Big Bend Station. Source: Tampa Electric

Tampa Electric could ask Florida regulators for permission to convert its Big Bend power plant from coal to natural gas.

If approved, the conversion could cost $1 billion and take a decade to complete. Studies and engineering analysis on the conversion have been under way for a few years, according to the Tampa Bay Times newspaper.

The four coal-fired units at the Big Bend Power Station have a combined generating capacity of 1,700 megawatts and are the oldest in Tampa Electric’s fleet.

The first unit began service in 1970; the second and third generating units were added in 1973 and 1976; and unit four was added in 1985. A natural gas- and fuel oil-fired peaking unit was installed in 2009 to provide additional power during periods of peak demand.

With "black start" capability, power from the peaking unit can start Big Bend's larger generating units in a blackout when power from the grid is not available.

Three of the four are known as "wet-bottom boilers," which use water to cool a molten byproduct of burning coal known as slag. That technology is being phased out nationwide, and by 2015 only about 30 of the nation’s roughly 800 main electric utilities still had them. Tampa Electric’s wet-bottom boilers are the only ones left in Florida, the newspaper says.

Bennett said two of the four units would be converted to natural gas combined cycle technology.

The other two existing coal-fired units, which are newer than the first two, would be converted to natural gas over the next five to 10 years.

The utility replaced the coal-fired Gannon Power Station with the natural-gas powered H.L. Culbreath Bayside Power Station in 2003. A third plant, Polk Power Station, uses a combination of coal and gas.

A fatal accident at Big Bend took place last June as workers cleaned hardened slag from the bottom of a cooling tank. With the generator’s boiler still running, a blockage burst, sending molten slag onto the men below.

Killed were senior plant manager Michael McCort, 60, and four contract workers: Christopher Irvin, 40, and Frank Lee Jones, 55, of Gaffin Industrial Services of Riverview, and Antonio Navarrete, 21, and Amando Perez, of the BRACE Industrial Group, based in Houston.

Gary Marine Jr., a 32-year-old Gaffin employee, was seriously injured, but survived.