Halton Hills combined cycle plant is a 683MW natural-gas fired power plant. Credit: Ontario Power Generation Inc.
The Halton Hills generating station was opened in 2010. Credit: Ontario Power Generation Inc.
The Halton Hills power plant comprises fully enclosed HRSGs and steam turbines. Credit: Hatch.

The Halton Hills combined cycle plant (CCP), also known as Halton Hills Generating Station (HHGS), is a 683MW natural gas-fired power plant located in the Town of Halton Hills, Ontario, Canada.

The plant was built to address the critical energy and stability requirements of the southwest greater Toronto area. Officially opened in October 2010, the plant has sufficient power generating capacity to meet the requirements of approximately 700,000 households.

It uses state-of-the-art low emissions technology and is built in compliance with high environmental standards. The project required an investment of C$700m ($681m).

The plant is owned and operated by Atura Power, a subsidiary of government-owned Ontario Power Generation. Atura Power acquired the project from TC Energy Corporation in April 2020.

The electricity generated by the plant is purchased by the Ontario Power Authority (OPA) under a 20-year power purchase agreement.

Natural gas to fuel the station is supplied by Union Gas Limited, an Ontario-based company responsible for storage, transmission, and distribution of natural gas.

Key contractors involved in the project

Halton Hills Power Partners, a joint venture between Aker Kvaerner Songer Canada and Burns & McDonnell, was appointed as the engineering, procurement, and construction (EPC) contractor for the project in December 2006.

“The Halton Hills combined cycle plant (CCP), also known as Halton Hills Generating Station (HHGS), is a 683MW natural gas-fired power plant.”

Aker Kvaerner Songer Canada, a subsidiary of Aker Solutions, was responsible for construction and construction management. It was also involved in certain portions of procurement and commissioning.

Burns & McDonnell provided project design and procured engineered equipment. The company rendered technical assistance for construction and was also responsible for commissioning and start-up of the plant.

Aecon Construction and Materials was subcontracted by Aker Kvaerner Songer Canada in September 2007 to prepare the site for the construction project. The contract value was $6m. Hatch provided detailed design and construction support service to the combined-cycle power plant.

Construction of the Canadian gas-fired power plant

The HHGS site occupies 80 acres of land in the 401 Industrial Corridor in the Town of Halton Hills. The land is owned by TCE and is situated between Highway 401 and Steeles Avenue west of 6th Line.

The construction of the plant began in late 2007 and was completed in several phases in time and within budget.

Site preparatory work that commenced in October 2007 and involved site grading, construction of access roads, and creation of temporary parking space. A traffic signal was also erected on Steeles Avenue to manage the construction traffic.

Two large stormwater ponds were built prior to the beginning of construction to control run-off during construction and protect the groundwater.

Foundation and piling installation commenced after the completion of site clearing and grading works. In the next phase of the project, respective equipment was installed and connections between them were established.

Halton Hills combined cycle plant details

The HHGS is a natural gas-fuelled 2×1 CCP plant with an electricity generating capacity of 683MW.

Power is produced by two Siemens SGT-PAC 5000F gas turbine generator sets, two Alstom heat recovery steam generators (HRSGs), and a single 300MW Alstom steam turbine generator (STG).

Each gas turbine has a reported output of 190MW and is equipped with a Dry Low NOx (DLN) combustion system. The two turbines are also fitted with evaporative coolers to keep the inlet air cool.

Steam required to feed the STG is generated by two HRSGs. Each HRSG has a capacity to produce 675,000kg of steam an hour with maximum duct firing and 465,000kg of steam an hour without duct firing.

An air-cooled condenser (ACC) is used to condense the steam leaving the STG. Process water to the site is delivered through the municipal water system. Waste water from the plant is discharged to the municipal sanitary sewer.

Natural gas pipeline

The natural gas fuel is supplied through a 4.5km-long, 20in diameter pipeline, which was laid along the west side of 5th Line from the Union Gas Corridor. The gas corridor is located south of Derry Road to Highway 401.

Route selection and environmental and socio-economic impact assessment for the pipeline was undertaken by Stantec Consulting.

Electricity generated at the plant flows through step-up transformers. These transformers are used to raise the voltage to 230kV.

A connection was established from the Halton Transformer Station to the Hydro One transmission lines T38B and T39B. The electricity to the connection point is transmitted through underground transmission lines.