Entries by Kim Still

Post Combustion Reduction of PM2.5

Both automobiles and the biomass industry rely on improving combustion efficiency and post combustion reduction of PM2.5 to achieve “clean burning.” It’s really hard to rely on the combustion chamber to burn up enough of the harmful smoke to protect health, especially in large scale applications. Of course, all efforts should be made to be […]

Mass, Insulation and Thermal Efficiency

It is more likely that close to 50% thermal efficiency will be achieved with a biomass burning stove when: Small sticks are burned that produce tall, hot flames while using the least amount of wood. A 30cm in diameter aluminum pot is used with a 14cm high pot skirt that creates a 6mm channel gap. […]

Justa, Dos por Tres, Patsari Stoves!

During an ETHOS panel discussion on Cooking, Health, and Climate, it was great to see that the Justa stove with chimney protected health so well. Chimneys are mandated by law in the USA/Europe/China and many other countries. When Mahatma Gandhi returned to India from England he introduced chimneys as a logical upgrade of kitchens. The […]

ETHOS is Great!

Yesterday morning I was on an ETHOS panel discussing stoves, health and climate change. I loved the discussion and was filled with hope that facing the end of the fossil fuel era might catalyze better use of resources.  Living sustainably has been a dream of mine since I was 15 years old in 1967. Like […]

Temperature, CO & PM 2.5

High temperatures in the combustion chamber seem to have both positive and negative effects on emission rates of biomass. Higher temperatures lower the residence time needed for more complete combustion. At the same time, especially with dry wood, the rate of reactions (how much wood gas is being made per unit of time) is increased. […]

A Multi-tiered Framework for Evaluating Cooking Systems

ISO 19867-1:2018 is a set of laboratory test protocols for evaluating cookstove performance, published by the International Organization for Standardization. Their Voluntary Performance Targets are a set of baseline criteria defined as tiers – Tier 0 is worst, Tier 5 is best. These ISO Targets measure Thermal Efficiency, Exposure (PM2.5 and CO), Safety, and Durability. […]

One Acre Energy Comparisons

One of my favorite reference books is “The Energy Primer” published in 1974. It has comprehensive review articles on solar, wind, water, and biomass energy. The following chart comes from a great article on biomass written by Richard Merrill. When I taught semester courses to college students at ARC, I tried to give students useful […]

Natural Draft Top Lit Up Draft Stoves, 2021

A natural draft TLUD can be as clean burning as a forced draft TLUD burning wood pellets. On the other hand, a natural draft Rocket stove needs a fan to be clean burning. Dr. Tom Reed’s forced draft (FD) Woodgas stove achieved an emissions rate of 2mg/min of PM2.5 with pellet fuel (ARC, 2015). The […]

Appropriate Technology as Craft

Before I met Dr. Larry Winiarski I was a boat builder, but I had already realized that my love for making boats was mostly supported by rich people. And when my friends and I built a 36’ ocean going sailboat it was great but after several years of exploring it started to be a bit […]

Back to Basics – Fire, part 2

In our Nov. 24 newsletter, we shared a basic description of how wood burns from Samuel Baldwin’s book “Biomass Stoves: Engineering Design, Development, and Dissemination” (1987). Here are more details about the process from the same book: “The temperature of the hot gas above the wood is typically around 1100ºC and is limited by radiant […]