Research

Historic Average Emissions Intensities of Grid-Supplied Electricity in Ontario

Ontario has experienced a significant decrease in electrical emissions as a result of the removal of coal and natural gas generation from the electricity grid. Understanding and quantifying the impact of this decarbonization is key in terms of community energy and sustainability planning.

In order to investigate the quantitative impacts of decarbonization, such that historic grid emissions intensities can be integrated into the living inventory model, a analysis of data recently released by the IESO was completed. A composite dataset was formed by extracting datapoints from the Ontario Electricity Sector Historic Emissions and Projected Emissions plot, sourced from The IESO Decarbonization and Ontario’s Electricity System, and the The Evolution of Energy Demand in Ontario published in 2020 by the IESO. The Figure below displays the extracted datasets.

Utilizing the two datasets, the emissions intensity are calculated for the historic range of interest and the results compared to the 2019 and 2005 emissions intensities reported by the Canada Energy Regulator Provincial Energy Profile for Ontario.

The 2005 and 2019 emissions intensities calculated from composite dataset were 231 grams CO2e/KWh and 30.3 grams CO2e/KWh respectively, matching the CER data to less than 0.5% error. This indicates that the composite model of historic emissions intensities can serve as a reference when considering electrical emissions from past reports, where emissions intensities are not explicitly reported.

This also agrees with the the 2020 average emissions intensity of 31 grams CO2e/KWh reported by The Atmospheric Fund Emissions Factors Guidelines.

The standard calculation methodology for emissions based on average emissions factors and activity data represents an estimate and not an exact value. The utilization of this estimate is due to the readily obtainable data format i.e yearly totals for activity data per sector and annual average emissions intensities. In the case of electricity, a more accurate representation of emissions would be calculated with hourly electricity consumption multiplied by hourly average emissions intensity. While this type of calculation can be useful for analyzing the operation of individual machines, or even factories, it is not practical for use in annual emissions inventories.