Thursday, November 18, 2010

Solar freebies

When I was a kid, I lived in a neighbourhood where a lot of the residents had swimming pools in their backyards. Not my family, though. We had a rusty swing set with plastic seats and a wobbly, too short slide attached on one side. And for some reason, none of my friends in the neighbourhood were the children of the type of parents who installed swimming pools. Which sucked. On the really hot summer days - and when I was a kid it seemed every day of summer was hot - our gang of 6 to 10 year olds would be draped over my swing set dreaming of ice cream trucks, air conditioning and wouldn't it be the best thing in the world to jump into the neighbour's pool.

The neighbour didn't like us, though. Maybe we were too loud and obnoxious. Maybe the neighbour was just a jerk. Hard to tell now, fading memory and all. Either way, we decided we had to go further afield. We identified a friendly, childless couple who lived half a block away and one afternoon when it seemed like the heat would fry us up like ants beneath a magnifying glass, we walked over into the empty field which bordered their backyard and stared longingly, and obviously, through their mesh wire fence at their swimming pool.

The couple was outside, doing some yard work. They saw us and took pity and amazingly, fifteen minutes later, they had half a dozen kids splashing in their swimming pool. In our jaded age of ever looming liabilities and paranoia of suspicious creepsters lurking around every corner, some might be thinking this story is going to end badly. Nope. None of us went missing. We all made it out and were back on the swing set before afternoon's end to review our adventure. It was unspoken but I think we all knew that this wasn't something that was going to be repeated. The couple invited us in once but to try again would be to overextend our welcome.

Aside from the fun we had, I also learned something that day. It was a bit of an a-ha moment actually.

I noticed when I was in the pool that the water was particularly warm (and no it wasn't because we had all peed in it - at least I didn't). I'd never been in a pool or lake that warm before so I said something about it to the owner and he told me the water was heated which I thought was silly. I imagined some sort of huge electric grill beneath the pool because, other than having a big campfire underneath the pool - which would've been even sillier, that was my only experience with how things got heated.

The man pointed up to his rooftop where there was long length of what looked like black garden hose coiled up into a large circle. He then showed me where the hose was attached to a pump and how the pump pumped water from the swimming pool to the rooftop where the sun would heat up the water in the black hose before draining back into the pool. I was quite impressed. Heating water by using the sun. In other words, it was a freebie. I'd heard my father complain about how much oil our house furnace burned up in the winter and how expensive it all was and yet here was this person, who surely must've been some kind of mad scientist, not six houses away, getting free heating from the sun!

Looking back on this guy, I realize how ahead of his time he was, how ahead of our time he was. So much free solar and still so few people taking advantage of it. I say better start using it before the government finds some way of taxing it or some corporation starts bottling it and selling it back to us.

Two of the more common ways to convert solar energy into something more useful is by installing solar panels which provide either heat (solar thermal) or electricity (solar PV short for solar photovoltaic). I'll get into the solar PV stuff in another post, but for now, check out this amazing solar thermal system created by Gary Reysa who lives in Montana. He built it with easy to find materials and it has pretty much replaced his hot water tank. Really impressive is that it only cost him a thousand dollars and he claims it does as good a job as many of the commercially available solar thermal hot water systems out there which will put you back several thousands of dollars. Of course, the downside is that you'll have to build it yourself but his instructions are very clear and imagine what a great boy scout moment you'll have when you tell your friends about your new hot water heating system that you made with your own two hands.

For those who just want the precis of how Gary's solar hot water heater works, and how, in theory, many solar hot water heaters work, it's like this:

You've got this big tub of water in the basement, say, and you pump this water outside through a bunch of black painted copper piping which sits inside an insulated box which faces the sun. As the water courses through the piping in the box, it gets heated by the sun to a fairly high temperature and it drains back into the big tub in the basement. So far, it sounds a lot like the swimming pool guy's set up, no? Except that if you build the insulated box properly and attach black aluminum fins onto the copper piping, you get way more efficient solar heat transfer and the water gets hotter, faster and if you've got it all sealed up and insulated really well and placed in the right location, at an angle facing the southerly sun, you could be getting hot water from the panels well into the fall season and maybe even beyond.

Now the tub of hot water in the basement isn't the hot water you actually run through your taps because that probably wouldn't be very healthy. This tub holds the hot water you use to heat the hot water that runs through your taps. It's a heat exchanger, in other words. You take the cold tap water that is going to your gas or electric hot water tank and you pipe it through coils sitting in the solar hot tub so that the cold water gets pre-heated. If the solar heated water in the tub is hot enough, it may even heat up the tap water to a high enough degree that the hot water tank doesn't have to do further heating and suddenly you've got no hot water heating bill. Freebie!

There are some electronics which should probably be installed to safeguard against freezing when the temperatures outside get too cold and the sun's behind clouds and also to make sure the water in the tub doesn't get too hot (yes, that can happen) but besides that, the system is pretty simple to understand, build and maintain.

So, have I built one of these things yet? Not yet, but it's a test project Adrian and I hope to do sooner than later. It's certainly something Adrian plans on setting up on his roof once his house is built. We'll be sure to let you know how it goes.

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