YELLOWSTONE NATIONAL PARK – More than a century after U.S. Army troops harnessed the power of flowing water to light Fort Yellowstone, the park is generating electricity from water again.

Hydro power first came to Yellowstone in 1903, when the U.S. Cavalry under the direction of engineer Hiram Chittenden installed the first 100-kilowatt water turbine generator near its Mammoth Hot Springs headquarters. Relying on water flowing from Glen Creek down through Golden Gate, the power plant supplied energy for residences, administrative offices, maintenance shops, lights on the parade grounds and the occasional picture show at the Mammoth Hot Springs Hotel.

In the years since, commercially supplied energy has largely supplied power for Yellowstone. But a new spin on hydro power is adding a few hundred extra kilowatts of power to what’s already being supplied by the grid.

According to YNP officials, a new micro hydro plant brought on line last December will help reduce greenhouse gas emissions by more than 800 metric tons annually. The park’s goal is to reduce greenhouse gas emissions 15 percent by 2016.

The new plant captures energy from water that flows 560 feet downhill from the combined Gardner River, Panther Creek and Indian Creek water intakes on Swan Lake Flats to the storage reservoir at Mammoth’s water treatment plant through an existing 12-inch pipe. A newly installed generator and turbine rely on an average water flow volume of four cubic feet per second to produce electricity.

Park officials expect it will generate an average of 175 kilowatts of energy, depending on the normal fluctuation of the water supply, though it is capable of producing up to 230 kilowatts. That should add up to more than 1.2 million kilowatt hours each year.

The plant will be synchronized directly with Northwestern Energy’s electric grid, providing an annual savings of approximately $73,000 on the park’s electrical bill.

The project was funded by American Recovery and Reinvestment Act funds at a cost of $1.1 million and is expected to pay for itself in about 12 years. It is part of a $750 million investment in nearly 800 projects throughout the National Park Service. The money will be used to fund projects that address critical park needs, generate regional jobs, improve experiences for park visitors, and implement sustainable green technologies.