Diminishing fuel sources, polluting cooking techniques and soil degradation compromise the livelihoods of Kenyan smallholder farmers. To address these challenges, the research project “Biochar and smallholder farmers in Kenya” studies the introduction of domestic gasifier stoves that produce char from locally available biomass, besides providing energy for cooking. While cleaner combustion reduces fuel consumption and detrimental emissions, the char can be used as an energy-rich fuel for cooking (i.e., charcoal), or as a soil amendment and means of carbon sequestration (i.e., biochar). Improved cook stoves, charcoal and biochar have been widely taken up in development research. Yet this thesis identifies three gaps in evaluation which it aims to fill by addressing (1) several goals of sustainable development; (2) alternative ways to source and convert biomass feedstocks; and (3) trade-offs between charcoal and biochar. Based on the Life Cycle Assessment methodology, two strategies of improved biofuel management are compared with the current practices. A dynamic model developed for this purpose calculates each systems climate impact when delivering the required amount of cooking energy. Furthermore, the model accounts for fuel consumption, soil amendment and detrimental pollutant emissions. Irrespective of modelling approach and parameter settings, the charcoal and the biochar system show clear advantages over the baseline. Applying char to soil is the best option as it reduces the climate impact by 85-157% depending on pollutant set and time frame; causes the lowest level of indoor air pollution; and allows for the agronomic benefits of 831 kg biochar per hectare and year. However, if organic resources are scarce and unsustainably harvested, it may be better to use char for energy and thus save primary feedstocks. In practice, not only fuel use efficiency and soil amendment but also stove handling and usability will determine how farmers use available feedstocks.