Dave Johnston Steam Electric Plant

The Dave Johnston Power Plant is a coal-fired electric generating station located on the North Platte River about six miles east of the town of Glenrock, Wyoming. Commissioned in 1958, the plant today is owned and operated by PacifiCorp, a subsidiary of MidAmerican Energy Holdings. The station is named for W.D. “Dave” Johnston, a former executive at the company who agreed to the local community’s suggestion of a new power generating facility in that region.

The first boiler unit was completed in the late 1950s and since that time three more units have been added; today the generating station has a maximum output of over 760 megawatts. The facility sits on a 2,500 acre site that uses water from the North Platte River for its operations. Originally, all of the nearly four million tons of coal burned at the plant came from the nearby Dave Johnston Mine, but since 2000 it is shipped in from other mines in the Powder River Basin, and the former site of the Dave Johnston Mine has been reclaimed as a wildlife area.

Water gathered from the river is heated to nearly 1,000° Fahrenheit and this steam is under nearly 2,400 pounds of pressure per square inch. From the tall boiler units, the steam travels to the turbines that operate the electromagnetic generators. Additional water is used in the condensing units, which cools the steam and returns it to liquid form. The cooled boiler water is thus used over and over, and the steam generated when the cooling water is heated in the condenser is expelled through the tall stacks that rise up from the power plant.

When the Dave Johnston Power Plant was built, there were few laws in effect that governed the amount of pollution expelled by steam plants. After the Clean Air Act was amended in 1977 many power stations including the Dave Johnston facility began to make a number of modifications to reduce particulate emission. Although the coal used at the facility is low in sulfur, nitrous oxide as well as certain heavy metals do end up in the atmosphere unless trapped at the source. A full scrubbing system complete with nitrous oxide burners and electrostatic precipitators is now employed at the Dave Johnston Power Plant.

Asbestos may also have been used at this facility; at the time of construction it was common for asbestos to be installed as a form of heat shield and fire retardant. Asbestos is a natural substance that is a type of silicate, fibrous and very lightweight. Because it a poor conductor of heat it was used to insulate hot pipes and protect facilities by being used in ceiling tiles and wall panels. Workers often inhaled loose fibers in some of the older buildings, and it is now known that this exposure can cause mesothelioma, asbestosis and other health problems. The symptoms of these diseases often will not show until years after long-term exposure to asbestos.