Big Bend in Tampa Electric’s road to decarbonisation

Work is now well underway on modernisation and repowering of Tampa Electric’s 1700 MW Big Bend pulverised coal power station, Apollo Beach, Florida, following the granting of final state approval in July and start of construction in August.

Like many power companies in the USA and around the world, Tampa Electric wants to reduce its dependence on coal. The modernisation will see conversion of unit 1 at Big Bend (which started up in 1970) to a 1090 MWe 2x2x1 natural gas fuelled combined cycle power plant and the retiring of unit 2 (which has been operation since 1973). The two other coal units, Big Bend 3 and 4 (which entered service in 1976 and 1985, respectively), will remain in operation at the site, which is also the location of a 60 MW natural gas fuelled peaking plant.

“This project will improve the land, water and air emissions at Big Bend,” said Nancy Tower, president and chief executive officer of Tampa Electric. “This project will save our customers money, and, coupled with our significant increase in solar power, will make Tampa Electric substantially cleaner and greener than it is today.”

Two GE 7HA.02 gas turbines, each with a downstream heat recovery steam generator, are being installed at the Big Bend site.

The heat recovery steam generators will supply steam to the unit 1 steam turbine, which will be reused but will undergo major modifications/upgrade.

In March 2018, Tampa Electric Company authorised Sargent & Lundy to begin work on the Big Bend modernisation project, as EPC contractor, with a scope that includes detailed engineering, design, procurement, project management, and onsite construction management/commissioning oversight of the repowering together with work on associated transmission and interconnection facilities and natural gas infrastructure.

As well supply of the gas turbines, GE’s scope will also include the facilitating of “a comprehensive upgrade of the station’s steam turbine island.”

The existing condenser and circulating water system will be refurbished and reused and the water intake systems will be modified for 316b rule compliance. Tampa Electric notes that the refurbished cooling system “will continue to produce the warm water that attracts manatees to the power station’s discharge canal each winter.”

Simple-cycle operation of the new gas turbines is scheduled for 2021, with combined- cycle operation of the repowered steam turbine generator in 2023.

The project will significantly change Tampa Electric’s fuel mix, the company says. In 1998, 90% of its electricity was generated from coal.

By 2018, that number dropped to 12%. In 2023, when the Big Bend modernisation is complete and all 650 MW or so of planned solar PV capacity is installed, more of Tampa Electric’s power will be generated from solar than from coal, which will contribute a mere 2% to the total. Natural gas generation will account for about 81% of the total, in line with other Florida utilities.

As well as the Big Bend facilities, Tampa Electric’s power plant portfolio as of 2023 will include Bayside (1800 MW natural gas combined cycle and four 60 MW gas fuelled peakers) and Polk (220 MW coal fuelled IGCC plus 1140 MW of natural gas combined cycle).

The Big Bend modernisation is part of Tampa Electric’s strategy to further reduce its carbon footprint, the company says. That process started in 1999, it notes, with the repowering of the former coal fired Gannon station (renamed Bayside) to natural gas, and most recently included the conversion of the Polk power station’s simple cycle natural gas units to combined cycle.

By 2021, Tampa Electric will have 6 million solar panels in 10 new photovoltaic solar facilities, making it the Florida utility with
the highest percentage of solar power, the company says. Seven of those 10 PV facilities have been completed.

Tampa Electric, one of Florida’s largest investor-owned electric utilities, serving about 765 000 customers in West Central Florida, is a subsidiary of Emera Inc., which is headquartered in Halifax, Nova Scotia, Canada.