California Coastal Commission Rejects Desalination

A balanced appraisal of desalination would acknowledge its potential while also recognizing the absurdity of suggesting it is a panacea. On one hand, desalination can be an indispensable solution to water scarcity. In Israel, for example, five massive desalination plants on the shores of the Mediterranean Sea produce nearly a half million acre feet of fresh water per year, an amount the nation plans to double by 2030. Israel’s Sorek Desalination Plant, located a few miles south of Tel Aviv, produces 185,000 acre feet of fresh water per year, from a highly automated operation that occupies only about 25 acres. Up to 80 percent of Israel’s municipal water comes from desalination. Thanks to desalination, this nation of 9 million people has achieved water abundance and is exporting its surplus water to Jordan.

On the other hand, just as renewable energy provides only a small fraction of the global energy supply, desalination constitutes only a small fraction of global water supply. Altogether, not quite 20,000 desalination plants worldwide produce less than 50 million acre feet of water per year. That’s an awful lot of water, but it’s less than 1 percent of global water consumption. To make a dent in the estimated 7,500 million acre feet per year of worldwide water consumption, desalination capacity would have to increase by, say, 500 million acre feet per year. In turn, that achievement would require about 200 gigawatts of continuous power, equivalent to the continuous output of 100 Hoover Dams.

The Energy Cost of Desalination Is Not ProhibitiveThen again, the frequently heard assertion that there isn’t enough energy available to spare any more of it for desalination is not true. For starters, 200 gigawatt-years is only 5.98 quadrillion BTUs. (A gigawatt-year, equivalent to 8.7 terawatt-hours, is the amount of electricity a one-gigawatt power plant, operating continuously, would produce in one year. BTU, or British thermal unit, is a unit of heat energy; when economists estimate the energy consumption of states and nations, they commonly do so in terms of quadrillion BTUs.) Daunting-sounding numbers, but total global energy production in 2020 was estimated at 528 quadrillion BTUs (or 17,653 gigawatt-years, or 557 exajoules, which is currently the energy mega-unit of choice of the authoritative BP Statistical Review of Global Energy). Therefore, to desalinate 500 million acre feet of water per year would consume only 1.1 percent of current global energy production. While worldwide demand for energy often exceeds supply, using 1 percent of available energy to relieve water scarcity for hundreds of millions of people is a reasonable priority.

Taking all of this into account, it’s fair to say that desalination is clearly part of the solution to water scarcity. The potential for a perpetual input of water from desalination plants to tilt the demand-and-supply equilibrium from one of scarcity to one of abundance should not be underestimated. Israel’s experience is proof of that.

Here in California, “finding” the energy required to desalinate seawater is considered one of the prohibitive obstacles to wider adoption of the technology. But when the alternative to desalinating seawater is paying the energy cost of pumping it from the Sacramento Delta through nearly 300 miles of aqueducts, then lifting it over the Tehachapi Pass, the energy costs become less daunting. If we can use energy to transport water hundreds of miles, we can certainly afford to use the same amount of energy to desalinate an equivalent amount of water.

Using data provided to me by engineers working at the California Department of Water Resources as well as at several regional water agencies, I have been able to compare the amount of energy necessary to deliver water to Southern California’s coastal cities from three differing sources: upgraded local wastewater treatment to indirect potable standards, inter-basin transfer via the California Aqueduct, and desalination.

The data show that processing wastewater for indirect potable reuse is far more energy-efficient than the alternatives. These figures are based on the average, taking into account the power requirements of two treatment plants, Orange County’s Groundwater Replenishment System (GWRS), along with the wastewater-recycling plant that is proposed to be built in the City of Carson in the Los Angeles Basin. According to engineers at GWRS, the plant draws 13 megawatts to treat 103,000 acre feet per year. Information on the Carson plant’s design provided by engineers at the Metropolitan Water District of Southern California suggests an estimate of a 30-megawatt draw to treat 168,000 acre feet per year. Based on the average of these two figures, these plants would require 1,309 gigawatt-hours to produce 1 million acre feet of water. However, energy is not, as I discuss below, the sole issue to be considered in weighing which water sources to tap, and the choice, of course, does not have to be either/or. Increasing the range of sources, under current conditions, comes with its own merits.

By comparison, the figures for desalination are based on the Carlsbad desalination plant, which draws 23 megawatts to produce 55,000 acre feet of water per year — not including power to deliver the desalinated water. That equates to 3,529 gigawatt-hours to produce 1 million acre feet of desalinated seawater.

The energy required to move water through the California Aqueduct was calculated based on adding up the power consumption per unit of water lifted for each of the six pumping stations that start with the Banks pumping plant, just south of the Sacramento Delta, and terminate with the Edmonston pumping plant, at the base of the Tehachapi Mountains. This titanic transfer of water has an energy cost of 3,448 gigawatt-hours per million acre feet of water delivered — only slightly better than desalination.

Addressing Other Concerns about Desalination

Ultimately, the energy cost for desalination means it cannot easily compete with wastewater reuse, which requires less than half as much energy per unit of output. But the inexhaustible feedstock, the imperative to have diverse sources of water in the event of supply disruption, and the fact that at some point breakthrough technologies will dramatically lower the cost of energy all make desalination an option that ought to be part of California’s portfolio of water-supply projects.

While the energy cost is one major objection to desalination, there is also concern over how the intake pipes and brine-disposal pipes affect aquatic life. But these concerns, spoonfed by environmentalist organizations to activists and repeated endlessly and verbatim, are completely overblown.

For example, one by-product of the desalination process is boron, which is present in the ocean but can be harmful to human health. But the reverse-osmosis process reduces concentrations of boron down to less than one milligram per liter, which is well within regulatory requirements.

Opponents of desalination also claim it will contaminate groundwater basins. But the Orange County Water District (OCWD) puts 100 million gallons of treated wastewater into their groundwater basins every day using that very same treatment process — reverse osmosis — that the Huntington Beach desalination plant would have used. Desalinated ocean water is so clean that it can be delivered to consumers directly through the potable-water pipeline system. Even treated wastewater cannot yet meet those standards and still has to be injected into groundwater basins to add another layer of filtration and treatment.

As for the impact on marine life, California state regulations require desalination plants to incorporate the best available and most feasible seawater-intake and -discharge technologies to minimize the intake and mortality of all forms of marine life. For example, the proposed Huntington Beach desalination plant would have had screens to limit the intake velocity and a brine diffuser on the outfall. There would have been no “dead zone” from the discharge. At a distance of 80 feet from the point of discharge, salinity from the discharge would have been 35.5 parts per thousand, only two parts per thousand above ambient salinity.

Finally, to mitigate whatever negative impact the proposed desalination plant would have had on the marine environment around Huntington Beach, the contractor would have been required to preserve, restore, or create 112 acres of coastal habitat, including wetlands restoration, and create a 41-acre artificial reef off the nearby coast of Palos Verdes.

Despite all this, environmental activists claimed the Huntington Beach desalination plant would damage marine life up to 25 miles away. The press simply repeated this allegation without any attempt to understand its basis. But anyone with a rudimentary understanding of toxicology — the dose makes the poison — can easily grasp the absurdity of such a claim. The Southern California coast is blessed with the California Current, which ensures that desalination brine cannot concentrate in one area but will always be swept away. The California Current sweeps 250 quadrillion gallons per day (let’s just say that’s a lot) of ocean water past the West Coast. The Huntington Beach desalination plant is designed to produce 50 million gallons per day of fresh water. The corresponding quantity of daily brine, around 55 million gallons, represents roughly one five-millionth of the water moved by natural current along the coast each day.

To better understand the significance of this fact, consider the studies done on the impact of brine on the Mediterranean Sea, where the equivalent of ten Huntington Beach desalination plants now operate. Compared to the California coast, there is almost no current in the Eastern Mediterranean. And yet these marine environments are not seriously compromised, and adjustments are being made continuously to ensure it stays that way. In fact, most studies concluded that there was more disruption to the marine environment from the movement of water caused by release of the brine under pressure than by the chemistry of the brine itself. Those studies can be referenced here, here, and here.

If Californians are serious about solving the water crisis and achieving a diversity of water sources as a hedge against disaster, they must pursue desalination. Build more plants, and build them right. It might never contribute more than a small fraction of California’s total water supply, but it will be a perennial source of water, serving the arid and densely packed coastal cities in Southern California where water is imported from other regions at great cost.

In the meantime, with or without California’s involvement in desalination, the nations of the world are adopting this technology. As the Coastal Commission prevents construction of new desalination plants in California, the state loses yet another way it might overcome water scarcity. But perhaps worse, California — the most environmentally attentive, and technologically innovative, place on earth — loses the opportunity to set an example of best practices to the world.

This article originally appeared in the National Review.