Residents of the humid and hurricane-prone US Gulf Coast region may not see water as anything but either a recreational resource or a nuisance. And writing a check for the water bill every month is about as involved as most of us here get in the politics of water. But as anyone who has ever lived or spent time in the more arid parts of the world knows, it’s a serious subject, as the fires currently raging in California remind us.

The problem, of course, is supposed to be scarcity. But wait — off California’s coast is the world’s largest ocean. Commercial water volumes are often measured in acre/feet. Adjacent to the state is far more than enough water to submerge California under an acre/mile of water.

It’s been said that water is the new oil. The similarity is uncanny. Demand is growing, supplies are constrained, costs are rising and politics plays a central part. But there is also a big difference. Unlike oil, a single factor stands between water’s scarcity and its surreal abundance — salt. Desalination technology is the X factor in the politics and economics of water, and just as rising oil prices create competition from alternative energy forms, rising water costs will make the costs of desalinated water competitive.

Commercial-scale desalination is accomplished by either distillation or reverse osmosis (RO), two mature technologies. One advantage of distillation plants is that there is a greater potential for economies of scale. Distillation plants also do not shut down a portion of their operations for cleaning or replacement of equipment as often as RO plants, although distillation plants have shut down for tube bundle replacement and cleaning. Pretreatment requirements are greater for RO plants because coagulants are needed to settle out particles before water passes through the membranes. Unlike RO plants, distillation plants do not generate waste from backwash of pretreatment filters.

Advantages of RO plants over distillation include: RO plant feedwater generally does not require heating, so the thermal impacts of discharges are lower; RO plants have fewer problems with corrosion; RO plants usually have lower energy requirements; RO plants tend to have higher recovery rates – about 45% for seawater; the RO process can remove unwanted contaminants, such as trihalomethane-precursors, pesticides and bacteria; and RO plants take up less surface area than distillation plants for the same amount of water production.

According to the US Geological Survey, it can cost more than US $1,000 per acre/ft to desalinate seawater as compared to about $200 per acre/ft for water from normal supply sources. But even though no game-changing technological breakthroughs loom, incremental advances are driving the cost down. The USGS says Tampa Bay, Florida is desalinating water at a cost of only $650 per acre/ft.

The planet’s ultimate renewable resource — none of it ever gets consumed — would seem to be a perfect match for a tidal or other ocean-based renewable energy source. Maybe the combination could create something like a perpetual-motion water source.

Life teems in the desert, as any viewer of television nature documentaries will confirm. But it is the kind of life that has adapted to the lack of abundant water. How much are we willing to pay to make the desert not the desert in order to live there securely?

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