Laboratory Comparison of the Global-Warming Potential of Six Categories of Biomass Cooking Stoves

Laboratory Comparison of the Global-Warming Potential of Six Categories of Biomass Cooking Stoves
Nordica MacCarty, Damon Ogle, Dean Still, Dr. Tami Bond, Christoph Roden, Dr. Bryan Willson, September 2007

Abstract
Improved cooking stoves have been shown to reduce the amount of fuel used to cook food and the air pollution produced in kitchens. Reducing deforestation and smoke inhalation have been the primary motivating factors for the dissemination of improved cook stoves. Recently, the potential of improved stoves to reduce the effects of biomass combustion on global warming has become a major interest, as well.

Gaseous and particle emissions from six cooking stoves were analyzed: a three-stone fire, a rocket stove, a fan stove, a gasifier stove, a charcoal stove, and a rice-hull burning stove. These stoves were chosen to highlight different methods of combustion. Results indicated a significant difference in emissions between the stoves when the overall climate-forcing effects were calculated as CO2 equivalents on a 100-year timeframe, known as Global Warming Potential, or GWP.

Overall data showed that as much as a 50% reduction of fuel use, air pollution and GWP can be achieved by three of the wood-burning stoves in comparison to a carefully-tended laboratory three-stone fire. The rocket and fan stoves produced 39%, a gasifier stove 56%, and a charcoal stove 84% of the three stone fire’s global warming potential when CO2 is included. If the fuel is harvested sustainably, then the CO2 is reabsorbed by the replacement biomass, and can be carbon neutral. In this case, only the products of incomplete combustion (PIC) are considered.

When fuel is harvested sustainably the rocket stove produced 41% of the warming potential of the three stone fire, the gasifier 29%, and the fan stove a remarkable 4%. The burning of charcoal produced 61% more warming emissions than the three stone fire, not counting the energy loss or emissions made when making the charcoal. Products of incomplete combustion (PIC) contributed from 26% to 51% to the overall Global Warming Potential produced by the direct burning natural draft stoves. Estimates of carbon reductions based on fuel use alone may not be accurate if PICs are not measured, especially if the fuel is harvested sustainably.

Measurements were based on the specific emissions, or grams of emissions produced per liter of water boiled and simmered. In this way, heat transfer efficiency is taken into account along with the combustion efficiency. It is important to consider that these results were from laboratory testing field results will differ and be highly variable. The intent of the investigation was to assess the performance of the stoves when operator-influence was minimized in order to better understand the capability of each type of stove technology.

The articles are being revised and will be posted soon.