Where I grew up, nearly every summer our
well ran dry. My father had an arrangement with our neighbor Charlie to lay a
hose down through the woods from his spring to our back yard. My brother,
sisters, and I would fill buckets of water from the hose and carry them into
the house. On Saturday night, my older sister and I shared the tub, dribbling
each other in about two-inches of this hard-won water. It wasn't a traumatic childhood experience,
but it was lousy.
Occasionally, my father, who was always
reluctant to part with money when it wasn't a "pretty good deal",
would consider digging a new well. During one of these periods, my mother, who
was known to have witchy qualities, decided to try her hand at dousing. She
broke off a branch from one of our old fruit trees, and, fists face up, clenching
each forked end and with the end of the branch extended straight out, she began
pacing the property. We followed impressed and optimistic every time the point of
the branch nose-dove into the earth. A
sign of water! (I tried dousing a few years later and experienced this same
earthward movement against definite resistance.
I have no idea if the end of the branch was pointing toward water or
not, but the magnetic pull was mysterious and unsettling.) At the time my mother doused, however, in
spite of her obvious (to us) gift, my Dad wouldn't risk what could have been a
lot of money based on a magic stick and we never had a new well. After my
parents sold our house and moved down to Westchester, the new owners hired a
driller who went down 6 feet and punched into an aquifer that produced enough
water to supply daily baths through all later drought-stricken summers. Ah
well.
On my first day of college, I took eight
baths, after which tub world became a necessity – a place of meditation,
therapy, and warmth. Now, my bath life has come full circle. The bath that was
a luxury when I was kid is a luxury once again. Our barn apartment has no tub,
so since we moved upstate full time, my only water experience for the last two
years comes from our half-assed shower, which spits out mineral-laden water
that mysteriously and unadjustably swings sadistically between scalding and
freezing. Years ago on the Upper West
Side, deep in pain from my brother's death and the end of my marriage, I sank
within the hot healing water of our old cracked tub and experienced the bottom
of grief. I miss my baths. I hate my shower.
In our future fantasy house on the site
next door, we will have two tubs. And,
in anticipation, we now have a well on the site. In fact, not just a well for water, but three
more for the geothermal delivery of heat. To do this work, we hired Keyser
Drilling Company, which, like many small businesses around here, is a
multigenerational one. (Dan Keyser Junior, who dug our wells with one other
young man, is the great grandson of the man who started the business in 1946.)
This winter has been so mud-ridden that Dan and his colleague couldn't start
working until mid January, when the ground surface finally froze. On the day they were able to start, Michael
and I walked down to watch. Two red trucks were lodged a few feet from our
house site: one carried the casings -- long tubes stacked along the side like fittings
for a pipe organ. The other sported a
shaft extending from the back of its bed about thirty feet into air like the
main mast on the prow of a ship. Hydraulic tubes and fittings dangled from it, the
riggings that would pound the drills and casings into the earth.
They dug the water well first, going down 360
feet and piercing an aquifer with an artesian spring that produced enough water
to propel it up the shaft without a pump. Multi-bath time! Over the next three
days they dug three geothermal wells, with one producing a gusher twenty feet
into the air. Water is everywhere here (raising the specter of a floating
basement!).
Right now each of the geothermal wells,
which go down about 300 feet each, has two ends of a tube sticking up like
rabbit ears out of their bores. Each
pair of tubes is joined at the bottom of its well to form a loop. In a week or so Dan Junior and his colleague will
come back and push grout up from the bottom of the wells around the tubing to
anchor them and seal off the water.
The ecological match-up between our solar
trackers and a geothermal system is gratifying. The earth sources the heat for
the system, and the sun feeds the solar panels to produce electricity required
by the heat pump, the heart of this process.
But how does a geothermal system work, one might ask (although one
rarely does). And can one answer this
question without the asker dying of boredom?
And since I am both the asker and, with this blog, the answerer, and
since I took only one physics course, which was designed for poets, I risked
boredom death to whack through the Google
jungle of faux knowledge for geothermal clarification. Here goes.
The primum mobile of the system is the heat
pump. On its behalf, an ordinary water
pump sends a mix of water and glycol (basically anti-freeze) through the loops
down into the wells and back to the heat pump.
After about 10 feet in depth, the earth in our region maintains a constant temperature
of 47 degrees, so as this fluid mix passes through the tubes it absorbs
heat. Now, when I was idly wondering how
this process could actually heat a house to 70 degrees in winter, I was a victim
of a popular misconception: that the fluid was heated to the temperature of the
earth as it voyaged through the loops and when it reached the house, the heat
pump boosted that 47ish temperature up 23 degrees. Wrong.
As Michael reminded me, "Temperature isn’t heat. Heat is energy."
The geothermal system, I discovered, is a
slave to the second law of thermodynamics, which I had to look up. It dictates that when hot and cold bodies
meet up heat energy will flow from the warmer to the colder body until it
reaches equilibrium. So, in winter when the cold fluid is passing through the warmer
earth, an exchange of energy occurs and the fluid warms up. (Heat doesn't move
backwards!) As the fluid moves up into the heat pump, the earth-warmed tube passes
through another one that contains the refrigerant R-410a – a tube combo called a
coaxial coil. Once more, the thermal law #2 police go into action. Liquid R-410a
has a very low boiling point and vaporizes into a gas as it absorbs heat even at the tepid earth
temperature during this legal exchange of warm to cold. The
gas then passes through a compressor, which squeezes the gas back to a liquid. Heat is released during this process and produces the hot water that will someday pass through coils
under our floor, where TL#2 will keep my feet warm. Ta Da!!!
And, although still long months away, let
us not forget the hot water in the soaking tub poised to enact the second law,
exchanging grief and irritation for peace of mind.
(A
note: Unlike the refrigerant Freon, R-410a does not deplete the ozone layer. It
does, however, have 1725 times the effect on global warming than carbon
dioxide. One trusts that reducing
dependence on polluting sources of energy offsets this impact)
