Enhanced geothermal system
A geothermal energy approach that creates or improves underground fluid pathways so hot rock can provide power or heat beyond naturally permeable geothermal fields.
What it is
An enhanced geothermal system is an engineered geothermal reservoir. Conventional hydrothermal power needs naturally hot rock, underground fluid, and enough permeability for that fluid to move. EGS targets places where the rock is hot but the natural cracks or fluids are not sufficient, then uses drilling, injection, and monitoring to create usable flow paths.
How it works
A project drills into hot rock and injects fluid under controlled conditions. The pressure can open small fractures or reconnect existing ones, increasing permeability. Water or another working fluid then circulates through the heated rock, returns to the surface, and transfers heat to a power plant or direct-use heat system.
Why it differs from ordinary geothermal
Traditional geothermal plants are usually built where nature already provides a productive hydrothermal reservoir. EGS tries to make more of the subsurface usable by engineering part of the reservoir. That could move geothermal energy from a location-limited resource toward a broader firm clean energy option.
Field demonstrations
EGS research depends on field testing because the key questions are underground: fracture growth, fluid circulation, heat drawdown, induced seismicity, well integrity, and long-term output. U.S. projects such as Utah FORGE and earlier demonstrations at Newberry, The Geysers, Brady, and Desert Peak have helped researchers test stimulation, monitoring, and reservoir-management methods.
Risks and controls
The main concerns include drilling cost, uncertain reservoir performance, water use, mineral scaling, equipment wear, and small earthquakes triggered by fluid injection. Operators manage those risks with site characterization, pressure limits, seismic monitoring, traffic-light protocols, chemical analysis, and staged testing before commercial operation.
Power and heat uses
EGS is often discussed for electricity because deep hot rock can provide steady heat for generators. The same engineering ideas may also support industrial heat, district heating, thermal storage, or hybrid systems. The useful application depends on depth, temperature, flow rate, distance to users, and the economics of wells and surface equipment.
Why it matters
Wind and solar are variable, while geothermal heat is available around the clock when a reservoir performs well. Enhanced geothermal systems matter because they could add a firm, low-carbon energy source in regions that do not have obvious natural geothermal resources, making clean grids easier to balance.