A southwest Missouri Dam is replacing its aging transformers with new, environmentally safe models that are not being used anywhere else in North America.

The Jefferson City News Tribune  reports the third of four transformers at Bagnell Dam on the Lake of the Ozarks is being installed, and the fourth will follow in a few years.

Ameren Missouri owns the dam and is installing the gas-powered transformers at a cost about $4 million apiece. They are manufactured is the Mitsubishi Plant in Tokyo and mainly used in Asia.

They replace oil-powered units that were installed in 1931 when the dam was built. The new transformers will turn 14,000 volts of electricity put out by the dam's generators into 140,000 volts before sending them to the electrical grid.