What is pumped storage?


A clean, quiet, renewable opportunity

Pumped storage 101

Pumped storage hydro power represents nearly 95 per cent of global energy storage and there are 100 projects underway as more countries embrace this tried and true technology.

Pumped storage is a proven technology that has been utilized for more than a century. Over 127,000 megawatts (MW) of pumped storage capacity exists worldwide today, including 165 MW right here in Ontario. There is a need for additional new capacity to meet Ontario’s future energy demand. This is particularly true following the anticipated closure of the Pickering Nuclear Station in 2024.

The Ontario Independent Electricity System Operator (IESO) estimates between 2,000 and 3,000 MW of new supply will be required to meet Ontario’s future demand.


TC Energy is proposing to design, construct and operate a grid-scale energy storage facility for Ontario’s electricity system. The proposed project would:

  • Provide needed capacity
  • Reduce electricity costs and greenhouse gas emissions
  • Drive local economic benefits and growth
  • Provide storage for Ontario’s excess baseload generation

We will continue scheduling open houses in the community and providing opportunities for community members to provide input into, and review the outcomes of, the various environmental and socio-economic studies and assessments that will be undertaken. We are committed to keeping you updated as the proposed project progresses.

Current supply and future demand

Creating a reliable, powerful climate solution


Creating a reliable, powerful climate solution


The current installed capacity on Ontario’s electricity grid is about 39,000 Megawatts (MW). But the closure of the Pickering Nuclear Station by 2025 will leave a 3,100 MW gap in that supply. The proposed project will provide 1,000 MW of much-needed, flexible, on-demand, clean energy capacity daily, for up to 11 hours, and power one million Ontario homes.

With its long duration, long lifespan (50+ years), and fast response and start-up capability, pumped storage is the technology of choice for large-scale storage. It also has the smallest environmental footprint over its lifecycle.

We believe pumped storage is the most proven, economical and environmentally responsible solution for meeting Ontario’s unique electricity and power system needs.



How pumped storage works

The proposed project would provide 1,000 MW of flexible, clean energy to Ontario’s electricity system using a technology known as pumped storage. It would be designed to store excess baseload generation — energy that is typically exported at a loss or entirely wasted. That stored energy would then provide emission-free electricity back to Ontarians when they need it most.

Once operating, the proposed facility would withdraw water from Georgian Bay, temporarily store it in a newly constructed upper reservoir, and later return the water to Georgian Bay. During periods of low electricity demand, water would be pumped upslope from Georgian Bay through enclosed pipes to the upper reservoir. When demand for electricity is high, the water is released down through the same pipes to generate electricity for the grid.

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