The Ohio Environmental Protection Agency on May 19 released a draft air permit-to-install (PTI) that would cover South Field Energy LLC‘s application for the installation of a nominal net 1,150-MW combined-cycle gas turbine (CCGT) facility located in Columbiana County.
This facility is similar to the recently-permitted Lordstown Energy, Oregon Clean Energy Center and Carroll County Energy Center gas-fired projects, hence similar permit terms and conditions. The facility will utilize two General Electric Model 7HA.02 combustion turbines with natural gas being the primary fuel and Ultra Low Sulfur Diesel (ULSD) fuel being the secondary fuel. The design net plant base heat rate is 7,165 Btu/kW-hr HHV (ISO conditions without duct firing) which is an indicator of the efficiency of heat input being converted to electricity.
The South Field Energy CCGT is in a 2x2x2 configuration. The facility is intended to operate as a base-load facility and is proposed to be available to operate up to 8,760 hours per year, incorporating a range of load conditions. The facility also seeks the flexibility to operate with frequent starts in order to meet energy demands.
Duct firing will be incorporated into the facility’s design using natural gas only. An auxiliary boiler will be used to assist plant start-up and maintain warm-start conditions during standby periods. Other ancillary equipment having emissions includes an emergency generator and an emergency fire pump. Primary fuel for CTG and auxiliary boiler firing operations will consist of natural gas with ultra low sulfur diesel (ULSD) fuel as the secondary fuel. The emergency generator and emergency fire pump will be fired with ULSD fuel.
The facility will utilize water-cooled condensers to cool the steam discharged from the steam turbines and the circulating water will be cooled by wet mechanical draft cooling towers. The project will include the following major and ancillary equipment:
- Two combustion turbine generators (CTGs);
- Two heat recovery steam generators (HRSGs) with supplemental duct firing;
- Two steam turbine generators (STG);
- Two water cooled condensers;
- Two wet mechanical draft cooling towers;
- One 2,000-kilowatt (kW) emergency diesel generator;
- One natural gas-fired, 99-million British thermal units (MMBtu) steam production auxiliary boiler;
- One 311-horsepower (hp) emergency fire pump; and
- Storage tanks for aqueous ammonia (NH3), ultra low sulfur diesel (ULSD) and water.
ULSD fuel may be employed for up to 1,440 hours per year when natural gas is not available. Each CTG is capable of running independently of the other. The maximum heat input rate of each CTG while burning natural gas is 3,131 million British thermal units per hour (MMBtu/hr) (higher heating value [HHV]) at 100 percent load, 59 degrees Fahrenheit (°F) and 60 percent relative humidity with the evaporative cooler on. Under the same conditions while burning ULSD fuel, the maximum heat input rate of each CTG would be 3,173 MMBtu/hr.
In combined cycle configuration, each CTG will exhaust through a dedicated HRSG to generate steam from the waste heat energy in the exhaust gas. Each HRSG will be equipped with supplemental firing via a duct burner. The duct burners provide additional thermal energy to the HRSG, to provide more steam to the STG during periods of high electricity demand. The duct burners will be natural gas-fired and each will have a maximum input capacity of 800 MMBtu/hr (HHV), although the duct burners will not always operate at maximum capacity. The use of the duct burners will vary based upon different temperature and operating conditions.
Steam generated in the HRSGs will be expanded through multi-stage, reheat-capable, condensing steam turbines. The discharge steam from the steam turbines will be directed to water-cooled condensers. The condenser cooling water (also referred to as circulating water) is the heat sink for the heat released by the condensing steam. The circulating water provides non-contact cooling using heat exchangers. Rotational power created by the steam turbines will be converted to electric power via the connected generators.
The auxiliary boiler will use natural gas as the primary fuel and ULSD as the secondary fuel, and operate as needed to keep the HRSG warm during periods of facility shutdown and provide steam to the STG during start-ups. The auxiliary boiler will have a maximum input capacity of 99 MMBtu/hr and will be limited to 5,000 hours of total operation per year with an annual limit of 1,440 hours on ULSD.
The facility will have an emergency diesel generator with a nominally rated electrical output of 2,000 kilowatts (kW) powered with a 2,947-horsepower (hp) diesel engine to provide on-site emergency power capabilities independent of the utility grid. The emergency generator will fire ULSD fuel and will typically only operate for testing and to maintain operational readiness in the event of an emergency. A small ULSD storage tank will be integrated into this equipment. Routine operation of the generator will be limited to a maximum of 500 operating hours per year.
The facility will have a 311-hp (232.1-kW mechanical) emergency fire pump to provide on-site firefighting capabilities independent of the off-site electrical utilities grid. The emergency fire pump will fire ULSD fuel and will typically only operate for testing and to maintain operational readiness in the event of an emergency. A small ULSD storage tank will be integrated into this equipment. Similar to the emergency generator, it will be limited to a maximum of 500 operating hours per year.
The proposed facility will have a nominal 3 million gallon capacity above ground fixed roof fuel oil storage tank for storing ULSD as a backup fuel. The tank will be equipped with secondary containment sized to accommodate the entire volume of the tank and sufficient freeboard for precipitation.
Incidentally, the Ohio Power Siting Board staff filed on May 20 a report that generally recommended approval, with certain routine conditions attached, of an application by South Field Energy for a site certificate on this project. South Field Energy falls within the corporate structure of Advanced Power AG, an international developer of independent power generation projects.