 The capacity of Tacoma's hydroelectric system as of 2004 was 713,000 kilowatts, or about 50% of the demand made up by TPU's customers (the rest is purchased from other utilities).According to TPU, hydroelectricity provides about 87% of Tacoma's power; coal 3%; natural gas 1%; nuclear 9%; and biomass and wind at less than 1%.Tacoma Power also operates the Click!