By Patti Meagher
Mama Coney (left) and husband Papa Carlos demonstrate the water heater on the roof of their home in Xela, one of the households testing the CalSolAgua prototype. The unit uses a black sheet-metal absorber covered with glass to heat water supplied by a city pipeline.
PHOTO COURTESY CALSOLAGUA
Hot, running water is a luxury. But many families in developing countries don’t have water heaters or even showers, and those who do pay up to twice what U.S. consumers pay for electricity.
Now, a team of UC Berkeley students is developing a solar water heater that could make hot showers a part of daily life in such
households. The group is testing and refining their third prototype in Quetzaltenango, better known as Xela, Guatemala’s second largest city.
“For a project like this, you really need an interdisciplinary approach,” says mechanical engineering Ph.D. student Sara Al-Beaini (M.S.’08 ME). “We have people from different backgrounds and experiences, and it’s a big plus that a lot of our teammates have worked worldwide.” The group includes mechanical and materials engineers and students of environmental studies and public policy. While applying for grants, they realized they also needed production and marketing advice, so they recruited two M.B.A. students from Haas. It’s a labor
of love: all are doing their primary research in other areas; two already graduated and work full time but are still involved.
It started in Ashok Gadgil’s 2007 class, Design for Sustainable Communities. A physicist at Lawrence Berkeley National Laboratory and professor of civil and environmental engineering, Gadgil is famous for his creative scientific approaches to solving day-to-day problems.
He challenged his students to design solar water heaters that could be built from locally available materials in the developing world for about $100.
Team members traveled to Guatemala to inspect homes and survey residents about their water use. Back home they tested materials and prototypes, developing a simple design based not on photovoltaics but on gravity and the greenhouse effect, the process that bakes
your car in the sun. The only requirements are an incoming water supply to fill the rooftop-mounted unit and sunlight to heat up the water inside. The hot water—25 to 30 gallons heated to a comfortable shower temperature of 104 degrees Fahrenheit—flows down when you open the valve.
“The incentive is huge because electricity in Guatemala is so expensive,” says mechanical engineering Ph.D. candidate Merwan Benhabib, adding that the heater could be marketed in Central and South America, Mexico, Asia, Africa, wherever the sun shines, including about 100 million households in China alone. The team is working with local nonprofit Appropriate Infrastructure Development Group, which has strong roots in Xela and helps address local problems with cost-effective technological innovations.
The students aren’t sure how their product performs in the rainy season, when sunlight is limited, so further refinements may be needed. Although the initial design was for showers, they hope to modify it for other domestic hot water uses. The work is supported by competitive grants and funding from several academic and nongovernmental organizations, including the National Collegiate Investors & Innovators Alliance and UC Berkeley’s Blum Center for Developing Economies.
Go to http://www.me.berkeley.edu/calsolagua.
