The destabilizing thermal gradient across the Earth's lithosphere drives convection in superconfined hydrothermal environments at mid-ocean ridges and geothermal reservoirs in the continental crust. Deep, hot waters rise in these regions and meet cold surface water that percolates through open fractures, creating complex and poorly understood mixing dynamics. This Letter explores the relationship between energy, convection, and mixing in analog hydrothermal systems. Leveraging energetics theory and lab-scale experiments, we present a scaling formulation for estimating the irreversible mixing boosted by convective flows occurring within faulted and fractured hydrothermal environments. These findings bear relevance to natural Earth processes and human-engineered applications, such as geothermal energy harvesting and geologic CO2 sequestration. Plain Language Summary Earth's internal heat continuously escapes from its hot core to the cold lithosphere, creating a temperature gradient that drives convective fluid motion in confined hydrothermal environments, such as those at mid-ocean ridges and geothermal reservoirs in the continental crust. In these regions, deep, hot waters rise and mix with colder surface waters seeping through fractures, producing complex and poorly understood mixing patterns. This study explores the interplay between energy, convection, and mixing in these systems. Using theoretical frameworks on energy transformation in fluids and innovative lab-scale experiments, we derive mathematical expressions to estimate fluid mixing rates in faulted and fractured hydrothermal environments. Our findings provide insights into the physics of fluids in the Earth's crust and have implications for advancing technologies such as geothermal energy production and underground CO2 storage.