Making More Potable Water for the World

water spout
water spouts

Published Oct 1, 2015 8:55 PM by Harry Valentine

Since time immemorial, the world supply of potable water was the result of the interaction between solar thermal energy and the world’s oceans. The different rate at which land and ocean temperatures increase in response to solar heat causes air masses to move, in turn causing waves on the ocean that break along the world’s beaches. Solar heat causes a percentage of surface seawater and coastal sea spray to convert to vapor that winds carry to cooler temperatures found at high altitudes in mountains, where the vapor converts to the rain that sustains life on land.

Many regions around the world have increasing need for potable water. It is becoming scarce at many locations. Overuse and mismanagement of water has caused the once bountiful Aral Sea to become a desert. In some years, a weather phenomenon called El Niño causes flooding in some locations and drought in others. Where droughts occur predictably and seasonally, human populations have responded by developing methods to store massive volumes of water or to desalinate ocean water such as in some Middle Eastern nations.

Coastal Sea Spray

The ingenuity of human innovation needs to take initiative and intervene when natural solar-driven desalination of ocean water is unable to provide sufficient potable water to sustain local populations. One option is to introduce innovations that assist the natural world to produce more potable water at specific locations, such as modifying coastlines by placing additional rocks, boulders and wave deflectors at strategic locations so as to increase the volume of coastal sea spray. Increasing sea spray upwind of a coastal mountain could increase the amount of evaporation that occurs along the coast and increasing possible rainfall at higher elevations.

A coastal windfarm in Western England receives moisture laden winds that blow inland off the Irish Sea, except that the wind turbines cool the incoming air mass and produces fog downwind of the wind turbines. This occurrence suggests possible benefit to placing wind turbines on the slopes of coastal mountains where moisture laden winds blow inland. The wind turbines could cool the incoming wind and increase prospects for rainfall in the coastal mountains. Alternatively, it may be possible to install fog fences downwind of the wind turbines, to collect droplets of moisture from the mountain fog.

Making Water Spouts

The water spout phenomenon is a cyclone of rapidly swirling air mass that occurs over mainly warm water, lifting droplets of water to high elevation where it converts to vapor and generates a cloud that winds often push inland, with salt dropping back to earth. It is possible to use technology to trigger water spouts, with the technology providing a focal point for ambient thermal energy of solar heated seawater to help sustain a water spout offshore and upwind of a coastal mountain where wind turbines and fog fences may be installed. The result would be a highly localized micro-climate.

A thermal source to sustain a controlled water spout may include waste heat from a steam-based thermal power station built along the coast, low grade geothermal energy or perhaps even concentrated solar thermal energy from shore based collectors. An insulated closed-loop pipe would carry heated water from shore to a spiral-and-coiled pipe made of corrosion-resistant metal that flotation devices suspend below ocean surface, with an anchor to the seafloor. The assembly would include a lightweight circular barrier around the suspended spiral/coil, to concentrate heat within a small area and provide the trigger to start and sustain a mini-cyclone and water spout.

Wave Energy

The renewable energy sector has developed technology that converts the energy of wind-driven ocean waves to electrical power. Some of these technologies are designed for offshore installation and include hydraulic pumps that push oil through a turbine that drives an electrical generator. However, their offshore presence greatly reduces the wave energy that reaches the coast. The fact that these units drive hydraulic pumps also allows for the possibility of them to drive corrosion-resistant water pumps that push seawater through reverse-osmosis desalination technology. This could also be located offshore, on board a floating barge so as reduce any increase in salinity of coastal seawater.

Perhaps the optimal location for such technology would be near offshore islands that could provide a location for potable water storage tanks, either with an undersea pipeline connection to a mainland or with tanker barges regularly carrying potable water to the mainland. There are many uninhabited islands around the world where wave powered desalination technology may produce potable water, with maritime tanker transport carrying potable water to populated locations. The combination of undersea power cable technology and optical telecommunications technology could allow for remote monitoring and remote control of desalination equipment and operations.

Maritime Transport and Flooding

Tanker ships have already carried potable water from regions of excess water to regions of limited water supply, such as the recent movements between France and Israel. There are regions where seasonal floods occur and where water storage capacity is limited, resulting in a deluge of potable water flowing into the ocean. Other regions with limited water storage capacity will experience occasional unexpected occurrences of excess flooding due to a weather anomaly such as El Niño that results in massive volumes of potable water flowing out to sea. It may be possible to collect water from such locations.

There may be scope at some locations to install pipelines between coastal and inland riverbank locations to source a portion of seasonal excess water from upstream and transfer it into tanker ships berthed at a port. The installation of intense UV-lighting technology in the pipeline and inside ship tanks would destroy harmful waterborne bacteria. During the flood season, shipborne water cleansing technology could provide clean potable water for export as well as for local consumption.

In this way, wealthy Middle Eastern nations could explore the option of importing seasonal flood water from their Asian neighbors.

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.