The Virginia Department of Environmental Quality is out for comment until mid April on air permit changes needed by Virginia Electric and Power d/b/a Dominion Virginia Power as the utility gains operating experience with two small power plants that were converted in 2013 from coal to biomass.
The Altavista Power Station (APS) is located in Campbell County. In 2012, APS received a permit to change the two primary boilers at the facility to biomass units. Dominion’s operating experience at APS now indicates that several changes to that permit are needed because the magnitude of biomass fuel variability (i.e., both moisture content and species mix) is greater than anticipated. This variability results in less stable combustion. The principle pollutant impacted by this variability is carbon monoxide (CO) and the central focus of the requested changes is the short term limit on CO in units of pounds per hour (lbCO/hr).
The Southampton Power Station (SPS) is located in Franklin, Virginia. SPS has requested various air permit changes, including the removal of the lb/hr limit on CO and replace individual boiler heat input limits with a common limit.
“During the permitting process in 2012 to convert the boilers to biomass, the BACT analysis determined that Good Combustion Practices (GCP) with a CO emission limit of 0.3 lb CO/MMBtu met BACT,” the agency noted. “For SPS, GCP includes adjusting the speed of the traveling grate, air adjustments, and fuel feed rates. Since the switch from coal to biomass at SPS, the facility has gained experience, information, and data related to the use of biomass fuel in the boilers. Maintaining compliance with the hourly limit of CO on an hour-by-hour basis has proven difficult due to the inconsistency in fuel characteristics such as moisture content and wood type. Dominion has requested the removal of the pounds per hour limit with no requested changes to the lb/MMBtu or annual limit on CO.”