POWER March 2016 - 22

WATER & WASTEWATER
Desalination Expands, but Energy
Challenges Remain
Courtesy: Poseidon Water
Fearing widespread water scarcity, companies and governments around the world
are scoping out desalination technologies to convert seawater to potable water.
That's a rocky path that involves lots of energy and high costs-and potentially high
rewards.
Kennedy Maize
A
t the ballyhooed Paris climate conference
last December, a little-noticed
event occurred that could lead to important
developments for electric generators.
At the Paris meeting, some 80 signatories-
including national governments, energy and
water industries, research groups, universities,
and nongovernmental organizations-
launched the Global Clean Water Desalination
Alliance. The group's focus, which it
calls " H2O minus CO2, " is on how to reduce
carbon dioxide emissions from the energyintensive
process of turning seawater into a
potable product.
A press release from Paris announcing the
organization's founding noted that access to
clean water is " already a major challenge for
as much as one-quarter of the world's population, "
and that some forecasts are " predicting
that by 2030, 47% of the global population
will face water scarcity. " It's not that the
world is short of water-which covers some
70% of the planet's surface and is entirely
renewable-but that most of it is seawater.
22
Turning to the Sea
Just a couple of weeks after the Paris meeting,
a $1 billion reverse-osmosis (RO) desalination
plant in Carlsbad, Calif., went into
service next door to NRG Energy's 950-MW
gas-fired Encina power plant, nearly 25 years
after its conception during an early 1990s
California drought (Figure 1). Construction
began in late 2012, amid the most recent of
many Golden State droughts.
The Carlsbad project is the largest desalination
plant in the Western Hemisphere and
is designed to produce up to 50 million gallons
(190,000 m3) of water per day, supplying
the San Diego County Water Authority
with up to 10% of its water needs. Poseidon
Water of Boston, which develops large-scale
seawater RO plants co-located with coastal
power plants, owns the facility. Poseidon's
CEO is Carlos Riva, a veteran of the U.S. independent
power industry. IDE Americas, a
subsidiary of Israel's IDE Technologies, provided
the Carlsbad design, and J.F. Shea Co.
and Kiewit Corp. built it. The water authority
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has a contract to buy up to 56,000 acre-feet
of water per year from Poseidon under a 30year
water-purchase agreement.
Until Encina shuts down in 2017, the
Carlsbad plant will take up to 100 million
gallons per day of once-through cooling water
from the power plant, filtering it to reduce
particulates before sending it through RO
(shown in the header photo). After half of
the intake is converted into pure water, the
briny residue will go into the power plant's
discharge channel and back to the sea. After
Encina shuts down, the desalination plant
will continue using the plant intake to draw
directly from the ocean.
Some local environmental groups opposed
the project. They are also campaigning
against another Poseidon plant under development
up the coast in Huntington Beach,
near the planned 450-MW repowered gasfired
AES Huntington Beach Power Plant,
scheduled to operate in 2019. According to
Orange County Coastkeeper, " If the Poseidon
desalination plant is built on the HunPOWER
| March 2016
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POWER March 2016

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