What’s an hour worth?
In “The Juice” I discussed the quantity of power my house had consumed in one year. I was surprised out how far below the national average we were, but that wasn’t the most surprising thing I saw in the numbers below.
The surprising thing was the per-kwh cost. Nine cents!
What does that mean? It takes an old fashioned incandescent 60 watt bulb over sixteen hours to use one kilowatt-hour, almost 67 hours with a compact fluorescent. So if you go off to school or work and leave a light on all day you spend a nickel if you’re old school and not even a full penny if you’re newfangled. Worst case, do it for a month old-school and you’ve cost yourself one sixteen ounce soft drink.
According to the US Energy Information Administration, it takes about a pound of coal to generate one kilowatt-hour of electric power. So electricity (conveniently delivered right to my home, 60 watts, 8 hours a day for a month) and root beer (at a local convenience store, chilled, bottled, 16 oz) cost about the same.
At first I thought we were environmental superheroes.
One thing I had to put in perspective when I wrote I Town was energy usage. According to good ole Wikipedia the US uses 3.7 trillion kilowatt-hours of electricity per year and has a population of just under 313 million. That’s about 11,820 kilowatt-hours that each of us use. (We’re 12th in the world, by the way.) My home consumed 14,360 kilowatt-hours of electricity and 1,470 cubic feet of natural gas in one year. To figure our annual kwh equivalent I had to convert the natural gas usage in kilowatt-hours, which is a factor of about 0.8, one ccf of gas is equal to about 0.8 kilowatt-hours of electricity. So that’s about 1,180 kwh in gas. Altogether a house of five people used 15,540 kilowatt-hours in twelve months, or about 3,110 kwh per person. Just over a third of the national average.
I was proud of us. We were really keeping our consumption down! We actually have a pretty big house compared to the one I grew up in, 2800 square feet, but we keep the thermostat on very conservative settings: 79 in the summer and 65 in the winter.
Almost a third , though. Really?
No. Not really. There are lots of other factors to consider in our individual energy consumption. For example, I run. Most of the time I run late in the evening or early in the morning because I have other things to do during the day. The trail I run on is lit all night long so I can run on it anytime. Very convenient! (I do love the Fayetteville trail system, especially after running in other towns.) Now I could figure the amount of time it takes me to run the distance from one light to the next to figure the amount of electricity I need while I’m running. Or I could use my average running time and how many bulbs light the length of the trail where I run to get a little broader view of my electricity consumption on the trails. But all those bulbs are using electricity all night long whether I’m running or sleeping. They’re on for whoever to use whenever they choose. So, to be fair and accurate, I should take the total energy consumption of the trail lights and divide it by the total population of Fayetteville. Then there are all the streetlights burning all night. And all the traffic signals running all day long, using convenient electrically powered sensors so we don’t have those crazy old timers that were absolutely maddening. There are all the city government buildings. And schools. And that’s just local power usage.
What about the state?
What about the usage of all the stores I visit? I can’t very well turn the lights off when I leave.
Basically, what I’ve discovered is that for every kilowatt-hour I use at home, the society I live in uses two on my behalf.