The heating profiles of the water for different dung types and total burn times are illustrated in Fig 2. In general, the rates at which the water heats up to 100oC are similar, although giraffe and cow dung depart from the trend slightly. More important is the duration of combustion. For a given mass of fuel, the duration of combustion ranged from 700 seconds (11.7 minutes) for rhinoceros dung to 2700 seconds (45 minutes) for giraffe dung. This is important in the application of cooking food and boiling water. Insufficiently cooked food can result in food poisoning. As the TLUD cookstove design is a batch-feed fuel system, it can not be refueled during combustion. American bison dung was similar in size and shape to cow dung. While a fuel canister of both dung types had approximately the same mass, the bison dung may have a higher energy content due to differences in diet. The American bison had a diet rich in lucerne hay, whereas the free grazing Angus beef cattle used for cow dung were occasionally fed meadow hay. This slight difference in diet likely had a marginal effect on the heating value of each dung because both fuels produced flames with similar characteristics. The flame produced by the bison dung surrounded the bottom of the pot, producing smoke and blackening the pot. It was also observed that air was not induced through the secondary air inlet holes, suggesting the stove was not operating as a microgasifier. It is likely that air was induced through small gaps between the secondary air adapter and the fuel chamber, reducing the effect of secondary air holes on the combustion process.