Viability of waste-based cooking fuels for Developing countries : combustion emissions and field feasibility

Abstract

Biomass-derived cooking fuels are used by three billion people worldwide. The drawbacks of such fuels, typically wood or wood-derived charcoal, include health hazards, negative environmental effects, and perpetuation of poverty. Briquettes made from various waste materials have been proposed as an alternative to address these issues. The purpose of this work is to understand whether such fuels are viable as compared to wood charcoal considering toxicity, usability, and economic criteria. Briquettes made from carbonized agricultural waste (AWC) using a process developed by MIT's D-Lab were investigated. These briquettes were comparable to wood charcoal in terms of energy density, carbon monoxide, and polycyclic aromatic hydrocarbon emissions. Particulate matter emissions from these briquettes were 3-5 times higher but the emissions were only dominant during the initial stages of the fire. Methods for mitigating these emissions are proposed. Ultra-fine particles from wood charcoal and AWC were characterized, offering a novel understanding of these emissions. The effect of variations in raw material inputs on combustion emissions was documented and manure was found to be a promising binder material. Field studies were conducted on AWC, assessing cooking fuel emissions in households in Nicaragua, ascertaining end user perception of the fuel, piloting production with a women's cooperative, and conducting an economic analysis of the viability of this production model. Emissions were found to be comparable to wood, user perception was cautiously positive, and production was hypothetically profitable if systems are introduced effectively. Briquettes produced in Haiti from paper waste and fabric scraps were also studied and found to be highly problematic from the perspective of emissions and cooking performance. Most concerning from a health perspective is the increased particulate emissions, as compared to wood charcoal, by a factor of up to 45. These types of briquettes are being disseminated and no prior art on their emissions has been identified. In summary, AWC has promise as an alternative fuel but care must be taken in terms of particulate matter exposure and minimizing deviation from the studied briquette formula. Any alternative fuels should not be introduced until the emissions hazards and cooking performance limitations are addressed.