Desalination Expands, but Energy Challenges Remain

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.

At 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 energy-intensive 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.

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. 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 has a contract to buy up to 56,000 acre-feet of water per year from Poseidon under a 30-year 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 gas-fired AES Huntington Beach Power Plant, scheduled to operate in 2019. According to Orange County Coastkeeper, “If the Poseidon desalination plant is built on the Huntington Beach floodplains, the project will require structural protection barriers such as seawalls, groins, breakwaters and other coastal armoring structures, triggering an additional suite of costs and impacts to our state and coast.”

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Taxonomy

• Scarcity
• Energy
• Desalination