EPRI Renewable Energy Part One

Geothermal energy already provides a small portion of California's energy but that's because California is the Saudi Arabia of geothermal resources.  GTM did a quick rundown of geothermal power available hereThe Geysers is one of California's geothermal prizes.  Luis Cerezo of EPRI spoke on the topic of geothermal on Wednesday afternoon.

Enhanced geothermal is a technology that looks to coax more energy from the earth in sites that are not exactly low-hanging geothermal fruit.

Current deployments of EGS require two wells and a large water source.  They also have garnered some spectacularly bad press of late as some EGS deployments in Germany and Switzerland have instigated serious earthquakes.   

The Electric Power Research Institute (EPRI) has a project investigating a new type of Enhanced Geothermal Systems (EGS) - single well geothermal.  Single Well Geothermal potentially resolves many of the problems with conventional EGS - lower environmental impact, less ground water contamination, and mercifully less seismic events.

Another advantage to Single Well Geothermal is that there are over 4,000 abandoned bore holes from the oil and industry that can be used for the geothermal industry and the single well architecture.
Here's an illustration of GTherm's single well closed loop system with a heat exchanger that uses a high thermal conductivity material (like cement) and a binary cycle closed system.