Tuesday, August 18, 2009
The Colony Experiment
Almost a month ago, Discovery channel debuted a new reality show called "The Colony", a post-apocalyptic exercise based on the premise of a handful of survivors of a viral pandemic banding together in Los Angeles and attempting to work together to survive in their new reality.
Time Magazine reviewed the show, saying in part: "Of course, The Colony can't really reproduce the strain of surviving the end of the world. Its subjects haven't actually seen most of their loved ones die; they know they will return to a functioning society; we know (and a title card reminds us at the end) that experts are standing by to help them if they meet any actual danger. Still, the show is loaded with interviews with psychologists and homeland-security experts to remind us of the theoretical stakes." And they're right. However, the show does contain some useful information.
Actually, I had not even watched the show until tonight. In fact, I only heard about it for the first time a few days ago on an online forum, where some folks were discussing the fact that the team members built a generator using a small engine and an automotive alternator (something longtime readers know I am quite familiar with), and had to switch to a smaller pulley on the engine, from the 8 inch or so pulley they started out with, in order to get enough power to charge their battery bank. The commenters on the forum agreed that this was backwards from their understanding of how it should work.
This piqued my interest, so tonight when I noticed that Discovery was running a marathon session of the show, I sat down and watched a few hours of it. So here are my comments.
First of all, the forum members are correct in that a larger pulley on the engine spins the alternator faster and thus should produce more, not less power. The problem is that, with the small engine used, that large pulley brings the alternator to a speed which produces maximum power at an engine speed too low to supply that power. The engine they used needs to reach at least 2000 rpm and preferably 2500 rpm before very much load is put on it, and the 8" pulley doesn't allow that to happen. Also, even if you controlled the field and didn't switch it in until the engine reached 2500 rpm, the 8" pulley doesn't allow enough torque transfer because it "gears up" and trades needed torque for unnecessary speed. I know this, because I've tried it. If they hadn't just happened to have a smaller pulley, though, they could have bypassed the built-in regulator in the alternator, and scrounged something to build a power resistor to gain more control over the field, bringing down the output to something the engine could handle, even with the oversized pulley. That would be a good idea, even with the proper sized pulley, because the stock regulator does a terrible job of charging a battery bank.
In such a situation, the thing to find to build such a power resistor would be a piece of nichrome wire from an electric heating element in a space heater, water heater, stove, or something like that.
While on the subject of the electrical system, I noticed something else I would like to mention: in the episode where the traders came around in their truck, they had a little "difficulty" getting power to demonstrate the functionality of the air compressor they were trying to trade. They covered it by yelling about the inverter being off, the cord unplugged, etc. But I chuckled as I imagined the set technicians scrambling in the background to plug into line power when they suddenly realized that inverter wasn't ever going to start that compressor! In fact, there's a pretty good chance they had to replace the inverter after that little fiasco; which highlights another reason a decent-sized AC generator (like the one they were bartering for) is better than the alternator setup: the inverter is the bottleneck when it comes to running big loads.
They had their stuff together a bit more with the plumbing. That shower is a work of art, and they demonstrated flushing a toilet by pouring water directly into the bowl. They do need to tie the two together, by using the greywater saved from the shower (not to mention greywater from other washing chores) for flushing.
Just a couple more comments: IMHO, they need to keep the nanny goat for her milk, but barbeque the young goat. Also, somebody is gonna have to put Michael in his place. He has some useful skills, yeah; but in every other way he is detrimental (and I stress mental) to the group.
Added Aug. 18: I'm watching the show right now, and Michael is lamenting that, since their new genny doesn't work right, he can't weld. Actually, all he would have to do is connect 3 of the batteries in series for 36 volts, and he can weld with that. Or, if he controlled the field of the alternator as discussed earlier, he could use the output of the alternator directly for welding. Like this:
The pedal-powered washing machine was pretty ingenious. I would like to try that, but I think I would prefer to use a 15-gallon plastic drum.