Climate Change Impact Assessment of a Biochar System in Rural Kenya

Abstract: Biochar systems have been beneficial to Kenyan residents living in the rural areas, particularly in Kwale, following recent research interventions. Biochar system starts from the biomass feedstock sourcing, its production method, and finally its application to soil. The aim of this study is to assess the climate change impacts of the application of biochar in smallholder farms and households in rural Kenya, against the traditional agriculture and cooking practices under realistic conditions and from a life cycle perspective. The scope of this study includes the biomass sourcing identification, biomass availability measurement, cooking practice observation and biochar application during planting season (April to May) at one of the rural areas, the Waa Ward in Kwale County under The Biochar Project. Field observation was carried out to identify and measure on-farm biomass availability and cooking performance. The identification and measurement of biomass weight were conducted through survey and manual scale, respectively. While the cooking performance was observed with uncontrolled Kitchen Performance Test (KPT) method. A life cycle assessment was conducted to evaluate the climate change impact of biochar system in Kwale. The biochar production method, also called the improved system in this study, is compared against the traditional system. This study focuses at the cookstove used for the two systems, Gastov and three-stone open fire. Gastov is a type of Top-Lit UpDraft (TLUD) natural draft gasifier cookstove investigated. The biomass measurement established the biomass and energy availability on-farms in Kwale. Meanwhile, the KPT found that Gastov required lesser fuel for cooking due to higher thermal efficiency in comparison to three-stone open fire. The LCA results showed that the improved system performs better than the traditional system in terms of climate change impacts and that the improved system potentially offset GHG emissions caused by traditional system as well as generates a net carbon credit. Lastly, the ‘hotspot’ of the improved system was identified in the cooking process, although it was also significantly better than the traditional cooking process. The sensitivity analysis showed that both fraction of stable carbon and fraction of non- renewable biomass (fNRB) were major factors in the biochar system in Kwale, Kenya. The conclusion is that the biochar system presents more advantages as applied in Kwale compared to the traditional system through biomass management, improved cooking method, and biochar application to soil.