Bringing Water From Sol to Soul
- Africa, Cape Verde
Peace Corps Volunteers Nicholas Hanson and Brian Newhouse help develop plans to use solar stills to solve the problem of Cape Verde's perennial water shortage. This video illustrates how students and community members can come together to achieve lasting, meaningful results.
Cape Verde receives less than seven centimeters of annual precipitation. Most of their fresh water comes from deep wells that tap the water table hundreds of meters underground. Because of the amount of water drawn from the wells, salt water is saturating the water table near the coast.
Local language: It depends on the rain. If it rains we'll be fine-but there is little rain-it is weak.
In recent decades, desalinization plants have been a widely-accepted alternative. Desalinization plants are fuel-powered systems that break down water molecules to purify seawater through reverse osmosis. Although this process works, it is expensive and energy-intensive. It is important for Cape Verdeans to start looking elsewhere for a more sustainable and economical supply of fresh water.
Local language: All of the pieces that are above here, you need to cut. We're making the formwork here for a solar still so we can transform salt water into distilled water.
Solar stills are systems that use energy from the sun to distill salt water. The first day this prototype was in operation, it distilled 1.75 liters of water. This prototype cost 17,000 escudos, about 213 dollars.
With hundreds of kilometers of coastline around each of the nine inhabited islands providing an endless supply of seawater, and receiving hot sun almost year-round, solar stills may prove to be a promising, cost-effective alternative for fresh water.
Local language: Now we drop concrete into each side. And tamp it down to fill the sides. Not very rough. If you tamp it roughly, it might open the form. Remember, we're taking out the air bubbles.
For months, Nick researched solar stills and designed a cost-effective model using local materials. When I arrived three months ago, together we wrote a proposal and pitched the idea to our school directors. They agreed to fund a prototype.
Local language: When students have the opportunity to apply the knowledge to practice, it increases their motivation for both the students and the teachers. If this project has positive results, it would be the goal of the administration to implement desalinization to the island of Santiago.
This is something that is perfectly designed to benefit our country and specifically civil construction. The primary objective of the project is to help the school and transmit to the students how to build something like this. And I feel this is the fundamental idea of the school.
We have two civil construction students. And right now they're taking off the formwork. When it's ready, the mixture of both the saltwater and the distilled water is where water can come and be consumed. Now, we're stuccoing the outside to make it nice, to make it pretty, to make it flat.
We arranged to build the prototype with the other civil construction professors and eleventh-grade students in the back of the workshop during their practical lab.
A solar still is a concrete basin with a large, black surface area to absorb the heat from the sun. An inclined piece of glass rests above the basin. When the water evaporates, it condenses on the glass, then trickles down into a trough that leads outside to a catch basin.
Local language: We're painting the interior sides white to reflect the rays of the sun. The bottom of the basin is black to absorb the heat from the sun. Insulation has thermal properties to keep the difference in temperatures. The system must have a good closure. If it doesn't have a good closure, when the air gets hot, it can escape.
A little silicone. After, we'll put a second piece of plastic. The heat from the sun is absorbed by the black plastic and heats the water until it vaporizes. The water rises, catches on the glass, runs into the trough and out of the still.
Now that we finished the prototype, our goal was to increase the output by improving the design. With each of our three senior civil construction classes, we want to design an improved still, write another proposal, and present it to the school directors for funding. If funding gets approved, we want to build each class's design during the final trimester of the school year.
The main goal of the project is to teach the students about solar distillation and improve technical education in Cape Verde. Because of the limited supply of fresh water in the country, recent reports say the local government is looking to fund fresh-water projects. This gives the students something to shoot for.
Local language: You can use this for drip irrigation, to take a shower, for cooking. If every person had a solar still, they wouldn't need to spend money to buy fresh water. They would only have to take water from the ocean and make vapor.