Control of Metal Sulfide Deposits in Geothermal Binary Plants

• Main Authors: Logan Muller, Jasbir S Gill, David Rodman, Kevin Brown, Ray Robinson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2015
• Subjects: New Zealand; Iceland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1074.9477

ABSTRACT Geothermal power generation is growing due to the need for clean renewable energy. Traditional dry steam generation plants have been in operation in countries where Geothermal dry steam is prevalent for several decades e.g., New Zealand, Iceland, Philippines. However as the cost and environmental impact of fossil fuel power generation is realized, more effort is being placed into more complex geothermal use such as low enthalpy power plants and EGS or Hot Rock technology plants. These latter technologies bring a raft of chemical complexity to power generation in particular Silica and metal Sulfides. Whilst Silica and Arsenic Sulfides are well researched, comparatively little is known about Antimony Sulfide. The absence of chemical inhibitors for the sulfide compounds has resulted in significant fouling of some geothermal plants causing losses of power output, thereby reducing the economic viability of these plants. Recent developmental work at the Ngawha Generation site in New Zealand has shown a significant step forward in the control of Antimony Sulfide deposition in binary plant heat exchangers. This plant was taking generation units off line for cleans every 12 weeks due to the loss of power production resulting from Antimony Sulfide scale. This paper outlines how these metal Sulfides have been prevented from depositing, providing improved power output, reduced need for cleaning and, subsequent, minimization of handling these toxics deposits. There may be important implications for EGS technologies as the toxic metal Sulfides have presented a barrier to consistent power production in at least one test site.