Monday, November 26, 2007

Desalination Is A Damn Poor Answer

People who live in drought afflicted areas always point to desalination as the answer to all their problems.

Desalination may solve their problems but only by creating additional problems elsewhere. We don't have a lot of experience with desalination plants in Canada because we usually have enough rain and groundwater. Parts of the US, however, aren't so blessed. Now, with large tracts of the American south facing drought and water depletion, the clamour for desalination is getting louder and more strident.

Desalination - the production of freshwater by removing salts and other ingredients in sea water - sounds like the perfect solution. It's not. Desalination plants create enormous environmental problems. They're expensive to build and expensive to run. They use an awful lot of energy, typically fossil fuel, and generate a lot of greenhouse gases. The pipes tend to leak and saltwater causes immense problems once it gets into groundwater supplies (remember how the Romans took revenge on Carthage?)). The worst part, however, is the brine effluent that's left over.

The standard approach is to simply pump the brine, along with all the other chemical residue from the desalination process, right back into the coastal sea. There it plays utter havoc with the marine environment ranging from turbidity, salinity imbalances, destruction of fish habitats and stocks and algae blooms.

In North America, our coastal waters already face enough challenges. We don't need to add the consequences of desalination to the mix.


JimBobby said...

Whooee! Good points, Mound. I reckon we like to think technology will solve any problem we might have.

Just spiballin' here but what about capturing the sea salt and using it. Here in Ontariariario, we got a bigass salt mine up near Goderich. The operation, no doubt, uses considerable fossil fueled energy to dig and refine the salt. Could that be offset by captured salt from desalination?

Here in Norfolk County, they been experimentin' with saltin' the winter roads with a liquid brine solution. Is there an opportunity to use desalination byproduct for road maintenance?

Concentrated solar energy (using parabolic mirrors) can boil massive amounts of water. Geothermal reserves in California are already being used to power steam turbines and generate electricity. Offshore wind and or tidal power is also readily available at the same loaction as the salt water. Perhaps, a holistic, renewable approach to designing and operating desalination plants could utilize something other than fossil fuels. The desalination proccess you've described uses 19th century technology. I'll bet we can do a lot better.

As with other types of overconsumption by humans, a big step could be taken wrt conservation. I read recently that an Atlanta area sports stadium had enacted a "don't flush urine" policy in its public washrooms. Other places can be found where water can be conserved.

What about Coca-Cola. Coke's main headquarters is in Atlanta. Coke is 95%+ water. How much of Atlanta's water shortage could be alleviated by moving production out of the drought stricken region?


JimBobby said...
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The Mound of Sound said...

I don't know if evaporating the brine and selling the sale would be feasible. The best markets - cold, snowy winters/heavy populations - would be a long distance from either coast. Salt is cheap but it's heavy in solid form. Heavy means expensive to transport, more fossil fuels. Then there is the issue of the rest of the contaminants in the brine, including the chemicals from the desalination process itself. All of it eventually leaches into your groundwater system and you would have to be careful to first ensure you would want to drink it or use it in watering your crops.

The Mound of Sound said...

Sorry, JB, I forgot your other points. I agree about the benefits of geothermal power. Here on the coast with all the seismic activity we ought to be able to somehow harness some energy from that source. As for bottled water products in drought areas, look at it this way. Rising transportation costs will offset bulk water costs any day. Even in a relatively dry market I'll bet commercial bottlers will always be able to get an ample supply of water.
It requires a lot of sacrifice but we can live without oil. We can actually live reasonably well with just a fraction of the oil we now consume.

When it comes to water, though, that's another matter.
We can stop filling swimming pools and use the California toilet etiquette: "If it's brown, it goes down; if it's yellow, let it mellow." We can stop watering lawns and shut down the golf courses and let our cars go dirty. We can employ more efficient means of irrigation.

There's so much we can do but, then again, only so much. Long before most of us would die of thirst we'd decide we didn't want to live in a permanent, conservation extreme regime. We not only need water to live but we truly enjoy what we can do, how we can live with an abundant supply of it.

Water conservation is definitely worthwhile but it probably won't be enough in areas of true megadrought, should that come to pass. Don't forget that the crisis in surface water comes at the same time as we're realizing we've over-exploited the aquifers. We built communities, even cities, and vast agricultural areas by wilfully exceeding the sustainable "recharge" rates, even in the wet years.

It will be interesting to see how the Americans respond to this drought as it worsens. Will they treat water as a commodity, money talks, or as a necessity, a common resource?

JimBobby said...

It will be interesting to see how the Americans respond to this drought as it worsens.

You bet!! I reckon we'll see some of Naomi Klein's Shock Doctrine in action.

Americans suffered a catastrophic drought in the 30's. Millions of people left the dustbowl states and moved either to California or to the industrialized north. Eventually, California put roadblocks at the state line and turned back many of the dustbowl refugees. Woody Guthrie wrote a coupla hunnert songs about it.

That ecological disaster coincided with the Great Depression. We're seeing some badass signs in the US economy right now. GWB spent it to death over there in EyeRack. There might be some good techno-fixes and high-tech adaptations we could make but all the R&D money went into weapons.

Keep to the high ground, Mound.