Fuel out of Thin Air: CO2 Capture from Air and Conversion to Methanol

Authors: Raktim Sen, Alain Goeppert, Sayan Kar, G. K. Surya Prakash*Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, Los Angeles, California, United States.

Full citation: Sen, R.; Goeppert, A.; Kar, S.; Prakash, G. K. S., Hydroxide Based Integrated CO2 Capture from Air and Conversion to Methanol. Journal of the American Chemical Society 2020, 142, 4544-4549.

Over the past two centuries, surging greenhouse gas emissions have led to an enormous rise in atmospheric CO2 levels, causing a significant increase in the average global temperature and ocean acidification. Humankind is now releasing every year > 36 billion tons of CO2 to the environment! Among various solutions explored to mitigate this problem, direct air capture (DAC) of CO2 is highly promising. DAC has significant advantages. It enables the point of capture to be independent from the emission sources. It also targets CO2 emissions from dispersed point sources, which are responsible for about half of total anthropogenic emissions but would otherwise be difficult to address. Furthermore, utilization of the captured CO2 (Carbon Capture and Utilization, CCU) as a carbon source for various chemical feedstocks and polymeric materials is very promising. In this context, CO2 is combined with hydrogen obtained by electrolysis of water using renewable energy sources such as solar and wind. Among various CO2 hydrogenation products, methanol is one of the most attractive and versatile alcohol. Methanol is a feedstock for a multitude of chemicals and products, already used on a scale of over 100 billion liters per year. Additionally, methanol, which is a liquid with a boiling point of 64.7 °C, is a superior fuel for internal combustion engines and fuel cells, as well as a convenient high density liquid hydrogen carrier. Methanol can be converted to ethylene and propylene through the MTO (methanol to olefins) process. Hence, the production of renewable methanol and the associated methanol economy holds significant potential to replace current fossil fuel-based economies.

Following the legacy of their late colleague Nobel Laureate George Olah, a major proponent of the methanol economy, G. K. Surya Prakash, professor and director at Loker Hydrocarbon Institute and his team including senior research scientist, Alain Goeppert have successfully combined the two steps of CO2 capture and hydrogenation to methanol into a seamless reaction sequence to transform the greenhouse gas into its combustible cousin. Until now, the integrated capture and conversion processes relied on organic bases called amines to capture CO2. While amines are easily regenerable, they are prone to oxidative degradation and suffer from notable toxicity and volatility. Hence, in order to improve the system, Prakash and his team turned to inorganic bases like sodium/potassium hydroxides which are superior CO2 capturing agents forming their respective bicarbonates/carbonates. Conventionally, however, recycling of the base by thermally decomposing bicarbonates/carbonates requires extreme temperatures above 700 °C making the process highly energy intensive. In initial efforts by the group, CO2 captured from air by a solution of hydroxide in water was converted to formate salts. However; further hydrogenation to methanol was ineffective. 

In their current study, the authors discovered that switching water with alcohols like ethylene glycol as a reaction medium could mediate effectively the process to methanol. When air was bubbled through potassium hydroxide dissolved in ethylene glycol and the CO2-loaded solution subsequently hydrogenated in the presence of H2 and a metal catalyst, complete conversion to methanol was observed at 140 °C. Moreover, regeneration of the hydroxide base occurred at mild temperatures of 100-140 °C. Notably, a fraction of the base was deactivated in an unwanted side reaction. Currently, the researchers are aiming to minimize the side reactions to efficiently recycle the potassium hydroxide. This system offers easy integration of existing hydroxide-based CO2 scrubbing industries to utilize the captured CO2 to produce methanol, paving a way for a sustainable and carbon neutral future. As Prakash says, “All living things are primarily made of carbon and therefore carbon has to be managed. Humankind requires carbon based fuels and chemical feedstocks currently obtained from fossil fuels. Renewable methanol can easily replace fossil fuels without requiring major changes to our current chemical and transportation infrastructures.   If CO2 is a one-carbon problem, then methanol is a one-carbon solution.”

The study authored by Prakash, Goeppert and graduate assistants Raktim Sen and Sayan Kar was recently published in Journal of the American Chemical Society (DOI: 10.1021/jacs.9b12711) and also featured in C&E News (https://cen.acs.org/content/cen/articles/98/i10/One-pot-process-converts-CO2.html). 

What influences farmers’ decision to adopt technologies that enhance soil carbon sequestration? A case study from East Africa.

Fig. 1. A map of Africa showing the location of Kenya and Ethiopia

Authors and their affiliation

Ng’ang’a Karanja Stanley1,**, Jalang’o, Dorcas Anyango2, Girvertz Evan2 1,**International Center for Tropical Agriculture (CIAT), Sub-regional Office – Kampala, Uganda 2International Center for Tropical Agriculture (CIAT), Regional office – Nairobi, Kenya

Soil nutrient depletion limits the agricultural potential of a majority of farmers in developing countries. Technologies that enhance soil carbon can potentially increase farm productivity, income opportunities for farmers, and improve food security. Nonetheless, the adoption of, and investment in agricultural practices that build up carbon in soils is still limited among farming households in East Africa. This study examines the factors that influence the uptake of soil carbon enhancing practices among 45 and 50 smallholder farmers from selected places in Kenya and Ethiopia (Fig. 1) respectively, using secondary data that were extracted from the World Overview of Conservation Approaches and Technology (WOCAT) database. Understanding this is requisite for the government, policy experts and development partners to effectively plan, and target interventions to scale up adoption among farmers in the region.

A probit model was used to analyse the data that spanned across socioeconomic, institutional, off-farm income, technical knowhow, farmers’ perceptions, and land use characteristics that influence the adoption of technologies that have the potential of enhancing the soil carbon sequestration. The descriptive results from the data reveal that farming is dominated by women in both countries. Mixed market orientation is dominant, with a moderate wealth status of between 100 and 500 US$ for the majority of the households.  Results from the model show that both farmers’ perceptions, and socio-economic, farm level, and institutional factors significantly contribute to the decision to implement these practices. For example, smallholder farmers that reported to have perceived the net benefits and strengths of the soil carbon enhancing technologies had a higher likelihood of adopting technologies that enhance the sequestration of soil carbon in both Kenya and Ethiopia.

At the same time, off-farm income influenced the adoption of soil carbon enhancing practices positively among farmers with a moderate annual income (100-500 US$) as compared to the rich (>500US$). Farming for subsistence basis and moderate know-how of the technologies in question negatively affected adoption. Similarly, land ownership without title deeds negatively influenced adoption. The results point to the speedy need for policy measures that would promote the adoption of soil carbon enhancing practices. Interventions such as training farmers to equip them with implementation skills, and enforcing technical assistance through extension delivery would help bridge the knowledge deficiency. Encouraging farmers’ involvement in off-farm income-generating activities, and improving access to credit is also commendable. To a greater extent, farmers would be incentivized thus boosting their intake for soil carbon enhancing practices at the individual farm level.  

Keywords: Adoption, Factors, Enhances, Constrain, Soil carbon, Practices, Kenya, Ethiopia 


**Corresponding author details

Email: stanley.karanja@gmail.com

Orcid number: http://orcid.org/0000-0002-6166-7920


ICRLP Webinar Explainer Series Provides A Deeper Understanding on Many Issues Surrounding Carbon Dioxide Removal

One of the streams of work for The Institute for Carbon Removal Law and Policy is to provide broad education on carbon removal approaches and implications. Carbon removal is a big and complex subject matter, with much to unpack and debate. With this in mind, we launched our “Assessing Carbon Removal Webinar Explainer Series” in 2018. 

These one-hour webinars bring together Institute staff and guest speakers to explain what is known about varying carbon removal approaches and to explore big themes. The presentations and conversations delve into research needed to assess technical, legal, and social aspects and considerations of carbon removal technologies.,

Most recently presented in this series have been webinars on Agroforestry and Carbon Removal and Corporate Commitments, both of which have accompanying blog entries that outline the main points covered in the presentations, which can be found on ICRLP Carbon Removal Blog Posts page.

In addition to these recent webinars, there are a number of past presentations that provide a wealth of knowledge on carbon removal:

  • Enhanced Oil Recovery: A discussion on the technological, economic, and political issues associated with Enhanced Oil Recovery (EOR), including the costs involved, the project development perspective, EOR relative to saline storage necessary to scale up carbon storage, and why EOR should be decoupled from the decarbonatization agenda and policy.
  • Mitigation Deterrence: Mitigation Deterrence (MD) is where the pursuit of greenhouse gas removal (GGR) delays or deters other mitigation options. This webinar presents the results of a project that analyzes this issue and explores conditions in which GGR technologies can be used with minimal MD.
  • Direct Air Capture: The presentations within this webinar provide a comprehensive overview of mechanisms behind Direct Air Capture of carbon dioxide, which is the practice of utilizing chemicals to remove carbon dioxide from the air. 
  • Enhanced Mineral Weathering: This webinar presents the ins and outs behind varying proposed methods of Enhanced Mineral Weathering utilizing an array of minerals on land and in the oceans. 
  • Governance of Marine Geoengineering: This webinar followed the release of a CIGI Special Report on this topic. The presentations dig into the potential role of marine climate geoengineering approaches such as ocean alkalization and “blue carbon,” with a focus on the governance, research, deployment and potential risks associated with these approaches to carbon dioxide removal.
  • Communicating Carbon Removal: This webinar was presented following the release of ICRLP report “The Carbon Removal Debate” and explores the challenges associated with communicating the necessity for, and options behind, carbon dioxide removal.
  • The Brazilian Amazon Fires: What Do They Mean for the Climate?: As thousands of fires ripped across the Amazon in 2019, wreaking havoc and devastation, this webinar seeks to explore what these fires mean for the climate, and lessons are to be learned regarding global forest protection.
  • Soil-Based Carbon Removal: Soil harbors three times more carbon than is present in the atmosphere, and this webinar investigates whether healthy soils can help tackle climate change. Experts on the panel provide a scientific overview of soil carbon sequestration while examining the risks, benefits, and uncertainties.  
  • NAS “Negative Emissions Technologies and Reliable Sequestration: A Research Agenda” Report: This report released by the National Academy of Sciences, Engineering, and Medicine is the focus of discussion in this webinar. A few of the points addressed are the current state and potential for negative emissions technologies, conceptualizing scale in addressing climate change, and the impact of carbon removal on land use and soil, among others.
  • Potential Role of Carbon Removal in the IPCC’s 1.5 Degree Special Report: The panelists in this webinar examine this special report, released by the IPCC in 2018, examine what this report says about many aspects of carbon removal such as the potential need, governance, and classification. 
  • What We Know and Don’t Know about Negative Emissions: This webinar is aimed at providing a systematic overview of negative emissions technologies, discussing the status of research, ethical considerations, and how to spur future innovation and upscale research for advancing utilizations.
  • Accessing Carbon Dioxide Removal: As the introductory webinar that kicked off the series in 2018, the panelists dive into what carbon removal technologies are, their role in the portfolio of response to climate change, risks, ways to manage technologies in beneficial ways, and what the future could potentially hold. This webinar in particular serves as a valuable springboard for those who are relatively unfamiliar with carbon removal and seeking to learn more. 

All of these webinars are also available to view on our YouTube channel and on the ICRLP website. As this series continues to evolve, we encourage you to stay tuned for upcoming webinars going forward. If you are interested in joining our mailing list to receive notifications of upcoming webinars and our Newsletter, feel free to reach out to us at icrlp@american.edu.

Agroforestry and Carbon Removal

Authored by Allison Tennant, Carbon Removal Program Assistant, Institute for Carbon Removal Law and Policy & Union of Concerned Scientists

On September 2nd, the Institute for Carbon Removal Law and Policy (ICR) hosted a webinar on agroforestry, the latest in our explainer series. ICR Fellow Jason Funk moderated a panel that featured: 

  • Susan Stein, Director of the USDA National Agroforestry Center 
  • John Munsell, Professor and Forest Management Extension Specialist in the Department of Forest Resources and Environmental Conservation at Virginia Tech
  • Patrick Worms, Senior Science Policy Advisor at the World Agroforestry Centre, presented on the different technical and economic aspects of agroforestry.

Susan Stein kicked off the presentations by giving the USDA definition of agroforestry: “The intentional integration of trees or shrubs with crop and animal production to create environmental, economic, and social benefits.” She then explained five types of agroforestry — forest buffer, alley cropping, silvopasture, windbreak, forest farming — and how they remove and store carbon. In the U.S., over 30,000 farms practice some form of agroforestry with government and private support.

John Munsell followed with the social, environmental, and economic benefits of agroforestry, such as increasing yield, increasing soil, improving air and water quality, and strengthening social capital. He also explained some of the barriers to widespread adoption and potential policies to address those issues. While a lack of awareness and knowledge of agroforestry among farmers poses one barrier, the time and space needed to see returns poses a more formidable obstacle.  Professor Munsell discussed upfront payments for land conversion, performance-based payments, and cost-share programs as ways to address that barrier. 

Patrick Worms rounded out the presentations by giving an international perspective and examples. He pointed out the great potential for agroforestry, and land management solutions in general, to remove carbon dioxide worldwide and the need for broader adoption. Currently, 43% of all agricultural land has more than 10% tree cover, but there are many opportunities for growth.

The presentations were followed by questions from the audience. 

The Institute for Carbon Removal Law and Policy would like to thank environmental journalist Erik Hoffner for helping to organize this webinar. Erik publishes a series on agroforestry for the award-winning environmental news site Mongabay.com, which you can find at https://news.mongabay.com/series/global-agroforestry/

The next webinar in this series is “Equity and Justice in Carbon Removal” which will take place Monday, September 21 at 10am ET. Sign up here. You can find recordings of all past webinars on our website.

Carbon Removal and Corporate Climate Commitments

Authored by Allison Tennant Carbon Removal Program Assistant, Institute for Carbon Removal Law and Policy & Union of Concerned Scientists

The latest webinar in the explainer series presented by the Institute for Carbon Removal Law and Policy (ICR)  delves into the role of carbon removal practices in corporate climate commitments. Recently, many companies have released net-zero climate commitments that include carbon dioxide removal technologies. In July, Apple, for instance, committed to becoming 100% carbon neutral for its supply chain and products by 2030, in addition to already having carbon-neutral operations. To reach this goal, the company plans to reduce emissions by 75% and develop innovative carbon removal solutions for the remaining 25% of their footprint. Apple will mostly focus on natural climate solutions, partnering with Conservation International on ecosystem restoration and protection. Earlier this year, Microsoft also committed to going carbon negative by 2030 by utilizing methods of reforestation, soil carbon sequestration, and new carbon capture technologies. With companies continuing to play a larger role in the carbon removal sphere, ICR gathered a panel to evaluate the role that the corporate world plays and might play in the carbon removal world.

The panelists were Betty Cremmins, Lead at 1t.org (Trillion Trees Platform) North America; Jeremy Freeman, Founder/Executive Director at CarbonPlan; and Alex Laplaza, Analyst at Lowercarbon Capital. The panel was moderated by Nicole Pinko, Corporate Analyst and Engagement Specialist at Union of Concerned Scientists. Discussion revolved around questions such as: 

  • What sorts of commitments are companies making, and how does carbon removal fit into those plans?
  •  Are these commitments and the plans for achieving them realistic, especially with respect to carbon removal?
  •  When it comes to the carbon removal portion of their plans, how are companies currently investing in nature-based and/or technical solutions? 
  • How are these commitments likely to affect the development or deployment of carbon removal?
  • What should people be paying attention to when they read about these commitments and the plans to achieve them? 

A Q&A session followed the discussion in which the audience inquired about terminology companies should use, the Global North’s responsibility for off-shore emissions, and the issues with carbon offsets.

To watch this webinar, click here. Make sure to keep up-to-date on new additions to our webinar explainer series, and watch past webinars here. In addition, you can keep abreast of corporate carbon removal commitments via our regularly updated action tracker.


ICR Fact Sheets Provide a Comprehensive Overview of All Things Carbon Removal

Although the emerging field of carbon removal has great potential to help curb climate change when coupled with more traditional methods of mitigation, it is riddled with uncertainty. There are many risk factors and many components within each individual method that are still poorly misunderstood. The Institute for Carbon Removal Law and Policy is dedicated to creating a set of comprehensive tools that can aid in providing clarity on carbon removal practices and technologies on many different levels.

Among these valuable resources are a comprehensive set of Fact Sheets that provide overviews on each of the individual topics regarding carbon removal, the production of which was provided for by a grant from The New York Community Trust. These fact sheets are broken down into two categories, topics in carbon removal and approaches to carbon removal. 

The topics in carbon removal fact sheets provide an overview and background on:

What is carbon removal?

Nature-based solutions to climate change and 

Carbon capture & use and carbon removal

The approaches to carbon removal fact sheets break down the ten different topics, providing a deeper context to the potential methods behind carbon removal. Each of these provides not only an overview but weigh in on the co-benefits & concerns, potential scales and costs, technological readiness, governance consideration, and provide sources for further readings. These methods include:

Agroforestry: Incorporates trees with other agricultural land use which not only removes carbon dioxide but also provides benefits to farmers and their communities.

Bioenergy with carbon capture and storage: A technique dependent on two technologies. Biomass that is converted into heat, electricity, liquid gas, or fuels make up the bioenergy component. The carbon emissions generated from this bioenergy conversion are then captured and stored in geological formations or long-lasting products, this being the second component of this method.

Biochar: A type of charcoal that is produced by burning organic material in a low oxygen environment, converting the carbon within to a form that resists decay. It is then buried or added to soils where that carbon can remain harbored for decades to centuries.

Blue Carbon: Refers to the carbon that is sequestered in peatlands and coastal wetlands such as mangroves, tidal marshes and seagrass among others, many of which have been destroyed in recent decades. 

Direct Air Capture: An approach that employs mechanical systems that capture carbon directly and compress it to be injected into geological storage, or used to make long-lasting products.

Enhanced Mineralization: Also known as enhanced or accelerated weathering. Accelerates the natural processes in which various minerals absorb carbon dioxide from the atmosphere. One implementation involves grinding basalt into powder and spreading it over soils, causing a reaction with CO2 in the air, forming stable carbonate materials.

Forestation: This includes forest restoration, reforestation and afforestation. Forests remove carbon dioxide and through the trees within, and have the potential to store that carbon for long periods of time.

Mass Timber: A method that involves utilizing specialized wood products to construct buildings, therefore replacing emission-intensive material such as concrete and steel. Further, this wood stores carbon that was captured from the atmosphere through photosynthesis. 

Ocean Alkalization: A process involving adding alkaline substances, such as olivine or lime, to the seawater to enhance the ocean’s natural carbon sink.

Soil Carbon Sequestration: Also referred to as “carbon farming” or “regenerative agriculture.” This process involves managing land in ways that promote carbon absorption and sequestration within soils, especially prominent among farmland.

By reviewing each of these succinctly written fact sheets, it is possible for one to gain a solid understanding of what is happening in the world of carbon removal; the good, the bad, and the misunderstood. 


NGO Engagement with Carbon Removal: Announcing a New Project for the Institute for Carbon Removal Law and Policy and the Union of Concerned Scientists

Authored by Allison Tennant, Project Assistant, Institute for Carbon Removal Law and Policy & Union of Concerned Scientists

Two years ago, The Institute for Carbon Removal Law and Policy (ICR) convened a group of representatives from over 20 national environmental groups at the Wingspread Center in Racine, WI. The goal was to spark and facilitate an ongoing sharing of perspectives and resources about carbon removal. Space was created for meeting attendees to probe various carbon removal approaches and issues, with the intent that information and findings from the meeting would inform exploration of carbon removal in their home institutions. 

Now, ICR has partnered with the Union of Concerned Scientists for a new and newly imagined round of work with the NGO community. In my new position, created with the kind support of the New York Community Trust, I will be reconvening the group that gathered at Wingspread and working with them to imagine and promote a more just, equitable, and inclusive understandings of carbon removal. We will be seeking to expand the carbon removal conversation to draw on the knowledge, interests, and perspectives of a wider array of voices, recognizing that different carbon removal approaches are poised to have implications across a diverse set of sectors and communities.

As the IPCC Special Report on Global Warming of 1.5°C makes clear, carbon removal will need to be a part of the approach to keeping warming under 1.5°C; emissions reductions alone will no longer be enough. Governments and companies must now make large investments in R,D&D of carbon removal approaches to get technologies up to scale. Just as importantly, we need robust forms of evaluation and assessment of carbon removal options to ensure that any developments in this fast-moving field are attending to social and environmental imperatives. Careful evaluation of what carbon removal can and can’t do won’t happen without increased attention by civil society actors. 

With an upcoming US presidential election, there is an opportunity for increased funding towards carbon removal, but there are also equity issues and guardrails to be considered. Over the next weeks and months, we’ll be working with the Wingspread group and an expanding set of civil society actors to find out what carbon removal questions still need to be addressed and work with them to try to figure out answers. They don’t all have to be on the same page, but the dialogue will help expose existing issues and workshop potential solutions. It’s going to be a big project, and I’m excited to see what will come out of it.

If you’re interested in finding out more about this new joint project between the Institute for Carbon Removal Law and Policy and the Union of Concerned Scientists, please contact me: ATennant@ucsusa.org. 

The Democratic Party’s Draft Policy Platform and the Potential Role of Carbon Dioxide Removal/Negative Emissions Technologies to Combat Climate Change

Authored by Wil Burns, Co-Director, Institute for Carbon Removal Law & Policy, American University

The Democratic party’s draft policy platform, drafted by the Democratic National Committees platform drafting committee, was released this week. The platform will be considered by the delegates to the upcoming Democratic National Convention in Milwaukee convention next month, where the delegates will make final decisions on the text of the non-binding policy document. 

The draft’s climate section contains a number of provisions pertinent to carbon dioxide/negative emissions approaches, including the following:

  • In seeking to develop a “thriving, equitable, and globally competitive clean energy economy,” the United States should seek to “develop and manufacture next-generation technologies to address the climate crisis …” [p.44]. These technologies include “direct air capture and net-negative emissions technologies,” as well as “carbon capture and sequestration that permanently stores greenhouse gases …” [p. 48).  The platform also calls for support for “the most historically far-reaching public investments and private sector incentives for research, development, demonstration, and employment of net-generation technologies …” [p. 48];
  • In pursuit of the objective of eliminating power plant carbon pollution by 2035 to “reach net-zero emissions as rapidly as possible [and no later than by 2050],” decarbonization strategies should include carbon capture and storage [p. 45];
  • In the context of the agricultural sector, the platform calls for a partnership to help farmers develop new sources of income including through, inter alia, lower-emission, and regenerative agricultural practices.” [p.47] While the contours of these practices are not outlined in the document, one would presume that it would include methods to rebuild soil organic matter, such as no-till agriculture and cover crops;
  • There are also several provisions related to public lands stewardship that, albeit vague, might help facilitate enhanced carbon sequestration. The platform calls for the development of a youth corps to conserve public lands. [p. 45] Moreover, it advocates full funding of the Land and Water Conservation Fund to ensure the conservation of public lands, as well as programs to incentivize conservation initiatives on private lands, “including through private sector ecosystems markets.” [pp.48-9];
  • There is only one reference to the potential role of afforestation/reforestation in climate policy, with a focus on temperature impacts, with the platform calling for the planting of “millions of trees” in urban areas to “help reduce heat stress.” [p. 47]

The drafters’ engagement in the potential role of CDR/NETs approaches in climate policymaking is laudable, and reflects a potentially expanded role for such options compared to that contemplated in the New Green Deal, which briefly discussed tree-planting as a carbon sequestration strategy. At the same time, the draft platform is also an extremely underdeveloped set of proposals in terms of fleshing out potentially requisite levels of funding, necessary regulatory frameworks to facilitate research, development, and potential deployment of many of these options, and the daunting issue of how to integrate such approaches into the current climate policymaking domain at the state, national and international level. It is also notable that one of the most widely discussed potential carbon dioxide removal approaches, afforestation/reforestation, is given extremely short shrift in the document, with the only reference to tree planting focused on albedo effects rather than carbon sequestration potential. While the delegates will have the opportunity to hone the document, it’s unclear if they will have the expertise to address some of these concerns. 

However, in the end, perhaps it’s helpful in itself to have a major party acknowledge the potentially important role of CDR/NETs options in pursuing the critical objective of net emissions neutrality in the next few decades. The platform establishes a foundation for the hard work that would inevitably need to follow to make this a reality. 

The technological and economic prospects for CO2 utilization and removal


Cameron Hepburn, Ella Adlen, John Beddington, Emily A. Carter, Sabine Fuss, Niall Mac Dowell, Jan C. Minx, Pete Smith & Charlotte K. Williams


Carbon dioxide utilisation – making valuable products from CO2 – is a potential way to lower the net costs of reducing emissions or of removing carbon dioxide from the atmosphere.  We review the economic and technological prospects of ten such pathways to assess scale and cost prospects in 2050. Using CO2 in chemicals, fuels, and via microalgae to make products, comprise ‘cycling’ pathways: they might reduce carbon dioxide emissions by displacing fossil fuel derived CO2 but they have limited potential for carbon dioxide removal.  Some CO2 chemicals, such as CO2 based polymers, are profitable in the present day, but CO2 based fuels are high up on the cost curve. ‘Closed’ pathways such as those involving construction materials can both utilise and remove carbon dioxide for the long term. They might be low cost, and the end-markets are large, but they have high regulatory barriers to scale.  Land-based CO2 utilisation pathways such as soil carbon sequestration, afforestation/reforestation and biochar can increase agricultural output and remove carbon dioxide. They can be characterised as ‘open’ pathways wherein the CO2 can return to the atmosphere easily, and they are relatively low cost. Using a process of structured estimation and an expert opinion survey, our assessment suggests that each of the ten pathways could scale to over 0.5 Gt carbon dioxide utilisation annually, although barriers remain substantial and resource constraints prevent the simultaneous deployment of all pathways.  Uncertainty over scaling means that there is a wide range of potential outcomes for 2050. Notwithstanding the many caveats, the potential scale of utilisation could be considerable. Much of this potential CO2 utilisation – notably in ‘closed’ and ‘open’ pathways – may be economically viable without dramatic shifts in prices. The specific assumptions of the low scenario imply an upper bound of over 1.5 Gt CO2 yr-1 at well under $100/t CO2u. For policymakers interested in climate change, these figures demonstrate the theoretical potential for correctly designed policies to incentivise the displacement of fossil fuels or the removal of CO2 from the atmosphere.  



Fixing the Climate? How Geoengineering Threatens to Undermine the SDGs and Climate Justice

Author: Linda Schneider


Over the past two decades, policy-makers and economists have often talked about climate policy in terms of the social cost of carbon. The social cost of carbon is the monetary cost that future generations incur due to decreased economic growth caused by the emission of one tonne of CO2 today. Many economists and policy-makers have suggested using the social cost of carbon as a just means of setting a carbon tax. After all, if my emission of 1 tonne of CO2 incurs a cost of $50 to future generations, it seems fair that I should be taxed at $50 per tonne.

Estimates of the social cost of carbon vary widely, and it has a number of practical and philosophical problems. Practically, estimates of the social cost of carbon range over about 7 orders of magnitude, which makes using it in policy challenging. Philosophically, imagine that climate change leads to a famine that kills a few million people. The famine would be a profound social cost of climate change, but might have little impact on the global economy, and thus would not be counted in estimates of the social cost of carbon. Thus, another metric is needed.

Here, we suggest that the costs of atmospheric removal of CO2 could be a better metric for climate change policy. There are a number of technologies that remove CO2 from the atmosphere (called carbon dioxide removal or negative emissions technologies) but, like most other pollution control systems, they require financial inputs. We propose that the per tonne subsidy needed to capture and store CO2 from the atmosphere would be a more appropriate metric than the social cost of carbon because it would allow for a climate policy that is based on an observable cost and could be directly linked to the physical removal of CO2 from the atmosphere. In the proposed policy, emitters would pay a tax, based on the marginal cost of CO2 removal and the proceeds from that tax would be used to remove an equivalent amount of CO2 from the atmosphere.

While more research on the costs of negative emissions technologies is needed, early estimates suggest that a negative emissions-based system would be higher than the social costs of carbon preferred by policy-makers but roughly similar to the average social cost of carbon derived from academic estimates. 


In the early 21st century, the world faces multiple existential challenges and global crises – among them is the climate crisis, but equally dramatic – and intimately related – are the escalating loss of biodiversity and natural ecosystems, growing social inequality, human rights violations, poverty and hunger, concentration of wealth, power and control, and authoritarian state tendencies. 

The international community adopted the Sustainable Development Goals (SDGs) in 2015, which aim to, among other goals, end poverty, hunger, reduce inequality, protect life on land and achieve gender equality, peace and justice. The framework of climate justice, promoted by grassroots social movements around the world, highlights the crucial role of global environmental and social justice in addressing the climate crisis – rather than treating it as a purely technical problem.

Both the SDGs at the international-institutional level, and the call for climate justice from the grassroots and social movement level, serve as a framework for addressing the interrelated crises of the 21st century in an integrated fashion. 

In the wake of the Paris Agreement, however, and with global emissions still on the rise, one set of alleged responses to the climate crisis is pushing to the front in international climate policy discussions. 

Geoengineering—large-scale technological interventions in the Earth’s natural processes and ecosystems are being promoted to counteract or delay some of the symptoms of climate change.

In the present paper I argue that geoengineering – both large-scale Carbon Dioxide Removal and Solar Radiation Management, the two main categories of climate geoengineering – are fundamentally at odds with the SDGs and with the strive for climate justice. In fact, they threaten to undermine the achievement of SDGs and climate justice for three broad reasons that I develop in the present article.

First, geoengineering is bound to exacerbate many of the other socio-ecological and socio-economic global crises we are facing. I show this for several of the proposed geoengineering technologies on land, in the oceans and in the atmosphere and how they would detrimentally affect the SDGs and the strive for climate justice. 

Furthermore, I elaborate on how geoengineering would deepen societal dependence on large-scale technological systems and on technocratic elites controlling them. One of the effects of such technological dominance in trying to solve global problems is that alternative and more holistic forms of knowledge, expertise, and practices that allow for complexity, diversity and resilience are excluded. By the same token, concerns over ecological and social risks and rights violations are pushed aside. Such one-dimensional large-scale technological fixes for the climate crisis run counter the aim of achieving global ecological and social justice and redressing past unjustness.

Finally, rather than overcoming the economic and political power structures that have caused the climate crisis in the first place, they create new spaces for profit and power for new and old economic elites and thereby serve to uphold the current status quo. As such, it is fundamentally incompatible with the notion of climate justice and will make it impossible to achieve the SDGs.