If stoves pollute in the lab, they certainly will in the field. We estimate at least 3 times more. Commercially available biomass cookstoves that meet WHO standards are very rare. ARC continues to be committed to doing research and development to help to get the needed new stoves to market so that field studies will show success in sales, protecting health, saving wood, and making cooks happy. We believe that sharing what we learn is very important! So, we updated our “textbook” and it’s available for free here. The chapters have been updated and rewritten to try and share everything that we have learned in the lab in the last five years.
Here are some highlights:
- With clean outdoor air, doubling the air exchange rate halves the concentrations of PM and CO in the kitchen.
- Using an EPA model of Oakridge, Oregon, the outdoor air concentration of PM2.5 would only be increased from 13.1 μg/m3 to 13.3 μg/m3 if homeowners used an ISO Tier 4 PM2.5 cooking stove.
- A catalytic converter works well with gases (30-95% reduction of CO) but not with smoke (30-40% reduction of PM2.5) (Hukkanen et al., 2012).
- We think that the Harris TLUD is perhaps the first “close to optimal” cookstove. It scored 0.7mg/minute PM2.5 with pellets at Lawrence Berkeley National Laboratory. It has a 3 to 1 turn down ratio. Large natural draft static mixers create thorough mixing. Decreasing primary air reduces the rate of reactions (production of wood gas) if the air/fuel mixture becomes too rich. A stationary fan blade spins the flame for longer dwell time. And cooks at ARC love to use it.
- When carefully tested at ARC, the SSM Jet-Flame in the CQC earthen stove scored Tier 4 for thermal efficiency, CO, and PM2.5.
- Renewably harvested biomass can be a carbon neutral energy source when burned very cleanly.
We are getting closer to practical solutions! The ones we know about are in the book.