Removal: February 8-15, 2015

The second week of February, 2015, proved to be a busy week in all things carbon dioxide removal (“CDR”). First and foremost, the National Academy of Sciences came out with an extensive report on CDR that garnered significant media attention (including my own). The full report is worth the read, but if you only read two lines, I'd recommend the following in terms of importance for the CDR field:

"Even if CDR technologies never scale up to the point where they could remove a substantial fraction of current carbon emissions at an economically acceptable price, and even if it took many decades to develop even a modest capability, CDR technologies still have an important role to play.”


“If carbon removal technologies are to be viable, it is critical now to embark on a research program to lower the technical barriers to efficacy and affordability while remaining open to new ideas, approaches and synergies.”

Second, a great article was published in Nature Climate Change on the potential for bioenergy with carbon capture and storage ("bio-CCS") to generate net-negative electricity for the Western US. A summary of the report is available from UC Berkeley, and the research has garnered considerable outside media coverage. The biomass fuel supply curve developed by the report's authors is particularly interesting, and suggests that 100MM+ ton CDR from bio-CCS is possible in the western US largely from waste and residue feedstocks (which hold the potential to be more sustainable than dedicated feedstocks, assuming wastes aren't valued for other competing uses...).

Supply curve of available solid biomass post-2030.

Above: Biomass supply curve in Western US from Nature Climate Change "Biomass enables the transition to a carbon-negative power system across western North America"

Third, the AAAS Annual Meeting hosted a session titled, “Going Negative: Removing Carbon Dioxide From the Atmosphere” that looked into a wide range of CDR-related issues. The highlights from the session included:

  • Pete Smith from the University of Aberdeen kicked off the session with the conclusion that there is no magic bullet for CDR – pros and cons exist for all approaches – and that more RD&D is needed to develop viable CDR approaches. In addition, Pete noted that sustainability will be critical for developing CDR solutions, and that a negative emission technology strategy will have to develop hand in hand with food-, water-, and biodiversity-security strategies.
  • Jen Wilcox from Stanford summarized some of the key findings from the NAS report on CDR. One of the more interesting results she highlighted was from a paper she authored that estimated the amount of CDR potential in the existing fly ash, cement kiln dust, and iron/steel slag industries today -- which could present low-hanging fruit for turning today's industrial wastes into valuable inputs for tomorrow's CDR process (even though the study finds that such industrial sources represent about 0.1% of total US emissions). More importantly, Jen highlighted that CDR and CCS technologies share a number of open research questions, and could benefit from an overlapping research agenda.
  • Peter Byck from ASU presented his video Soil Carbon Cowboys and discussed the exciting scientific research his team is planning to conduct to assess the potential of adaptive management practices of livestock rearing. And Lisamarie Windham-Myers from the USGS shared her work with soil carbon sequestration, highlighting groups like the Marin Carbon Project
  • The final two presentations of the session, from Ken Caldeira of Carnegie Institution for Science  and Jae Edmonds of Joint Global Change Research Institute, provided an interesting point of conclusion for the session. In particular, Jae's work showed that integrated assessment models of energy systems enthusiastically build bio-CCS projects as a means to decarbonize the energy sector. Bio-CCS (as well as its cousin direct air capture and sequestration, or "DACS") are highly industrial systems, which contrast greatly to the ranching and "carbon farming" techniques highlighted by Peter and Lisa Marie in the previous two sessions. The industrial CDR approaches lag far behind the biological approaches in terms of early enthusiasm outside of the academic community, and it will be critical for these industrial approaches to find an enthusiastic supporter base in industry (or elsewhere) for them to gain traction and meet the promise identified in the integrated assessment models.

Fourth and finally, interesting CCS innovations were on display at the ARPA-E conference in DC. Such innovations from ARPA-E programs like IMPACCT will prove critical for enabling both fossil and bioenergy CCS projects in the future. CCS was only a small fraction of the overall ARPA-E conference, and the session dedicated to CCS focused on the nascent market for utilizing CO2 in industrial applications. I am hopeful that the ARPA-E conferences in the future will highlight more innovations with shared CDR applications, including direct air capture, gasification, and thermochemical biomass conversion technologies.

What "net-zero" emission targets means for the carbon removal field

The Carbon Brief recently published a fantastic article explaining the implications of “net zero” climate targets in the context of international climate negotiations. The Carbon Brief article does a great job of highlighting the fact that “negative emission technologies” – or carbon dioxide removal (“CDR”) approaches are critical for enabling the global economy to achieve a "net zero” commitment. The article goes on to note that, “however, there are clear limits to negative emissions and many options...remain unproven.”  The emphasis is mine, as I think this fact has enormous implications for preventing climate change.  Without proven, scalable, and sustainable CDR solutions, “net-zero” targets will prove highly challenging to meet: “net-zero emission” would become simply “zero emission” targets – certainly doable, but today looking far from certain from occurring.

A “net-zero” (let alone “below-zero”) target, then, risks being an empty goal if such targets are not accompanied by increased efforts to develop CDR technologies. A recent report on CDR from the National Academy of Sciences highlights that:

“If carbon removal technologies are to be viable, it is critical now to embark on a research program to lower the technical barriers to efficacy and affordability while remaining open to new ideas, approaches and synergies.”

The NAS study stops short of identifying details of what research is needed to develop scalable, sustainable, CDR solutions, and there is little talk in established science/technology R&D funding agencies about scaling up levels of CDR R&D. So as talk of “net zero” targets increase, so too must conversation about increased R&D funding for CDR in order to make such “net zero” targets credible.

Media coverage of carbon removal post-NAS report

In past several days, numerous media outlets have weighed in on the National Academy of Sciences ("NAS") report on "climate interventions" (including yours truly). The Carbon Brief does a great job of aggregating these responses, which reveal both positive and negative signs for future discourse on carbon dioxide removal ("CDR") -- i.e. removing and sequestering excess carbon from the atmosphere and oceans. The main negative sign is that many media outlets are still conflating CDR as “geoengineering” alongside Albedo Modification ("AM") – despite the fact that the NAS report specifically fought against this this confusion:

"Carbon Dioxide Removal and Albedo Modification (i.e., modification of the fraction of short-wavelength solar radiation reflected from Earth back into space) have traditionally been lumped together under the term “geoengineering” but are sufficiently different that they deserved to be discussed in separate volumes.”

For example, the review from the Guardian quotes Eli Kintisch from Science Magazine who describes both CDR and AM as “a bad idea whose time has come.”

The Union of Concerned Scientists response does a better job of separating CDR from AM in its coverage. But their coverage, which focuses on the conclusion that "carbon removal and sequestration are more costly than reducing emissions,” risks leaving their readers with the wrong impression that we shouldn't invest in developing CDR systems today. In fact, the NAS report highlights that it is very important to invest in developing CDR systems in addition to rapidly scaling up climate mitigation and adaptation solutions (given the importance of viable, sustainable, CDR options in the event we do not decarbonize as quickly as necessary to prevent climate change). CDR solutions are in a similar state of development as solar energy solutions were in the 1970s -- concluding that such 1970's solar projects were "expensive" misses the point that large cost reductions were possible and, if achieved, could prove transformative to our energy industry.

The best news I see from this coverage is that there seems to be little opposition from mainstream outlets to CDR (definitely not the case with AM). The only opposition to CDR comes from the Guardian article, which cites Naomi Klein and Rachel Smolker from Biofuels Watch as detractors. The overwhelming majority of leading NGOs, policy, and industry leaders have not called for CDR research and development to be limited, which is highly encouraging for the CDR field .

Recap and Commentary: National Academy of Sciences Report on Carbon Removal

Earlier today, the National Academy of Sciences (“NAS”) released a comprehensive study dedicated to carbon dioxide removal (“CDR”). To date, CDR has largely been relegated to the fringes of the conversation on climate change, despite the fact that major reports from the IPCC and the UN Environment Program have noted that CDR will likely be critically important for preventing climate change. Two factors have likely contributed to CDR’s position on the sideline for the climate conversation:

  1. CDR solutions have historically been conflated with the too-risky/speculative-to-even-research Albedo Modification (formerly Solar Radiation Management) “geoengineering” techniques
  2. Most CDR solutions cost more than other greenhouse gas (“GHG”) abatement approaches (e.g. solar, wind, energy efficiency, avoided deforestation, etc.), leaving little economic incentive for CDR approaches to develop organically.

The release of the NAS report takes important steps towards reducing both of these barriers for CDR to enter the mainstream climate change conversation. First, the NAS released two distinct reports – one on CDR and the other on Albedo Modification – with language explicitly stating that these two categories of “climate interventions” should not be analyzed together. Second, the report unequivocally endorses expanded R&D funding into CDR approaches, in hopes that such funding will enable the eventual commercialization of these CDR approaches.

The NAS analysis stops before identifying the necessary R&D required for developing and commercializing CDR solutions. But this report has hopefully cleared the way for this conversation to happen – along with the many other mainstream policy and industry discussions necessary for the development of CDR solutions.

The NAS study is worth the full read, but I have pulled out a handful of key sentences and figures from the report, below, along with some commentary on their context to the overall conversation on CDR and preventing climate change:

The definition of CDR according to the NAS:

The NAS study defines CDR as:

Carbon Dioxide Removal (CDR)—intentional efforts to remove carbon dioxide from the atmosphere, including land management strategies, accelerated weathering, ocean iron fertilization, biomass energy with carbon capture and sequestration (BECCS), and direct air capture and sequestration (DACS). CDR techniques complement carbon capture and sequestration (CCS) methods that primarily focus on reducing CO2 emissions from point sources such as fossil fuel power plants.”

Under the umbrella of CDR, the NAS identifies two broad classes of CDR approaches:

1. “Some carbon dioxide removal (CDR) strategies seek to sequester carbon in the terrestrial biosphere or the ocean by accelerating processes that are already occurring as part of the natural carbon cycle and which already remove significant quantities of CO2 from the atmosphere.”

2. “Other CDR approaches involve capturing CO2 from the atmosphere and disposing of it by pumping it underground at high pressure”

A graphic that I’ve created to understand how these CDR pathways are related to each other and to non-CDR pathways is below:

CDR pathways 3
CDR pathways 3

Note 1: the NAS study includes ocean iron fertilization, which I haven’t included in the above graphic because “previous studies nearly all agree that deploying ocean iron fertilization at climatically relevant levels poses risks that outweigh potential benefits.” In contrast, no other CDR approaches in the NAS study are given that assessment, and many others are even given endorsements on the grounds that they "can often generate substantial co-benefits.”

Note 2: Including “Carbon Sequestration on Agricultural Lands “ as part of a “Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration” (emphasis added) report is an important win for advocates of soil carbon sequestration: many geologic sequestration proponents have called into question the permanence of soil carbon sequestration as a major issue with these approaches, which the NAS report largely doesn't raise as an issue.

Note 3: I have included biochar in the above graphic, but the NAS does not, citing "literature [on biochar] is still limited, and the impacts of utilization on net greenhouse gas emissions are not well defined."

The NAS report unequivocally separates CDR from “Albedo Modification” techniques…

The NAS study notes,

Carbon Dioxide Removal and Albedo Modification (i.e., modification of the fraction of short-wavelength solar radiation reflected from Earth back into space) have traditionally been lumped together under the term “geoengineering” but are sufficiently different that they deserved to be discussed in separate volumes.”

Separating CDR from Albedo Modification has been in the works for a long time – and I am hopeful that this report will definitively end the discussion of whether CDR falls under the geoengineering umbrella.

The below table from the NAS report highlights a number of key differences between CDR and Albedo Modification proposals. I have added commentary in italics in each cell:

figure 1.2
figure 1.2

...and links CDR as an extension of other GHG mitigation approaches.

“As a society, we need to better understand the potential cost and performance of CDR strategies for the same reason that we need to better understand the cost and performance of emission mitigation strategies—they may be important parts of a portfolio of options to stabilize and reduce atmospheric concentrations of carbon dioxide”

The report clearly states that the first-best option for preventing climate change is stopping GHG emissions, and that neither the development of CDR approaches nor the development of Albedo Modification approaches will change this finding.

The report’s first recommendation is that

“efforts to address climate change should continue to focus most heavily on mitigating greenhouse gas emissions in combination with adapting to the impacts of climate change because these approaches do not present poorly defined and poorly quantified risks and are at a greater state of technological readiness.”

The report goes on to reiterate that

“there is no substitute for dramatic reductions in the emissions of CO2 and other greenhouse gases to mitigate the negative consequences of climate change, and concurrently to reduce ocean acidification.” And by “helping to bring light to this topic area, carbon dioxide removal technologies could become one more viable strategy for addressing climate change.”

Figure 1.4 visualizes this hierarchy of desirable climate responses nicely:

figure 1.4
figure 1.4

The deployment of CDR techniques is limited by their cost, not by their riskiness or likely effectiveness (as is the case for Albedo Modification approaches).

“Carbon dioxide removal strategies… are generally of lower risk and of almost certain benefit given what is currently known of likely global emissions trajectories and the climate change future. Currently, cost and lack of technical maturity are factors limiting the deployment of carbon dioxide removal strategies for helping to reduce atmospheric CO2 levels.”


“Absent some new technological innovation, large-scale CDR techniques have costs comparable to or exceeding those of avoiding carbon dioxide emissions by replacing fossil fuels with low-carbon energy sources.”

The solar energy field in the 1970s provides a decent analog to the CDR field today. That is, the potential benefits from CDR are as clear as the potential benefits from solar were back in the 70s. But like solar in the 70s, CDR will not be able to scale up overnight.

Only CDR approaches can generate net-negative emissions... so if we need to deploy net-negative emissions to prevent climate change, we will need to have viable/scalable CDR solutions.

“industrialized and industrializing societies have not collectively reduced the rate of growth of GHG emissions, let alone the absolute amount of emissions, and thus the world will experience significant and growing impacts from climate change even if rapid decarbonization of energy systems begins.”


“Although such estimates of future deployment of carbon-free energy sources indicate that it may be possible to achieve a decarbonized energy system, great uncertainties remain regarding the implementation of such scenarios due to factors such as costs, technology evolution, public policies, and barriers to deployment of new technologies (NRC, 2010b)”

NAS to science funding government agencies – Part 1: more CDR R&D, please.

“Recommendation 2: The Committee recommends research and development investment to improve methods of carbon dioxide removal and disposal at scales that would have a global impact on reducing greenhouse warming, in particular to minimize energy and materials consumption, identify and quantify risks, lower costs, and develop reliable sequestration and monitoring.”

And from later in the report:

“Developing the ability to capture climatically important amounts of CO2 from the atmosphere and sequester it reliably and safely on scales of significance to climate change requires research into how to make the more promising options more effective, more environmentally friendly, and less costly. At this early stage successful development also requires soliciting and encouraging new synergies and approaches to CDR. Such research investments would accelerate this development and could help avoid some of the greatest climate risks that the lack of timely emissions reduction may make inevitable. The Committee recognizes that a research program in CDR faces difficult challenges to create viable, scalable, and affordable techniques, but the Committee argues that the situation with human-induced climate change is critical enough (see Chapter 1) that these CDR techniques need to be explored to assess their potential viability and potential breakthrough technologies need to nurtured as they arise.”

NAS to science funding government agencies – Part 2: more CDR R&D from everyone, please.

 “Several federal agencies should have a role in defining and supporting CDR research and development. The Committee recommends a coordinated approach that draws upon the historical strength of the various agencies involved and uses existing coordination mechanisms, such as the U.S. Global Change Research Program, to the extent possible.”

Other notes:

  • Page 25: We have to remove a lot of carbon to get back to preindustrial atmospheric CO2 concentration levels – “Reducing CO2 concentration by 1 ppm/yr would require removing and sequestering CO2 at a rate of about 18 GtCO2/yr; reducing CO2 concentrations by 100 ppm would require removing and sequestering a total of about 1800 GtCO2, or roughly the same amount of CO2 as was added to the atmosphere from 1750 to 2000.”
  • Page 26: an interesting history of CDR
  • Page 31: figure 2.2 comparing fossil CCS, DACS, and BECCS.
  • Page 39: Not good grades given to biochar for carbon sequestration purposes: “The residence time of biochar in situ is not well established (Gurwick et al., 2013). Although there has been research associated with the role biochar could play on carbon and nitrogen dynamics, the literature is still limited, and the impacts of utilization on net greenhouse gas emissions are not well defined (Gurwick et al., 2013).” and “Despite not being among the CDR approaches…”
  • Page 57: Interesting graph showing thermodynamics of DACS vs. other CCS approaches
  • Page 62: “In general seawater capture is much less technologically mature than air capture, so research in this area could yield potential benefits.”
  • Pages 72-81: Interesting summary of what characteristics of CDR approaches the NAS committee thought were most important.

In summary and conclusion, in two quotes:

“Even if CDR technologies never scale up to the point where they could remove a substantial fraction of current carbon emissions at an economically acceptable price, and even if it took many decades to develop even a modest capability, CDR technologies still have an important role to play.”


“If carbon removal technologies are to be viable, it is critical now to embark on a research program to lower the technical barriers to efficacy and affordability while remaining open to new ideas, approaches and synergies.”

Biomass Sustainability: Critical for Carbon Removal

Today, prominent climate models project that biomass energy with carbon capture and storage ("bio-CCS") projects will play a significant role in the fight against climate change:

Above: The blue line in the chart above, from the paper "BECCS capability of dedicated bioenergy crops under a future land-use scenario targeting net negative carbon emissions" by Etsushi Kato and Yoshiki Yamagata, shows that billions of tonnes of biomass will be needed to generate the net-negative carbon emissions required to prevent climate change. 

Deploying such large quantities of bio-CCS, however, will not be without its challenges, as highlighted by a recent report from the World Resources Institute (WRI). For example, the report finds that "dedicating crops and/or land to generating bioenergy makes it harder to sustainably feed the planet."

WRI Figure 3
WRI Figure 3

Above: Figure from the WRI report "Avoiding Bioenergy Competition for Food Crops and Land"

The report, however, goes on to conclude that "phasing out bioenergy that uses crops or that otherwise makes dedicated use of land is a sound step toward a sustainable food future." A sustainable food future, perhaps. But a sustainable climate future? This recommendation to phase out dedicated bio-energy crops would severely curtail biomass energy fuel supplies, in the process making billion+ ton deployments of bio-CCS very challenging.

What's more, the suggestion from the WRI report of deploying solar PV instead of bioenergy is likely to increase the cost of negative-emission goals considerably. Solar PV could be used with direct air capture ("DAC") systems with CCS to remove carbon from the atmosphere, but today this type of carbon dioxide removal ("CDR") system would likely cost significantly more than biomass-based CDR projects.

The potential for bio-CCS to provide large-scale, cost-effective CDR is an often overlooked aspect of the bioenergy conversation. But the WRI report does specifically provide three such reasons why even pursuing bio-CCS for CDR is not worthwhile. The rationale given for each argument, however, falls flat:

WRI Report Argument Against Bio-CCS #1: "Carbon capture does not transform non-additional biomass that cannot generate carbon savings into additional biomass that can." Bio-CCS can utilize "additional" biomass -- cellulosic ethanol projects that utilize crop wastes, for example, have been slow to develop, but that doesn't mean such projects cannot scale up with the right policy and market support. It will be important to ensure sustainability and "additionality" of biomass supplies for energy, and while this is likely to prove challenging, it is far from impossible. Argument grade: C

WRI Report Argument Against Bio-CCS #2: "There is no benefit to applying carbon capture and storage even to additional biomass until all fossil fuel emissions have been eliminated or captured and stored." There might not be benefits to atmospheric carbon concentrations, but there are almost certainly benefits for learning how to optimize bioenergy systems, build out biomass supply chains, and smooth the transition to a carbon-removing economy. If our economy eventually has to generate net-negative levels of carbon emissions, it will prove politically and economically beneficial to de-risk bio-CCS technology as much as possible today so that once we do stop using coal and natural gas, we are able to generate energy from biomass as economically as possible. Argument grade: D.

WRI Report Argument Against Bio-CCS #3: "even if there were a special benefit from BECCS, this is not a reason to use biomass today without carbon capture and storage." The same logic applies as above: it is important to de-risk biomass generation systems and build biomass supply chains today. Biomass projects without CCS technology could pave the way for most cost-effective bio-CCS project in the future. Argument grade: D.

So where does this leave us? The most important conclusion is that we are likely going to need both increased crop production and increased bioenergy consumption to prevent climate change while feeding a growing population. As a result, it is critical that we expand the conversation on developing systems that achieve both goals. We need to understand the conditions under which bioenergy can be scaled "additionally" and sustainably, so we can focus on building the most sustainable and cost-effective portfolio of CDR systems to prevent climate change while meeting the other basic social and environmental needs of a growing global population.