By Mark Jones
On the second pull, there was a cloud of white smoke and the engine sputtered to life. My 20-year-old snowblower was ready to tackle the fresh snow. The 2-cycle fumes hitting my face come with twinges of guilty. I don’t need to use the snowblower. My trusty snow shovel offers a fumeless, fossil fuel free option.
The snowblower has been mostly idle recently. Snowfall is well below average this winter and, now retired, I have been shoveling. It is better for the environment. It gives me some exercise, too. I’ve done testing and I’ve done some math. Shoveling takes four times longer than snowblowing when the snow is less than an inch or so. More snow doesn’t change the time required to blow by much — but it increases shoveling time significantly. The four inches on the drive today would require five times longer to shovel.
Creating a new unit is almost the height of arrogance. Thinking I’ve come up with something so profound it requires a new unit is a big leap. I am about to do it, wishing my last name was more interesting, something more akin to Volta or Kelvin, and didn’t share the same first letter as Joule. Jones is sure to be a tough sell as the name for a new unit.
My snowblower saves me time by converting energy to useful work. Time Saved per Energy Consumed, TSEC, is my new unit. Seconds saved per megajoule expended in the SI implementation. Today’s snowblowing took me about 36 minutes and 0.2 gallons of gasoline, 26 megajoules. Shoveling would have taken 3.25 hours. I saved 363 seconds per megajoule. That’s 363 Joneses.
Not all energy is used to replace labor, but much is. Ads may lead us to think we drive and fly for the thrill, but we do it to save time. Snowblowing is a nice case since there is such an obvious manual comparison.
A TSEC of 363 Joneses is higher than most other activities. Compared to walking to my local grocery store, driving saves only about 175 seconds per megajoule consumed. Flying to visit my son rather than driving, a 600-mile trip, is a relatively low 30 Joneses.
Time is money. Both time and energy are easily converted to dollars, further justifying my use of the snowblower. Energy cost for the snowblower is $3.12/gallon today. Time doesn’t trade so transparently. Using $15/hour as the cost of time, 363 Joneses means every dollar spent on gasoline avoids $64 of labor. Return increases with higher wages, with higher value time. Parity for 363 Joneses is easily calculated. $200/gal of gasoline is where energy cost and labor cost at $15/hour are equal, at least in my driveway in the snow.
Gaining time at 363 Joneses, a pint and a half of gasoline, 62 cents worth, processed through my snowblower, freed up two and a half hours of time. The megajoules were well-spent. I am skeptical, but hopeful, Jones will stick as the unit of TSEC. Only time will tell.
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Filed Under: Technical Thinking