human heat in kilowatt-hours/year
Monday, December 12 2005
I'd left my solar sufficiency controller on last night. Through the cold wintery wee hours it was the decisionmaker responsible for deciding whether or not to run the pump circulating water from the solar panel through the plastic hoses embedded in the basement slab. Had it wanted to fail me, it could have easily switched on the pump in the dead of night (when temperatures hovered in the single digits Fahrenheit) and run that frigid hydronic fluid through the slab. Perhaps for this reason I became more acutely aware of the various frequencies of my tinnitus. I've been to some loud rock and roll shows without ear protection and, at 37, my hearing seems as good as ever, though late at night when everything should be silent what I hear instead is various tones layered one on top of the other. They vary in intensity and frequency, but more often than not they are extremely high notes that, in aggregate, sound like the faint hiss of the Big Bang. Hell, that might be what it actually is. But tonight as I lay sleeping, subconsciously monitoring the house for the sound of unwanted pumping, I heard a much lower frequency drone that woke me from my slumber. What was it? I went down to the basement and was relieved - yes - relieved, to find that no pumps were on. What I was hearing was happening entirely inside my head. It was tinnitus, but at a low frequencies I'd never noticed before. Interestingly, the higher of the two new tones (one that happened to be very close to the familiar 60 Hz hum of AC current) would come and go depending on the movement of my head. It was loud enough to keep me from easily falling back to sleep, but by the next morning this particular set of tinnitus notes had mostly faded away.
Perhaps, though, I'd actually been awaken by something else, something very real, in the middle of last night. This morning the neighbor across the street called to tell me I had a pickup truck lodged at a weird angle in the snow bank just below out house, on the outside of the sharpest, most treacherous curve on all of Dug Hill Road. This curve is complicated by the fact that it lies at the beginning of a steep half-mile-long downgrade, though our downhill neighbors tell us that people have even had accidents in this curve coming up the hill. On my way out to do some bank business I slowed down to examine the truck. It was an old and rusty American model and its one legible bumpersticker suggested that I recycle. Aside from being mired to its axles in the snow, it looked uninjured. But if it had gone a few more inches it would have dashed itself against a tree. The thick bank created by the Town of Hurley snowplow had unwittingly set up something of a de facto runaway truck ramp for it.
The weather had become extremely cold by the mid afternoon, and I was out in it using the ever-versatile/ever-shopliftable Gorilla GlueTM to attach a fresh set of reflective numbers to our vinyl mailbox when an old dump truck drove up and a young man hopped out, set up an orange traffic cone, and proceeded to extricate the pickup from the snow bank. He didn't say anything to me and I didn't say anything to him because I knew it all must be extremely embarrassing for him. Later when the dogs ran out to bark at him and I had to call them back, the other guy shouted an apology at me and I shouted back, "Don't worry about it! It doesn't even look like the truck was hurt!" His retort: "I don't know. We'll see when we get 'er down the hill!"
Meanwhile the robot of my solar sufficiency circuitry was making very astute decisions about when to declare solar sufficiency, a condition allowing the valves to swing open and the circulator pump to run. It turned out that the potentiometer adjustments for the specific temperatures of sufficiency weren't all that critical for basic pump control, since the difference between true sufficiency and the absence thereof is a good sixty or seventy degrees. And, since the only suitable application for solar energy in such cold weather is the basement slab, I can actually make use of any water warmer than seventy degrees Fahrenheit.
Meanwhile, the hydronic water coming out of the other end of the slab's hydronic tubing has been a remarkably consistent 55 to 57 degrees Fahrenheit (the thermometer is obviously granular to degrees Celsius, which means that it often changes in two-degree increments while in Fahrenheit mode). I've been unable to increase the temperature of the water leaving the slab above 57 degrees, but on at least two occasions I've been able to correct a downward drift of temperature from 55 back up to 57 by circulating a full day of collected solar energy.
Just for fun, let's do a calculation of the energy required to achieve a modest two degree difference in the slab. The slab is a concrete structure of about 50 by (on average) 26 feet and it is about four inches in depth. That's 433 cubic feet of concrete, which weighs 150 pounds per cubic foot. So that's 65,000 pounds of weight, or 32.5 tons, or 29,480 kilograms of mass. Concrete has a specific heat of 3300 J/kg°K, so to raise its temperature two degrees requires 195 megajoules. 1 joule = 0.000277777778 watt-hours, so this is 53.970 kilowatt-hours, or roughly the amount of energy our new refrigerator uses in six weeks. For comparison, a human, on average, emits about 2.4 kilowatt-hours of heat per day, meaning that I personally burn about twice as much fuel as the new refrigerator, and I do it using one of the most expensive energy sources available: human-grade food. (Remember what happened when I tried car-grade food!)
I prepared the human-grade dinner tonight in the form of a tempeh and rice-based vegan curry, one whose flavor I completely improvised. I don't like east-Asian-style foods as much as Gretchen does, but I was hoping to impress her with my versatility (or, rather, lack of monotony, since I usually only make chili, pasta with hearty sauce, or pasta stir fry). Happily, it turned out better than expected. I've found that the key to the good preparation of tempeh is to brown it in boiling oil. But then again, what isn't improved by being browned in boiling oil? I'm sure the process would even improve the savoriness of Tom Delay, though probably not Dick Cheney.
The truck stuck on the side of Dug Hill Road. That's our house in the background.
The solar sufficiency controller, built into the chassis of an old 2400 baud modem. Those knobs are from that 50 year old oscilloscope I dumpster-dived at UVA in May of 1998. Below it is the household security system controller. The thermometer on it is just for keeping track of ambient boiler room temperature.
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