Thread by @geoengineering1

🚨NEW STUDY🚨

Recent research submitted in the @researchsquare “presents first-of-its-kind process concepts for co-removal of #methane and #CO2 that combine the catalytic conversion of methane step (thermal/photo-catalytic) with #CO2Capture (#DirectAirCapture).”
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“The proposed solution to co-remove methane and CO2 from low concentration sources has the potential of #removing more CO2-equivalents from the atmosphere at lower energy penalty when compared to technologies that focus on removing only CO2 from the air, the study affirmed.”
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Based on the analysis of this study, researchers summarize the following challenges and opportunities with the proposed solution for co-removing methane and CO2 from the atmosphere:
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1️⃣ “Methane conversion and co-removal of CH4 and CO2 is a possibility from low concentration sources, but the total energy demand is very sensitive to the concentration of methane in the source.”
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1a) “At lower concentration of methane (<450 ppmv CH4), co-removal is more energy efficient than just converting methane into CO2.”

1b) However, “for higher concentration of CH4 (>450 ppmv), just converting CH4 into CO2 could be enough to efficiently remove CO2-equivalents.”
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2️⃣ “Placing the co-removal process closer to the source of methane emissions provides an opportunity to convert methane and co-remove methane and CO2 at a lower energy penalty than the process that only removes CO2 from ambient air.”
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2a) “These places can be for example:
💨 air from ventilation stables
💨 air above the manure storage headspace
💨 air above the wetlands where the methane concentration is more than in ambient air.”
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2b) “The total energy demand for CH4 conversion & co-removal is:
🔸302 & 23 GJ/t-CO2eq for ambient air having 2 ppmv CH4
🔸1.5 & 3.5 GJ/t-CO2eq for ventilation air from stables (with 300 ppmv CH4)”
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🔸“86-13 & 21-12 GJ/t-CO2eq for air above the wetlands (with 7-40 ppmv CH4)
🔸0.05 & 1.16 GJ/t-CO2eq for air above manure storage pits (with 10000 ppmv CH4)”
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3️⃣ “Several challenges need to be overcome for the co-removal process to be energy efficient to remove CO2-equivalents from the atmosphere.”
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3a) “These are:
🔸w.r.t. materials (catalysts)
that can convert CH4 at low conc. in air
🔸heat exchanger design
🔸reactor conditions & design
🔸heat integration with the #CO2Capture step
🔸treating other impurities like NH4, VOCs & dust that may inhibit the catalyst.”
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4️⃣ “Photocatalytic route has the potential of removing methane at lower energy penalty if artificial illumination can be eliminated, and the catalyst is effective in the presence of direct sunlight. However, the process is limited to the place and time for the sunlight.”
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5️⃣ Although this article doesn't provide a life cycle analysis for the proposed concepts, “LCA will decide if the process will enable achieving #NegativeEmissions or not. Similarly, a techno-economic analysis will help in understanding the viability of the proposed concepts.”
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6️⃣ “Co-removal process also presents potential for process intensification where CH4 conversion & #CO2Capture can be done in 1 step or CH4 & CO2 can be converted to valuable products in 1 step. These processes can be unified with N2O removal/conversion, where N2O——> N & O.”
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7️⃣ “The proposed concepts have the potential to remove 40% of anthropogenic non-fossil & 40% of natural CH4 from the atm. The agri sector is likely to be the first mover of tech since the conc. of CH4 in ventilation stables & manure storage is > CH4 conc. in the ambient air.”
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8️⃣ “The scope of this work is limited to non-fossil methane, and researchers have avoided any methane coming from fossil sources, for example, leaks in the natural gas value chain or ventilation air in coal mines.”
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📖 Read the open-access publication submitted in @researchsquare entitled “Co-removing methane and carbon dioxide from the atmosphere: Process concepts and analysis” (Preprint) here ⬇️
researchsquare.com/article/rs-295…

#CO2Removal
#CH4Removal

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