Kenyan biochar

Biochar produced in cookstoves can contribute to negative carbon emissions through sequestration of biomass carbon, while also providing clean renewable energy and increasing yields in tropical agriculture.

In this research project the production and use of biochar in 150 smallholder farming households in three different regions in Kenya is investigated. Biochar-producing cookstoves have been distributed and the fuel use efficiency, emissions and biochar production are quantified. Effects on crop yields after application of biochar to soil is also studied.

Results show that cookstoves provided benefits through reduced smoke, savings on fuel wood and production of char, but challenges were found related to labour for fuel preparation, lighting, and refilling of stoves.

On-farm trials with varying rates of biochar application to soils show significant increases in maize yield both in combination and without mineral fertilization. Yield increases are persistent according to our results from an ongoing long-term trial which was started in 2006. More recent participatory trials where the farmers used their own biochar from the cookstoves also showed positive correlations between biochar rates and yields.

The climate impact in a life cycle perspective is quantified, taking biomass production and use, cookstove efficiency and biochar use in agriculture into account. Climate benefits are possible through reduced use of biomass in cooking, reduced emissions and sequestration of stable biochar carbon in soils.

The farmers perceptions of the technology and the reasons for changes in practices are also investigated in the project.

The project is a transdisciplinary collaboration between researchers in Kenya (IITA, ICRAF and CIFOR) and Sweden (KTH, SLU and Lund University).

The research is funded by the Swedish Research Council, grant No. 2015 03180, and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, grants No. 924-2015-1112 and 942-2015-1648.

Project participants

Cecilia Sundberg, KTH – Royal Institute of Technology, Stockholm, Sweden

Erik Karltun, Thomas Kätterer, Gert Nyberg, Swedish University of Agricultural Sciences (SLU), Uppsala and Umeå, Sweden

Yahia Mahmoud, Lund University, Lund, Sweden

Mary Njenga, James Gitau, World Agroforestry Centre (ICRAF), Nairobi, Kenya

Kristina Roing De Nowina, CIFOR, Nairobi. Kenya

Dries Roobroeck, Geoffrey Kimutai,  IITA, Nairobi, Kenya


Project flier: 2-page flier

Policy brief: Biochar stoves for socio-ecological resilience

Papers in peer-reviewed scientific journals

Sundberg, C.; Karltun, E.; Gitau, J.K.; Kätterer, T.; Kimutai, G.M.; Mahmoud, Y.; Njenga, M.; Nyberg, G.; Roing de Nowina, K.; Roobroeck, D.; Sieber, P. Biochar from cookstoves reduces greenhouse gas emissions from smallholder farms in Africa. Mitigation and Adaptation Strategies for Global Change. 2020

Gitau, K. J.; Sundberg, C.; Mendum, R.; Mutune, J.; Njenga, M. Use of Biochar-Producing Gasifier Cookstove Improves Energy Use Efficiency and Indoor Air Quality in Rural Households. Energies. 2019

Gitau, K. J.; Mutune, J.; Sundberg, C.; Mendum, R.; Njenga, M. Factors Influencing the Adoption of Biochar-Producing Gasifier Cookstoves by Households in Rural Kenya. Energy Sustain. Dev. 2019, 52, 63–71

Kätterer, T.; Roobroeck, D.; Andrén, O.; Kimutai, G.; Karltun, E.; Kirchmann, H.; Nyberg, G.; Vanlauwe, B.; Röing de Nowina, K. Biochar Addition Persistently Increased Soil Fertility and Yields in Maize-Soybean Rotations over 10 Years in Sub-Humid Regions of Kenya. F. Crop. Res. 2019, 235, 18–26

Gitau, J.K., Mutune, J., Sundberg, C., Mendum, R., Njenga, M. 2019. Implications on Livelihoods and the Environment of Uptake of Gasifier Cook Stoves among Kenya’s Rural Households. Applied Sciences. 9, 1205

Njenga, M, Mahmoud Y, Mendum R, Iiyama M, Jamnadass R, Roing de Nowina K, Sundberg C. 2017. Quality of charcoal produced using micro gasification and how the new cook stove works in rural Kenya. Environmental Research Letters. 12(9),095001

Njenga M,  Iiyama M, Jamnadass R, Helander H, Larsson L, de Leeuw J, Neufeldt H, Roing de Nowina K, Sundberg C. 2016. Gasifier as a cleaner cooking system in rural Kenya. Journal of Cleaner Production. 121, 208-217.

 Book chapters

James K. Gitau,  Ruth Mendum and Mary Njenga. 2018.  Gender and Improvement of Cooking Systems with Biochar-producing Gasifier Stoves. In: Njenga, M.; Mendum, R. (Eds.). 2018. Recovering bioenergy in Sub-Saharan Africa: gender dimensions, lessons and challenges. Colombo, Sri Lanka: International Water Management Institute (IWMI). CGIAR Research Program on Water, Land and Ecosystems (WLE). (Resource Recovery and Reuse: Special Issue). doi: 10.5337/2018.226

 MSc & BSc theses

Ranung Siri and Ruud Jessica. 2019. Use of Biochar Producing Cookstoves in Rural Kenya: Energy efficiency, air pollution concentrations and biochar production potential. SEED, KTH

Made Sania Saraswati.  2018. Design Improvements for Top-Lit UpDraft Biochar-Producing Gasifier Stove in Rural Kenya from the Users’ Perspective. Department of Earth Sciences, Uppsala University. ISSN 1650-6553

Libbis Sujessy. 2018. Climate Change Impact Assessment of a Biochar System in Rural Kenya. SEED, KTH

Caterina Celi. 2018. Characterization of biochar and biomass samples from Kenyan cookstove to assess the use of biochar as soil improver and as fuel. Chemical Engineerging, Università degli studi dell’Aquila, Italy