(GP/GT) for Additional Water Supply in the Lower Rio Grande

2.2 The gas can be burned in a gas engine to produce
electric power.
3. The geopressured hot water is used in a binary module to
produce electric power.
The main components of the binary module are shown in Figure
2. It consists of heat exchangers which transfer heat energy from
the geothermal water to the working fluid. The heat supplied is
sufficient to completely vaporize the working fluid at a relative
high pressure. The vaporized working fluid is expanded through a
turbine where shaft power is produced to drive a generator. The
working fluid then flows to the condenser where heat is rejected to
a heat sink (such as the evaporation of water or ambient air). The
liquid working fluid fr~m the condenser is pumped back to the heat
exchanger, thus completing the cycle. The design of the binary
module, including the selection of the working fluid, is tailored
to match the resource temperature to provide the maximum
utilization for that resource. The equipment layout for a binary
module is shown in Figure 3.
The characteristics for a representative geopressured
resource are shown at the top of Table 1 along with the assumed
sales rate for gas and electric power. Following this are the
estimated costs for the equipment as outlined previously and the
revenue produced by.the different energy sources. option I is for
a plant in which the gas is sold directly. option II is for a
plant in which the gas is burned to produce electricity. It should
be noted that the binary module in Option II is larger than Option
I. This is because the binary module in Option II uses some of the
waste heat from the gas engine in addition to that from the
geofluid.
The results of this simplified model indicate that while the
cost of option II (converting the gas to electricity) is higher
than Option I, the increased revenue has actually improved the rate
of return. A detailed economic analysis with actual sales rates
and costs are based on actual resource characteristics should be
performed before the final option is selected. This model
indicates that there may be options that are superior to the direct
sale of the gas.
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