Potential air quality impact of geothermal power production in the Imperial Valley

A regional assessment of the potential impact on air quality of developing the Imperial Valley's geothermal resources for power production is presented. A network of six stations was installed to characterize the air quality and atmospheric transport properties of the valley before development. These measured the ambient air concentrations of H/sub 2/S, SO/sub 2/, O/sub 3/, NO, NO/sub x/, CO/sub 2/, Hg, Rn, and particulates. Wind velocity and the directional variability of the winds were also measured to determine atmospheric stability. The geothermal fluids were analyzed chemically to estimate potential emission rates of H/sub 2/S, NH/sub 3/, CO/sub 2/, CH/sub 4/, Hg, and Rn from future power plants. Using these data and advanced air quality modeling led to the prediction of the potential valley-wide impact of a 3000 MW development scenario. The impact analysis reveals that H/sub 2/S is the principal gaseous pollutant of concern due to its noxious odor and the potential release rate. The ambient H/sub 2/S concentrations that would result from generating 3000 MW without emission controls exceed the California air quality standard (30 ppb) at least 1% of the time for an area in the northern part of the valley that is roughly 1500 km/sup 2/more » in size. This compares with current ambient air concentrations that exceed the standard much less than 0.1% of the time. The population center most impacted is Calipatria, where the standard could be exceeded almost 10% of the time. In addition, the odor of H/sub 2/S will be noticeable at least 1% of the time for most of the valley if the 3000 MW are placed on-line without abatement systems.« less