This report is the first in the UKERC Energy 2050 project series. It focuses on a range of low carbon scenarios underpinned by energy systems analysis using the newly developed and updated UK MARKAL elastic demand (MED) model. Such modelling is designed to develop insights on a range of scenarios of future energy system evolution and the resultant technology pathways, sectoral trade-offs and economic implications. Long-term energy scenario-modelling analysis is characterised by deep uncertainty over a range of drivers including resources, technology development, behavioural change and policy mechanisms.Therefore, subsequent UKERC Energy 2050 reports focus on a broad scope of sensitivity analysis to investigate alternative scenarios of energy system evolution. In particular, these alternative scenarios investigate different drivers of the UK’s energy supply and demand, and combine the twin goals of decarbonisation and energy system resilience.Future analysis includes the use of complementary macro-econometric and detailed sectoral energy models.