Stanford Geothermal WorkshopFebruary 9-11, 2026

Enhanced Geothermal Systems (EGS) were first introduced in the mid-1970s to augment natural hydrothermal production, whose commercial use began roughly a century ago. Yet, despite this long development history and the vast global endowment of accessible geothermal heat, geothermal power has remained a minor contributor to global energy supply. The persistent underperformance of conventional EGS arises from two fundamental technical limitations. First, effective access to subsurface heat is intrinsically limited by hydraulic and thermal short-circuiting. The conventional EGS design, which depends on intersecting perpendicular injection and production wells through an augmented fracture network via hydraulic fracturing, allows the circulating working fluid to flow along the lowest-resistance pathways preferentially. This channeling minimizes contact area with large volumes of hot rock mass and results in premature thermal breakthroughs, drastically reducing the useful life and output of the system. Second, the EGS system suffers from insufficient thermal replenishment within the fracture-stimulated rock volume. Closely spaced, congested fractures restrict the rate at which conductive heat from the surrounding formation can recharge the cooled fracture faces. As a result, EGS reservoirs experience rapid temperature decline and are forced into intermittent operational modes, effectively functioning as costly, low-efficiency thermal storage systems, rather than continuous power sources. Consequently, EGS and related Hot Dry Rock (HDR) and Super-Hot Dry Rock (SHR) approaches have struggled to deliver the sustained, high-capacity power output envisioned decades ago. VegaGeo 3.0’s Hybrid-Semi-Loop System (HSLS) technology, constructed in zero-permeability, plutonic rock, modifies the traditional EGS multiple-well deviated configuration by using a single vertical wellbore trajectory with induced bifurcated propped hydraulic fractures that are co-planar. It maintains full hydraulic communication with the propagation plane of induced fractures. This integrated geometry enables continuous sweeping of the induced fracture surface area, eliminating flow bypass and maximizing hot rock contact. Numerical simulations indicate that VegaGeo 3.0 can sustain high long-term baseload production exceeding 50 MWₜ, demonstrating efficient heat extraction through complete utilization of fracture flow paths. Long-length flow diverters are constructed in the propped fractures, bifurcating them, and causing lengthy heat-collecting fluid flow away from and back to the wellbore, super heating fluids over several hours of exposure to 350 – 750°F rock. Accessing deeper vertical depths within the earth’s upper crust, with heat levels well beyond traditional practice, the reconfigured system fractures are separated laterally by more than 1000 ft, thus allowing high baseload level heat replenishment. Respecting all preferences and advantages for heat extraction from significant depth, the newer method is called the VegaGeo 3.0. This paper presents this novel approach and analysis of simulated performance in deep HDR and SHR. The advanced VegaGeo 3.0 HSLS configuration was evaluated using Computational Fluid Dynamics (CFD) coupled with conjugate heat-transfer (CHT) analysis to predict production temperature and thermal power output under a range of geological, geothermal, and operational conditions. The modeling encompassed variations in rock thermal gradient, fracture geometry, vertical fracture separation, inlet temperature, and circulation rate, allowing a comprehensive assessment of system behavior from early-time transients to long-term steady-state operation. Analytical optimization indicated that a configuration incorporating approximately 15 hydraulically connected co-planar fractures, vertically separated by up to 1,100 ft (~335 m), provides the most practical balance between drilling complexity, reservoir recharge, and sustained heat extraction. Results from both transient and steady-state simulations demonstrate that the VegaGeo 3.0 architecture can achieve 10 to 30× increases in baseload geothermal energy output relative to conventional multi-well EGS systems. Modeled thermal production exceeds 110 MWₜ at initial startup, maintains an average of approximately 50 MWₜ over a 20-year operational period, and does not reach steady-state production of roughly 30 MWₜ until after 25 years of continuous operation. These findings confirm that the VegaGeo 3.0 framework enables unprecedented longevity and capacity in engineered geothermal systems, firmly establishing its potential as a true high-enthalpy baseload geothermal technology.

Topic: Emerging Technology