page_title: Tracy Thermal Generating Station
section_title: Technical overview
hierarchical_section_title: Tracy Thermal Generating Station / Technical overview
caption_attribution_description: Français&#160;: Cheminées de la Centrale thermique de Tracy, au Québec. English: Chimneys of the Tracy thermal generating station in Quebec.
context_page_description: The Tracy Thermal Generating Station is a retired 660-megawatt heavy fuel oil-fueled thermal power station built from 1962 by the Shawinigan Water & Power Company and completed by Hydro-Québec after the buyout of all private electric utilities by the government of Quebec in 1963. Commissioned between 1964 and 1968, the plant is located on the banks of the Saint Lawrence River in the city of Sorel-Tracy, in the Montérégie Region.
  Mainly used as a peaker plant, the Tracy facility was usually running during cold spells in the winter. It was sometimes operated year-round to supplement hydroelectric generation during low-water years.
  Although it was operated only sporadically, the generating station has been criticized for its contribution to air pollution as it was one of Quebec's major sources of carbon dioxide, sulfur dioxide, nitrogen oxides and particulates. Some commentators have accused Hydro-Québec of unnecessarily operating the Tracy thermal plant to export electricity by taking advantage of low fuel prices at certain times.
  The Tracy Thermal Generating Station was kept as a reserve during the 2010–2011 winter and permanently shut down on March 1, 2011.
context_section_description: Thermal power plants play a marginal role in Hydro-Québec's system, which is dominated by hydropower. In 2009, non-nuclear thermal generation accounted for 4.4% of nameplate capacity but only generated 446 GWh, 0.3% of total energy production. More expensive to run and more polluting than hydroelectric power plants, thermal plants are used to generate power during peak conditions, but most of the company's thermal plants serve remote communities not connected to the main power grid in Nunavik, on the Lower North Shore, in Haute-Mauricie and in the Magdalen Islands.
  A thermal power station such as Tracy converts the energy contained in heavy fuel oil into heat, motion, and then into electrical energy. Burning fuel vaporize water and the steam expands to drive a turbine that spins the rotor of an alternator to generate electricity. Condensing water is then reused for another cycle. In the process, water is preheated six times, raising its temperature from 27 °C (80 °F) to 238 °C (460 °F), and goes through a deaerator and an economizer before entering the boiler at a temperature of 340.5 °C (645 °F), close to the boiling point under pressure.
  Each boiler is 12 m (40 ft) long and 9 m (30 ft) wide at its base and rises to 55 m (180 ft), the equivalent of a 13-floor building. At the top, a 16 m (50 ft) long steam drum separates water and saturated steam. The boiler is heated by 16 burners, four in each corner, which can be retracted and tilted to control the steam temperature. The steam becomes an ideal gas at 539.4 °C (1,003 °F) and a pressure of 12.75 MPa (1,850 PSI) after being forced into the superheater. The plant boilers have been designed to be converted to coal in the event that it became a cheaper solution. Spaces for storing and handling coal were set aside in the planning phase.
  At its rated power, the plant burned 159,000 litres (1,000 barrels) of heavy fuel oil per hour. Ten 200,000-barrel fuel storage tanks are located behind the plant and were supplied with fuel from the Montreal and Lévis refineries by tanker or by rail.
  Each unit was designed to "hot" start within 20 or 30 minutes. A cold start can take between three and four hours. It is a delicate operation, since moving parts must be relatively uniformly warmed to prevent damage. The success of this operation involves more than 70 steps and is controlled by a sequence monitoring system to avoid missteps. Cooling off a unit after use required precautions to prevent buckling of the main shaft.
  The plant was easily recognizable by its four 137-metre (449 ft) high red-and-white smokestacks. Framed with safety valves, the chimneys were only 82 m (270 ft) tall when the plant opened in the 1960s, but were raised in 1980 in response to environmental considerations. The plant's maximum annual output was limited to 2.6 TWh due to air pollution regulations.
  The transmission towers near the plant is part of a 735 kV transmission line crossing the Saint Lawrence River. They are 174.6 m (573 ft) high, making them the tallest in Canada. The power station's terminal substation is linked to the power grid by four 230 kV lines to Boucherville, Varennes, Contrecoeur, Carignan (lines 2320 and 2322) and Sorel-Tracy (lines 2332 and 2336).
caption: The generating station's four smokestacks.
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