The word geothermal
stems from the Greek words "geo" for earth, and "therme"
for heat, which literally means heat from the earth.
Our ancestors used
primitive geothermal energy in the form of hot springs
for bathing and cooking. In 1852, Lord Kelvin invented
the heat pump and brought geothermal to a new level. But
it took Robert C. Webber in the 1940s to harness
geothermal for home use.
Webber ran freon gas
through copper tubing underground. The gas condensed in
the piping through his cellar, released its heat and
expanded. The expansion moved it through the ground coil
to pick up another load. He set up a fan to distribute
the "conditioned air" through his home. He was so
pleased with the results that the next year, Webber sold
his old coal furnace.
Webber's system
worked because air temperatures change constantly, yet
soil temperature in the earth's upper 10 feet stay
consistently between 50 and 60 degrees Fahrenheit. That
means that in the winter, the soil is much warmer than
the air, so heat can be taken from the soil to warm a
home to 50 or 60 degrees. A supplementary heater can
warm the air the rest of the way as it circulates
through the house.
In the summer when
the soil is cooler than the air temperature, the process
is reversed and warm air from the house is cooled by
underground temperatures brought into the house.
Geothermal heat
pumps are vastly more efficient than regular heat pumps
because the heat is moved around through water
circulating between the building and the earth in
"ground-loop" piping buried in the ground.
In the summer the
water is warmed by the heat of the building and
transfers that warmth into the ground. In the winter,
the water is warmed by heat from the ground and
transfers that heat to the building. Heat pumps move the
water through the tubing so that the transfer is
continuous.
According to the
U.S. Environmental Protection Agency, geothermal heat
pumps are the most energy-efficient, environmentally
clean, and cost-effective systems for heating and
cooling. The EPA found that geothermal heat pumps are on
average 48 percent more efficient than gas furnaces and
75 percent more efficient than fuel oil furnaces. This
translates into a savings to consumers of 30 percent to
70 percent of their heating costs, and 20 percent to 50
percent of their cooling costs. These reductions help
offset the costs of installing the expensive equipment.
John Lynch wrote in
"Home Power Magazine" that the average payback for a
geothermal system for residential use is about seven
years. He notes "if the cost of maintenance and
replacing equipment over the long term are taken into
account, the payback period becomes shorter."
"Inside-the-home
costs of installing a 10 kilowatt heat pump system is
$7,656, and the cost of the ground loop is $3,364 for a
total of $11,020," says Lynch.
Other estimates for
geothermal systems can go as high as $30,000 for a
similarly sized home. Compare that to the cost of a new
oil-fired boiler which is around $8,000, and you see why
the cost difference can scare many homeowners away.
The payback period
on larger buildings can be as small as five years,
making geothermal especially appealing to schools and
community centers. The Howland Cultural Center in
Beacon, N.Y., raised $90,000 from city, county and state
grants, and from the community by hosting concerts by
local musicians, poetry readings, coffee houses, and
membership donations, according to Michael Jurkovic,
Howland board member.
Geothermal installer
Charles Lazin of Altren Consulting, drilled five
geothermal wells 400 feet deep between the Howland and a
neighboring brownstone building. Two heat pumps
distribute air to two main zones at the Howland - a
large performance and exhibition space and a smaller
office area. Lazin estimates the Howland's system will
cut heating costs by 50 percent or more, helping to
offset the installation costs with energy savings.
Jurkovic points out
that the Howland system delivers "hot water, that comes
as a result of the exchange process, has made our
patrons and visitors who use the restrooms real happy."
According to the
Geothermal Heat Pump Consortium:
- Surveys by
utilities indicate higher levels of customer
satisfaction from geothermal systems. Of all geothermal
customers, 95 percent would recommend the system to a
friend.
- The 900,000
current geothermal installations have eliminated more
than 5.2 million (metric) tons of carbon dioxide
annually.
- Current geothermal
systems have saved more than 7 billion kilowatts in
electricity, and 36 trillion BTUs of fossil fuels.
- The energy savings
of these geothermal installations are equal to taking
more than 1,165,000 cars off the road, planting more
than 346 million trees, and reducing U.S. reliance on
imported fossil fuels by 19.3 million barrels of crude
oil per year.
For more info
contact the Geothermal Heat Pump Consortium at
www.geoexchange.org/
Shawn Dell Joyce is
an award-winning sustainable artist and writer who lives
in a green home in the Hudson Valley of New York.
Visit Copley News
Service at
www.copleynews.com.