Reviewer 2 does geoengineering

Hosted by Andrew Lockley

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228

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May 2026

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About the show

Reviewer 2 quibbles with actual experts in Solar Radiation Modification and Carbon Dioxide Removal, before rejecting their work on spurious, spiteful and capricious grounds. You'd expect nothing less from R2.

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May 15, 202650 min

Viridas Pressurised DAC, El-Sayed

In this episode, @geoengineering1 speaks with Ahmed El-Sayed of Viridas Technologies, a company aiming to revolutionize Direct Air Capture (DAC) by redesigning the process from the ground up, including the fan system itself.The conversation explores why DAC remains expensive, largely due to the extremely low concentration of CO2 in ambient air. While most research focuses on developing new solvents and materials to reduce energy use, Ahmed argues that the thermodynamic limits of capture efficiency may already have been reached. Instead, Viridas is pursuing a different strategy i.e. increasing the volume of air processed.Their proposed high-pressure system reduces contactor size by 70x while delivering more than 3100x better performance through major gains in absorption capacity and absorption rate. Ahmed also discusses the use of scalable, oxygen-resistant solvents derived from widely produced industrial chemicals, and why the future of DAC may depend on breakthroughs in turbomachinery and membrane technologies to drive costs down to ultra-low levels and enable gigaton-scale deployment.Paper Discussed: Elsayed, A., & Alawadh, T. (2026). Scaling Carbon Removal to Gigaton Capacity using Pressurized Direct Air Capture. https://doi.org/10.26434/chemrxiv.15002130/v1Viridas Technologies: https://www.viridastechnologies.com/

April 16, 202650 min

Avantium: Engineering Sorbents for DAC - Wessels

@geoengineering1 interviews Rudolf Wessels, Director of Technology and Innovation at Avantium R&D Solutions in the Netherlands (founded in 2000 as a Shell spin-out). The discussion examines Avantium’s contribution to advancing Direct Air Capture (DAC) through high-throughput experimentation platforms designed to accelerate the discovery and optimization of sorbent materials, enabling rapid, parallel testing under controlled conditions.Wessels also discusses the company’s recent collaboration with the U.S. National Institute of Standards and Technology (NIST) Carbon Dioxide Removal Consortium, focused on improving measurement protocols, benchmarking practices, and validation in DAC systems. The episode highlights how standardized testing, process optimization, and material innovation can support the scale-up and credibility of carbon removal technologies.Links: https://rds.avantium.com/products/direct-air-capture-solutions/https://rds.avantium.com/avantium-joins-nist-to-accelerate-dac-innovation/To stay updated on all things geoengineering-related, subscribe to:Carbon Removal Updates Substack: https://carbonremovalupdates.substack.com/Solar Geoengineering Updates Substack: https://solargeoengineeringupdates.substack.com/

April 4, 20261 hr 14 min

Sustaera - electric DAC

@geoengineering1 interviews Cory Sanderson, CTO and co-founder of Sustaera, a North Carolina-based Direct Air Capture (DAC) startup focused on low-cost carbon capture, separations chemistry, and process scale-up.Sanderson traces his journey from Air Products, where he worked on vacuum swing adsorption CO₂ capture for an SMR hydrogen plant and encountered economic and infrastructure constraints, to founding Sustaera. He also explains the company’s shift from CO₂-to-methane materials, which depended on costly clean hydrogen, to a pure DAC approach.He then outlines Sustaera’s system, which utilises a fixed, cartridge-based monolithic contactor with laminar-flow channels and a conductive, structured sorbent that integrates resistive (Joule) heating directly into the material, thereby improving efficiency, stability, and regeneration speed.He highlights the novelty of the design, noting that Sustaera has achieved over 90% heating efficiency in lab tests, 20-30 minute adsorption cycles, and multi-year sorbent lifetimes. With a modular, catalytic-converter-style manufacturing approach, the company is currently at TRL 5, has pre-sold removals at $700/ton to Stripe and Shopify, and is raising $8.6M to build its first outdoor commercial unit.For more details, visit: https://www.sustaera.com/To stay updated on all things geoengineering-related, subscribe to:Carbon Removal Updates Substack: https://carbonremovalupdates.substack.com/Solar Geoengineering Updates Substack: https://solargeoengineeringupdates.substack.com/

March 20, 202646 min

Climefi - supporting CDR buyers

@geoengineering1 interviews Paolo Piffaretti, co-founder of ClimeFi (https://www.climefi.com/), on how durable carbon dioxide removal (CDR) credits are verified and delivered for corporate buyers.ClimeFi acts as a buyer-side agent, helping organizations define contribution vs. compensation goals, run reverse-auction RFPs, build diversified portfolios, conduct due diligence, negotiate contracts with risk-mitigation clauses, and monitor suppliers through delivery.They also unpack how CDR deals work in practice, covering offtakes, pre-purchases, and newer call options for flexibility, along with what is changing in the market and how buyers manage risk in a space where many projects fail.ClimeFi has also recently opened its Beyond 2030 request for proposals (RFP) on behalf of multiple buyers. It is the company’s most ambitious procurement to date, targeting 100,000 to 500,000 tonnes of durable carbon removal. All pathways are eligible, provided permanence of 200+ years. Submissions close on Wednesday 8 April. Details: https://www.climefi.com/blog-posts/climefi-launches-beyond-2030-rfp-for-durable-carbon-removalTo stay updated on all things geoengineering-related, subscribe to:Carbon Removal Updates Substack: https://carbonremovalupdates.substack.com/Solar Geoengineering Updates Substack: https://solargeoengineeringupdates.substack.com/

January 24, 20261 hr 19 min

Comparing SRM and Opioids - Clark

In this episode, @geoengineering1 is joined by Britta Clark, a postdoctoral researcher at Harvard University, to unpack why solar geoengineering is increasingly compared to opioids. They discuss how this framing casts SRM as temporary “relief” from climate warming and why it raises concerns about potentially slowing emissions cuts. The conversation focuses on how climate models, policy debates, and public discourse can quietly shift expectations about how fast emissions reductions should happen once solar geoengineering is considered, even when people say it should not delay the energy transition. Together, they explore why this tension matters and what it could mean for future climate decisions.Paper: Clark, B. (2025). Solar geoengineering, delay, and addiction. Climatic Change, 178(11), 209. https://doi.org/10.1007/s10584-025-04059-3Open access version: https://philpapers.org/rec/CLASGD-2To stay updated on all things geoengineering-related, subscribe to:Carbon Removal Updates Substack: https://carbonremovalupdates.substack.com/Solar Geoengineering Updates Substack: https://solargeoengineeringupdates.substack.com/

January 9, 20261 hr 23 min

Malaria Trends and SRM - Hussain

In this episode, @geoengineering1 interviews Athar Hussain, physicist and professor of atmospheric science at COMSATS University, Pakistan, about his recent study examining how SAI could influence malaria transmission across South Asia. Using the VECTRI malaria model, the research compares an unmitigated high-emissions pathway (RCP8.5) with the GLENS-SAI scenario, which stabilizes global temperatures at 2020 levels, across seven countries: Afghanistan, Bangladesh, Bhutan, Iran, India, Nepal, and Pakistan.The discussion highlights that while SAI could reduce overall malaria transmission intensity across much of the region by lowering vector density, entomological inoculation rates (EIR), and case numbers, its effects are spatially uneven, with localized increases projected in parts of Pakistan, Afghanistan, Iran, and Nepal. The conversation also explores the public-health implications of these shifts, the potential risks and trade-offs of solar geoengineering, and the importance of region-specific strategies, local expertise, and international collaboration in addressing climate-related health risks.Paper: Hussain, A., Shoaib, M., & Latif, M. (2025). Malaria transmission dynamics under climate change and solar geoengineering in South Asia: a GLENS-based assessment. Malaria Journal, 24(1), 439. https://doi.org/10.1186/s12936-025-05666-2To stay updated on all things geoengineering-related, subscribe to:Carbon Removal Updates Substack: https://carbonremovalupdates.substack.com/Solar Geoengineering Updates Substack: https://solargeoengineeringupdates.substack.com/

December 22, 20251 hr 11 min

Adaptation vs Geoengineering - Gambill

@geoengineering1 interviews Paul Gambill to discuss the intricate dynamics between adaptation and geoengineering. Drawing on his experience as the former founder of Nori, the first carbon removal marketplace, Paul reflects on why scaling durable carbon removal has proven so difficult and what those barriers suggest for stabilizing the climate in an era of overshoot. The conversation then turns to the growing relevance of geoengineering approaches, including solar radiation management (SRM) and other large-scale interventions, and the conditions under which they might move from taboo to serious consideration. The episode explores a spectrum of techniques that blur the line between adaptation and planetary engineering, from ocean iron fertilization and ice-sheet stabilization to localized cooling strategies. Throughout, Paul stresses the need for public awareness, strategic policy development, philanthropic investment, and credible long-term governance to ensure that any future climate interventions are deliberate, legitimate, and responsibly managed.Articles referenced in the episode:What’s the Difference Between Adaptation and Geoengineering?https://www.inevitableandobvious.com/p/adaptation-vs-geoengineeringA Climate Goal for the Overshoot Erahttps://www.inevitableandobvious.com/p/a-climate-goal-for-the-overshoot-eraWhat It Takes to Make Cooling Interventions Thinkablehttps://www.inevitableandobvious.com/p/what-it-takes-to-make-cooling-thinkablePaul Gamble’s current project:https://pitch.com/v/light-the-beacons-pitch-deck-hchvkqTo stay updated on all things geoengineering-related, subscribe to:Carbon Removal Updates Substack: https://carbonremovalupdates.substack.com/Solar Geoengineering Updates Substack: https://solargeoengineeringupdates.substack.com/

December 13, 20251 hr 12 min

Festive snowy forests - D'Souza

What could be more festive than carbon storage in snowy evergreen forests?@geoengineering1 interviews Kevin Bradley D'Souza, a postdoctoral researcher at the University of Waterloo, about the real climate potential of reforesting Boreal forests. Kevin explains the crucial role these forests play in carbon storage, biodiversity, and permafrost protection, while noting that reforestation in the Boreal comes with important challenges. The conversation explores key factors such as albedo effects, wildfire risks, and the importance of Indigenous perspectives in forest management. Kevin also stresses the need for careful, multi-dimensional approaches to reforestation and urges caution around commercial forest-based carbon credits, given the scientific uncertainties that still remain.Papers discussed:Dsouza, K. B., Ofosu, E., Salkeld, J., Boudreault, R., Moreno-Cruz, J., & Leonenko, Y. (2025). Assessing the climate benefits of afforestation in the Canadian Northern Boreal and Southern Arctic. Nature Communications, 16(1), 1964. https://doi.org/10.1038/s41467-025-56699-9Dsouza, K. B., Ofosu, E., Boudreault, R., Moreno-Cruz, J., & Leonenko, Y. (2025). Substantial carbon removal capacity of Taiga reforestation and afforestation at Canada’s boreal edge. Communications Earth & Environment, 6(1), 893. https://doi.org/10.1038/s43247-025-02822-zTo stay updated on all things CDR-related, subscribe to the Carbon Removal Updates Substack newsletter: https://carbonremovalupdates.substack.com/

November 9, 202559 min

Distributing solid aerosols - Hack

Miranda Hack provides an in-depth look at the often-overlooked engineering and logistical barriers to large-scale deployment of solid particles for stratospheric aerosol injection (SAI). She explains how dispersing sub-micron mineral particles at altitude, including challenges like agglomeration, complex nozzle flows, and supply-chain constraints, introduces significant uncertainties and costs. These challenges may reduce cooling efficiency and narrow the design space for “low-risk” SAI strategies, suggesting that solid aerosols could be far less viable than existing models assume.Paper: Hack, M., McNeill, V. F., Steingart, D., & Wagner, G. (2025). Engineering and logistical concerns add practical limitations to stratospheric aerosol injection strategies. Scientific Reports, 15(1), 34635. https://doi.org/10.1038/s41598-025-20447-2To stay updated on all things SRM-related, subscribe to the Solar Geoengineering Updates newsletter: https://solargeoengineeringupdates.substack.com/

October 4, 202543 min

SRM hoses - Hyde

Roderick Hyde discusses his recent paper on using high-altitude hoses for solar geoengineering. While most proposals focus on aircraft delivery, Hyde revisits an older but largely dismissed concept. He describes suspending a 20 km hose by balloons to continuously pump sulfur-bearing fluids into the stratosphere, and argues that advances in modern materials and engineering may overcome past barriers.The conversation covers the technical hurdles such as wind dynamics, hose stability, extreme pressures, and material stress, as well as design variations for pumping H₂S as liquid or gas. Hyde explains how streamlining, intermediate pumps, and lightweight aero-shrouds could make the system viable.The discussion also highlights the potential advantages of this approach, including affordability, continuous operation, and scalability. While a single hose could not halt global warming, Hyde suggests that a distributed network of ~20 installations could offset warming from CO₂, offering a near-term, low-cost option to buy time while longer-term climate solutions take effect.Paper: Hyde, R. A. (2025). A Planetary Cooling Hose. arXiv preprint arXiv:2509.07985. https://doi.org/10.48550/arXiv.2509.07985