**4. Conclusions**

Considering the premise that local-based and renewable energy solutions are needed in the short to medium term to address HAP in developing countries, this study shows that the transition to biogas and micro-gasifying cookstove systems combusting upgraded biofuels, i.e., biogas and biomass pellets, greatly contributes to reducing critical environmental impacts beyond deforestation and HAP associated with a potential future phase out of traditional cooking practices in Western Kenya. In the BGS scenario, the availability of animal manure and organic waste in the year 2015 (661 thousand t) is 4% higher than the expected consumption of this feedstock in the year 2035 (408 thousand t). In the PGS scenario, the availability of agricultural land to produce agroforestry woody biomass in the

Kisumu County in 2015 (around 57 thousand t) is not sufficient to satisfy the projected demands for this feedstock in the year 2035 (around 134 t); imports from the neighboring county of Siaya should be considered to adjust future supply and demand. Additionally, in this scenario, the amount of sugarcane bagasse available in 2015 (260 thousand t) is more than enough to satisfy 100% of the demands for this feedstock in the projected PGS scenario in the year 2035 (around 105 thousand t).

Overall, the LCA confirms the hypothesis of increasing the environmental sustainability of current cooking systems and related fuel value-chains in Western Kenya through the introduction of advanced cookstoves combusting either biogas (BGS scenario) or pelletized fuels (PGS scenario). Such measures are expected to reduce by over 80% the environmental impacts for all the referred categories analyzed in relation to the BAU scenario in the year 2035. Although this study has demonstrated the grea<sup>t</sup> environmental benefits of the suggested measures, further studies are required to consolidate this sustainability assessment through the performance of both social and economic assessments of the proposed valorization alternatives.

By showing that biogas and pellet fuel/advanced cookstove value-chains are viable in terms of the mitigation of the environmental impacts, this study may orient the scientific community and energy sector stakeholders about the environmental benefits of such valorization and energy efficiency alternatives at the sub-national level. As the suggested bioenergy cooking strategies mitigate a wide range of life-cycle environmental impacts beyond HAP, an interesting and specifically relevant area for future research is related to the analysis of the environmental externalities (e.g., on human health) associated with the mitigation of greenhouse gas and PM emissions in Western Kenya. In such a context, this study does not ye<sup>t</sup> fully provide consolidated recommendations to decision-makers responsible for designing energy policies in the Kisumu County, which will only be possible after a solid socio-economic assessment is carried out.

Future work in this area is highly relevant in order to provide key recommendations not only for policy makers, but also for local biomass industries, which could be interested in capitalizing investments in alternate value-chains. Furthermore, governmen<sup>t</sup> incentives for the deployment of innovative logistical systems and tax credits—including the deployment of advanced biomass valuation alternatives and cookstove via local community-based projects—present a potential to enhance sustainable livelihoods through bottom-up policies design with the participation of the population.

**Author Contributions:** R.L.C., corresponding author, worked on the conceptualization, methodology, formal analysis, data collection and writing of the original draft. P.Y., V.K.K.U. and D.A. collaborated with R.C. in the modelling work with the software LEAP and Simapro. They also collaborated in the validation of the results in collaboration with the other co-authors. C.B., G.N., N.G.-L., R.L. and R.D.-C. contributed to the conceptualization of the work and writing review and editing. C.B. and D.A. were responsible for the project administration and supervised the work conducted in collaboration with the other co-authors. They were also involved in funding acquisition for the achievement of the goals of this research. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Swedish Research Council FORMAS through the project Sustainable Biomass Utilization in Sub-Saharan Africa for an Improved Environment and Health, Dnr. 942-2015-1385. The work conducted by the researcher Ricardo Carvalho was financed by the Postdoctoral gran<sup>t</sup> number JCK-1516, funded by the Kempe Foundation, and thanks are also due to FCT/MCTES for the financial support to CESAM (UID/AMB/50017/2019), through Portuguese national funds. The LCA work was financed by Bio4Energy, a strategic research environment appointed by the Swedish government.

**Acknowledgments:** Part of the work conducted by Ricardo Carvalho was funded with the technical support of the Group of Energy and Environment of the Federal Institute of Education, Science and Technology of Ceará, where the researcher is integrated.

**Conflicts of Interest:** The authors declare no conflict of interest.
