By Karlee Bamford, Treasurer for the GCI
The attention of international media has been captured by the remarkable success in CO2 sequestration achieved by the Canadian company Carbon Engineering, located in Squamish, British Columbia. Sustainability-related, world-saving initiatives often have an easier sell in the media than, say, incremental advances reported by researchers on equally sustainable academic pursuits (rough, eh?). In this instance the craze over Carbon Engineering’s advances has been amplified by the news of their recent partnerships with household-name energy and oil giants, such as Chevron, BHP, and Occidental Petroleum, in the form of a CAD $68 million investment. So, what is this incredible advance?
From the success of their pilot plant and the data they’ve accumulated thus far, Carbon Engineering implementation of their technology has achieved capture of The technology in question can be split into two major advances. Referred to as direct air capture, or DAC, the first process developed by Carbon Engineering involves the transfer of gaseous CO2 from ambient air to an absorber fluid, a strongly basic solution of sodium or potassium hydroxide. The transfer process is achieved using an air-liquid contactor, designed and described by the company in 2012,4 that involves an array of fans, pumps, cheap PVC piping and structure, and fluid distributors. These components are fundamentally no different than those commonly found in cooling towers used as heat exchangers for water cooling. However, the orthogonal geometry (Figure 1) of air (atmospheric, ~ 400 ppm CO2) and fluid (the absorber) flow differs significantly, making repurposing of existing cooling tower designs for DAC an inefficient and expensive strategy for CO2 capture.
The CO2 taken up by the alkaline absorber fluid is converted to carbonate (CO32-) salts and can be precipitated from the aqueous solution by treatment with calcium hydroxide to give calcium carbonate pellets. The captured CO2 can thus be stored as calcium carbonate or can be cleanly regenerated as pure CO2 gas, with elimination of a CaO , at high temperatures (650 °C) for commercial resale. The byproduct CaO may even repurposed by conversion back to Ca(OH)2 in a lime slaker, using water.1 Carbon Engineering has been piloting this process at their facility in Squamish since 2015, according to their website, after having tested a smaller prototype from 2010 and published the performance results in 2013.6 At the time of Carbon Engineering’s founding and until as recently as 2018, no commercial-scale air capture systems had been developed, which was a direct result of the anticipated inefficiency of CO2 capture using conventional cooling tower designs.4 Undeterred, Carbon Engineering has proven otherwise with their innovative use of cross-flow geometry.
The second break-through technology from Carbon Engineering is their patented Air To FuelsTM process, which they’ve been piloting since 2017. Taking the stored CO2 from their DAC process, Carbon Engineering has successfully produced a clean, sulfur-free, source of hydrocarbon fuel that requires no further modification for consumer consumption. The process involves passing the regenerated CO2 gas through a reactor containing hydrogen (H2) gas to generate synthesis gas (syn-gas), a mixture of CO and . The syn-gas is then passed through a Fischer-Tropsch reactor where the synthetic hydrocarbon fuel is thermally generated over a heterogenous base-metal catalyst (e.g. iron, cobalt, nickel).7
The technologies have been developed by the research groups of founder and U of T alumnus Prof. David Keith. Prof. Keith is currently faculty at Harvard University in the School of Engineering and Applied Sciences. To date, the company has filed 13 patents and produced numerous publications describing their innovations. According to media reports,8 recent multimillion-dollar investments will allow their and the company has already signed a memorandum of understanding with Squamish First Nations about their intentions.9
One of the most attractive aspects of the DAC and Air to FuelsTM technology is location. Plants could, hypothetically, be built anywhere, as CO2 is well mixed in the atmosphere and Carbon Engineering’s technology does not require that CO2 capture occur at the point of CO2 generation as in, for example, CO2-scrubbers used in exhaust systems.
However, with the excitement surrounding Carbon Engineering’s projected ability to capture CO2 at low cost and high volume, controversy has inevitably been close to follow. The interest from large oil corporations in this technology may not be as principled in sustainability as it appears but driven in part by their need for large volumes of CO2 for so-called green fracking (hydraulic fracturing). Supporting further oil extraction in this way goes completely counter to the need for elimination of emissions that the 2018 Intergovernmental Panel on Climate Change (IPCC) report clearly indicates must accompany advances in carbon capture and storage.10 Still, perhaps the positives outweigh the negatives in this instance. This very week, Environment and Climate Change Canada reported that Canada is warming at twice the rate of the rest of the globe.11 The need for efficient technologies to address climate change has never been more immediate. Fortunately, Carbon Engineering is not alone: at least two other companies with commercial plans for CO2 capture have started in Switzerland (Climeworks)12 and the USA (Global Thermostat).13 Whether the Canadian solution is adapted worldwide will depend not only upon Carbon Engineering, but also upon how these alternative approaches evolve. For once, it is probably best not to pick a team to cheer for but, instead, hope that each country’s company develop a complimentary capture strategy to address the international dilemma that is climate change.
- Keith, D. W.; Holmes, G.; St. Angelo, D.; Heidel, K., Joule 2018, 2, 1573-1594.
- American Physical Society. Direct Air Capture of CO2 with Chemicals: A Technology Assessment for the APS Panel on Public Affairs. June 1, 2011 https://www.aps.org/policy/reports/assessments/upload/dac2011.pdf ; accessed April 24, 2019.
- Carbon Engineering, https://carbonengineering.com/ .
- Holmes, G.; Keith, D. W., Trans. R. Soc. A 2012, 370, 4380-403.
- Artist’s rendition of a commercial scale Carbon Engineering contactor, CanTech Letter. https://www.cantechletter.com/2016/10/squamish-b-c-s-carbon-engineering-begins-scale-co2-capture-new-deal/ ; accessed April 4, 2019.
- Holmes, K. Nold, T. Walsh, K. Heidel, M. A. Henderson, J. Ritchie, P. Klavins, A. Singh and D. W. Keith, Energy Procedia, 2013, 37, 6079-6095.
- Heidel, Keton et al. Method and system for synthesizing fuel from dilute carbon dioxide source. WO2018112654A1, 2017.
- BBC News, Matt McGrath. Climate change: ‘Magic bullet’ carbon solution takes big step. April 3, 2019 https://www.bbc.com/news/science-environment-47638586 ; accesed April 3, 2019.
- CBC News, Angela Sterritt. In fight to combat climate change, Squamish Nation joins forces to capture carbon. November 29, 2018. https://www.cbc.ca/news/canada/british-columbia/in-fight-to-combat-climate-change-squamish-nation-joins-forces-to-capture-carbon-1.4924017 ; accesesd April 4, 2019.
- Intergovernmental Panel on Climate Change 2018 Summary for Policy Makers, Global Warming of 1.5 °C. https://www.ipcc.ch/site/assets/uploads/sites/2/2018/07/SR15_SPM_version_stand_alone_LR.pdf ; accessed April 4, 2019.
- Environment and Climate Change Canada, Canada’s Changing Climate Report, April 1, 2019. https://www.nrcan.gc.ca/environment/impacts-adaptation/21177 ; accesed April 4, 2019.
- Climeworks, http://www.climeworks.com/
- Global Thermostat, https://globalthermostat.com/