GREENPATH SYSTEMS LLC — Department of Energy SBIR Phase II: C52-20g

Description

GHPs (ground heat pumps) have extensive potential applications 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. The key to reducing geothermal project costs is to minimize well construction costs, 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. These geopolymer grouts 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. Based on funding provided by DOE SBIR Phase I, Greenpath systems (GPS) successfully designed, tested, and evaluated new products for geothermal applications by conducting intensive lab work (with an academic partner), feasibility, and numerical studies. The new cement(grout) developed by GPS shows an average 150% increase in thermal conductivity (TC) achieved at a 50% lower cost [11]. The new product offers several key advantages such as: -Reduced CO2 footprint because of using by-products -High TC geopolymer will lower levelized cost of heat (LCOH) because of saving in drilling and well cost (shallower well needed) -Reduced cost in long-term workover because of superior performance such as better bonding, higher strength, and durability in an aggressive environment In order to scale the product from lab to field conditions, in Phase II, GPS and its partners will conduct a field demonstration project using Phase I products. The proposed solution is scalable and marketable in the geothermal industry and will lower down Levelized Cost of Heat (LCOH). The primary benefit of this project is the utilization of economical and environmentally friendly geopolymers for geothermal applications. This will be a novel application by re-purposing waste materials for renewable energy production from coal power plants. The economic advantage is the reduction in the cost of well construction, and the environmental benefit is to recycle waste materials (reduce the carbon footprint for producing construction material) for renewable energy production.