Low-Cost Catalytic Biomass Cookstove for Improved Indoor Air Quality

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Project Summary An estimated 2.5 billion people, or about one-third of the world’s population, rely on biomass fuel for cooking. Emissions from biomass cookstoves contribute to global climate change, indoor/local air quality issues, and related health effects. In particular, indoor air quality issues related to biomass cookstoves contribute significantly to rates of acute respiratory infection. Recently developed forced air and “rocket” stoves offer improvements, but are unlikely to consistently meet WHO guidelines for indoor air quality. Emissions of CO, unburned hydrocarbons (including air toxins like formaldehyde) and particulate matter (PM) are especially problematic. Similar to the evolution of emissions controls for automobiles, advanced biomass cookstoves have progressed to the point where inclusion of an oxidation catalyst is the logical next step. However, widely used noble-metal oxidation catalysts are prohibitively expensive. Instead, we proposed the inclusion of a low-cost, alternative oxidation catalyst that is integrated into the stove. In Phase I, the catalyst, originally developed as a diesel soot oxidation catalyst, was synthesized, characterized, and tested in a specialized prototype cookstove. The prototype stove designed and tested in Phase I improved heat transfer to the cooking vessel and included design features that allow fine tuning of the air flow, fuel/air mixing, and heat release. In addition, the prototype stove includes several design features to improve ease-of-use and safety. The Phase I technical approach relied heavily on computational fluid dynamics (CFD), rapid prototyping, and laboratory testing. In Phase II the catalyst was refined further and long term stability was confirmed. Catalyst doping with additional metals was also explored. A focus group conducted in Guatemala was used to design the stove to meet the needs of potential users. After incorporating design changes, a field trial was performed to gauge real-world performance and user acceptance. CRP work will focus on manufacturing the stoves in developing countries where the stoves would be sold or distributed. This approach will lower manufacturing costs and provide local jobs. Unlike other catalysts, the proposed catalyst requires no specialized wet chemistry methods for its synthesis. Catalyst synthesis requires only a furnace and commodity chemicals. All stages of the development will consider local manufacturability, maintenance, and user acceptance. During the CRP we will protect our intellectual property by applying for necessary patents. We will also partner with manufacturing companies to refine drip pan manufacture and catalyst-to-monolith adhesion to ensure artisanal manufacturers can easily replicate the stove. Finally we will work with local Guatemalan partners to identify the best local markets for the stove and explore charitable and carbon-credit stove dissemination programs.