Air Quality Modeling of Geothermal Power Plants in Complex Terrain

Abstract

Commercial energy development at the Geysers KGRA, California - the world's largest producing geothermal field - is confronted with increasingly more stringent air quality impact assessment requirements for not only regulated pollutants, (e.g. hydrogen sulfide and primary particulates) but also unregulated species including benzene, ammonia, arsenic, Radon222, boron, and mercury. An integrated program of ambient aerometric monitoring, tracer diffusion experiments, cooling tower plume rise studies, and numerical air quality simulation modeling was conducted for this mountainous region to provide estimates of potential short term (i.e. 1 hour) impacts attributable to development of the Geysers steam resources. A series of atmospheric tracer diffusion experiments, focusing on aerodynamic downwash, nocturnal drainage, fumigation, and limited vertical mixing were conducted to provide a basis for air quality model performance evaluation. Upper air metrological measurement and cooling tower plume rise studies were performed to develop data useful in evaluating wind field and plume rise sub models.