Technology
Figure 1: P-VES vs. RO cost comparison
The P-VES plant
is designed to
recover all of
the thermal
energy required
to operate the
process, except
loss of thermal
energy to the
atmosphere.
now distilled, high-temperature water leaving the
heat exchanger is drawn from the heat exchanger and
passed back through the heat exchanger. This water's
residual heat supplies the additional heat to the steam
generator and further reduces BTU consumption.
There is also potential for cogeneration, using waste
heat from other adjacent operations and/or solar to
further reduce the energy cost.
Simulation studies of P-VES have shown no more
than 10 BTUs are needed per pound of seawater, but
Water Desalination International (WDI) is confident
that the BTU usage could be considerably less.
Assuming 10 BTU per pound as our base, that equals
22,602.6 BTU per m³. There are 28,400,000 lbs. in an
acre-foot (AF) of water; multiplying that by 10 BTUs
per pound equals 28,400,000 (or 28.4 million) BTUs
per AF. Current natural gas shows a market price of
USD $7.54 per 1 million BTUs3, and 28.4 multiplied
by $7.54 equals $214.00, which is the cost of energy
per AF. Correspondingly, one m³ of P-VES-produced
distillated seawater would cost $0.17. This shows
a cost that is more than 82 percent less than RO
and represents the lowest consumption of energy
compared to all other desalination processes that we
know.
wateronline.com
WDI is currently working with partners to beta
test the process. The patent for P-VES desalination
is among seven held by Frank Passarelli, whose skill
lies in taking accepted limits of a process and finding
a far more simple and efficient design to maximize
results and minimize cost. P-VES, he says, is his gift to
a world seeking water. Inquiries can be sent to nam@
waterdesalination.com.
1. http://wrri.nmsu.edu/conf/conf11/reverse_osmosis_deep.pdf (see pg. 8
of 13)
2. http://digitalcommons.calpoly.edu/cgi/viewcontent.
cgi?article=1021&context;=braesp (pg. 24 of 59)
3. http://www.google.com/url?sa=t&rct;=j&q;=&esrc;=s&source;=web&cd;=1&ved;=
0CC0QFjAA&url;=http%3A%2F%2Fwww.eia.gov%2Fneic%2Fex perts%2Fheatcalc.
xls&ei;=LiTLUa74LLKMigK0k4DYBA&usg;=AFQjCNEI3O4-27x7XDhiFFJKOpjvhE
ZHsA&sig2;=st3DotqvRTaAld-lfSf8GQ&bvm;=bv.48340889,d.cGE interactive excel
spreadsheet
Neil A. McCarthy, BA, MSEd, is currently a middle school math
teacher at a South-Central Los Angeles parochial school. He
previously worked for Golden State Water (formerly Southern
California Water Co.) and has consulted with Frank Passarelli
for 16 years on research and presentations. McCarthy holds
both multi- and single-subject credentials issued by the state of
California.
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Water Online The Magazine
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