Image: View into a reverse osmosis desalination plant. Credit: Wikimedia Commons
Last week I observed a panel discussion on the benefits and trade-offs of using desalination to augment the state’s water supply that was put on by the Berkeley Energy & Resources Collaborative (BERC) at U.C. Berkeley. The discussion, titled “Innovation in Desalination- An Answer to Our Water Woes”, featured commentary by water regulators, water experts, engineers, and others, all grappling with the question of when and if desalination makes sense as a water resource strategy. The takeaway message seemed to be that in California’s complex system of water rights, population, climate and location considerations, desalination emerges as one in a suite of strategies that can be used to meet an area’s water supply needs, but that it should remain at this time, something of a last resort.
Desalination is the process of removing the salt from a sea-water or brackish-water supply in order to make it potable, clean water. In a seasonally dry, coastal state like California that has a major conveyance system in order to get precious water resources from the north to the densely populated and more arid south, desalination might sound like a great idea. However, the technology comes at steep price, both financially and environmentally.
What are those costs? First, there is the financial cost; the USGS estimates that desalinated water can cost up to $1,000 per acre-foot as compared to roughly $200 per acre-foot from typical supplies. It is heavily consumptive in terms of energy use; and sea-water systems can disrupt local ecosystems at intake, as well as pollute them with the concentrated discharge at the end of the process.
Despite all of these hurdles and drawbacks, desalination has already been employed in California at a small scale for many years. Desalination will likely also become a more prominent feature of the state’s water profile as the price of the technology continues to come down. At present however, it makes sense for desalination to take a back seat to conservation, water recycling and consumer education.
Read the Pacific Institute’s report, Desalination: With a Grain of Salt
Desalination in the news:
KQED’s Forum featured a segment on The Cost and Benefits of Desalination, on October 25, 2010.
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