Tent Mountain Pumped Hydro Energy Storage

Developing a 320 MW / 4,955 MWh pumped hydro energy storage facility with our partner TransAlta Corporation

Transformative Pumped Hydro Energy Storage Project

Evolve and TransAlta Corporation (TransAlta) have partnered to develop the Tent Mountain Pumped Hydro Energy Storage (TM-PHES) project.

The TM-PHES will repurpose the historical Tent Mountain Mine which is a reclaimed legacy coal mine, located in the Crowsnest Pass, approximately 16 km west of the township of Coleman, Alberta.

The TM-PHES leverages existing assets at Tent Mountain, which includes a 300m drop (or “head”) between two large water reservoirs, located on private land owned by Evolve, and left behind from historical mining operations.

In 2022, Evolve completed a Pre-Feasibility Study (PFS) for the TM-PHES which found Tent Mountain is suitable for hosting a PHES with an 80+ year project life, 320 MW installed capacity, with a continuous generation duration of more than 15 hours, resulting in up to 4,955 MWh of energy storage. Evolve and TransAlta are now in the process of advancing the project through the front-end engineering design (FEED) phase.

Upper Reservoir
Upper Intake
Access Road
Access Road
South Dam
Lower Intakes
North Dam
Lower Reservoir

Pumped Hydro Energy Storage in Alberta

As the Alberta power grid transitions to an increased reliance on intermittent renewable power sources (wind and solar), solutions are required to manage the equilibrium between supply and demand as well as ensuring the stability of the electricity grid. The TM-PHES has the potential to be the cornerstone of this equilibrium, providing dispatchable renewable energy to the Alberta power grid whenever it needs it.

The TM-PHES acts as a large battery, recharging when there is an abundance of wind and solar power available and dispatching power to Alberta’s electricity grid when there is a shortage of wind and solar power. By building the TM-PHES we provide the platform of storage that facilitates thousands of megawatts of intermittent renewables.

The TM-PHES provides energy storage at scale with a capital cost efficiency and duration capability that cannot be matched by Lithium-Ion battery technology. The TM-PHES will also provide ancillary services necessary to support grid stability, services typically provided by a shrinking fleet of turbine-based power plants, that cannot be provided by wind or solar plants.


Water is pumped into the upper reservoir using cheaper electricity when there is an abundance of renewable energy generation or overall demand for electricity is low.


When there is a drop off in renewable energy generation or a spike in electricity demand, resulting in higher power prices, water is released from the upper reservoir.


Water flows quickly down the pipes, turning the turbines at the bottom to generate power. The power generated is then dispatched to the electricity grid.

TM-PHES Highlights

Lowering power prices for Albertans

The TM-PHES has the potential to power up to 400,000 Albertan homes simultaneously. This will provide stability to the electrical grid which will help lower power prices for all Albertans.

Creating jobs and powering the economy

Over its 80+ year project life, the TM-PHES will create up to 200 construction jobs and 30 long-term operational jobs in the Crowsnest Pass.

Supporting the energy transition

The TM-PHES will abate up to 500,000 tonnes* of CO2 emissions per year.
* Assumes cycling once per day and powered by renewable electricity

Project Attributes

Project Life80+ Years
Installed Capacity320 MW
Storage CapacityUp to 4,955 MWh
Continuous Generation Duration15+ hours
Upper Reservoir Active Volume3.55 million m3
Upper Reservoir Minimum Operating Level1,783m
Lower Reservoir Minimum Operating Level1,480m
Maximum Gross Head320m
Minimum Gross Head288m

TM-PHES Grid Stability Benefits

Renewables Firming

The TM-PHES can supply much needed energy when the wind is not blowing, and the sun is not shining.

Excess Supply

When the grid has too much renewable energy, the TM-PHES can absorb the excess power.

Ancillary Services

The TM-PHES can respond quickly to unexpected disruptions on the grid.


The TM-PHES will contribute inertia to the grid, which helps keep the frequency stable and avoid blackouts.

Learn More About the TM-PHES

Evolve and our partner TransAlta are repurposing the historical Tent Mountain Mine to develop a 320 MW / 4,955 MWh pumped hydro energy storage facility. Contact us to learn more about this transformative project.

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