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

FINDINGS AND CONCLUSIONS
Applying geopressured-geothermal resources to direct use is feasible.
Of the various applications that were considered, desalination and
agriculture/aquaculture appear to have high potential for near-term
economic utilization. The sale of methane gas contained in the
geopressured fluid will probably be accomplished irrespective of the
applications selected to use the energy contained in the geopressured
fluid. Additionally, commercialization would also include electric power
generation, which was effectively proven at the DOE geopressure test
facility at Pleasant Bayou, located about 50 mi south of Houston, TX.
Evaluation of the various applications indicates that multiple uses
incorporated at a common location increases the odds of profitability.
For example, a complex served by a 20,000 barrels per day geopressured
well that provides for the sale of the contained methane gas, the sale of
potable water produced by desalination, bottled water, and the brines
resulting from desalination will have a 15% discounted payback period of
- 4.3 years (Figure 2). The addition of an agriculture/aquaculture
complex producing roses and catfish that is made up of a 4 acre
greenhouse structure, service building, three 20-ft diameter aquaculture
tanks in an enclosure, and an 8 x 45 ft outdoor raceway would reduce the
payback period to -4 years (Figure 3). However, when electricity
production is added to the gas/potable water/bottled water/brine complex,
the expected discounted payback period increased to more than 10 years
when the electricity is sold for 6 cents/kWh. If the complex is selling
gas at market price, electricity at 6 cents/kWh, and includes an
agriculture/aquaculture facility, the discounted payback is >10 years
because of the high front end costs for the electric generation equipment
and the relatively small return for the agriculture/aquaculture facility.
Practically, the actual installation will be determined by the
specific geopressured resource. Utility restrictions and financial
requirements have typically limited these developments because of the
complexity of operation and management.
7