Reactions: Carbon capture from fermentation processes, and safety in C&EN images

Letters to the editor

Carbon capture from fermentation processes

Two items in the Feb. 12/19, 2024, issue (the letter “Direct Air Capture,” page 5, and the article “Researchers Caution about Reliance on CO₂ Removal,”page 17) discuss some economic and sustainability issues related to the reduction of atmospheric carbon dioxide, which is needed to achieve goals on mitigating global warming. Ultimately, multiple approaches will be required. One approach that I hear little about is the capture and reuse of CO₂ generated as a by-product of fermentation processes, including the anaerobic digestion of food and sewage waste. The CO₂ is derived from various forms of biomass and generated in enclosed spaces at higher concentrations than air, which should make capture more efficient. I believe that the CO₂ produced is typically just vented into the air.

Anaerobic digestion facilities are already separating the digestion-generated CO₂ from the biogas before the methane is used to generate renewable electricity. More CO₂ could be captured from the flue gas. The Quantum Biopower anaerobic digestion facility where I send my food waste processes about 36,000 metric tons (t) of material annually and has reported that it avoids roughly 4,500 t of CO2 emissions annually. I’ve read that anaerobic digestion of sewage sludge at Boston’s regional sewage treatment facility on Deer Island produces about 5 million ft3 (about 142,000 m³) of biogas daily, which I calculate as resulting in over 10 times as much CO₂(from the biogas and burning of methane) as the total CO₂ produced from the Quantum Biopower facility. Scaling such facilities widely and capturing and using the generated CO₂ in the production of, for example, aviation and other transportation fuels could significantly contribute to reducing fossil CO₂ emissions and eventually to reducing atmospheric CO₂ levels.

William C. Horne
Branford, Connecticut

Safety in images

I read with interest the article by Geoffrey Kamadi “C&EN Talks with Stephen Cochrane, Antibiotics Researcher”(C&EN, Feb. 12/19, 2024, page 26). It looks like Dr. Cochrane is in a lab without his personal protective equipment (PPE). I recommend that future publications respect lab safety protocols by either showing people in lab with their PPE or adding a qualifying statement that all chemicals, etc. have been removed—as is done in the current American Chemical Society RAMP (recognize hazards, assess risks, minimize risks, and prepare for emergencies) lab safety videos. C&EN should set the correct example. We faculty have enough trouble getting students to comply with lab safety regulations. C&EN’s support is requested. Thank you!

Ruth Ann Cook Murphy
Austin, Texas