Final Report: Pyrolytic Cook Stoves and Biochar Production in Kenya: A Whole Systems Approach to Sustainable Energy, Environmental Health, and Human Prosperity

EPA Grant Number: SU835341
Title: Pyrolytic Cook Stoves and Biochar Production in Kenya: A Whole Systems Approach to Sustainable Energy, Environmental Health, and Human Prosperity
Investigators: Lehmann, Johannes , Davis, Jennifer , Fisher, Elizabeth , Guerena, David , Hestrin, Rachel , Hsu, Tedman , Torres, Dorisel , Zwetsloot, Marie
Institution: Cornell University
EPA Project Officer: Hahn, Intaek
Phase: I
Project Period: August 15, 2012 through August 14, 2013
Project Amount: $14,990
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2012) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Agriculture , P3 Challenge Area - Cook Stoves , P3 Awards , Sustainability


Sub-optimal cook stove design and performance results in substantial emissions of greenhouse gases and particulate matter. This leads to air pollution and poses serious health hazards, particularly in developing nations. Women and young children suffer most from exposure to indoor smoke and associated respiratory problems, which lead to 3.5 million premature deaths every year (Lim et al., 2011). Additionally, stove inefficiency increases pressure on ecosystems that provide biomass for fuel and contributes to deforestation, reductions in biodiversity, and loss of ecosystem services. In Africa, the harvest of woody biomass for fuel or charcoal production leads to estimated losses of 5 million hectares (ha) of forest per year (Okello et al., 2001). Deforestation can increase greenhouse gas emissions and accelerate soil degradation. Several authors have reported a rapid decrease in soil organic matter (SOM) and soil carbon (C) due to deforestation (Solomon et al., 2007; Lal, 2006). Furthermore, the soil nutrient losses that follow deforestation are one of the largest non-point sources of water pollution (Agrawal et al., 1999).

The principal objectives of our Phase I project were to improve human health, economic prosperity, and environmental protection by reducing air pollution from cook stoves, conserving natural resources, and minimizing water contamination from fertilizer. In order to achieve these objectives, our Phase I research goals were 1) to design and test a combined pyrolysis-biochar cook stove that was clean-burning, efficient, and user friendly 2) to assess the stove’s performance in rural Kenyan households, and 3) to evaluate the potential for biochar (a byproduct of pyrolytic cook stoves) to improve ecosystem services and water quality.

Summary/Accomplishments (Outputs/Outcomes):

Research Goal 1: Cook stove design and testing
Our first research goal was to design an efficient and clean-burning pyrolysis cook stove. Using data from previous cook stove research conducted in Kenya, we modeled the stove design and combustion process. The model allowed us to assess the performance of many different stove designs without physically building each individual stove. This gave us the ability to vary many stove parameters and test a much higher number of stove designs. The modeling process resulted in our current stove geometry and design, which has been laboratory tested for heat transfer efficiency, emissions and biochar production. In addition, a TLUD stove was also tested to compare the emissions of these two stoves to each other and traditional combustion stoves.

Reductions in emissions from TLUD – Our results showed that TLUD stoves can reduce emission factors (EF’s) for CO and NO when compared to some reported values for combustion stoves. CO emissions from our TLUD stove were at the lower end the reported range of these values. Thermal efficiency was improved over the traditional open fire which results in significant fuel reductions for households.

Reductions in emissions from Cornell pyrolysis stove – Laboratory testing of the Cornell pyrolysis stove is ongoing. Our team has been testing this stove’s emissions and performance. The initial stove design phase took longer than expected; therefore, the results of the test are not currently being analyzed and we cannot yet report them.

Research Goal 2: Assessment of Stove Performance in Kenyan Households

Our second research goal was to assess stove performance in Kenyan households. However, due to the unanticipated extension of the stove design and laboratory testing phase, the stoves have not yet been field-tested with Kenyan stakeholders. A survey to determine participating households is scheduled for the spring of 2013. We plan to distribute and field-test the stoves shortly after the survey is completed (see Phase II proposal).

Research Goal 3: Evaluation of Biochar as a Tool for Environmental Management
Our third research goal was to investigate multiple ways in which biochar—the byproduct of pyrolysis cook stoves—could be used as a tool for environmental management. In particular, we investigated biochar’s potential to reduce dependence on synthetic fertilizers, reduce nutrient losses through gaseous and aqueous forms (and associated pollution), help maintain soil quality and biodiversity, and divert nutrient-rich products from the agricultural waste stream.

Reduced dependence on synthetic fertilizers—Nitrogen (N): A greenhouse trial was conducted in Western Kenya, with local soil and biochar produced from local agricultural waste products. Regardless of biochar feedstock, bean plants grown in soil amended with biochar fixed much more N than bean plants grown without biochar. On average, N derived from biological nitrogen fixation (Ndfa) in biochar amended soils was more than fourfold higher than Ndfa in unamended soils. This represents tremendous potential savings in N fertilizer. Such a reduction in N fertilizer has many benefits, including: reduced dependence on the fossil fuels that are used in N fertilizer synthesis, reduced N2O emissions from fertilizer, reduced soil acidification, protection of soil biodiversity, and reduced water contamination by nitrate runoff. Additionally, this practice removes agricultural residues from the waste stream.

Reduced dependence on synthetic fertilizers—Phosphorus (P): Results from our experiments with charred bone meal show that after pyrolysis, bone meal can provide a P fertilizer that outperforms rock phosphate in P content and solubility. This represents another tremendous savings in the fossil fuels that are used to process and transport synthetic fertilizers. It also removes a nutrient-rich product from the waste stream and reduces the threat of disease transmission through bones (pyrolysis results in a sterile product). Charred bone meal also provides a stable P fertilizer, which is unlikely to contribute to water contamination (as do some other P fertilizers).


We were successful in achieving most of our Phase I research goals, including stove design, testing and construction, and investigation of biochar as a tool for environmental management. Three key elements were critical to our success: (1) the combined expertise of our P3 team, (2) our interdisciplinary, whole-systems approach, and (3) our long-term, “on-the- ground” experience working with NGOs and smallholders in rural Kenya. The members of our P3 team represent many academic disciplines, including Engineering, International Agriculture and Rural Development, Epidemiology, Crop and Soil Science, Horticulture, and Water Resource Management. Several team members have long-term experience working with Kenyan smallholders. The broad expertise of our team has been essential to our success.

We were unable to implement and field-test the improved cook stoves in Kenyan households during Phase I. The delay in implementation was due to an unanticipated extension of the stove design and testing process. Due to our extensive design, testing, and improvement, our current stove design has greater potential to bring about positive impacts in human health and environmental sustainability. We hope to implement and field test the improved cook stoves during Phase II.

Journal Articles:

No journal articles submitted with this report: View all 2 publications for this project

Supplemental Keywords:

Minimizing nutrient and fertilizer runoff, green engineering, productive use of agricultural waste, land conservation, renewable feedstocks

P3 Phase II:

Pyrolytic Cook Stoves And Biochar Production In Kenya: A Whole Systems Approach to Sustainable Energy, Environmental Health, and Human Prosperity