Halophytic Atriplex atacamensis as a platform for in situ plant-microbial fuel cells under Atacama Desert conditions

This study evaluates the in-situ feasibility of electricity generation using a PMFC associated with an endemic halophytic plant, Atriplex atacamensis Phil., located in the Atacama Desert, Chile. The experimental system, comprising graphite anodes and AISI 316 L stainless steel cathodes, was deployed in Yungay near the Atacama Desert Solar Platform (PSDA), one of the regions with the highest solar irradiance on Earth. Electrical output was continuously monitored together with key environmental variables, including air and root temperature, relative humidity, and distinct components of solar radiation: global horizontal irradiance (GHI), diffuse horizontal irradiance (DHI), and photosynthetically active radiation (PAR). Exploratory correlation analyses indicate that temperature, particularly root-zone temperature, shows the strongest association with PMFC energy production under hyper-arid conditions. Microbiological analysis of the A. atacamensis rhizosphere revealed the predominance of Bacillus foraminis . Electrochemical characterisation of the AISI 316 L cathode, based on a superposition model derived from mixed potential theory, indicated a moderate corrosion rate (i_corr = 0.048 A m⁻²) and diffusion-controlled oxygen reduction reaction kinetics (iₗ = −2.42 A m⁻²), identifying mass transport limitations and low oxygen availability as key constraints on bioenergy recovery in saline desert soils. Overall, the results demonstrate the technical feasibility of PMFC operation under hyper-arid and saline desert conditions. Rather than establishing performance benchmarks, this work should be interpreted as an in-situ proof of concept that extends the environmental scope of PMFC research to conditions that remain largely unexplored.