Chemical disequilibrium quantified using the available free energy has previously been proposed as a potential biosignature. However, researchers remotely sensing exoplanet biosignatures have not yet investigated how observational uncertainties impact the ability to infer a life-generated available free energy. This study's researchers pair an atmospheric retrieval tool to a thermodynamics model to assess the detectability of chemical disequilibrium signatures of Earth-like exoplanets, focusing on the Proterozoic eon when the atmospheric abundances of oxygen–methane disequilibrium pairs may have been relatively high. One of the study's authors is Chris Reinhard, associate professor in the School of Earth and Atmospheric Sciences.