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| Courtesy Wikipedia |
There does not seem to be the urgency about upcoming water shortages that the situation warrants. The evidence for a foreboding future, though, are all around us. Just look at Cape Town, Africa. Their draconian emergency measures include restricting toilet flushing to once a day unless using grey water or rain water. Municipal drinking water cannot be used for kiddie play pools, water fountains, any outdoor water feature, hosing down paved surfaces, or car washing. In March of 2018, the Climate Reality Project published an articles examining how Los Angeles, Salt Lake City, and Miami may not be far behind Cape Town on water problems. In India, the demand for water by 2030 will be twice the available supply. It will affect 600 million people.
The major constriction for producing food for a burgeoning population is water - not land. According to the International Food Policy Research Institute, nearly 5 billion people, about half of global grain production, and 45% of the GPD ($63 trillion dollars) will be at risk due to lack of water with current consumption practices. Eighteen countries; including the big-three grain producers China, India, and the U.S.; are now over-pumping their aquifers. For 20 years Saudi Arabia was self-sufficient in growing wheat. They have nearly exhausted their aquifer and will soon quit growing wheat. Recent droughts in California and Texas seem bad but there is evidence that a major portion of the Southwest U.S. underwent a 10-year drought with hardly a drop of rain several hundred years ago. That was before climate change. An inexpensive, alternative water source is needed. There is a way. This is how it will work.
Paper bags take 5 X the water to make and 7 X the fuel to transport than plastic bags
There is a lot of talk about the oceans warming up. They are mainly referring to the top layer, the Epipelagic or Sunlight Zone, of the oceans, which is warming at a rate of about 0.2 degrees Fahrenheit every decade since the 1800s. If you go down about 2,500 feet, though, where sunlight never reaches, the temperature drops to about 46 degrees Fahrenheit. It gets colder as you go deeper until it is between 32 and 37 degrees Fahrenheit. Ninety percent of the ocean is 46 degrees Fahrenheit or colder.
This means there is a large thermal gradient for about forty percent of the world between this cold ocean water and the Sunlight Zone and tropospheric, or lower, layer of the atmosphere. This thermal gradient can be exploited for the production of huge amounts of water.
New desalination plants require a lot of pressure to force ocean water through reverse osmosis filters. Old style plants heated up the water to vaporize it, then condense it. These processes use a lot of power, an ongoing overhead cost. The filters themselves are also expensive. With both processes you wind up dumping much saltier water back into the ocean. The other type of water extractor creates, through standard refrigeration technology, a cold surface for humidity in the air to condense upon. Think how much it costs to run an air conditioner in the summer in a hot climate. The same problem exists with these types of water production units.
It costs $4000 to recycle ton of plastic bags worth $500 on open market.
What we need to do is work with nature to produce water. Take the cold ocean water, run it through a heat exchanger at the surface of the ocean while at the same time forcing warm, humid air through that heat exchanger with fans. The humidity in the air condenses out on the cold surface of the coils containing seawater. You see this principle every time you go to a restaurant and order a cold beverage in a glass. Beads of water form on the glass and run down the sides. This is the simplicity of the process we are talking about.
The electricity used is for simple water pumps and air fans, not compressors having to produce hundreds of pounds of pressure. Comparatively cheap initial cost and every-day energy consumption. They could be matched to solar panel / lithium ion battery combos that would keep them running night and day. These water production units can be scaled from tiny to gargantuan.
The electricity used is for simple water pumps and air fans, not compressors having to produce hundreds of pounds of pressure. Comparatively cheap initial cost and every-day energy consumption. They could be matched to solar panel / lithium ion battery combos that would keep them running night and day. These water production units can be scaled from tiny to gargantuan.
So where are these things going to be located? Anywhere along the coast about 40 degrees above and below the equator. There is an alternative that will be common in the future. These units will be designed to coexist with offshore wind farms. It is a simple thing to integrate these devices into the support towers for windmills. Along with the cables collecting electricity will be the pipes collecting water.
Wind farms are currently located near shore, anchored in 200 feet depth or shallower. With the advent of floating windmills (first ones installed off Norway), this depth can be increased to 2,600 feet with direct access to cold ocean water. If energy developers are smart they will pick up on this opportunity and incorporate the water production units from the beginning.
Plastic bags are made from ethane, a part of natural gas burned as waste before they started making plastic bags.
You might be asking how much water are we talking about. An experiment was done using copper coils, ice chests of cold water, and a fan. With an average air velocity of 4 mph, humidity of 66 percent, 87 degree F. air temperature, and 47 degree F. water temperature the production was .0191 gallons of water per hour for every square foot of coil. Doesn’t sound like much, but lets apply it somewhere.
We will use Los Angeles as a case study because it is strapped for water, and I happen to have the year round average weather for LA; 65.4 degrees F. air temperature and 71 percent humidity. An offshore wind farm is being installed near LA. There will be 50 turbines 500 feet in diameter. They will be the new floating type in 2,500 feet of water where the water temperature at the bottom is 46 degrees F. Fans will force ambient air through the heat exchanger coils at 16 mph. Mainly because of the increased air volume, the production factor goes up to .062 gallons of water per hour per square foot of coil surface area.
Plastic grocery bags prefer this as their second career.
The coil will encircle the support tower of the windmill. Looking at it from above, it only has a square footage of about 950 square feet, the size of a small house. The coils are 45 feet long. They are 1” diameter tubes with (7) 7/8” high fins attached axially to increase the surface area of the coil. Examining the pictures you get a sense of what this would look like in comparison to the windmill because it was drawn to scale. Though it looks small, the total surface area is about 202,000 square feet, which means this unit produces about 12,500 gallons per hour, 300,000 gallons per day, and 109,500,000 gallons per year. Multiply this times the 50 windmills and 5.5 billion gallons of water per year can be extracted from the atmosphere. A dedicated floating facility for just producing water could produce many times this amount making a sizable contribution to the couple of trillion gallons required by LA every year
This water production method could easily be applied to the floating island idea espoused by the Seasteading Institute and being tested by the Maritime Research Institute Netherlands. The cool, nutrient-rich water brought up from the depths could also be used in fish farming, a burgeoning industry that lends itself as a food and revenue source to the concept of floating islands.
One thing is for certain, something must be done to assure mankind’s access to pure water. The lack of it is one of the major reasons the Middle East is in such turmoil. This political unrest can only spread as water becomes more and more scarce. I predict this method of water production will be a future godsend to the warmer climate regions of the planet.
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