Sometimes crowds push their governments to change course and then there are times when an individual makes the difference. It seems to me that technological advance is more dependent on individuals. A human being chews on a problem long enough to create a new solution that is clearly superior.
At this Summer Stove Camp, Kirk Harris brought a ‘super-clean’ TLUD that scored in the high 3 to 4 range at both high and low power. The stove had a remarkable turn-down ratio. High power was above 5kW! The water boiled quickly and simply pushing a lever lowered the flame. His TLUD also has well developed swirl and high temperatures just below the pot assisting the heat transfer efficiency.
Kirk had also brought a version of the stove to the Aprovecho Open House in January 2014 but by Summer he had evolved a true innovation.
I think that one of the most important tenants at ARC is that almost anyone can solve technological problems. I’m living proof that stubbornness, not brilliance, is the most important requirement for progress on improving stoves. You also need sufficient time to make enough experiments to let the solution emerge.
It is so heartwarming to see that Kirk persevered. It was one of many things that made Stove Camp so encouraging.
Shotgun Data Again at Stove Camp
This was one of my favorite Stove Camps because almost all the participants were from stove projects and spent the week doing tests to improve their stove. One $250 prize was for the ‘best’ TLUD. The other prize was for the ‘best’ bread oven. ‘Best’ was determined by voting on the last day. Flip Anderson may have won with her Barbeque Oven in no small part because treats poured out of the oven daily: bread, cookies, blackberry cobbler, brownies, etc.
There were more than 25 Water Boiling tests accomplished under the emissions hood. (All of the Stove Camp IWA results will be seen soon at Aprovecho.org.) Seven stoves scored Tier 4 for thermal efficiency. (Tier 4 is the highest score.) Kirk Harris’ stove also got a 4 for Low Power Specific Consumption! As seen before, 21 of the 25 stoves were in the Tier 4 category for High Power CO. All of the Low Power CO scores (7 tests) were also in Tier 4. Again, the data suggests that wood burning stoves generally don’t make a lot of CO unless there is too little air entering the combustion chamber and charcoal is being made.
Although it’s easy to score well on the CO metrics it’s a lot harder to get a 4 on measures of PM. Only 7 stoves out of the 25 emitted a low enough amount (41mg/MJd) to get a 4 for High Power PM. Even TLUDs or forced air stoves have to be well tuned to be that clean. The gravimetric filter used to measure PM has to be white without a hint of grey after the water boils to get a 4. A representative sample of the smoke is pulled through the filter. Imagine how clean the stove sized cigarette would have to be to leave the filter almost completely white! Tier 4 is very clean.
Aprovecho Research Center
PO Box 1175
Cottage Grove, OR 97424, USA