Way, way back. Back when we seemed to care about our infrastructure, we promised that we would have swimmable and drinkable water all over this country. A good portion of that promise relied on waste water reuse and desalination plants.

Now, Florida and California are using them. As a matter of fact, the biggest desalination plant should be on line soon (later this year)- under the direction of Poseidon Resources (Stamford, CT) in the city of Carlsbad (CA). And, the constructions cost is approaching $ 1 billion. Certainly not chicken feed. This project also assumes that it won’t deplete our energy stores as it restores our depleted water supplies.

I’ve already described the situation in the San Joaquin Valley last year. A solar array is producing power to run the reverse osmosis membranes that purify water. The cost for the produced water is about $ 1.20 per thousand gallons. (Remember that water prefers to cross a membrane from where it is more pure to where it is less pure, trying to equalize the concentration of water on both sides of the membrane. Reverse osmosis (RO) uses energy to make the water from the less pure side traverse the membrane and create more pure water, in other words, we are “squeezing” water from its mixture with impurities through the membrane which only lets pure water cross.)

The problem (water shortage)  also is exacerbated because of the way farming has changed. Nowadays, 80% of the world’s almonds is derived from California (San Joaquin and Central Valley regions), which brings in $ 11 billion in trade. And, this farming is not only water intensive- but labor intensive. While one person with a tractor could clear 100 acres of alfalfa, it takes 1 man-day to clear ½ to 1 acre of almonds.

We need to use high pressures to ‘reverse’ the course of osmosis. And, using sea water as a feedstock for RO is the most expensive feedstock choice of all. The general cost (depending upon how much one spends to generate electricity) ranges from $1K to 2.5K per acre foot of produced water. But with 80% of the State of California manifesting years of extreme drought, this process is no longer a luxury item, but a necessity.

And, the almond cultivation within the state is increasing. In 2000, about 5% of the Westlands District was covered with almonds- now it’s 15%. And, as opposed to alfalfa and other crops, where not having sufficient water for a year is bad but not devastating; almond groves need water all the time. And, couple that with the fact that these (wealthy) farmers are big political donors, so the politicians have been insuring that almond groves are getting more than their fair share of the water- to the exclusion of the salmon in the Sacramento River and the local citizenry,

Which is another reason why San Diego will be the big customer of this new Carlsbad RO plant, buying half the plant’s output- or about 48000 acre feet a year… at a cost of $ 2K per acre-foot. (That’s 48 MGD [or 7% of  San Diego water’s requirements] for those of you who don’t talk acre-feet at a cost of about $6 per thousand gallons- which is 3X what we, as consumers, pay in Alexandria, VA for water- and twice what it costs San Diego now from the Metropolitan Water District [LA] now. And, as stated above about 5X the cost for water from the San Joaquin Water project described above.)

It looks like we need to have some serious research (there has not been much progress- or research- in 30 years) to improve the RO process. Let’s hope graphene membranes can do the trick and lower the costs dramatically.

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