Technologies, trends, and trajectories across 100% renewable energy system analyses

The energy system is the primary source of greenhouse gas emissions and a major driver of climate change. This study conducts a systematic review of articles published between 1975 and 2023, selecting those that examine energy systems with at least 95% renewable energy in at least one energy sector within a defined geographic context. Based on these criteria, a total of 1067 articles were identified and included in the review. The review identifies trends in technologies, models, and techniques used in 100% renewable energy system analyses. The power sector was the most assessed, appearing in 99.5% of studies and exclusively analysed in 47%. Optimisation target functions were used in 68% of studies. Hourly time resolution was the most common, featured in 73% of the studies, while 77% used overnight greenfield modelling. Wind power and solar photovoltaics emerged as the most prevalent technologies, contributing to the energy system in 1002 and 1001 studies, respectively. Batteries were the most used storage technology with 642 studies, followed by e-hydrogen in 486 studies. Heat pumps were the leading technology in the heat sector, featured in 32% of studies based on usage. In the transport sector, battery electric vehicles were the most common technology, appearing in 33% of studies. Despite the growing volume of research, comprehensive cross-sectoral analyses remain limited, and further research is needed to assess the value contribution of each element in energy system transitions.