Feb 09, 2015

Top Two

Highlighting technologies that bring clean water to the developing world

In my day job, I often meet or work with developers of new technologies. I recently ran across two that I would like to tell you about.  

As with past technologies I have written about, I have no connection with these technologies or the companies developing them. I have no financial interest in either of these technologies or organizations, only a curiosity and interest in how they are applied to water and wastewater issues that may be of interest to you.

These two technologies come from opposite ends of the technological spectrum. The first, called the Warka Water Tower, is simple in its design, yet elegant in its operation to produce drinking water in arid areas by taking advantage of day-night temperature changes to collect condensation. The second, from Star Core Nuclear, is a small package nuclear power plant capable of generating enough power to provide electricity and utilities to a small town or outpost in a remote area.

Traveling Tower 

Dehumidification to produce drinking water is not a new concept. There are many types of air-to-water technologies that use temperature differentials to produce drinking water through condensation. The beauty of the Warka Water Tower is in the simplicity of its design and the fact that it can be inexpensively constructed from locally available materials almost anywhere in the world.  

The Warka Water Tower was developed and designed by Auturo Vittori of Architecture and Vision in Italy to solve the issue of drinking water collection in the arid mountain regions of Ethiopia. As in other similar regions, the people there spend many hours collecting and carrying drinking water great distances. A local source of reliable drinking water frees them from this chore and liberates many hours in their day for education, community development or just the luxury of some free time.

The Warka Water Tower  is 30 ft tall and holds an internal mesh membrane that takes advantage of the large differences in day and night temperatures to produce condensation. The tower is built using locally available natural materials such as tree branches or brush woven into a basket-like structure. The tower structure is designed to hold an internal nylon mesh bag (similar to the mesh bags that might hold oranges in a grocery store) and expand its surface area so that it is exposed to the air. With the change in temperature from night to day, condensation forms in the mesh structure in the same way that you may see dew droplets on a spider web in the morning. The shape of the internal mesh structure channels the dew toward a collection device at the base of the tower. The tower has no moving parts and requires no energy to run.

The Warka Water Tower has been shown to be able to produce up to 25 gal of drinking water daily depending on weather and temperature. Each tower costs approximately $500 to construct and can be built in about one week using local materials (save the nylon mesh) and local labor. The construction process also can be easily taught and replicated and transferred from town to town. This provides an easily scalable means to deliver drinking water to many towns and villages across a wide area. 

Star Power

Star Core Nuclear is at the opposite end of the technology spectrum and was designed to bring power to remote areas well off the grid. This technology is based on the use of small, packaged nuclear generating plants to produce electric and thermal power in remote areas where other sources of power are not available. The developers envision that these plants could be employed at remote mining sites, military installations and industrial operations, as well as in developing countries in need of local power and utilities.  

Unlike the large nuclear power plants that power entire cities and involve large construction projects that may need a decade or more to design, build and permit before operation, Star Core’s reactor is based on a small package plant, constructed using a single standard design, built in a plant assembly line style and shipped to the installation site. The reactor itself is installed more than 100 ft underground in a sand bed to provide security, protect the reactor and manage the heat generated. Each reactor is capable of generating 10 to 20 MW of electricity (a typical nuclear power plant, by comparison, may generate 100 to 200 times that amount; a typical plant on a nuclear-powered warship or submarine may have 10 to 50 times that capacity), and the heat generated by the reaction can provide heat for the town or outpost in which it is installed and power to operate desalination or water purification systems.  

This idea of using small packaged nuclear generating systems in remote areas is not new. Small nuclear reactors were used years ago in remote areas such as Antarctic research stations, Arctic military stations and for water treatment operations in the Panama Canal Zone. The design of the reactor being used by Star Core is different and safer than those used in the past in remote locations and, while the design elements and safety features of these reactors are beyond the scope of this column, the design has, according to the company, been called “inherently safe” by the International Atomic Energy Authority.  

What I find interesting is that the company plans to continue to own, operate and monitor each reactor installation, and the local user will only need to pay for the power generated and provide maintenance and operation of the local distribution system (which would be needed regardless of the source of the power generation). The package plants are designed to operate for five years before refueling is needed, and the company will collect and replace the reactor, if remaining in operation, or decommission the site if it is not, and remain responsible for the fuel reprocessing and disposal. This technology has the capability of bringing power and water to remote areas of the world without the need for local nuclear technical expertise or local responsibility for cradle-to-grave fuel management.  

The Warka Water Tower and Star Core’s nuclear reactor technologies certainly are at opposite ends of the scale in terms of technology, cost and operation, but each is elegant in its own way in its ability to solve the problem of safe drinking water and development in areas of the world that have few other options. It will be interesting to watch the development and deployment of each in the coming years. 

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