A DIRECT SOLAR WATER HEATING SYSTEM FOR THE HEALTH CLINIC IN THE TOWN OF SANTA ISABEL CHOLULA, STATE OF PUEBLA, MEXICO Roberto Rosas-Romero Universidad de las Américas Puebla Jeffrey S. Tiller and Brian W. Raichle Appalachian State University
ASU Appropriate Tech
Introduction U.S. AID funded a project to expand a partnership between Appalachian State University and Universidad de las Americas Puebla Develop curriculum for a graduate program at UDLAP in renewable energy Educate faculty at UDLAP about renewable energy technologies and provide educational programs Help develop lab facilities Engage students at both institutions to develop designs for energy projects and conduct joint installations community project Appalachian State (above) San Pedro Cholula (location of UDLAP below)
Santa Isabel Cholula Ideal climatic conditions for the use of solar radiation Isolated, rural community with a vareity of social needs, but close to Puebla and UDLAP
The Health Clinic
The Current Hot Water System A 100 liter propane heated water tank Pressure provided by a 500 liter cold water tank on the roof (2 m above hot water tank)
The Community Solar Project UDLAP and ASU faculty and students Design solar thermal and photovoltaic system Plan the installation Install the system Monitor the performance
Design Process Students in ASU Solar Thermal class and course UDLAP engineering students combined worked on a variety of project designs The students compared the cost and installation time for team-assembled projects versus systems with integral storage A collector/ storage tank system was identified that costs $500 (with minimal assembly)
The Solar Hot Water System The integrated collector/ storage collector contains: 200 liter storage tank 24 evacuated glass tubes (47 mm x 1.5 meters) A drip valve provides modest freeze protection Of course, the solar storage tank sends preheated water into the regular propane water heater
The PV System The team investigated a variety of possible applications for PVs in the town of Santa Isabel Cholula Due to concerns about possible theft or vandalism, we decided to install the system on the health clinic With our quite limited budget, we decided on a small system that powered the exterior lighting for the building, mainly as an educational project for the students involved
The PV System Average monthly electricity consumption is around 300 kwh Installation of a battery and a solar panel provide outside lighting LED lighting was selected, and installed on a light sensor (designed and built by UDLAP students) The design and implementation was entirely done by students at very low cost.
The Solar Hot Water System
The Solar Hot Water System Installation Mounting system developed at Laboratory of Mechanical Engineering at Universidad de las Américas-Puebla Roof was solid concrete with waterproof coating We took care to properly water seal all penetrations through the roof coating Climate is moderately dry: 37 inches/ year rainfall
Performance The solar thermal system is currently saving about 50% of the propane consumption at the clinic. Savings would be approximately
Final Observations and Conclusions Central Mexico has a moderate climate in both summer and winter, with relatively small demands for heating and cooling. As a consequence, water heating represents a high fraction of building energy demands. With the high number of sun hours in central Mexico, solar thermal systems would be excellent candidates to provide a major share of hot water needs. The project showed that a small, inexpensive system can provide 50% of the hot water needs.
Final Observations and Conclusions (cont.) Propane and electricity provide hot water at $29 to $52/ million Btu thermal The solar water heating system, at a projected installed cost of $1,200 Annual savings on propane -- 10 MMBtu Annualized cost of solar thermal system -- $122 Cost per MMBtu saved = a little over $16/ MMBtu the cost effective choice, without any incentives
Final Observations and Conclusions Collaborative international projects are an excellent learning opportunity; however, they are difficult coordination, logistics, language, commitment Training of professionals with skills to investigate and innovate is indeed critical, especially considering the rapidly growing economies of countries with mild climates and high hot water use Such projects to help reduce the operating budgets of those serving community needs in poor areas can be very beneficial Students are highly effective ambassadors and are indeed our future