I saved 3 kilowatt-hours of electricity and kept 6 pounds of CO2 out of the air today! (And much more by staying off the road!)

How much energy did I save today by line-drying, I wondered, 

as I hauled a full basket of boy-clothes (including three heavy sweat jackets and a pair of jeans) indoors after dark.  This particular basket weighed* 27lb out of the washer, 23lb after it came off the line, and (because it was still damp with no prospect of improvement in the near future) 20lb coming warm from the dryer. 

Because the dryer is electric, this is easier to figure out than you might imagine.  Key fact: evaporating water takes about 2265 kJ/kg.  (A kiloJoule is about a quarter of a Calorie--a more familiar measure of energy--while a kilogram of water weighs 2.2lb and works out to one liter.)  In other words, the two kilograms of water that evaporated from the clothes while on the line absorbed about 4500 kiloJoules or roughly a thousand Calories of energy in the form of (free!) sunlight. 

I also benefited from my time outside on a sunny, breezy day.

Now for the easiest part: we can directly convert the energy needed to evaporate that water into energy units familiar on our electric bill.  (Stay with me here.)  The familiar Watt of energy is actually a metric unit of power equal to 1J/s (one Joule per second).  And the nearly-as-familiar kilowatt-hour we see on our electric bills is 1000 Watts (1kJ/s) of power expended for one hour's time; in other words, 1 kW-hr equals 3600kJ.  The 4500kJ needed to evaporate the 5lb of water in my son's clothes needed 1.25kW-Hours of electricity just for the evaporation.  If done in the dryer, more electricity would have gone to the motor that keeps the clothes tumbling, and a bit more to see to it that the moist air coming out of the vent was warmer than the dry air that went in. 

That was just the one load.  Before that, I had line-dried a big load of towels and other heavy, absorbent cotton things, and also a smallish load of whites.  I'm guessing the sun evaporated about 5kg of water in all, saving 11,000kJ of energy, equal to at least 3 kilowatt-hours. 

That might not seem like much in monetary terms, but consider that the electric clothes dryer is typically the biggest energy hog in the home, and alone accounts for over one-quarter of the electric bill.  Consider also that--in most areas of the US--generating that energy produces planet-warming carbon dioxide.  Just how much?  Well, that turns out to depend on what fossil fuel is being burned.  Coal runs a little over 2lb of CO2 per kW-hr, while natural gas produces only 1.2lb.  That compares to about 18lb of CO2 produced for every gallon of gasoline your car uses. 

An eye-opening comparison.

My Ford Focus goes about 30 miles on a gallon of gas, which produces about 18lb of carbon dioxide.  So the amount of carbon dioxide I save by a month's worth of line-drying is cancelled out by one day's 30-mile-round-trip commute to work.  (That result surprised me: cars are an even bigger problem than I thought!)**

If you have a gas dryer, by the way, the numbers are much better.  Only a half-pound or so of CO2 is given off by enough natural gas to produce 1 kilowatt of heat--making it four times more efficient.  This is partly because natural gas is a better fossil fuel than coal, but more because a lot of energy is saved by burning the gas directly, and not generating electricity as an intermediate step.  


*And no, if I had any friends I suppose I wouldn't be doing geeky things like weighing my wash and calculating energy use!

**If you own a big car, the best and easiest gift you can give the environment is to switch to a smaller one!  (That makes an even bigger difference than going from a small car to a Prius!)

Doing the Wash

A truism* among nature enthusiasts is that our ancestors** were on average far more intimately familiar with the natural world than we are.  This has become even more true since the electronic revolution made us unable to see farther than our hands.  

I was reminded of that truism this afternoon as I hung out the wash.  

A  month or so ago the clothes dryer stopped getting hot, only endlessly tumbling damp clothes.  Having a certain confidence in my own abilites--not to mention much more time than money--I researched its inner workings with a very helpful appliance repair guru, got my tools out, and quickly found that I needed a new heating coil.  Meanwhile, I lassoed a bathroom vent pipe with a spare anchor line and tied the other end to the garage for a serviceable clothesline.  

We are not new to line drying, having done it for most of a year when we bought the house and hadn't money left over for a dryer.  It came to an end late in spring when a winter moth epidemic sent a rain of frass out of the overhanging tree onto our freshly-washed clothes.  The caterpillars came back in force for several years (spelling doom to two of my favorite oak trees) and confirming us in the machine drying habit.
 
Though it was only 4pm when I hung the wash, I had nearly lost the sun already, the shadow of the house falling on the clothesline so much earlier than even a few weeks ago.  (Likewise, the vegetable garden, which, in July got a full six hours of sun per day, is now down to four; the squash are long dead and the tomatoes won't hang on much longer.  Alas! we only have another week or so of juicy tomato sandwiches.)  Fewer layers of technology necessitate greater attention to the real: time of day, cloud cover, a possible shower, changing seasons.  Clothes dry faster with a bit of breeze, with dryer air, and most of all with direct sunlight--especially if the clothes are not white, reflecting away the warming sunlight.  Towels dry rather slowly, but denim is about the worst.  Even so, with luck I can get a wash load dry in an hour or so--about as long as the next load needs in the washer.  (It helps that our "energy star" washer has a very high spin speed, so the clothes have little water left.)  On the other hand, poor planning, unexpected wet weather, or carelessness might be paid for in mildewed clothing. 

I know only one other household in the neighborhood where wash is hung outdoors.  The home is a few minutes walk away, and the family includes several young children, and a young mother of, I think, Asian extraction.  Hanging out the laundry is an almost daily event, year-round.  The dad is handy, painted the house himself, and did a professional job building a large shed.  The yard is the sort that hints of regular construction projects.  The children play on the porch, or help their parents in the vegetable garden.  The family works and plays together, often outdoors.  I wish I knew them.

When the new heater coil arrived ahead of schedule, I was a little disappointed.  Then I decided that I wanted to see the difference in the electric bill of not using the (electric) dryer.  (Unfortunately, the freezer chose that same time to begin leaking heat, driving the bill through the roof.)  Then I decided I simply liked being outdoors fussing with the wash.  Maybe a Zen thing.  An unexpected bonus was the reduced washing: some of the teenage contingent wash their clothes constantly--until it becomes a little more onerous. 

I dragged my feet on the repair for a good month, and finally got around to it during a rainy spell, as wash--some already wet--waited impatiently for attention.  When I got it all back together, the dryer heated up nicely--and then refused to shut off when it reached operating temperature.  I could stand there and nurse a wash through, judging the temperature and changing settings accordingly, but it was annoying.  I was not too put out, though: back to the clothesline!

I know the languid summer will soon end and time become tighter.  I also know how long it takes to dry wash as the weather cools.  And one good rainy spell will send me back to the basement to install the new thermostat--which I hope fixes it.  And a new spring might bring new caterpillars.  Even so, for now I will enjoy communing with the sun and breeze, basket and clothespins in hand.

*a truism has been defined as something "everybody knows," but which nevertheless is, in fact, generally true!

**Notwithstanding rumors that Thoreau, during the two years he lived in the cabin he built at Walden Pond, used to bring his wash home to his mother.