Entries by Kim Still

Clean Combustion Needs More Than Just Heat

Dr. Larry Winiarski wrote the ten rocket design principles We have been having a lot of fun doing a modern literature search: Surfing YouTube. YouTube is often years ahead of the slower, but probably more accurate, information in peer reviewed journal articles. I suppose that many people are looking at both. A shared misunderstanding seems […]


Electricity: Planning for Net Zero by 2040

www.weforum.org/agenda/2023/04/electricity-generation-solar-wind-renewables-ember/ Transitioning to carbon neutral electric generation would replace a big climate problem in the U.S., since about 60% of its electricity comes from burning natural gas. The World Energy Forum forecasts that around 40% of electricity could be from wind and solar doing most of the heavy lifting by 2040, enabling a net zero global […]


Earth Day 2023: The Future Can Be Fun!

(R. Crumb) If renewable switch grass, for example, was burned cleanly enough biomass could join solar, wind, hydro, and thermal energy as sustainable energy replacements in the post fossil fuel era. ARC estimates that an emissions rate of 0.3 grams/hour of PM2.5 would protect air quality in cities and meet the Paris Agreements when replacing […]


Clean Burning Also Necessary for Biomass Home Heating

Since 1976, ARC has been investigating how to improve heat transfer and combustion efficiency in Low Middle Income Countries’ wood burning cook stoves. Emissions of Particulate Matter have been shown to kill millions of people annually. PM concentrations are frighteningly high in homes without chimneys but emissions into outdoor air are an increasing health/climate concern. […]


50% Thermal Efficiency Depends on Several Factors Including the Surface Area of the Pot

Illustration from The Smithsonian’s explanation of how a boundary layer works  A boundary layer of still air on the bottom and sides of a pot keeps the hot gases from actually contacting the surface and is a dominant factor in heat transfer efficiency. According to Newton’s Law, doubling the surface area doubles the heat transfer when […]

Using Air Changes to Meet ISO PM2.5 Performance Targets

Almost 20 years ago, ARC was invited to a conference in Bonn, Germany to consider standards for cook stoves including emissions. In preparation, we met with Dr. Kirk Smith and his protégés at the University of California at Berkeley. We discussed the beneficial effect of increased air exchanges that decrease the concentrations of CO and […]

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Secondary Air in TLUDs and Rocket Stoves

Forced draft mixing with 2nd air jets in Dr. Tom Reed’s WoodGas Stove at around 1,000C Forced draft mixing with preheated jets of primary air reduced emissions of PM 2.5 by around 90% in our stove tests with the Jet-Flame. Would adding secondary air jets further decrease emissions? Secondary Air Works in TLUDs Lefebvre, Vanormelingen, and […]