The US Bureau of Reclamation has announced that the 12 single-phase transformers and appurtenant equipment at the 1320MW Glen Canyon power plant in the Upper Colorado region are to be replaced in a S37 million contract awarded to Yellowstone Electric Co.

Design, manufacture and installation work for the new transformers will take place between August 2017 and the spring of 2020.

The project is a first for USBR, as it will be the first to use transformers of this size filled with natural ester oils derived from seed and nut oils as the insulating liquid rather than petroleum-based mineral oils typically used in most transformers. The sustainable, bio-based ester oils are safer because of the higher flash-point, which reduces the risk of fire, and they are environmentally beneficial because they disperse quickly in water and bio-degrade readily in oxygen and sunlight in the unlikely event of an oil spill, USBR said in a statement.

"Bringing sustainable design to our powerplants is key to guaranteeing their length of service," said Upper Colorado Regional Director, Brent Rhees. "It is important to our region and across Reclamation that we support green initiatives when and where we are able."

Each of the transformers being replaced is original equipment that has been in service since the power plant became operational in 1964.