The U.S. Environmental Protection Agency’s Region 6 office is taking comment until Sept. 5 on a draft air permit for a gas-fired expansion by Austin Energy of its Sand Hill power plant in Texas.
In September 2013, the City of Austin d/b/a Austin Energy submitted to EPA Region 6 a Prevention of Significant Deterioration (PSD) permit application for Greenhouse Gas (GHG) emissions. The covered project is an additional natural gas-fired combined-cycle unit at the existing Sand Hill Energy Center (SHEC) in Del Valle, Travis County, Texas.
In connection with the same proposed construction project, Austin Energy submitted an application for a PSD permit for non-GHG pollutants to the Texas Commission on Environmental Quality (TCEQ) in September 2013.
The existing SHEC is a natural gas-fired combined-cycle baseload station that currently operates in a 1 by 1 by 1 (1x1x1) configuration with a combustion turbine, heat recovery steam generator (HRSG) equipped with duct burners, and a steam turbine.
The proposed modification includes a new combustion turbine (a General Electric 7FA.04 model) and new HRSG equipped with duct burners. The resulting new facility will be a natural gas-fired combined-cycle power generating station in a 2 by 2 by 1 (2x2x1) configuration that utilizes the existing combustion turbine and HRSG, the new combustion turbine and HRSG, and the existing non-modified steam turbine. The SHEC will retain the ability to operate in either a 1x1x1 combined-cycle configuration or in a 2x2x1 combined-cycle configuration.
The new units at the SHEC (along with the increased output from the existing steam turbine) will generate an additional 222 MW (gross). The gross power output figure is based on a combustion turbine rated at 187 MW at ISO conditions and the steam from the HRSG driving the existing steam turbine at an increased capacity of about 32 MW.
The existing 164-MW (nominal at ISO) GE 7FA.03 combined-cycle combustion turbine at the SHEC is operating in a 1×1 x1 configuration with a HRSG and a 189-MW GE D-11 steam turbine.
The SHEC addition will consist of the following new sources of GHG emissions:
- One natural gas-fired combustion turbine;
- One HRSG equipped with natural gas-fired duct burners; and
- Electrical equipment insulated with sulfur hexafluoride (SF6).
The HRSG’s duct burners will be fired with pipeline quality natural gas. The duct burners have a maximum heat input capacity of 681.5 MMBtu/hr per unit.
A project contact is: Ravi Joseph, Consulting Engineer, 721 Barton Springs Road, Austin, TX, (512) 322-6284.