Golden Spread nears revised air permit for Antelope Elk power project

Golden Spread Electric Cooperative is nearing a modified greenhouse gas air permit from the Texas Commission on Environmental Quality (TCEQ) that would authorize construction of the Antelope Elk Energy Center located in Hale County, Texas.

The TCEQ on April 7 posted to its website an April 2 notice of its plan to approve this permit change. This proposed decision authorizes the modification to a greenhouse gas permit issued by Region 6 of the U.S. Environmental Protection Agency in June 2014. EPA Region 6 last fall gave up such permitting in Texas after the TCEQ put in place its own permitting program on the state level.

Golden Spread is requesting authorization for three additional simple cycle electric generating plants at an existing site to meet increased energy demand in the area. The generating equipment consists of three new General Electric 7F5-Series natural gas-fired combustion turbine-generators (CTGs). Each turbine has a maximum electric output of 202 MW. Each CTG will be coupled to an electric generator to produce electricity for sale to the Electric Reliability Council of Texas (ERCOT) and Southwest Power Pool power grids. Supporting equipment for each turbine are a fuel gas heater, a diesel emergency generator, and an associated diesel tank.

The new units at Antelope Elk Energy Center (AEEC) will each be a new GE 7F 5- Series gas turbine in a simple cycle application, rated at a maximum output of 202 MW with a maximum design capacity of 1,941 million British thermal units per hour (MMBtu/hr). Each turbine will operate a maximum of 4,572 hours per year. Supply air will be compressed by the integral 14-stage compressor.

Natural gas fuel will be combusted in GE’s Dry Low Nitrogen Oxide (NOx, DLN) 2.6 combustion systems and the combustion exhaust gases will power the 3-stage expansion turbines. The turbines are air-cooled, and evaporative air coolers are also used for inlet air cooling during summer peak ambient air temperatures.

The main components of a CTG consist of a compressor, combustor, turbine, and generator. The compressor pressurizes combustion air to the combustor where pipeline natural gas is mixed with the combustion air and burned. Hot exhaust gases then enter the turbine where the gases expand across the turbine power blades (buckets), driving a shaft to power an electric generator. The exhaust gases will exit through stacks into the atmosphere.

Each new GE aero-derived turbine can achieve efficiency greater than 38.7% and produce up to 202 MW in cold weather and nominally 190.1 MW in peak summer conditions. During normal startup, the turbine will achieve 50% capacity load in 30 minutes and thereafter operate at design emission limits. Each CTG may operate at reduced load to respond to changes in system power requirements and/or stability.

One natural gas-fired auxiliary heater per turbine will be available to facilitate startup of the simple cycle unit, with a heat input of 5.5 MMBtu/hr. Each heater will be authorized to operate up to 4,572 hours per year.

Each turbine will be equipped with one 1,500-kW diesel-fired emergency generator. The engines running this equipment will fire low sulfur diesel fuel. Operation of each emergency generator for testing purposes will be limited to 100 hours per year. 

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.