Geothermal analog of pumped storage for electrical demand load following

摘要

A 6 day cycle Load-Following Experiment, conducted in July 1995 at the Fenton Hill Hot Dry Rock (HDR) test site in New Mexico, has verified that an HDR geothermal reservoir has the capability for a significant, rapid increase in thermal power output upon demand. The objective was to study the behavior of the HDR reservoir in a high-production-backpressure (2200 psi) baseload operating condition when there was superimposed a demand for significantly increased power production for a 4 hour period each day. In practice, this enhanced production, an increase of 65%, was accomplished by a programmed decrease in the production well backpressure over 4 hours, from an initial 2200 psi down to 500 psi. One of the advantages of geothermal load following over utility options such as pumped storage or compressed air storage is that the HDR power plant would be operated during off-peak hours in a baseline mode, with an augmented return on investment compared to these other peaking systems which would normally not be operated during off-peak periods. The surface power plant and the geofluid reinjection pumps would need to be sized for the peak rate of thermal energy production, adding somewhat to the overall HDR system capital costs when compared to a simple baseload power plant design.