Project Highlights

320MW/2,560MWh (8 hours) Pumped Hydro Energy Storage

Potential to increase Upper Reservoir storage to 4,955MWh (15 hours)

Powering up to 400,000 Albertan homes simultaneously

Will create up to 200 construction jobs and 30 full time operational jobs over an 80+ year project life

Up to 400,000 tonnes of CO2 emissions abated annually

PFS confirms TM-PHES as an outstanding renewable energy project with compelling economics

The Tent Mountain Pumped Hydro Energy Storage (TM-PHES) will be the key element of the TM-REX. The TM-PHES leverages Montem’s existing assets at Tent Mountain, which includes a 300m drop (or “head”) between two large water reservoirs, located on land owned by Montem, and left behind from historical mining operations.

TM-PHES Pre-Feasibility Study Results

In 2022, Montem completed a Pre-Feasibility Study (PFS) for the PHES element of the TM-REX, indicating that Tent Mountain is suitable for hosting a PHES with an 80+ year project life, 320 MW installed capacity, 2,560 MWh storage capacity and a continuous generation duration of 8 hours.

The PFS recommends optimization work be completed to investigate increasing the size of the upper reservoir, which has the potential to increase the TM-PHES storage capacity to 4,955 MWh, with a continuous generation duration of 15 hours.

Project Life80+ Year
Installed Capacity320 MW
Storage Capacity2,560 MWh (potential for up to 4,955 MWh)
Continuous Generation Duration8 hours (potential for up to 15 hours)
Targeted Capital Cost (PHES)C$750M
Targeted Capital Cost (Interconnection)C$70M
Turbine Configuration4 x 80 MW fixed speed reversible Francis turbines
Upper Reservoir Active Volume3.55 million m3
Upper Reservoir Minimum Operating Level1783m
Lower Reservoir Minimum Operating Level1480m
Maximum Gross Head320m
Minimum Gross Head288m
Project Life80+ Year
Installed Capacity320 MW
Storage Capacity2,560 MWh (potential for up to
4,955 MWh
Generation Duration
8 hours (potential for up to 15 hours)
Targeted Capital
Cost (PHES)
Targeted Capital
Cost (Interconnection)
Turbine Configuration4 x 80 MW fixed speed
reversible Francis turbines
Upper Reservoir
Active Volume
3.55 million m3
Upper Reservoir
Minimum Operating
Lower Reservoir
Minimum Operating
Maximum Gross Head320m
Minimum Gross Head288m

On a $/MW (power output) and $/MWh (energy stored) basis, the TM-PHES compares favourably to similar PHES projects globally.

Project economics were evaluated for two projected energy price forecasts: base case and Net Zero Electricity. Preliminary project economics for the TM-PHES indicate attractive returns for both cases over the 80+ year project life.

How Does a PHES Work?

Water is pumped into the upper reservoir using cheaper energy when demand is low or there is an excess of renewable energy.

When there is a spike in demand, or a drop off in wind or solar generation the water is released.

The water flows quickly down the pipes which turns the turbines to generate power.

TM-PHES Permitting Pathway

Permitting for the TM-PHES will be administered by numerous provincial regulatory bodies, and will follow a process led by the Alberta Utilities Commission (AUC).

A key component of the permitting process is the participant involvement program (PIP). The PIP follows a well-established framework for stakeholder consultation with all information gathered during the PIP process being submitted to both the AUC and Alberta environment and Parks (AEP).

Montem has been working directly with the Alberta Electric System Operator (AESO) to establish access to the power grid for the TM-PHES with the project being accepted into the interconnection queue in 2022. The transmission infrastructure in the Crowsnest Pass and surrounding area provides for both 500 kV and 240 kV interconnection options.

The TM-PHES is leveraging a significant portion of the environmental monitoring and reporting completed as part of the Tent Mountain Mine Redevelopment Project. To date no critical environmental risks or barriers have been identified regarding the development of the TM-PHES.


The AUC approval process is in accordance with the Hydro and Electric Energy Act, Alberta Utilities Commission Act, and AUC Rule 7 and includes geotechnical engineering, facility and infrastructure design, the investigation of potential impacts on wildlife and wildlife habitat, and stakeholder engagement.



In accordance with Dam and Canal Safety regulations, AEP will administer Water Act approvals for the design and construction of the TM-PHES reservoirs.

AEP will review and provide recommendations related to wildlife and habitat assessments.



The grid interconnection process overseen by the AESO includes required approvals specific to the interconnection asset, creating a link between AUC and AESO activities.



Concurrent to the PIP the TM-PHES will be required to complete consultation with Indigenous groups in accordance with the Aboriginal Consultation Office’s (ACO) requirements.

Alberta needs dispatchable energy to firm intermittent renewables

Last 30 Days
Last 7 Days

Solar Generation

Wind Generation

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


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

Transmission Congestion

The TM-PHES is located near a major cluster of wind generators, and will help reduce congestion on transmission lines leading out of the region

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