Highly Conductive Nano-engineered Geopolymer Cements for Geothermal Applications

GHPs (ground heat pumps) have an extensive potential application in the US. Shallow-earth resources exist across all 50 states and can be used for GHPs wherever the ground can be cost-effectively accessed to depths below seasonal temperature variations. Key to reducing geothermal project cost is to minimize well construction cost, including borehole length. Using a thermally conductive grout (cement) with good bonding and strength is a solution to accomplish this. The proposed project will investigate and develop geopolymer grouts enhanced by nano-material fillers. We call the proposed product in this application “Nano-engineered geopolymers (NEGs)”. NEGs are considered for the application as advanced grouts in the GHP's well construction. Geopolymer precursors are typically waste streams from mining industries and power plants. These materials have shown better performance in short- and long-term properties than conventional cement and grouts. They are also inexpensive, environmentally friendly, and can be enhanced for higher thermal conductivities using nano-additives. Previous research indicates the application of these materials for the high-temperature environment (>150 oC), which makes them suitable for geothermal purposes. Current statistics show at least 75 million tons/year of these materials are available in the United States alone which only 30% are efficiently utilized [10]. In Phase I, GreenPath Systems (GPS) plans to design, test, and evaluate NEGs for geothermal applications by conducting intensive lab work (with an academic partner), feasibility, and numerical studies. In Phase II, GPS and academic research partner will conduct a field demonstration project using products developed in Phase I. The proposed solution is both scalable and marketable in the geothermal industry. The primary benefit of this project is the utilization of economical and environmentally friendly geopolymers for geothermal application. This will be a novel application by re- purposing waste materials from power plants for renewable energy production. The economic advantage is the reduction in the cost of well construction, and the environmental benefit is to recycle waste materials for renewable energy production. GPS’s experience in projects with similar complexity along with our collective experienced experts and our key relationships with key industry players will catalyze our commercialization efforts.