Inexpensive Transport of Fresh Water
Fresh water is scarce in many areas on the earth and some of them are located near oceans or large seas. This proposal describes a method for moving fresh water from places where it is plentiful on a seacoast to other places where it is needed. This would make use of the ocean for low cost transportation of fresh water to benefit large arid coastal areas. It would also permit raising crops in areas now too dry for agriculture.
The water would be moved in bulk inside floating bladders. For example, on the west coast of North America fresh water is plentiful in the north but scarce in the south. The California current flows south along the coast and could be used to assist in moving fresh water to southern California. A similar condition exists on the east coast of Australia. Southeast Australia now has a major drought and could use water from the north, which is plentiful.
The fresh water could be pumped into large bladders, which would float on the salt water of the ocean and could be moved south with minimal towing, as the current would do most of the work. After arrival at the destination, and pumping the fresh water into reservoirs on shore, the empty bladders could be returned for refill. For this plan to be economical, the bladders would have to be very large. For example, they could be made in the shape of sausages, perhaps 100 ft in diameter and 1000 ft long. Ten of these could be strung together and slowly towed. This would deliver 1805 acre-feet of water. Los Angeles has a severe water shortage and is now considering desalination with a projected cost of $1080 per acre-foot. The value of the water delivered on each trip of the bladders would therefore be $1,950,000. This method will become even more attractive compared to desalinization as the cost of fossil fuel energy increases. It also might substantially replace present energy intensive, less sustainable irrigation schemes such as the current practice of transporting electrically pumped water in canals and pipes running over mountains from the Sacramento River Delta region to the Los Angeles area.
The bladder material should probably be the same as is used for large tarps. I am thinking of the common ones based on a woven fabric of polypropylene cords covered on both sides with layers of polyethylene fused to the fabric. The plastics can have pigment and UV inhibitors included so they will be protected from solar exposure. Fabrication of the bladders is easy. Overlapping the material by an inch or so and fusing it with heat makes the seams. This works because polyethylene melts between 120 and 130 degrees C and polypropylene melts at about 160 C. The tarps are commercially available with the short edge measuring up to 100 ft so we know that rolls of the tarp material of that width and probably any arbitrary length should be available.
Strong, durable, and inexpensive sausage shaped bladders can be constructed of this material. The material can be tapered down as the ends of the bladders are approached and finally clamped tightly to a large pipe fitting with a valve and coupling so that the bladders can be filled, emptied and coupled to each other for transit.
The bladders could be inexpensively made very strong to survive the inertial forces involved in starting, turning and stopping them. The force of surging water due to the effects of inertia or rogue waves could be absorbed by elastic bands around the bladders near the ends. They should not be much affected by stormy weather because if they were not tightly filled, they would be transparent to the waves in the ocean, which would pass through them with little effect.
As they would be moving very slowly relative to the water around them, and the fabric that they are made from will not be tightly stretched, they would yield when contacted and gently push aside any debris that they encountered on the water surface. If there is a problem with floating debris damaging the bladders, they could be protected by using old carpets as fenders along the water line of the bladders. A mast with a flashing light and radar reflector could be mounted at the end of each bladder to warn boat traffic away.
For the particular case of delivering water to southern California, In order to get large quantities of fresh water without political problems, I think that it may be necessary to go further north than the California border to get the fresh water. The Columbia River is fed by the runoff from the Canadian Rockies and a large fraction of its fresh water flows into the pacific. The US Army corps says that the average annual runoff of this river is 198,000,000 acre-feet. The amount taken for southern California would be a very tiny fraction of that. Where the Fraser River flows into Puget Sound at Vancouver BC Canada is another possible source. The small amount transported could be very significant for southern California or western Mexico. There is a lot more water available further north from other rivers that could also be used. The transit time would be longer, but the current would still do most of the work.
This scheme could possibly be used for water delivery to any arid coastal area. For example, the south and east coasts of the Mediterranean Sea are arid and the north and west coasts have adequate water. The effects of global warming seem to be reducing the rainfall on the south Mediterranean coast and northern Africa, but increasing it in Europe so it seems that that the need and supply situation will improve with time. In regions such as this, where there is little natural current to assist in the movement of the bladders, a very energy efficient method of moving them would be to use a very long cable that would be pulled from a fixed point. This fixed point could be a ship that is anchored. The long cable would pull the bladder up to the ship using a winch. The ship would then move to a new anchor point, while paying out the cable, then pull the cable in again. This would necessitate following a route with water shallow enough to anchor, usually near a shoreline.
This would obviously need considerable investment capital because the design and construction of the large bladders and construction of the necessary shore facilities for filling and emptying the bladders would be costly. However, the facilities and materials would be reusable and should have a long useful life. There would be necessary political connections, commitments, and payments for the system to function. However, the high value and need for the fresh water delivered should result in a large economic gain despite the start-up costs,
Increasing the size of the bladders should be cost effective as the amount of material needed and the energy required for towing increases more slowly than the capacity of the bladders. There would be a practical limit on size because of the need to transport the empty bladders back for refill. Carrying them on a ship or barge would probably be more efficient than towing the empties, but that may depend on local conditions.
This idea will increase in value with time because of the continuing depletion of the aquifers in many arid but highly populated seacoast regions. Fresh water will become increasingly scarce and desalination is very energy intensive and is becoming more costly as oil and gas are depleted
There are other economic and political considerations. In my opinion, the sale of the water to private companies could result in very undesirable consequences. Privatization of water systems in many areas has resulted in large increases in rates, government corruption, and compromise of public safety. The question of who should own the water is an important consideration that must not be ignored. The water is a natural resource that is owned by the citizens and they should pay for the operation of the distribution system but not for the water itself. The way to structure the transport deals should be for the government agencies involved to deal directly with each other. They could hire contractors to do the work of transporting the water, but should never sell the water to a private company. The price that users pay may need to be set higher than the cost of transport and distribution in order to limit consumption to the amount of water available, but the excess income in this case should go to the general funds of the governments involved, and not to corporate profit.
Another consideration is that the level of fresh water removal from a source river system should be kept low enough that there would be no significant effects on the natural biological systems of the river and so that there is enough extra water available to permit a considerable increase in local consumption without the necessity of reducing the amount of water provided to the receiving area, which may be expected to become dependent on its continued availability. The rate of extraction and transport of fresh water will need to vary seasonally according to the rate of river flow and therefore the water storage at the delivery point must be large enough so that the rate of consumption can remain reasonably constant. It may be that the bladders can be economically used for storage as well as transportation. The costs of this transportation system are not small, but the energy requirements are low. Operating the system will create many jobs. The alternative sources of fresh water such as desalinization are still more costly and have large energy requirements with much greater climate change consequences.
With the help of several people on a web based discussion group, I have found out that there have been previous attempts to transport water with similar technology. I had difficulty finding out about the previous activity because what I was calling bladders, they referred to as Medusas the most advanced operation was by Nordic Water Supply ASA, which transported water from Turkey to Cyprus. Unfortunately, due to some equipment failures and other problems, this company, after operating since 1994 declared bankruptcy in May of 2003. I believe that there have been other small-scale operations in the Mediterranean area, some of which may still be operating. Due to the length of time that this sort of operation has been in operation or attempted, it seems likely that there are no patent related obstacles to further development. Perhaps now, with the greater economic need, and using some of the ideas described above, there can be some successful large-scale applications of this system.
I have done some daydreaming about other uses for the tarp material, not just transportation, but storage. The one with the most potential seems to be the creation of artificial lakes in areas where the rainfall is very seasonal. For example, the regions where there are seasonal monsoon rains with lots of water available, in fact, way too much during the rainy season, so that there are disastrous floods with loss of life and property.
In regions that are mostly flat, such as Bangladesh, (which is barely above sea level), it seems that a good plan would be to start in the beginning of the dry season, excavate a large area, as deeply as possible, use the removed material to raise the level of the surrounding area, then surround the excavation with a high levee and line the bottom of the new lake with impermeable material such as the tarp fabric.
When the rains come, use massive pumps to fill the lake with water from the swollen rivers. This avoids the usual flooding for two reasons: one is that the area in now higher because of the material removed to make the lake, and the other reason is that the excess river water was pumped into the lake which should be filled to the top of the levees, and will now have a level well above the surrounding land. During the following dry season, the lake water is used for irrigation and other needs. The lake can be stocked with fish, such as tilapia, so that it will be productive of food as well.
Obviously, this is not a cheap project. It requires massive earth moving equipment, massive pumps, and the energy to run them. However, it may be cheap compared to the cost of not doing it and also considering the increased year round agricultural production that it makes possible. The elevated land will also provide protection during the periodic cyclones (hurricanes) that flood the land with seawater and often cause major loss of life due to drowning. Even if the raised land is not high enough to avoid flooding in the storm, the levees will be much higher and can be topped with concrete storm shelters for the local population.
I don't know if any of this is politically possible, or where, but I can dream…
Bill Isecke
bisecke@gmail.com
1 201 836 8403
