Water, Water everywhere…

Yes, I did quote that poem by that guy…(The Albatross, Samuel Taylor Coleridge)…scientists are literate, too!

I had someone at a Film Athens event ask me why we don’t use salt water since we’re running out of fresh water.  I told him…I didn’t know!  (I was there telling people about The Ripple Effect Film Project.)

So I did some research, and no, I haven’t come up with an answer: I doubt I will, it would be a little presumptuous for me to answer on behalf of all water experts.

But I will explain some about saline water and its uses.

Saline water is defined as anything that has a significant amount of dissolved sodium chloride (regular salt) in it.  Usually it’s measured with something called parts per million (ppm), which is a unit used for solutions with very small percentages.

Okay, so it’s hard to explain, but basically, 1 ppm salinity would mean that 1 part for every million parts (of water molecules) was a dissolved salt molecule.

Now, 1ppm isn’t often found.  Saline water is defined by the United States Geological Survey as anything from 1,000ppm to 35,000ppm (ocean water).  Fresh water, on the other hand, is usually considered anything that has less than 0.5 ppt (parts per thousand)!  So much less salt than even the slightly salty saline water!

Fresh water is what’s in our rivers, saline water is pretty much everywhere else (except the ice caps, those are also fresh).  Fresh water is what we drink…fresh water is also what we don’t have a lot of.  Saline water is used by the thermoelectric power industry to cool the equipment, and sometimes it is used in mining and other industrial functions.

However, we do not drink it.  We can’t just pick up a bottle of salt water and drink it, it’s not clean, salt water doesn’t work in our bodies the same way fresh water does…it’s weird.  Anyway.  The question is: what about desalination?  What about making our salty water into fresh water?

The answer is, yes, it can be done.  Desalination is a pretty straightforward distilling process, in fact it was used on ships long ago to convert sea water into drinking water.  There are plants around the world that convert saline, but it uses a lot of energy.  It’s hard to find the line between when too much fuel (renewable…or not…) is being used on a process that could be less important if we all conserved our freshwater a little more!  The simplicity of the process does not remove the fact that it takes a lot of heat–which comes from somewhere–to complete, which could be more of a waste of energy than it’s worth. Not to mention the cost of transporting water from the ocean to the plants, and from the plants to the cities in need.

Bottom line?  Again, think at the sink.  Maybe we could build more desalination plants.  Maybe we could use the ocean water as drinking water after our rivers dry up.  Maybe we could…maybe we shouldn’t.  Maybe it’s a smarter choice to conserve water now, to be practical with our use now, so as to extend the ability to use our ready-made fresh water.

Maybe it’s better to keep thinking at the sink…for innovations for the future…and for conservation of our water now.

Annaliese Ashley-Intern

Originally posted on waterconservationstation.blogspot.com, 10/2/12


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