Holyrood Thermal Generating Station
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The initial installation included two 150 megawatt (MW) turbine generators which are propelled by steam heated by two large oil burning furnaces. The Number 6 fuel oil (high-viscosity residual oil) used in the plant to keep the furnaces going is delivered by shuttle tankers to the marine terminal constructed as part of the project.
Newfoundland and Labrador Hydro's Holyrood Thermal Generating Station is an essential part of the province’s generating system. The plant burns No. 6 heavy fuel oil at the rate of approximately 6,000 barrels (950 m3) per day, per unit at full load to produce steam at 1000 degrees Fahrenheit (540 degrees Celsius) and 13,790 kPa at a rate of over 500 megagrams per hour.
In a thermal generating station, fuel is burned in a boiler to convert water to steam. The high-pressure steam is directed into a turbine that is connected to an electrical generator that produces electricity as it turns. A seawater condenser is used for cooling the spent steam from the turbine, converting it back to water that is reused in the boiler. Holyrood uses over 250,000 litres per minute of sea water for cooling on each unit and 900,000 litres per day of fresh water for make up purpose.
The plant generators operate at 16,000 volts and 7000 amperes transformed up to 230,000 volts for transmission on the island grid to all parts of the system. In a single year the plant has the capability of generating over 3000 GW·h - which can be up to 40 per cent of the island’s annual requirements.
The plant has three smokestacks, one 360 ft (109.8 m) tall and two 300 ft (91.5 m) tall. These are the tallest freestanding structures built on land in Newfoundland.
Holyrood was placed in service in 1971 with two 150 MW units. A third 150 MW unit was added in 1980 to increase the output to 450 MW. In 1988/89 the original two units were modified to increase the plant capacity to 490 MW.