Mitigation of Hydrogen Sulfide Emissions in the Geysers KGRA (Staff Draft)

Violations of the ambient air quality standard (AAQS) for hydrogen sulfide (H2S) are currently being experienced in The Geysers KGRA and could significantly increase in the future. Attainment and maintenance of the H2S AAQS is a potential constraint to optimum development of this resource. The availability of reliable H2S controls and the development of a validated air dispersion model are critical to alleviating this constraint. The purpose of this report is to assess the performance capabilities for state-of-the-art controls, to identify potential cost-effective alternative controls, and to identify the California Energy Commission (CEC) staffs efforts to develop a validated air dispersion model. Currently available controls (Stretford, Hydrogen Peroxide, and EIC) are capable of abating H2S emissions from a proposed facility to five lbs/hr. Alternative controls, such as condensate stripping and condensate pH control, appear to promising, cost-effective control option. The CEC staff is currently developing a validated air dispersion model for The Geysers KGRA. The CEC staff recommends investigation of retrofit control options for existing units, investigation of alternative control technologies, and dispersion analysis for optimum plant location in order to maximize the development potential of The Geysers KGRA. Energy cost studies suggest that the EIC process would be the most cost-effective for retrofits at The Geysers. (DJE-2005