Abstract
Abstract
Energy systems must transition toward absolute environmental sustainability across all impact categories. However, energy systems are commonly designed focusing solely on the impact category climate change. To address this challenge, we optimize the greenfield design of the German energy system in 2050, encompassing the coupled power, heat, and private passenger mobility sectors, while penalizing the transgression of sustainability thresholds derived from the planetary boundaries. We find that sustainable energy system designs are achievable when sustainability thresholds are determined based on the economic value of the energy system. However, stricter sustainability thresholds, which may result from data uncertainties or the choice of allocation method, are transgressed in the atmospheric aerosol loading and phosphorus cycle categories due to impacts from the private passenger mobility sector and material supply. Sustainable energy systems thus require reductions in private passenger mobility demand and material-related environmental impacts, as well as sufficient carbon dioxide storage, particularly if sustainability thresholds prove to be more stringent.