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Ontario's electricity system is ready for winter

December 19, 2019

Winter weather can be punishing, and electricity systems across North America take extra precaution to ensure that a reliable supply of electricity can be maintained.

With the winter season officially beginning this Saturday, the IESO’s forecasts show that Ontario is well-positioned to manage the province’s electricity grid during this period. Sufficient electricity capacity and energy supply are expected to be available, and reserves will be at or above requirement.

Very cold weather can create high electricity demand due to the impact of electric heating. It is during these peak periods when natural gas-fired generation is especially important due to its ability to quickly increase and decrease output. This winter, natural gas storage levels are expected to be adequate, gas-fired generating units have been tested for readiness, and gas-electric coordination meetings have taken place.

Winter weather can create complications at electricity generating stations. For example, on January 21, 2019, approximately 2,100 MW of generator capacity was lost in the span of two hours due to cold weather-related issues. This included frazil ice buildup at nuclear plants that blocked cooling water intakes; icing at wind facilities; frozen water gates at hydroelectric facilities; and cold or frozen equipment at gas-fired facilities.

The IESO takes steps to prepare for situations like these to ensure the grid is reliable and resilient. For example, transmission and generation outages can be deferred to ensure there are enough resources available. In spring 2019, the IESO started using extreme weather criteria for outage assessment, increasing the resiliency of the Ontario power system and ensuring reliability during planned and unplanned outages.

Other steps include increasing operating reserve and testing generating units that are slow to start up to ensure they are available.

Collaboration with Ontario market participants and neighbouring jurisdictions is also critical. The gas transportation system is monitored in collaboration with gas pipeline operators to identify any issues that may impact fuel supply for gas-fired generators. Coordination with neighbouring system operators and local distribution companies also occurs in case support is required.

For more information, please see our Market Operations Fall 2019 Awareness Session or the latest Reliability Outlook.

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