Harnessing the Coolth !

In renewable-energy circles, the holy grail is solar energy. It can be harnessed to capture its electrical potential using photo-voltaic cells. You can harness the sun's energy in the form of heat. Since a large portion of our daily household energy consumption typically goes into heating water - to heat our living spaces; to bathe; to clean dishes and clothing - this is the area that gets the most attention.

But in many climates - unlike my own in here Southern Alberta - there is often great value in disseminating heat, and storing the "Coolth" - sorry, I just love that word ! We know that we can capture solar radiation and heat a body of water to over 200 F, but what if we wanted to cool it instead ? And once it is chilled, can we store it in an economical way for later use ?

Over at the BuildItSolar web-site, Gary Reysa has assembled a large collection of articles and HOW-TO's for the Do-It-Yourself crowd. An article caught my eye that showed a simple means of trickling water down the slope of a roof at night and capturing it again at the bottom. Gary demonstrated that this simple method could cool the water by about 1.9 degrees F each hour ! This is accomplished using nothing more than evaporation. By exposing the water to cooler night-time air and then transmitting it across a large surface area, the water is chilled in a reasonably short period of time.

While this doesn't sound particularly awe-inspiring, Gary points out that it is roughly the equivalent cooling in terms of BTUs as running a half-ton air-conditioner for 6 hours. That IS very impressive !

Interestingly, at the time the cooling is happening, we don't need the chilled water. So it is stored in a highly-insulated 500 gallon container, so that the chilled water can be used in a simple heat-exchanger later. Whether through an in-floor heat/cool system, or combined with some form of blower to send cool air throughout the living space, the coolth can be used later. As the returning water's temperature raises over time, the temperature in the storage tank also rises, but one would presume that the cooling effect is really only required in the mid-day heat.

I love the idea of being able to collect both warmth and coolth. I believe that one of the barriers to widespread adoption of renewable energy sources is complacency. People simply don't want to have to change their lifestyles. I have never owned an air-conditioned home, as I have never lived anywhere that required one. So for me, it was never a consideration. But imagine if I lived in California or Florida ! I suspect they care an awful lot less about heating their homes that I do !

But that's a topic for another post...

The opinions expressed are purely those of the author. Opinions are like noses - everyone has one, and they are entitled to it !