TM-REX Overview

Project Overview

Montem Resources (Montem) is advancing development plans to transition the Tent Mountain Mine to become a renewable energy complex. The planned development includes three primary elements: a 320 MW / 2,560 MWh Pumped Hydro Energy Storage (PHES), a 100 MW Green Hydrogen Electrolyser, and a 100 MW Offsite Wind Farm.

The Tent Mountain Mine is a steelmaking coal mine, located approximately 16 km west of the township of Coleman, Alberta, that ceased operating in 1983.

Developing Tent Mountain as a renewable energy complex could result in the first large scale production of green hydrogen in Canada.

Whilst renewable energy generation is rapidly increasing in Alberta, wind and solar power are inherently intermittent, only producing power when the wind blows or sun shines. The PHES element of the TM-REX provides dispatchable renewable energy to the Alberta power grid. The PHES will firm intermittent renewable generation and provide grid stabilizing ancillary services to Alberta’s electric system – this is a critical element of the energy transition.. The 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.

Montem first started looking at an end of mine life PHES for Tent Mountain in 2019, undertaking a site assessment and economic analysis. The results were promising, but at the time Montem decided to continue progressing Tent Mountain primarily as a steelmaking coal mine re-start. With the current uncertainty surrounding the timeline of the mine re-start, Montem have brought forward the planning for developing Tent Mountain into a renewable energy complex.

In 2022, Montem completed Pre-Feasibility Studies for the PHES and Green Hydrogen Electrolyser elements of the TM-REX, confirming the TM-REX as an outstanding renewable energy project with compelling economics.

The TM-REX 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. Additionally, the TM-REX has easy access to infrastructure, including rail, high voltage power lines, gas pipelines, and the interprovincial Highway 3.

Upper Reservoir

The upper water reservoir is a historical coal mine pit located at an elevation of 1,800m. The conceptual design of the upper reservoir allows for roughly 2.5GWh of energy storage.


Surface Penstock

During times of the day when electricity demand and prices are high, typically around breakfast and dinner time, the water from the upper reservoir will be released into the lower reservoir. The water travels via the surface penstock, dropping in elevation by 300m (which is also referred to as a 300m average “head”), before passing through turbines to generate electricity that can be sold into the Alberta power grid.



The powerhouse will host two turbines that generate electricity as water passes through them. During times of the day when there is an excess of renewable energy and energy prices are low, such as in the middle of the day, the turbines can be reversed, and using renewable power purchased cheaply from the grid, the water can be pumped back up to the upper reservoir. This process “recharges” the PHES which acts as a large battery.


Lower Reservoir

The lower reservoir is a manmade wetland that sits at an elevation of 1,500m. It was created as part of the historical coal mine’s water management system.



Powerlines will be constructed to connect the PHES to the nearby Alberta electricity grid. The electric interconnection with the Alberta grid will provide power for when the turbines are reversed, and the ability to send power to the grid when the PHES is generating electricity. Powerlines will also be constructed to provide electricity to the onsite green hydrogen electrolyser production facility.


Green Hydrogen Electrolyser

The hydrogen will be produced using an electrolyser that employs electricity to split apart water molecules into their component parts: oxygen and hydrogen. The electrolyser will be powered by renewable energy (wind and the PHES) resulting in the production of green hydrogen.


Wind Farm (Offsite)

A 100MW wind farm will be located off-site powering the PHES with renewable energy when the turbines are reversed to pump the water back up the hill.


Project Location Map

TM-REX Employment

The TM-REX will create jobs across a range of skill sets:


Montem is committed to being a good corporate citizen. Our aim is to foster sustainable growth in the areas in which we operate, providing job and business opportunities. We are committed to employing local people where possible.

Project History

Pumped Hydro Energy Storage at Tent Mountain

The Tent Mountain PHES will be one of the primary elements of the TM-REX. Montem has completed a Prefeasibility Study for the Tent Mountain PHES and continues to assess the feasibility of a PHES at Tent Mountain.

Green Hydrogen at Tent Mountain

The green hydrogen electrolyser will be one of the primary elements of the TM-REX. Montem has completed a Prefeasibility Study for the TM-REX green hydrogen electrolyser production facility and continues to assess the feasibility of the green hydrogen electrolyser.