Creativity captures sunshine: BSU students showcase homemade miniature solar water heaters
Bemidji State University professor Jim McCracken crouched down for a closer look at the disc-shaped contraption in front of him. It was painted black and topped with a reflective polyester film. Inside its funnel was an 8-ounce cup filled with water, held in pace by coiled wire.
McCracken looked down at his grading sheet, going over the check list that would determine the number of points the students would receive on their homemade solar heater.
- Heater raises the temperature of water. Check. Before going outside, the students measured the water in the cup at about 60 degrees. Now it was in the 70s.
- Heater must be no more than 18 inches high and 18 inches wide. Check. McCracken decided not to use the measuring tape in his pocket. Having years of experience teaching this project, he could tell this heater was the right size.
- Heater does not tip over. Check. McCracken touched the sides and tried to move the heater slightly. It wiggled a little, but not enough to dock points.
One by one, he went through the items on his check list, observing whether the heater reflected a high degree of craftsmanship, could be adjusted to follow the path of the sun and reflected sound research. Then he handed the grading sheet back to the students and went on to grade other heaters scattered around the sidewalk outside of Bridgeman Hall on the BSU campus.
Students in McCracken's Impacts of Technology class designed and fabricated solar water heaters, one of their first hands-on projects of the semester. The assignment was designed to teach students how technology can use alternative energy sources, such as solar energy, to reduce the amount of carbon emissions in the atmosphere.
Students were given only two pieces of material to start with - a plastic cup and a sheet of polyester film similar in appearance to aluminum foil. They were told they had to complete the project in less than two weeks. On Wednesday, students displayed their final projects, each group hoping their design would produce the most heat.
According to McCracken, the polyester film was given to each student pair as a way to "level the playing field."
"Beyond what they were originally given, they could use just about anything they wanted to," McCracken said.
Students David Morales and Cody Reilly built their solar heater with reused glass panes. Their heater was designed to use the principle of convection to heat the cup of water.
"What you're looking at has a price tag of about $10," Reilly said pointing to his glass-cube heater. "The (glass) lens was made out of all free materials. It's all reusable and very green."
Morales said he and Reilly spent more time designing the end product than building it.
"It was tough to start," Morales said. "We went through a period of different design phases. We came up with too many ideas. This is what we ended up with. Convection is what we're counting on here."
Fortunately, halfway through the class period, their design proved very efficient. In a matter of 20 minutes the temperature of the water in their cup went from roughly 60 degrees to more than 100 degrees.
Last year, McCracken said the highest temperature readings from students marked at around 120 degrees Fahrenheit.
"Just with a little bit of constraints, it seemed like creativity skyrocketed," Reilly said.
"If we were going to build a water heating system, it would be twice as easy, because at that point you could build whatever you want," Morales added.