The Halton Hills Generating Station (HHGS) is a 683MW natural gas-fired combined cycle power plant located in Ontario, Canada. Commissioned in 2010, the facility was developed to meet the electricity demands of the southwest Greater Toronto Area.
Originally developed by TransCanada (now TC Energy), HHGS was acquired by Ontario Power Generation’s subsidiary, Atura Power, in April 2020. The acquisition, part of a portfolio of natural gas assets, was valued at approximately C$2.8bn.
Atura Power now owns and operates HHGS, integrating it into its fleet of natural gas-fired generating stations across Ontario.
Project Location
HHGS is situated in the town of Halton Hills, Ontario, occupying an 80-acre site within the 401 Industrial Corridor. The facility is located between Highway 401 and Steeles Avenue, west of 6th Line, providing strategic access to Ontario’s energy infrastructure.
This location was selected for its proximity to major transmission lines and natural gas supply routes. Additionally, the area has industrial zoning, reducing land-use conflicts and simplifying permitting processes.
Capacity and Infrastructure
The plant operates as a 2×1 combined cycle facility, comprising two Siemens SGT-PAC 5000F gas turbines and a single Alstom steam turbine generator. Each gas turbine produces approximately 190MW, while the steam turbine contributes 300MW, resulting in a total capacity of 683MW.
The gas turbines are equipped with Dry Low NOx (DLN) combustion systems to minimise nitrogen oxide emissions. Evaporative coolers are installed to maintain optimal inlet air temperatures for the gas turbines. Steam required for the steam turbine is generated by two Alstom heat recovery steam generators (HRSGs), each capable of producing up to 675,000kg of steam per hour with duct firing.
An air-cooled condenser is utilised to condense steam from the turbine, reducing water usage. Process water is supplied through the municipal water system, and wastewater is discharged to the municipal sanitary sewer. The site also includes a control building, maintenance areas, auxiliary systems, and fire safety infrastructure.
Development and Timeline
Construction of HHGS began in late 2007, following site preparation activities such as grading and access road construction. The project progressed through several phases, including equipment installation and system integration. Commissioning was completed in September 2010, and the plant became operational in October 2010.
The project was completed on schedule and within budget, reflecting a coordinated effort between developers, regulators, and contractors. Environmental assessments and public consultations were conducted in the early planning stages to address concerns related to air quality and local impacts.
Halton Hills Generating Station Technological Details
HHGS uses combined cycle technology, where waste heat from gas turbines is harnessed to produce additional electricity via a steam turbine, improving overall efficiency. The plant features Dry Low NOx (DLN) combustion systems to reduce nitrogen oxide emissions. Evaporative coolers are installed to maintain optimal inlet air temperatures for the gas turbines. An air-cooled condenser system minimises water consumption by condensing steam without the need for large volumes of cooling water.
The facility operates under an advanced distributed control system (DCS) that enables remote monitoring and performance diagnostics. Redundant safety and backup systems support grid synchronisation, allowing the plant to rapidly ramp up or down in response to changing demand conditions.
Power Purchase Agreements
Electricity generated by HHGS is sold to the Ontario Power Authority under a 20-year power purchase agreement established at the time of commissioning. This agreement ensures a stable revenue stream for the facility and contributes to the province’s energy supply planning.
Such long-term contracts have historically provided revenue certainty to developers and supported investment in high-capital infrastructure projects, particularly in markets with regulated pricing structures.
Future Developments
Atura Power plans to upgrade HHGS to increase its capacity by 27MW, bringing the total output to 710MW. The upgrade involves replacing components within the existing turbines to allow for higher operating temperatures and improved efficiency. All upgrade activities will occur within the current facility footprint, with no expansion beyond existing boundaries.
Additionally, Atura Power intends to blend hydrogen into the natural gas supply at HHGS, starting with a 5%-15% mix, with potential expansion up to 30%. This initiative aims to reduce greenhouse gas emissions and support Ontario’s transition to a low-carbon energy system.
Contractors and Suppliers
The engineering, procurement, and construction (EPC) contract was awarded to Halton Hills Power Partners, a joint venture between Aker Kvaerner Songer Canada and Burns & McDonnell.
Aker Kvaerner Songer Canada managed construction and certain procurement aspects, while Burns & McDonnell provided project design and technical assistance.
Aecon Construction and Materials was subcontracted for site preparation, and Hatch contributed detailed design and construction support services.
Additional suppliers included Siemens for gas turbines, Alstom for HRSGs and the steam turbine, and various Canadian firms for control systems, electrical equipment, and on-site logistics.
