Good news!
In these times of high unemployment, and drought which
negatively affects our food supply, I have been promoting a major project of
land irrigation. At this stage of our understanding of climate and weather,
there is no possibility for us to affect either of these in a positive effort to
avoid drought conditions. However, we can use the traditional approach of land
irrigation to reduce our dependency on weather. The Romans did this many
centuries ago in the construction of aqueducts in most of the civilized portions
of Europe and the eastern portion of the Middle East.
I have had two
suggestions for water sources. The first was the Great Lakes, which involves
natural water already acceptable for irrigation. The second was sea water, which
requires treatment for removal of salt (desalination).
The good news is
that an associate has referred me to an excellent historical account of
desalination projects. http://www.edwardsaquifer.net/desalination.html.
The reference paper is entitled, "The Edwards Aquifer
Website" by Gregg Eckhardt. It covers only the technology of water desalination
by use of membranes and a historical account of various studies and
semi-commercial projects from the year 2000 to 2009.
The paper has
several points of significance. It describes that in the membrane desalination
process a side stream of higher salt content water is produced in addition to
the desalinated water. However, this is not unusual with respect to any of the
separation processes, including distillation and freezing. A question is whether
this waste stream is usable or should be discarded back into the source.
Industry now uses salt solutions for production of large volumes of sodium
hydroxide and sodium hypochlorite. The desalination waste stream may possibly be
used for that. Alternatively, return to the source is also practical. In the
process used by Dow for recovery of bromine from seawater, the waste stream was
returned to the source.
More important is the historical account of various
desalination projects reviewed in the paper. Many of these projects involved
desalinating brackish water from wells. A few involved studies and pilot plants
of seawater desalination. While brackish water typically has only 1/10 the salt
content of seawater, the quantity from wells is limited.
All of the
recounted projects were in Texas and all concentrated on supply of drinking
water, which we interpret as city water. The cities of Brownsville and San
Antonio had projects involving desalination of brackish water. The only use of
seawater, was a study by the Texas Water Development Board. It was concluded
that desalinating seawater from Matagorda Bay (between Galveston and Corpus
Christi) and bringing it to San Antonio for a 50-50 mix with available
freshwater would double the water cost. But, it is obvious that at some future
time fresh water supplies will be insufficient.
In 2002 Texas Governor
Rick Perry said "Though it may be many years, if not decades, before ocean water
is a prime source of water for Texas to use, we must begin the groundwork today
so that future Texans have an abundant, drought-proof supply of water." But, the
San Antonio Water System president said, "That’s finance science fiction today.
Ocean water desalination is extraordinarily expensive – more than 10 times the
cost of Aquifer water". However, aquifer water is not inexhaustible and much
Lubbock cotton production is dependent on it.
All of the above is
favorable, because it indicates serious consideration is being given to
desalination, at least in a limited capacity. However, my point is that we must
at some time bring it to practical reality for land irrigation. I foresee
several nuclear power plants in high mountain areas pumping sea water from
either the Gulf of Mexico or the Pacific, desalinating it at the high elevation
and allowing it to flow as land irrigation water to the High Plains. Nuclear
power plants require very small quantities of fuel, which allows their location
in remote areas away from civilization, such as mountains.
However we
should not ignore the possibly more favorable economics of supplying Great Lakes
water. The same aspects of creating jobs through pipe and earthmoving machinery
manufacture would exist and is a primary consideration. There would be ancillary
jobs, such as engineering, machinery operation for construction, etc., of the
same nature as that which has previously been used in building major
dams.
If we cannot yet think major desalination of seawater for land
irrigation of the Southwest, can we at least start smaller, such as move Great
Lakes water to surrounding states and perhaps over to Iowa?
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From Dave:
ReplyDeleteAt this point I’m thinking we should focus on seawater, for our water source, as that approach will be sustainable and even possibly environmentally favorable if sea level is indeed rising (it could have a miniscule positive impact on sea level). Using great lakes water would cause the water level in the lakes to drop, as they are much smaller sources and supplied by rainwater. Let’s build an infrastructure that we can use for more than just a few years.
Also, I’m leaning toward processing the seawater at point of intake, because it would be easier to deal with the effluent at that point. Nuclear power would be cost-effective, but faces significant political and emotional (and some practical) resistance. Water motion (wave/tide) or wind power for the power source to do the purification and pumping would probably be worth figuring out how to do, as it would be sustainable and probably have less long-term environmental impact.