Tests were conducted in several different ways. Here are some key results:
- Maximum firepower: 10.6 kW (36,000 Btus). For comparison, a standard gas burner produces 9,000 to 11,000 Btus.
- Fastest cooking: 12 minutes to boil 5 liters (1.3 gallons) of water
- Able to burn dried cow dung at high firepower with no other biomass needed to maintain the fire
- Efficiency as high as 34%, and emissions on par with market-leading stoves (see below for details)
Comparative test results are shown below, using the 5-tier system (0 worst, 4 best) established under cookstove testing protocols. We have included a small sample of competing stoves (the Envirofit M-5000 is one of the most widely distributed clean cookstoves worldwide). The Level Market provides an excellent overview of cookstoves available today.
Original testing data can be found at the following links:
Ganesha Stove: maximum firepower test, complete test
Envirofit M-5000 (natural-draft rocket stove)
Envirofit Econofire (natural-draft rocket stove)
EcoZoom Relief (natural-draft rocket stove)
CRT/N RSMS2 (natural-draft rocket stove produced for use in Nepal)
ACE 1 (forced-draft pellet gasifier stove)
We included the ACE 1 stove in this table to show both ends of the spectrum, from the $12 Ganesha stove to the $100 ACE 1. While the Ganesha stove and the other 4 cookstoves above are natural-draft stoves designed to burn wood and other biomass, the ACE 1 is a forced-draft (fan-powered) stove designed to burn pellets made of wood or agricultural waste. While the performance of this stove is high under testing protocols, a recent study raised the concern that forced-draft stoves can generate tiny particles that travel deep into the lungs, which is implicated in lung cancer.
Nepal was struck by a powerful earthquake on April 25, 2015, and subsequently by over 400 aftershocks. As the country tried to rebuild, it suffered through a political dispute that closed its border with India for almost five months, leading to shortages of fuel, medicines and other essentials. In the capital, Kathmandu, most residents turned to wood as the best and often the only available fuel for cooking. In the surrounding countryside, villagers began harvesting firewood in large quantities to sell to city dwellers, accelerating deforestation. Nepal’s government actively supports the development and dissemination of clean cookstoves through the Alternative Energy Promotion Centre (AEPC).
First Prototype - Brabal Village, Langtang
We tested our first prototype Ganesha stove in the Langtang region of Nepal in February 2016.
Villagers immediately accepted the stoves and began using them, with a high level of excitement. We found that no training was needed to operate the stove - they started a fire and began cooking within minutes. We trained them on assembly and disassembly of the stove, and within about half an hour all we observed were competent in the task.
We found that in this region, most households have a big metal woodstove that they use for all heating and cooking, with removable plates on top for cooking pots and pans. These stoves periodically generate large amounts of smoke, especially because villagers operate them with the front stove door open, wood pieces sticking out, and often the openings on top uncovered. To make a small meal or tea, they must start the stove and use 4-5 large pieces of hardwood (56cm-75cm long, 3-8cm in diameter). In this traditional method, boiling a large teapot of water (6.5 liters) can take 30 to 45 minutes. Currently, they cook on these stoves even in summer, when they produce far more heat than is needed.
Accordingly, villagers appreciated that on the Ganesha stove, they could bring the same amount of water to a boil within 20 minutes and use very little fuel. It also delighted them that it used small pieces of wood and bark, which they have in abundance and don’t use for any other purpose. In comparison to their current stoves, the Ganesha stove heated up and cooled down very quickly. We concluded that what villagers want is a fast-lighting, hot-burning stove, and they very much appreciated these qualities in the Ganesha stove.
Specific feedback from villagers included 1) they would like the metal to be a bit thicker than the 26-gauge stainless steel we used, and 2) would like the stove to be 20% to 40% bigger for kitchen use. They prefer the current size for portable uses such as yak herding.
Second Prototype - Sotang Village, Solukhumbu
Working with our partners the dZi Foundation, we sent our second prototype to a village in eastern Nepal. This time, we learned that the stove met many key needs: it could be started quickly, and cooked lentils, rice and tea very well. They asked that it be more of a pyramid shape for stability, and that we re-design the damper mechanism. And, they kept using the stove, as shown below.
On to Bigger Pilot Projects
The current version of the Ganesha stove has been updated to incorporate these changes. The stove is bigger, more stable, easier to operate, more durable, and the heat output is significantly higher.
We will continue iterating the design, based on usability studies of our pilot projects in different areas of Nepal. Please see the Pilot Projects page for more information.