What is a ground
source heat pump?
Ground source heat pumps (GSHPs) are electrically powered systems
that tap the stored energy of the greatest solar collector in existence:
the earth. These systems use the earth's relatively constant temperature
to provide heating, cooling, and hot water for homes and commercial
buildings.
How do ground source
heat pumps work?
Ground source heat pumps can be categorized as having closed or open loops, and those loops can be installed
in three ways: horizontally, vertically, or in a pond/lake.
The type chosen depends on the available land areas and the soil and
rock type at the installation site. These factors will help determine
the most economical choice for installation of the ground loop.
For closed
loop systems, water or antifreeze solution is circulated
through plastic pipes buried beneath the earth's surface. During the
winter, the fluid collects heat from the earth and carries it through
the system and into the building. During the summer, the system reverses
itself to cool the building by pulling heat from the building, carrying
it through the system and placing it in the ground. This process creates
free hot water in the summer and delivers substantial hot water savings
in the winter.
Open
loop systems operate on the same principle as closed
loop systems and can be installed where an adequate supply of suitable
water is available and open discharge is feasible. Benefits similar
to the closed loop system are obtained.
History
Ground source heat pump technology is the wave of the future, but
the concept isn't new at all. In fact, Lord Kelvin developed the concept
of the heat pump in 1852. In the late 1940's, Robert C. Webber, a
cellar inventor, was experimenting with his deep freezer. He dropped
the temperature in the freezer and touched the outlet pipe and almost
burned his hand. He realized heat was being thrown away, so he ran
outlets from his freezer to his boilers and provided his family with
more hot water than they could use! There was still wasted heat, so
he piped hot water through a coil and used a small fan to distribute
heat through the house to save coal. Mr. Webber was so pleased with
the results that he decided to build a full size heat pump to generate
heat for the entire home. Mr. Webber also came up with the idea to
pump heat from underground, where the temperature doesn't vary much
throughout the year. Copper tubing was placed in the ground and freon
gas ran through the tubing to gather the ground heat. The gas was
condensed in the cellar, gave off its heat and forced the expanded
gas to go through the ground coil to pick up another load. Air was
moved by a fan and distributed into the home. The next year, Mr. Webber
sold his old coal furnace.
In the forties,
the heat pump was known for its superior efficiency. The efficiency
was especially useful in the seventies. The Arab oil embargo awakened
conservation awareness and launched interest in energy conservation
despite cheap energy prices. That is when Dr. James Bose, professor
at Oklahoma State University, came across the heat pump concept in
an old engineering text. Dr. Bose used the idea to help a homeowner
whose heat pump was dumping scalding water into his pool. Dr. Bose
fashioned the heat pump to circulate the water through the pipes instead
of dumping the water into the pool. This was the beginning of the
new era in geothermal systems. Dr. Bose returned to Oklahoma State
University and began to develop his idea. Since then, Oklahoma has
become the center of ground source heat pump research and development.
The International Ground Source Heat Pump Association was formed in
Oklahoma, and is based on the campus of Oklahoma State University,
where Dr. Bose serves as executive director.
