Michael Buchner ¹ Hubert H. Nguyen ² Largus T. Angenent ^3,4,5,6 Christiane Zarfl ¹ Joseph G. Usack ^2,3,7,8*

• ¹ Environmental Systems Analysis Group, Department of Geosciences, University of Tübingen, Tübingen, Germany
• ² Sustainable Food Systems Engineering Group, Department of Food Science & Technology, University of Georgia, Athens, United States
• ³ Environmental Biotechnology Group, Department of Geosciences, University of Tübingen, Tübingen, Baden-Württemberg, Germany
• ⁴ Max Planck Institute for Developmental Biology, Max Planck Society, Tübingen, Baden-Württemberg, Germany
• ⁵ The Novo Nordisk Foundation CO2 Research Center (CORC), Aarhus University, Aahrus, Denmark
• ⁶ Cluster of Excellence - Controlling Microbes to Fight Infections, University of Tübingen, Tübingen, Germany
• ⁷ New Materials Institute, College of Engineering, University of Georgia, Athens, Georgia, United States
• ⁸ Institute for Integrative Precision Agriculture, University of Georgia, Athens, United States

Food insecurity in Ethiopia is an immediate humanitarian crisis that is expected to worsen due to population growth and climate change. This study applied GIS-based approaches to evaluate the feasibility of deploying an emergent type of single-cell protein (SCP) technology to supplement the nutritional needs of Ethiopian citizens who are most vulnerable to drought. The technologypowerto-protein (PtP)uses H2 and O2 from water electrolysis and CO2 from woody biomass combustion in a two-stage bioprocess to produce nutrient-rich protein powder for human consumption. Population density, land use, and other geographical data were used to identify optimal site locations for these PtP systems based on two deployment strategies: large centralized plants vs. small decentralized units. The model also accounted for biomass availability, collection, and distribution logistics. The analysis revealed three sites that are both (highly) vulnerable/food-insecure and accessible within walking distance. The identified sites are proximate to the urban areas of Mekele in northern Ethiopia, Addis Ababa in central Ethiopia, and Hawasa south of Addis Ababa. If centralized PtP were deployed, the protein requirements of these populations could be sustained for several months, assuming a modest biomass collection radius of 35 km. Decentralized PtP deployment was similarly effective, requiring a distribution density of 5.4 -11.0 PtP units per km 2 under conservative estimates and 0.76 -1.1 units per km 2 under optimistic estimates. Lastly, a theoretical comparison showed that PtP is more efficient than conventional agricultural food production regarding biomassto-protein conversion yields. Overall, our study suggests that PtP technology would be a feasible approach to supplement the nutritional needs of Ethiopian people in times of drought-related emergencies. However, given logistical limitations and considering social preference factors, it would be more practical to implement PtP in conjunction with standard emergency food aid measures.