Well-made charcoal that has no wood remaining in it burns without making appreciable amounts of smoke. ARC has been studying charcoal burning for many years. Ryan Thompson and Sam Bentson, ARC Lab Manager, worked on the new charcoal stove for two years. It is surprising that a charcoal stove was the best performing stove in the DOE funded R&D project achieving nine ‘Tier 4’ scores.
The DOE funded Charcoal Stove Prototype achieves Tier 4 ratings on all ISO/IWA metrics by quickly raising the combustion chamber temperature above 609 C.
While pure charcoal doesn’t smoke it often makes a lot of carbon monoxide (CO). The ARC team super insulated the combustion chamber resulting in temperatures above 609°C (the auto-ignition temperature of CO) about four minutes after ignition. Secondary air jets of pre-heated air also seem to assist CO combustion. A large airtight door is used to increase firepower for boiling when fully open and to reduce firepower (10 to 1 Turn Down Ratio!) for simmering when the door is almost completely closed.
Making charcoal wastes about 5/8ths of the energy in the wood. But the wood causes smoke that results in human respiratory diseases. Urban cooks frequently buy charcoal to minimize their exposure and to reduce fire tending. Dr. Rob Bailis, a student of Dr. Kirk Smith at UCB, suggested in his 2005 thesis that switching to charcoal could reduce exposure to PM2.5 which is also the current intent of switching to natural gas, a cleaner burning fuel.
Aprovecho Research Center
PO Box 1175
Cottage Grove, OR 97424, USA