Geology Home Page physical geology historical geology planetary gems
Roger Weller, geology instructor
by Bruce McKellar
Our inevitable thirst for salty water
Photo Credit: www.pimagazine-asia.com/wp-content/uploads/2013/04/desalination.jpg
“When the well runs dry, we know the worth of water.” – Benjamin Franklin
Water is and has
been an important part of human life and is perhaps humanity’s most vital
natural resource. Water is necessary to the physiological function of our
bodies, as our bodies are made up of approximately 53% water. Water is the
basis of economy, trade, industrial manufacturing, and an important natural
element in everyday life.
Photo Credit: www.environment.ucla.edu/media/images/water-fig1.jpg
Furthermore, geologically, water
has served as an important natural force that has shaped and formed our planet -
and continues to do so today. Water erosion and glacial movement has led to the
formation of rivers, streams, and lakes that has produced an above ground and
below ground supply of water for the needs of humans for millennia. Yet, as we
grow as a population, so does our dependence on fresh water. Because we have
become increasingly dependent on fresh water for needs beyond ourselves
(industrial manufacturing of goods and agricultural needs), the availability and
supply of fresh water has been diminishing in quantity, quality, and
Photo Credit: http://ga.water.usgs.gov/edu/graphics/watercyclesummary.jpg
One viable solution to fresh
water supply is desalination, or the purification and removal of salt from ocean
The concept of
desalination has been around for many centuries; it has been found in ancient
Egyptian Sanskrit, and has a history here in the United States. The first
desalination units were developed for and used in steam ship vessels. The idea
of desalination originated as a way to free up space in the cargo holds of ships
carrying freshwater to use in the ship’s steam engine boiler. Because of the
abundant supply of salt water surrounding the ship, desalination made sense on a
small scale, as it could supply an infinite amount of freshwater needed for
propulsion and on vessel consumption and hygiene needs by stewards.
Anatomically, fresh water is important because our body needs it to function properly. Freshwater is vital to the human race and necessary for the longevity of our population.
On the planet, we have an abundance of water; about 70% (326 million, trillion gallons) of the world is composed of water, but most of it is in the form of salty seawater. Less than 3% of the world’s water is actually freshwater and about two thirds of that 3% is contained in glaciers and ice; what remains is about one percent water for the seven billion plus inhabitants on the planet.
Moreover, with the population
increasing at such a rate, the need for life sustaining freshwater is crucial.
Furthermore, the concern is not just an increasing population, but rather, the
current populations that have access to sanitary freshwater. The World Health
Organization (WHO) estimates that one in five people on the planet do not have
access to clean, sanitary water.
Photo Credit: water.org
However, many of these
individuals are fortunate to live within close proximity to a body of water such
as an ocean or salt bearing lake: thus, desalination is a feasible option for
In 1961, President John F.
Kennedy proposed a hope for a way to get fresh water from salt water (by
utilizing desalination) that would “dwarf any other scientific accomplishment.”
We have moved closer to that goal, and today, there are more than 15,000
desalination plants in operation around the world producing more than 16 billion
gallons a day: but, this provides for less than 1% of the total world
consumption of fresh water.
Photo Credit: http://ngm.nationalgeographic.com/img/big-idea/desalination-main.jpg
In desalination, there are five
ways to remove salt from water to create freshwater. However, there are two
methods that are used the most and provide nearly 90% of freshwater from
saltwater. These two methods are reverse osmosis and multistage flash.
Multistage flash is similar to what was used in the steamships and resembles
the distillation process of spirits and liquor. Multistage flash desalination
requires an immense amount of heat as well as an elaborate, large, space
consuming, set up. Therefore, reverse osmosis (RO) is the prevalent method used
today. Its benefits are the availability of materials in the manufacturing of
RO components and RO’s cost effectiveness over other methods of desalination.
Osmosis Plant –
There are a few
drawbacks to desalination. One is is the accumulation of the salt left over
from the processing and purification processes and the other is cost.
Currently, when a desalinization plant is near a body of water, the leftover
salt is mixed into a briny mix of water and pumped back into the original body
of water with the hope it will become diluted to a similar concentration close
to the original solution. However, if the brine is not mixed thoroughly enough
with the original supply, it can potentially increase the total dissolved solids
of the water. This “wastewater” is denser than the surrounding water, which
in-turn settles atop organic matter on the ocean floor and depletes the oxygen
levels – thus creating a potential of an imbalance in the ecosystem.
Salt Heat Insulation Tile
Photo Credit: www.alibaba.com
One possible use for the
remaining salt is to use it to make building materials such as insulation tiles
or wallboard. In addition, new research is being developed on a saltwater fuel
for automobiles. As with all things in the natural world, moderation is
necessary. Water should only be taken and processed at a rate at which it can
be recharged or replenished.
There are other options that we
do have. Drilling for water; however this can be costly, and we can never know,
with certainty, about the quality, longevity or the quantity of water that the
well will produce.
Manufacturing water out of hydrogen and oxygen atoms is a costly and dangerous process. Furthermore, it cannot be created from these elements alone, but rather resourced from the water that is available on the planet.
Another option is the
possibility of harvesting, or mining water from outer space. However, at this
time, this is also cost prohibitive and logistically difficult.
This leaves desalination as the most likely source of future water collection.
Photo Credit: http://www.philipmetzger.com/blog/wp-content/uploads/2013/05/neo_eva.jpg
There are other methods to produce freshwater such as cloud seeding. This process is inconsistent and sometimes produces undesirable results. It is worth mentioning a historical event of cloud seeding by the British in the 1950s. As a response to curb invasion during World War II, the British flew planes into the clouds and seeded the clouds with dry ice, salt, and silver oxide to induce rain. The result was more than anticipated; the mission worked too well and resulted in a disastrous flood in the town of Lynmouth, England, uprooting trees and producing 250 times the normal amount of rainfall. This is proof that humankind cannot duplicate the natural geologic process with the same certainty and replication.
Photo Credit: http://savethewater.org/wp-content/uploads/2012/08/Rain-Cloud-Seed.jpg
Other possible foreseeable
benefits of desalinization would be its usefulness with agriculture production
and genetically modified foods or GMOs. Having an ample supply of water for
irrigation and agriculture processing would lessen the need to create GMOs to
utilize less water while growing. Also, as population does increase, other
issues will arise such as an increase in pollution, increased dam construction
for fresh water reservoirs, and the threat of drought to wetland wildlife areas
due to underground water pumping.
Currently, technology and research on desalinization and plant production is on the threshold of an expansive growth period. This means that as groundwater drilling becomes increasingly more expensive due to dwindling groundwater supplies, environmental restrictions and legislation, the construction of desalinization plants will become more prevalent.
Photo Credit: http://www.abc.net.au/reslib/200907/r408688_1929336.jpg.
In addition to the construction
of freshwater production plants, pipeline capacity and infrastructure to get
fresh water to the population of people will also occur. As population
increases, the cost of desalinization will decrease. Desalinization costs today
are less than half of what they were just ten years ago. Adding to the
conundrum is the fact that wastewater production will increase as population
increases; thus, the reclamation and purification costs of wastewater will
invariably decrease. Therefore, initially, wastewater purification will prevail
as a choice of fresh water - until this resource becomes diminished and energy
Photo Credit: www.studentreporter.org/wp-content/uploads/2012/04/
Ultimately, the deciding factor in the prevalence of desalination is a reliable and dependable source of energy. Considering the abundance of saltwater available on the planet; if we, as a population, are able to find an inexpensive source of energy, and can combine saltwater with new, cheaper water purification technologies, then we can all enjoy a long-term solution to the current freshwater shortage crisis.