Time for Eco Power
Looking for a way to demonstrate pollution free energy without the expense and complexity of getting a fuel cell? At $16, Bedol’s Eco Friendly Water Clock is an inexpensive classroom aid for a science or social studies lesson on everything from climate change to electrochemistry.
The spherical clock is available in four colors and remarkably simple. Inside are copper and zinc electrodes that react with salt water to coax electrons to flow between the two metal plates. This creates enough current to power its digital clock.
The directions spell out how to put it together, how much salt to use and how to set the clock’s time, making it perfect for a substitute teacher or chemistry lab project. It took a group of 11 year olds five minutes to put the clock together. They were amazed that it actually worked and kept accurate time on just salt water.
A big bonus is that if you remove the clock face, the teacher can attach a voltmeter to see how much electricity the cells are producing. Together, the clock’s two cells created 1.6 volts. As good as it is, the only thing it’s missing is a good explanation of the process that’s occurring behind the scenes, although there’re plenty of Web sites that can help create a lesson plan.
The best part is that in a few weeks as the battery starts to wear out, refilling the water tank can refresh it to the way it was when it was new. This allows a class to monitor it over months or a school year or the teacher to reuse it year after year. I’ll report back in a few weeks when it starts to run down.