Investigating Flexible Generation Capabilities at the Geysers

Electric system operators are concerned about large quantities of intermittent energy sources being reliably integrated onto the grid. While geothermal energy has served to provide a steady level of baseload energy, reducing impacts of intermittent energy will require quickly dispatchable sources of generation with the flexibility to ramp up or down as needed. Modifying geothermal operations to provide this flexibility would be valuable to system operation. However physical and operational issues are associated with providing such flexible generation from geothermal facilities.

This project conducted a study to investigate flexible electrical generation capabilities at The Geysers. The overall objective is to define steamfield and power plant operating constraints and find ways to increase flexible generating capabilities. The researchers developed an integrated numerical model to predict, study, and ultimately design strategies for flexible power generation. The modeling work performed under this project resulted in successful development and application of a simulation-optimization framework for the optimal control of a steamfield under load curtailment.

Upgrades installed during this study have removed turbine related constraints and made it feasible to achieve rapid cutbacks using existing ramp rates and provided an incremental increase in existing flexible generation capabilities. Field testing and modeling results show that steam well and pipeline corrosion is a major constraint on steam-field operations, however, results from this study will guide economic evaluations and future capital improvements needed to expand current Geysers flexible generation capabilities.