The number of geothermal plants using deep hydrothermal energy from the South German Molasse Basin has rapidly grown in the last ten years. At the end of 2018, 26 geothermal plants were in operation; five of these are geothermal plants with heat and power production. To forward the thermal brine from the underground, all 26 geothermal plants are using an electric submersible pump, which is a crucial component for reliable and efficient operation. Especially when the brine temperature exceeds 120 °C, which applies to all mentioned geothermal power plants, formation and deposition of scaling in the electrical submersible pump are challenging and cause deterioration of hydraulic performance indicators, e.g., a decrease in mass flow rate of thermal brine, which significantly affects the production of heat and power. A measure to counteract the drop in power caused by scaling is the acidification of the electrical submersible pump, which has proven to extend the lifetime and enhance the performance of this component in geothermal applications. The impact of scaling on electrical submersible pumps of several deep hydro-geothermal plants in the South German Molasse Basin and the effects of acidification of the electrical submersible pumps are investigated. Long-term operational data of electrical submersible pumps are processed, analyzed and evaluated. Trends of the main operational metrics and key performance indicators of four considered electrical submersible pumps in three geothermal plants are investigated and discussed. Similar trends in the main operational metrics and key performance indicators are identified for the operation of various electrical submersible pumps. As the results show, acidifications of electrical submersible pumps have similar positive effects on their operation and improve their main operational metrics and key performance indicators. After analyzing the operation of the electrical submersible pumps, a simulation model for a two-stage Organic Rankine Cycle power plant is developed to quantify the losses in electricity production and the related reduction in revenues, caused by the decrease of the thermal brine volume flow rate. Furthermore, scenario analyses of different acidification intervals are carried out to optimize acidification intervals economically and thus achieve a minimal amount of lost revenues associated with a minimal sum of costs for acidifications. As the results show, acidifications of the ESPs influence the operation significantly, and optimizing acidification intervals can considerably increase the profitability of the considered geothermal plants.     «

The number of geothermal plants using deep hydrothermal energy from the South German Molasse Basin has rapidly grown in the last ten years. At the end of 2018, 26 geothermal plants were in operation; five of these are geothermal plants with heat and power production. To forward the thermal brine from the underground, all 26 geothermal plants are using an electric submersible pump, which is a crucial component for reliable and efficient operation. Especially when the brine te...     »