A Better Understanding Of Desalination
As an expert on utility resiliency for a changing climate, John Batten, Global Water & Cities Director for ARCADIS, discusses the prospects of desalination for bolstering U.S. water supplies.
Batten joined Todd and Kelly of Water Online Radio to discuss the hurdles, advances, and future opportunities for desalination technology. Here’s a portion of the interview.
Todd: I hear a lot of people say that what’s happening in California is the new normal. Lead us off by talking about some of the solutions to this severe problem.
John Batten: I believe in a portfolio management approach. Desalination is one of the elements of a really good, balanced portfolio. But you also need to do conservation, you also need to consider reuse in its multiple forms … [and] you need to bring back impaired waters. …In portfolio management, a good municipal approach is to make sure you’re pulling water and treating water and managing water with a number of different options, and desal is one of those options.
Kelly: Desal has been on the radar for a very long time, and I suspect it’s been through many iterations. What does it look like today?
John Batten: The original desal technology was built around the Middle East, which [has] major, protracted scarcity … but they had the availability of oil, so they’ve been doing multi-stage flash desal, or almost distillation, for years — and they still do. That was the original cradle of desal.
Most municipalities and countries can’t afford to do flash desalination. It’s very expensive and very energy-intensive. Over the last 20 years, with the onset of membrane filtration and reverse osmosis and these kinds of processes and innovations, we’ve been able to make desalination much more affordable and much more manageable. The plant that’s coming online for Carlsbad is an example of the latest generation of desalination technology.
It’s a four-stage, low pressure-to-high pressure process. It has various stages of treatment, starting with some microfiltration and ending with ultrafiltration. It uses a lot less energy than the processes we were using 10-plus years ago.
…What’s really nice about the Carlsbad facility … [is that] the desal plant adjoins the power plant, and then the concentrated brine flows out with the cooling water from the power plant. The cooling water power plant [has] about 300 to 400 million gallons a day of cooling water that’s moving out into the ocean. Carlsbad’s brine is 50 million gallons, so a great deal of dilution there. For this reason, it was really approved through the CEQA process, the California Environmental Quality Act permitting process.
Siting facilities with power facilities like this, like desal and power coupled together as an operating unit, is an example of how you can overcome some of the environmental concerns.
Listen to the full interview below.