Prospective life cycle assessment framework for energy transition scenarios based on the EnergyPLAN tool

Energy Systems Analysis (ESA) is widely used to determine transition pathways towards renewable energy systems based on desired parameters, and decision-makers can thereby assess the cost and CO2eq emissions related to the modelled scenarios. However, ESA often only accounts for direct greenhouse gas (GHG) emissions from fuel combustion and does not include other environmental impact categories. Therefore, combining ESA with Life Cycle Assessment (LCA) is valuable, as LCA can compensate for these shortcomings. This research aims to develop a framework to combine the EnergyPLAN ESA tool with prospective LCA to allow for holistic assessments of different energy system scenarios, comparing them based on several environmental impact categories and accounting for indirect impacts such as those caused by the construction of energy capacity. The framework developed in this research couples EnergyPLAN with prospective LCA. EnergyPLAN is an ideal tool for flexible energy systems due to its hourly resolution. The prospective LCA is based on the Shared Socioeconomic Pathways (SSPs) implemented through the Premise tool as background databases to assess how the energy system performs based on different potential societal pathways, thus accounting for sensitivity to the background system. The framework is tested on a Danish energy scenario for 2045 (IDA₂045) and compared to a business-as-usual scenario to demonstrate its usefulness for decision-support. Through the EnergyPLAN-LCA framework we achieve a holistic assessment of environmental impacts of the modelled energy systems, finding that even though the IDA₂045 scenario requires massive capacity investments compared to the reference scenario, it still has lower impacts on global warming and land use. An impact trade-off is found for water use caused by the switch from fossil fuels to electrofuels in the transport sector. The framework also highlights the timing of emissions caused by capacity construction, showing that large up-front emissions are used to avoid continuous long-term emissions from energy system operation. However, in the case of IDA₂045, the impacts are still lower than in the reference scenario when accounting for the temporal aspect of emissions. We developed and demonstrated a coupling framework for prospective LCA and EnergyPLAN enabling the assessment of environmental impacts of energy system scenarios with a focus on flexible energy systems. The framework is developed for LCAs on the required energy production to achieve the scenario under assessment. We recommend that the framework is used in an iterative modelling process to increase the value of decision-support.