Enhancing Geothermal Enthalpy Extraction Using Quantum Nanofluids: Overcoming the Thermal Conductivity Limit of Aqueous Brines

Geothermal energy systems are fundamentally constrained by the thermal transport
properties of conventional working fluids, primarily water and saline brines. While subsur-
face reservoirs are capable of delivering heat at rates governed by rock thermal conductivity,
overall system performance is bottlenecked by the intrinsically low thermal conductivity
of fluids. This paper proposes the use of quantum nanofluids—aqueous fluids doped with
graphene- and carbon-nanotube-based nanoparticles—as an engineered solution to this lim-
itation. By leveraging ballistic phonon transport, nanoparticle percolation networks, and
interfacial liquid layering, nanofluids exhibit anomalous thermal conductivity enhancements
beyond classical diffusion-based predictions. We analyze the underlying physical mecha-
nisms, assess system-level performance impacts in Advanced and Enhanced Geothermal
Systems, and evaluate economic and environmental implications, with particular focus on
low-enthalpy geothermal deployment.