Proceed With Caution: California's Drought & Seawater Desalination
Posted May 21, 2014 in Reviving the World's Oceans
For California, 2013 was the driest calendar year ever recorded across virtually the entire State. On January 17, 2014, Governor Brown proclaimed the drought to be a State of Emergency. While some observers wonder whether the long-term answer to California’s drought lies in the ocean with the promotion of seawater desalination, a White Paper released today by NRDC and nine other organization explains why seawater desalination is generally the least promising option for drought relief.
The Natural Resources Defense Council, along with the California Coastkeeper Alliance, Surfrider Foundation, Heal the Bay, Orange County Coastkeeper, California Coastal Protection Network, Residents for Responsible Desalination, Southern California Watershed Alliance, the Desal Response Group, and the Sierra Club Angeles Chapter comprehensively reviewed California’s water supply options and have determined that seawater desalination should only be pursued with caution and only after conservation, stormwater capture through the use of “green infrastructure,” water use efficiency, and wastewater recycling have all been fully implemented. These preferred alternatives are not only less expensive, they have additional benefits of preventing pollution, contributing to habitat restoration, and reducing energy usage.
Here’s a detailed account of why other water supply solution should be prioritized over seawater desalination:
First, water produced by seawater desalination is very expensive with an average price per acre foot 4 to 8 times higher than water from other sources. Estimates for plants proposed in California range from $1,900 to more than $3,000 per acre-foot. A 50 million gallon per day (MGD) plant, such as the one under construction in Carlsbad is projected to have a price between $2042-$2290 per acre foot. By comparison, the Department of Water Resources data cited in the 2009 California Water Plan Update found that:
- The “estimated range of capital and operational costs of water recycling range from $300 to $1300 per acre-foot” depending on local conditions.
- The cost to realize an acre-foot of water savings through efficiency measures ranges from $223 to $522 per acre-foot.
- The agricultural efficiency improvements that result in water savings of between 120,000 to 563,000 acre-feet per year can be achieved at a cost ranging from $35-$900 per acre-foot.
Second, seawater desalination is typically the most energy-intensive water supply option, resulting in significant climate change pollution compared to less energy intensive options. A 2011 life-cycle energy assessment of California’s alternative water supplies commissioned by the California Energy Commission found that, while a desalination system can have a wide array of impacts depending on the water source: “In all cases, the energy use is higher than alternative water supply.”
Third, seawater desalination can have significant impacts on the marine environment. Seawater desalination plants typically only convert 45-55% of the water they withdraw into freshwater, which means they must take in twice as much seawater as the amount of freshwater they intend to produce. Many of the proposed desalination projects in California plan to use large pipes in the water column to suck in the source seawater": these open ocean intakes kill billions of fish eggs, adult fish, and other marine life each year, threatening the productivity of California’s marine ecosystems. The desalination process also generates large quantities of waste, known as brine, which can have serious impacts, including acute and chronic toxicity if improperly discharged into the marine environment.
Finally, experience demonstrates that large, expensive desalination facilities and associated infrastructure can take many years to build and bring online, yet the water demand and price may be insufficient to justify continued operation of the desalination plant when less expensive water supply and demand management alternatives are available: this creates significant financial risk for ratepayers and taxpayers. For example, in response to the 1986-1991 drought, Santa Barbara spent $34 million to build a reverse osmosis desalination plant that was promptly placed into long-term storage because of the plant’s very high operational costs. Now, the city is considering undertaking a two year process to reactivate the plant, at an additional cost of $20.2 million and with operating costs of approximately $1,500 per acre foot.
Similarly, severe drought from the mid-1990s until 2012 prompted Australia to construct six large-scale seawater desalination plants at a cost of $10 billion to provide an alternative source of drinking water. At the same time, water policy reforms and improved efficiency measures were implemented through the country’s National Water Initiative. The plants took years to build, and by the time they were operational, the drought had eased and cheaper alternatives, made possible by the National Water Initiative, made the water from the desalination plants impractical. Today, four of the six Australian plants stand idle.
Only after cheaper, less environmentally impactful water supply options such as conservation, stormwater capture, water use efficiency, and wastewater recycling have all been fully implemented should seawater desalination be considered. If and when seawater desalination is necessary, projects should be appropriately scaled to meet demonstrated water supply needs. Then, projects should be designed and sited, and best technology available should be used, to: minimize the intake and mortality of marine life; minimize adverse impacts to the marine environment from the facility’s waste discharge; and avoid conflict with ecosystem-based management activities, especially ongoing implementation of the Marine Life Protection Act, and climate change and disaster preparedness.
In the meantime, there are a number of 21st-century water solutions that cities, homeowners and farms can implement today that will help deal with this year’s drought and prepare for drier days ahead.
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