The ThermoVault GX-3 is a deep geothermal energy extraction system designed for urban subsurface installation in GLMZ's geological context — specifically optimized for the thermal gradient profiles found beneath the Great Lakes basin's post-industrial substrate. A GX-3 installation consists of a primary bore column extending 2.4 to 3.8 kilometers below street level, lined with Dredge Mining's proprietary ceramic-tungsten heat exchanger tubing. A working fluid — a pressurized supercritical CO2 mixture — circulates down the bore, absorbs geothermal heat, and returns to a surface-level turbine plant where the thermal differential drives generation. A single GX-3 tap produces between 4 and 9 megawatts of continuous baseload power, independent of weather, time of day, or grid conditions.

The GX-3's engineering distinction is its Adaptive Bore Optimization system, a Cinderblock AI-managed suite of subsurface sensors and micro-adjusters that continuously monitors rock thermal conductivity, fluid pressure, and bore wall integrity, dynamically adjusting fluid circulation rates and extraction depth to maximize output while preventing bore collapse or thermal depletion of the local rock column. Dredge Mining's metallurgical expertise in deep-bore operations gives the GX-3 a bore lifespan rated at 40+ years, significantly outlasting competing systems. The surface turbine plant is compact — approximately the footprint of a two-story warehouse — and can be integrated into existing industrial structures.

GX-3 installations are concentrated in GLMZ's industrial and port districts, where Dredge Mining holds subsurface extraction rights negotiated under legacy mining ordinances that predate the current corporate sovereignty framework. This legal quirk has made GX-3 taps one of the few significant energy sources in the city not formally controlled by Ouroboros Energy, and the installations have become focal points of energy independence movements and corporate territorial disputes. Approximately 23 GX-3 systems are currently active in GLMZ, collectively supplying around 8% of the city's total baseload power.