Chapter 6: Geothermal Energy Systems

Contents

Chapter 6:  GEOTHERMAL ENERGY

--Production of Electricity--

Draft Date:  December 31, 2007

Author's note:  This is a preliminary draft and a work in progress.  (Further explanation.) 

Examples of Installations:

Production of Space Heating and Cooling

In most areas of the United States, the ground temperature at a depth of 8 feet is over 50 degrees.  Placing tubes at such depth and circulating air through them causes the circulated air to be either warmed or cooled towards the temperature of the earth surrounding the tubes.

Examples of Installations:

1.  Oranges in the Snow Greenhouses in Alliance, Nebraska, have 1,100 feet of 6 inch tubes buried in the earth through which air is circulated by a three-quarter horsepower blower.  The ground-effect-heated air from the tubes keeps a 85-by-16-foot greenhouse above freezing at a cost of less than $500 per year for energy.  The ground-effect air is also used to cool the greenhouse in summer.  The greenhouse has been in operation growing citrus for 15 years, producing 120 pounds of top-quality fruit each year.

The housing for the operation uses the same ground-effect air to flow through a room that contains the outdoor unit of a standard heat pump.  The air warmed by the earth “fools” the heat pump into thinking it is in a warmer climate than is the case, so the unit runs on its compressor heat exchange mode year-around rather than engaging its energy-hogging high resistive heat mode.