Climate change impacts on ice loads for overhead transmission lines across Canada

Here, I provide a short summary of a recent research that we undertook to assess climate change impacts on ice loads for overhead transmission lines.

Ice accretion on transmission lines can lead to serious damages from line breakage and flashover. We investigated projected changes to design ice loads for overhead transmission lines for the 2071-2100 period with respect to the 1976-2005 period over Canada, using transient climate change simulations of the fifth generation Canadian Regional Climate Model (CRCM5), for two driving Global Climate Models (GCMs) and two Representative Concentration Pathways (RCP 4.5 and 8.5). Both freezing rain characteristics (frequency and amount) and associated ice loads were validated and the model seems to represent them reasonably well.

CRCM5 climate change simulations suggest decreases in 50-year return levels of annual maximum daily freezing rain for the south-eastern inland and coastal regions and south-western and north-eastern coastal regions of North America, but increases for other regions. Projected changes depend on the driving GCM and emission scenario. CRCM5 simulation driven by CanESM2 for RCP 8.5 suggests the largest changes, while that driven by MPI-ESM for RCP 4.5 yields the smallest changes for freezing rain characteristics considered in this study. The simulations suggest robust increases in future 50-year return levels of annual maximum ice thickness for regions of Quebec and west of the Hudson Bay (larger than 10 mm) and some scattered increases for south central and western Canada (mostly smaller than 3 mm). The simulations, however, show decreases in the ice loads for regions south of the Hudson Bay, south west coastal regions of BC, and maritime provinces of Canada. This study also helped identify regions where both wind and ice loads will increase in future climate, which can be detrimental to electric infrastructure. Results suggest that compound event assessments would be valuable, taking into consideration larger set of simulations, to obtain more robust projections.

Figure 1. 50-year return levels of annual maximum radial ice thickness (ice loads) for (a) CRCM5 simulations driven by ERA-Interim, CanESM2, and MPI-ESM (i.e., CRCM5-ERA, -CanHist, and -MPIHist) for the current 1976-2005 period and (b) projected changes for CRCM5 simulations driven by CanESM2 RCP4.5, MPI-ESM RCP4.5 and CanESM2 RCP8.5 (i.e., CRCM5-CanRCP4.5, -MPIRCP4.5, and -CanRCP8.5) for the future 2071-2100 period with respect to the current period. Projected changes are marked by open circles when they are statistically significant at the 10% significance level.

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