Development of a Highly Conductive Nano-Engineered Geopolymer for Geothermal Applications

Abstract

Geothermal energy presents a promising opportunity for sustainable and efficient energy production. To maximize the efficiency of geothermal systems, developing advanced materials capable of effectively transferring and withstanding thermal loads is crucial. This study focuses on demonstrating highly conductive nano-engineered geopolymer cement tailored for geothermal applications using prototype laboratory samples. The study included an evaluation of thermal conductivity, shear bond strength, and compressive strength of newly designed geopolymer mixtures as well as the thermal conductivity of large-scale geopolymer samples, with a specific emphasis on their performance in the handling fluid flow for enhanced geothermal systems. The results showed that, compared to the control geopolymer, the developed geopolymer formulations had a lower thermal conductivity performance due to higher air voids in the system. In general, the addition of carbon nanotubes and graphite in geopolymer mixtures reduces the strength and elastic modulus. The thermal conductivity of the large prototype sample cured for 7 days at 49 °C showed better thermal conductivity for the control geopolymer. Conversely, the water flow data reflected better performance for the modified mixtures. Additionally, numerical simulations were developed and validated by the experimental observations for further studies on the effect of geopolymer properties on the performance of geothermal systems.