Environmental Engineering Reference
In-Depth Information
To transmission
lines
AC
Secondary
coil
Primary
coil
Step-up transformer
Electric
generator
Heat exchanger
Turbine
Ground-
water
pump
Boiler
Condenser
Injection
well
Feed
pump
Production
well
Earth
FIGURE 6.5
Simplified functional diagram of a binary cycle geothermal power plant.
conversion occurs in a special low-temperature boiler. Then the vapor leaves the
turbine, is cooled back into liquid by a condenser, and is recirculated to the boiler.
Because this is a closed-loop system, virtually nothing is emitted to the atmosphere.
Moderate temperature water is by far the more common geothermal resource, and
most geothermal power plants in the future will be binary cycle plants.
ENHANCED GEOTHERMAL SYSTEMS
The great potential for dramatically expanding the use of geothermal energy can
be realized by using enhanced geothermal systems (EGSs), also sometimes called
engineered geothermal systems
. Current geothermal power generation comes from
hydrothermal reservoirs and is somewhat limited in geographic application to spe-
cific ideal places in the western United States. This represents the “lower hanging
