We've been flogging this issue for as long as there's been TreeHugger. Is it safe to burn ethanol inside, without a flue? TreeHugger emeritus and chemist John Laumer told us a few years ago that " alcohol molecules are very short and produce very little CO2 compared to any other hydrocarbon liquid. Much of the liberated energy is from hydrogen combustion."
So other than the fact that they are consuming the oxygen in the room and you should have some ventilation, they are OK, right? A new German study by the Fraunhofer Institute for Wood Research finds otherwise. According to Dr. Michael Wensing, quoted in Science Daily:
These stoves do not feature any guided exhaust system whatsoever, so all combustible products are released directly into the environment.. ...On a case-by-case basis, precisely how the course of that incineration runs really depends on the quality of the fuel and other factors – like the type of fuel, or the incineration temperature. As a rule, ethanol does not burn out completely. Rather, the incineration process results in CO2 – along with poisonous gases (like carbon monoxide, a respiratory toxin), organic compounds (like benzene, a carcinogen), and irritant gases (like nitrogen dioxide and formaldehyde), as well as ultrafine combustion particles.
Dr. Wensing concluded that the stoves are a health hazard, and should be avoided in apartments or anywhere but large, very well-ventilated spaces.
It should be noted that the study was done by the Fraunhofer Institute for Wood Research, which not surprisingly found that properly sealed and vented wood burning stoves resulted in significantly cleaner interior air.
As I noted when we last looked at this subject, burning stuff inside without proper balanced ventilation is probably not a good idea, no matter what it is. On the basis of this study it appears that these pretty ethanol fireplaces that are popping up everywhere are not so innocuous after all.
More at Science Daily