TransAlta Acquires 50% Interest in 320 MW Tent Mountain Renewable Energy Complex

TransAlta Corporation, a Canadian electricity generation and distribution company, has announced that it has signed a definitive agreement to acquire a 50% interest in the Tent Mountain Renewable Energy Complex, an early-stage 320 MW pumped hydro energy storage development project in southwest Alberta. The project is currently owned by Montem Resources Limited and leverages Montem’s existing assets, including large legacy water reservoirs from past mining operations.


Project Overview

The Tent Mountain Renewable Energy Complex is a pumped hydro storage facility that provides 15 hours of energy storage capability to the Alberta market. The project is located on private, industrial zoned land, and includes an existing upper reservoir that supports a cost-competitive pumped hydro project compared to other similar projects. The project has already completed key technical and environmental work, including a hydrology assessment, and additional geotechnical analysis is planned for 2023 to further advance the design of the project. The project is expected to be developed over the next four years, with construction targeted to start as early as 2026 and a commercial operation date between 2028 and 2030, subject to regulatory, commercial, and engineering considerations.


Partnership and Management

TransAlta and Montem will form a partnership and jointly manage the project, with TransAlta acting as project developer. The acquisition includes the land rights, fixed assets, and intellectual property associated with the pumped hydro development project. TransAlta has owned, operated, and constructed hydro facilities for over 110 years, and this project offers similar long-term advantages as TransAlta’s other Alberta hydro facilities. These long-term advantages include a life span of greater than 80 years, which will substantially reduce operating costs compared to other technologies over the life of the project.


Environmental Sustainability

Pumped hydro is an environmentally sustainable solution for managing the intermittency of increased renewable electricity generation in the Province of Alberta. The project’s closed-loop system will result in minimal impacts to Alberta’s natural river system and will have the ability to provide flexible, firm clean power to customers at scale. The project will actively seek an offtake agreement over the development period for the energy and environmental attributes generated by the facility, providing a unique value proposition to customers seeking carbon-free electricity.


Financial Details

TransAlta will pay Montem approximately $8 million upon closing the transaction with additional payments of up to $17 million (approximately $25 million total) contingent on the achievement of specific development and commercial milestones. The acquisition also includes the intellectual property associated with a 100 MW offsite green hydrogen electrolyser and a 100 MW offsite wind development project. The closing of the transaction remains subject to customary closing conditions, including receipt by Montem of shareholder approval, with closing expected to occur in March 2023. The project will be independent of TransAlta’s existing Alberta hydro assets and will be managed through this partnership. TransAlta bears no exposure to reclamation obligations nor to any environmental liabilities arising from Montem’s historical mining operations at the Tent Mountain site.



The Tent Mountain Renewable Energy Complex represents a significant step towards sustainable energy management in Alberta, offering an environmentally friendly solution to the intermittency of renewable electricity generation. The long-term advantages of the project, including a lifespan of greater than 80 years and minimal environmental impact, make it an excellent investment for TransAlta. The company’s experience in hydro facility operation and construction provides the necessary expertise to ensure the project’s success. With increasing renewable energy penetration on the path to net-zero electricity, long duration storage projects like Tent Mountain are essential to support the reliability of the grid in Alberta.

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