The Energy Underneath Our Feet

Geothermal energy has the potential to provide reliable, environmentally friendly, and affordable electricity and heat. Enhanced/Engineered Geothermal Systems (EGS) are a type of geothermal energy that is implemented in areas with any of the following combinations: low permeability, dry rock, and/or great depths. A site is engineered or enhanced by stimulating a reservoir, inducing fractures where water may be pumped through the reservoir to “farm” or extract out the thermal energy contained in the formation. Our research group investigates the complete integration of the low-temperature EGS and shallow geothermal systems including geothermal resource assessment, hydrothermal drilling, heat farming and thermal mapping, geothermal reservoir utilization, and ground-source heat pumps. In order to facilitate EGS project placement and design, the resource assessment study draws a more complete picture of geothermal resources by incorporating new temperature-depth data into a set of maps showing the inherent subsurface thermal gradient and surface heat flow. Once exploration sites are determined, hydrothermal drilling has the potential to provide access to deeper EGS reservoirs by penetrating crystalline bedrock at a much faster rate than conventional rotary drilling techniques. To determine the sustainability of EGS reservoirs, heat farming strategies, specifically conduction dominated models, are being studied. These models estimate heat transfer during subsequent periods of extraction and recovery. Low-temperature geothermal energy utilization can greatly increase the range of options for EGS development. The proposed solutions include electricity generation using subcritical and supercritical Organic Rankine Cycle, electricity and heat co-generation using geothermal energy and biomass, and use of district heating systems for community redevelopment projects. For shallow geothermal projects, ground-source heat pumps offer an environmentally-friendly and cost-effective way of heating and cooling.