Updated facility‐level inventory and LCIA of the public electricity grid in Ontario, Canada

Abstract As the composition of Ontario's electricity grid will change over time, it is important to have a comprehensive understanding of the environmental impacts of Ontario's electricity grid as it stands today. However, publicly available information on impacts of Ontario's electricity grid is available only in aggregate from government sources. To ameliorate this lack of granularity and transparency, this work presents a comprehensive database with categorization for all 186 electricity generating facilities listed in Ontario's Independent Electricity System Operator's Generator Output Capability Monthly Reports for the period from January 2025 to December 2025. This work includes categorization of each generating facility based on a framework provided by ecoinvent, a widely used life cycle assessment database; explanations for how those categories were determined; and the percentage of Ontario's electricity production contributed by each facility. Life cycle impact assessments were performed on the updated electricity mix by utilizing data from ecoinvent v3.6 and v3.12 with various impact assessment methods. The updated analyses of electricity mixes in this work have carbon intensities ranging from 114.2 to 138.7 gCO 2 e/kWh, compared to the value of 59 gCO 2 e/kWh provided by Environment and Climate Change Canada's National Inventory Report, demonstrating the utility of an updated database which can be easily modified as changes in the grid or electricity generation occur. Life cycle impact assessments using seasonal examples for the West region of Ontario were also performed and compared to demonstrate how the database enables detailed geographical and temporal analysis.