PEAK WATER: What I'm Doing About It

by Glen Hendrix


Everyone has heard of peak oil. Lester R. Brown, founder of the venerable environmental think tank Earth Policy Institute wrote in 2013 that peak oil literature was extensive, but it is peak water that is "the real threat to our future". Economist and ex-Bank of England Monetary Policy Committee member Willem Buiter said "Water will eventually become the single most important physical commodity-based asset class, dwarfing oil, copper, agricultural commodities, and precious metals".

There are three types of peak water; peak renewable water, peak non-renewable water, and peak ecological water.

Peak renewable water is like a river. In some cases, entire rivers disappear before they reach the ocean because of human consumption. Growth along that river is stymied because there is no more water. This is the case now with many rivers here in the U.S. and around the world.

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Peak non-renewable water is like an aquifer. Aquifers can recharge, but the timeline is such that for humankind and its insatiable thirst, they may as well be finite. About 40% of aquifers around the world are being used quicker than they replenish themselves.

Peak ecological water is where usage has begun to effect the environment to the point where that damage is greater than the economic benefit of using the water. This can result in species being lost and the natural ability of wetlands to purify water disabled. 

All three of these peak water definitions are applicable to many areas of the U.S. and the world and will continue to increase in magnitude as population growth climbs. Throw a monkey wrench like climate change into the mix, and the results may very well be catastrophic. Flood events like Harvey take our minds off of the real possibilities of drought. California is still in a drought condition. Texas lakes had taken a precipitous dip before recent rains filled them up again. It should be noted, however, that scientists believe there was a drought covering a large portion of the Southwest United States several hundred years ago during which it basically did not rain for 10 years. That got me to thinking that we, as stewards of the Earth and captains of our destiny, should be on a more proactive arc to mediate or prevent the upcoming catastrophe that would occur if there was not enough water to drink or grow crops. It has been suggested that the next wave of global conflict might very well be precipitated by the lack of precipitation, and it may occur within the next 50 years.

Drought.

Imagine a machine that works with the Sun, the wind, and cold ocean brine to provide clean, fresh water. Water so pure you have to add a little sodium bicarbonate to give it taste. This machine, once built, provides the electricity it needs to run itself and excess power is pumped back into the grid.

We call it the Sun, wind, cold ocean water; but it is all really just the Sun. It's uneven heating of the Earth's surface causes the wind. Even the energy transferred to the air from our spinning planet is traceable back to our primordial sun disk's swirl of transferred kinetic energy in the formation of the planets. The cold water that hides in the ocean's depths provides a vast heat sink, like a dark negative energy. Again, useful only because the Sun has heated the surface of the water and the air to provide that useful temperature difference.

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This machine allows the Sun to do most of the work. The Sun evaporates the seawater to create humidity. The Sun moves this humidity to the machine with the wind it creates. The machine takes this wind and turns a wind turbine, providing power. The machine uses this power to pump that cold water from the ocean depths into a heat exchanger. With that cold ocean water on one side of the heat exchanger and warm, humidity laden wind on the other side, a condensate forms. This condensate is pure water, even purer than rain.

Making the test coils.

Nesting the coils.

Testing of the first small prototype has begun. It consists of two nested helical 1/4" diameter copper coils inside an aluminum cylinder. The whole coil assembly is about 8 inches in diameter and 30 inches long. A fan at one end blows air at 4 mph through the coil. The cold water reservoir representing the depths of the ocean is an old Omaha Steaks styrofoam shipping container lined with a garbage bag. A submersible pump shoves a gallon of cold water through the coil every 5 1/2 minutes. The first tests were run during the first two weeks of August this year. Some of the results are in.

Leak testing the completed coil.

The styrofoam container was filled partially with water and partially with ice, giving an ice slurry that started out cold, melted, and got warm pretty quick. So the water production runs were done in batches from 1 to 2 hours long with air temp, water temp, and humidity averaged over that time period. An old Evian bottle was carefully measured and marked into a graduated cylinder to catch the output.

Fabricating the coil casing stiffeners - cardboard with taped edges, painted white, then coated with plastic to make them waterproof.

Fan installed on one end of coil can.

Open end of coil and can assembly with the inlet and outlet of the coil.

From these production runs come some averages. The average air temperature was 87 degrees F. Average water temperature was 47 degrees F. Average gallons per houre per square foot of coil was .01911 gallons.

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This machine works best in tropical and subtropical climates. This is because the disparity between the cold ocean water and the surface water/ air is greater. The greater this difference, the more potential energy there is to be exploited. Let's imagine one such machine bolted to the side of an oil production rig in the Gulf of Mexico off the coast of Texas. Let's turn on the pumps and see how it does. The average temperature (year round) is 72 degrees F. and the average humidity is 60%. Let's make it simple and conform the results of the experiment to these averages in a linear fashion through ratios.

Test coil and cold water reservoir connected by tubing.

The experimental production saw an average 87 degrees F. air temperature and the Gulf average is 72 degrees F. Since air holds more water at a higher temperature we will adjust the result downward with a factor of 72/87 = .83. The humidity in the experiment was 66% and the Gulf average is 60%. The adjustment factor will be 60/66 = .91. Cold ocean water should be about 38 degrees F. Since the colder the better, the adjustment factor will be 47/38 = 1.24. The big difference is the air flow. At average 18 mph, there will be much more air flow over the coil than at 4 mph in the experiment. That would give an adjustment factor of 18/4 = 4.5.

Another shot of the test equipment set up and running.

This assumes that air flow can be transmitted through the coil as was done in the experiment, and that the coil can process 4.5 times the humidity out of the air as easily at 18 mph as at 4 mph. I have done some airflow experiments using long radius ducting and a conical scoop. Preliminary results suggest horizontal wind velocity can be diverted 90 degrees without being diminished. More experimentation will have to be done but let's see what happens if we apply these adjustment factors to our experimental output: .01911 gallons/hour/foot squared x .83 x .91 x 1.24 x 4.5 = .081 gallons/hour/foot squared.

Long radius elbow attached to conical scoop with less than 60 degree apex angle.

Scoop and elbow assembly taped to the open rear window of my car. Drove around comparing speedometer with anemometer.

I have designed a prototype heat exchanger for the production of water that is 5 feet in diameter and 20 feet long. That is not a very big heat exchanger. It has 5,850 square feet of condensation surface. On average that 5 feet diameter, 20 feet long device could produce 474 gallons per hour, 11,376 gallons per day, and 4,152,000 gallons per year. If that water was bottled and sold in the grocery store competing with the lowest priced spring water (about 88 cents per gallon), it would retail for about 3.65 million dollars.

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Let's say I have accumulated mistakes so that I am off by a factor of three. Take the four million divided by three so now we have 1.217 million. The heat exchanger and attendant equipment would run an estimated quarter million and last at least for several years, so the gross would still be nearly a million dollars a year. Although one of these machines would be like owning your own spring, I am not really interested in going into the bottled water business. It's just a way to point out the financial viability to people that might be thinking of investing. I'm thinking big units and enough of them to supply agriculture and cities with the water they need for the future.

That's just the water. This machine can produce power as well. Theoretically, a lot of power. This portion of the machines's abilities are going to require testing similar to the tests for water production. At this time I cannot make any claims about the power production. But if it only produced enough power to maintain the cold water pumps, it would still be a breakthrough in cheap water production.

In addition to the water and power, there is chilled air as a byproduct which can be used as air conditioning or as a cooling source for refrigerated warehouses storing food. But wait, there's more. The cool seawater that comes from the outlet of the heat exchanger is loaded with nutrients for sea life that can be used for the farming of fish and shellfish.

This device could obviously be used on offshore platforms as a water source, saving the transportation cost of bringing it from shore or distilling seawater. The Seasteading Institute is proposing floating nations at sea. It would certainly come in handy for those. Any tropical or subtropical climate will be ideal. That includes about forty percent of the Earth. Maybe there won't be wars fought over water in the next 50 years after all. 

UPDATE: Test results have been combined with design work on the first working prototype. The cost of water from this machine built at the same scale as typical desalination plants will come in around $0.14 per cubic meter. The desalination plant water costs about $1.00 per cubic meter of water.