Industrial Gas Recovery and Utilization: New Lifecycle Modeling Shows Environmental Benefits but High Costs: Yielding Surfactant and Fuel via Fischer-Tropsch Synthesis

       This post could be classified as being about carbon utilization, the U in CCUS. In these cases, it involves changing waste industrial gases such as CO2 into chemicals and fuels, one of the major pathways of carbon utilization. Technical feasibility continues to be assessed via projects like the Flue2Chem Initiative which aims to convert captured carbon into products and is also considered recycling and developing a circular economy.

     One project modeled the lifecycle of industrial gas recovery for carbon utilization, concluding that the environmental benefits were considerable and desirable, but the costs were high. No real surprise there. Specifically, the study evaluated the life cycle of converting waste gases from steel plants and paper mills in the UK into the production of chemical surfactants. The researchers concluded that making surfactants from steel and paper mill waste gases would reduce global warming potential (GWP) by 82% over making them from conventional processes.  

     The waste gas recovery process requires heat, electricity, and hydrogen. Where those come from affects the final GWP of the process. The greenest scenario involves renewable electricity and green hydrogen. The steel and paper mill study was published in the Journal of CO2 Utilization. Highlights, tables, and figures from the study, and its abstract are shown below.

Abstract

This novel study presents an effective comprehensive life cycle assessment (LCA) of a novel sustainable carbon dioxide capture and utilization (CCU) system to co-produce alcohol ethoxylate (AE7), a valuable surfactant (a high-value chemical component of liquid detergents), and low-medium distillate range liquid fuel. Conventionally, AE7 is produced by reacting fatty alcohols with ethylene oxide from mostly fossil and marginally bio-based resources. This research develops novel AE7 production using carbon sources from flue gas of paper and steel industries, addressing a critical gap in the literature. The core process is Fischer-Tropsch (FT) synthesis using syngas formed by the reverse-water-gas-shift reaction, where recycled CO2 reacts with H2. FT produces C11-C13 alkanes and a light-to-medium fuel co-product. The alkanes are converted into C12-C14 fatty alcohols through dehydrogenation, hydroformylation, and hydrogenation. Fatty alcohols react with ethylene oxide to form AE7. The yields (w/w) of AE7 and the fuel co-products are 3.7 % and 3.4 % for paper industry flue gas, and 8.0 % and 9.5 % for steel industry flue gas, respectively. Renewable (wind) electricity meets the hydrogen demand and electricity needs for the reactions, a total of 13.4 and 33.3 kWh/kg flue gas, respectively. The life cycle impact assessment includes global warming potential (GWP) and other impacts using ReCiPe, Impact+ , and Product Environmental Footprint methods. Baseline scenarios show GWP ranging from 2.2 to 3.6 kg CO2e/kg surfactant for conventional cradle-to-gate AE production systems. The new systems have GWP ranging 0.4–1.3 kg CO2e/kg flue gas (cradle-to-gate) using mass allocation. Meanwhile, the paper industry’s flue gas system has biogenic CO2, while the steel industry’s CO2 is fossil-based. Considering the GWP reductions due to biogenic CO2 contents, their overall GWP is 2.56 kg CO2e and 10.33 kg CO2e per kg of product (AE7 +fuel) (cradle-to-grave) using economic allocation. Thus, biogenic CCU is critical for the sustainable co-production of high-value surfactants and fuel.

     Another study published in December 2024 in Digital Chemical Engineering modeled costs for converting steel mill waste gases the chemical surfactant alcohol ethoxylate (AE7). Perhaps the key finding is that the lowest minimum selling price MSP of $8.77/kg exceeds the forecasted $3.75/kg for fossil-based AE7 and the biggest factor affecting MSP was the cost of green hydrogen.

     It makes me wonder why they didn’t model blue hydrogen, made from the steam reforming of methane with CO2 capture, since blue hydrogen is cheaper than green hydrogen. Since, as MS Copilot informs me, green hydrogen is 2-3 times more costly than blue hydrogen, it seems to me utilizing blue hydrogen in the recovery and utilization process can be comparable or even better priced than fossil-based surfactants, presumably where the hydrogen is grey hydrogen sourced from the unabated steam reforming of methane. The total environmental benefits in the form of GWP would be somewhat less but the costs would make it feasible. I really think they should incorporate blue hydrogen into their modeling. If surfactants can be produced with blue hydrogen at a comparable cost to fossil-based methods then the environmental and climate benefits could be obtained with little to no change in costs, which makes it a no-brainer, right?

     An April 2025 study in Nature: Scientific Reports examined optimizing sintering by optimizing air volume. According to Wikipedia”

“Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms/molecules in the sintered material diffuse across the boundaries of the particles, fusing the particles together and creating a solid piece.”

The optimization of sintering means that the fuel chemical energy is utilized most efficiently. The researchers found an ideal air volume to optimize the process. It is another way waste industrial gases can be utilized most efficiently, which means less emissions. The abstract is shown below.

Abstract

This study examines the impact of sintering air volume on the characteristics of combustible lean gases (CO, H2, and CH4) in sintering flue gas. By conducting experiments using a fixed combustion test bench, we analyzed the changes in sintering negative pressure, flue gas composition, and sinter quality under various air volume conditions. The results demonstrate that an air volume of 90 m³/(m²·min) leads to a lower combustion ratio (ω(CO)/ω(CO + CO2)), indicating more efficient utilization of fuel chemical energy. Additionally, increasing the air volume per unit area reduces the sintering time. The mass fractions of CO and H2 decrease with increasing air volume, and the mass fraction of CH4 also decreases, underscoring the importance of its recovery due to its high global warming potential (28 times that of CO2). These findings provide guidance for optimizing sintering conditions to improve lean gas recovery and reduce environmental impacts.

    

References:

 

How industrial waste gases could replace fossil fuels in everyday consumer products. Science X staff. TechXplore. March 13, 2025. How industrial waste gases could replace fossil fuels in everyday consumer products

Novel comprehensive life cycle assessment (LCA) of sustainable flue gas carbon capture and utilization (CCU) for surfactant and fuel via Fischer-Tropsch synthesis. Jhuma Sadhukhan, Oliver J. Fisher, Benjamin Cummings, and Jin Xuan. Journal of CO2 Utilization. Volume 92, February 2025, 103013. Novel comprehensive life cycle assessment (LCA) of sustainable flue gas carbon capture and utilization (CCU) for surfactant and fuel via Fischer-Tropsch synthesis - ScienceDirect

Optimizing sintering air volume for enhanced lean gas recovery and environmental performance. Xinwei Guo, Jiaoyang Ji, Yanyang Gao, Xingyuan Wu, Yiming Guo, Weishu Wang, Meng Wen, Xiaojiang Wu & Zhongxiao Zhang. Scientific Reports volume 15, Article number: 11146 (2025). Optimizing sintering air volume for enhanced lean gas recovery and environmental performance | Scientific Reports

Flue2Chem: initiative to make products from CO2 begins. SCI. March 13, 2024. Flue2Chem: initiative to make products from CO2 begins

Techno-economic analysis and process simulation of alkoxylated surfactant production in a circular carbon economy framework. Oliver J. Fisher, Jhuma Sadhukhan, Thorin Daniel, and Jin Xuan. Digital Chemical Engineering. Volume 13, December 2024, 100199. Techno-economic analysis and process simulation of alkoxylated surfactant production in a circular carbon economy framework - ScienceDirect

Flue2Chem. SCI - Flue2Chem

Sintering. Wikipedia. Sintering - Wikipedia