Air Modeling for Hybrid Electric Generating Plant

TRC conducted air modeling testing to ensure compliance with all air quality regulations for both Class I and Class II areas.




Project Location

Virginia City, VA

Dominion proposed to design, construct, and operate a coal-fired steam electric generating plant in Virginia City. The proposed power plant consisted of two identical clean-technology CFB boilers with a total gross generating capacity of 580 MW. The project was a new major source subject to Prevention of Significant Deterioration (PSD) regulations.

The project is located in a deep river valley in an area with complex terrain. With the conventional modeling approach, a 100-meter-tall meteorological tower would have been required to be installed and operated long enough to collect one year of complete data. This would have caused at least an 18-month project delay.

A second challenge was the magnitude of the simulations required. Since background sources that consume PSD increments can be considered up to 300 kilometers from the Class I areas, hundreds of sources needed to be identified and modeled. For the Class II areas, more than 15,000 receptors were modeled for over 100 sources using the CALPUFF model. Using a standard workstation, more than one year of computational time would have been required to complete the required model runs for each revision of the plant emissions.

TRC conducted the air quality modeling for both Class I and Class II PSD areas using the CALPUFF model, which is ideal for near-field complex flow situations because it uses a three-dimensional wind field and avoids the need for measuring onsite meteorological data. Three years of hourly wind fields were predicted using the MM5 mesoscale model and CALMET. TRC used its 120-processor Linux cluster computer, which has the power of 120 workstations, to complete the required CALPUFF model runs. This computer, when dedicated to the Dominion modeling, completed the runs for each revision in only a few weeks.

Using CALPUFF for the near-field Class II modeling avoided the need to collect one year of onsite meteorological data and accounted for the plume trajectory within the valleys and during changing wind conditions as the plume traveled downwind. The modeling demonstrated compliance with all air quality regulations for both Class I and Class II areas. The project was unanimously approved by the State Air Pollution Control Board on June 25, 2008. The Virginia Department of Environmental Quality issued the necessary air permits on June 30, 2008 for the $1.8 billion project.

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