Thermal generation

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Puget Sound Energy strives to ensure reliable electric service at a reasonable cost by acquiring power supplies from a variety of different sources, both PSE-generated and purchased from other suppliers. These sources primarily are hydropower, wind power, natural gas-fired generation, and coal-fired power from Montana. This diversified-portfolio strategy minimizes risk – and costs – in the event that an unforeseen circumstance (a drought, for example) causes regional shortages in one form of power and, in turn, drives up wholesale power prices.

Electricity from clean-burning natural gas-fired generating stations makes up about one-fifth of PSE’s total power-supply mix. PSE currently owns nine facilities, all in Washington state – Encogen, Ferndale, Frederickson, Frederickson 1, Fredonia, Goldendale, Mint Farm, Sumas and Whitehorn.

Six employ modern, “combined-cycle, combustion-turbine” technology that allow the facilities to generate electricity using both a natural gas cycle and, from the exhaust heat of its power-generating turbines, a steam cycle. The two-stage process boosts operating efficiency, lowers fuel costs, and cuts air emissions. Combined-cycle plants often operate to help meet utility customers’ base power requirements. They also complement hydro and wind-powered generation because gas-fired plants can operate on a firm schedule, while power generation from hydro and wind-generating facilities is dependent upon Mother Nature.

The other three plants – Frederickson, Fredonia and Whitehorn – have single-cycle generating units and are used primarily to provide back-up “peaking” energy for our power system during daily or seasonal spikes in customers’ power usage. Additionally, Federickson and Whitehorn have the ability to be started remotely from PSE’s electric-dispatch center and reach full generating output within 10 minutes.

PSE’s Encogen Generating Station

Encogen Generating Station

Encogen is located in Bellingham, Wash., about 90 miles north of Seattle. The plant is situated east of the Port of Bellingham’s waterfront redevelopment site. The facility came online in 1993, and was acquired by PSE in 1999. PSE became the plant operator in 2005.

PSE's Ferndale Generating Station

Ferndale Generating Station

Built in 1994 by Tenaska Washington Partners, L.P., Ferndale Generating Station is located about 100 miles north of Seattle, near Ferndale, Wash., in Whatcom County. PSE acquired the facility in 2012.

Frederickson Generating Station

Frederickson and Frederickson 1 Generating Stations

The Frederickson Generating Station and the Frederickson 1 Generating Station are located about 18 miles southeast of Tacoma, near Frederickson, Pierce County. PSE is the sole owner of the older, Frederickson Generating Station. In 2004, PSE bought a 49.85 percent interest in the newer, Frederickson 1 facility (Atlantic Power owns the remaining share).

Fredonia Generating Station

Fredonia Generating Station

The Fredonia Generating Station is located 75 miles north of Seattle, or about seven miles northwest of Mount Vernon in Skagit County. The first two generating units, installed in the early 1980s, each can generate up to 104 MW of power. The other two turbine generators, installed in 2001, each have a 54-MW generating capacity.

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Goldendale Generating Station

Goldendale Generating Station

Goldendale is located 215 miles southeast of Seattle, roughly 10 miles north of the Columbia River and the Washington-Oregon border. Goldendale came online in 2004 and PSE purchased it in February 2007.

Mint Farm Generating Station Puget

Mint Farm Generating Station

The plant is located in the Mint Farm Industrial Park of Longview, Wash., about 130 miles south of Seattle. The facility came online in January 2008, and was acquired by PSE in December 2008.

PSE’s Whitehorn Generating Station

Whitehorn Generating Station

The Whitehorn facility is located near Ferndale, Wash., about 120 miles north of Seattle. Its two single-cycle units were installed in 1981; PSE overhauled one in 2006, and the other in 2008. PSE leased the two generating units until February 2009, and then purchased them outright. PSE’s original Whitehorn generating unit, installed in 1974, was decommissioned in 2000.

Generating typeNumber of generators

Power output (Megawatts)

Approx. number of households served by output

Personnel (full-time PSE employees)

EncogenCombined-cycle, combustion-turbine

3 gas-fired 1 steam-fired

165 120,000 17

FerndaleCombined-cycle, combustion-turbine

2 gas-fired 1 steam-fired

270 200,000 21

Frederickson Single-cycle 2 147 110,000 5

Frederickson 1Combined-cycle, combustion-turbine

1 gas-fired 1 steam-fired

275* 200,00016 full-time employees of Atlantic Power’s subsidiary

Fredonia Single-cycle 4 314 235,000 5

GoldendaleCombined-cycle, combustion-turbine

1 gas-fired 1 steam-fired

277 200,000 18

Mint FarmCombined-cycle, combustion-turbine

1 gas-fired 1 steam-fired

310 230,000 21

SumasCombined-cycle, combustion-turbine

1 gas-fired 1 steam-fired

125 94,000 16

Whitehorn Single-cycle 2 147 110,000 3

* PSE’s total share of capacity is 138 MW.

Sumas Generating Station

Sumas Generating Station

Sumas is located 115 miles north of Seattle in Sumas, Wash., just south of the U.S.-Canadian border. This facility includes partial PSE ownership of a 3.7-mile-long pipeline that brings natural gas to the plant from the Westcoast Energy Station in Huntingdon, B.C., the main Canadian gas-transmission supply point into Washington state.