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Learning Center
Geothermal Basics
So exactly what is Geothermal Energy?
Geothermal Energy is heat that comes from within the earth and is a powerful and under-used energy source. One of it's most popular occurances
historically stems from the many world renowned Hot Springs and Spas that feature streams and pools of warm or hot water. Naturally heated within the earth, the water eventually makes it's way up to the surface and creates quite the draw for a fun and relaxing time.
Aside from fun, Geothermal Energy can also act as a cooling agent in stifling hot summer months, or have a heating effect in the cooler months. The
temperature within the earth is remarkably consistant, and when harnessed properly, it allows us the opportunity to provide extra warmth or remove
excess heat.
Not only is Geothermal Energy beneficial in both the summer and winter months, but is exceptionally reliable and is a 'clean resource' (emitting little or no greenhouse gases). Geothermal Heat Pump systems differ from conventional furnaces or air conditioners because the geothermal system focuses on transferring hot air to the desired location as opposed to the latter which uses energy to create the hot or cold air.
Where can I find Geothermal Energy?
The most common Geothermal resources available to us are (1) hot water and rock that is located well below the earth's surface
(one mile or deeper) and (2) shallow earth located just under the frost line.
1. Hot water and rock deep inside the earth
Several miles below the earth's surface there are hidden pockets and reserviors of hot water and rock. By drilling a mile-or-more
down into the earth, in a process similar to drilling for oil, it is possible to create hot water or steam wells that provide a
valuable resource in creating energy. These geothermal reseviors are target spots for geothermal power plants who tap the hot water
and steam to drive their turbines and electricity generators.
2. Shallow earth under the frost line
Everyone who owns a home with a basement is well aware that it usually the coolest place in your home during the summer (not taking
an air-conditioner into account), and stays warmer throughout the winter months. It is in using this logic that we can take advantage
of the geothermal energy that is found within the top 10 feet of the earth's surface. The science behind the logic is that the top 10
feet of earth, basically anywhere in the world, maintains a nearly constant temperature of 50 and 60°F or 10 and 16°C. With such a stable
temperature, it allows the earth to act as either a heat source or heat sink depending on the season and the weather. For most residential
and small business dwellings, this is the most likely method that they too can take advantage of a geothermal energy system, or 'GeoExchange'.
How do you capture Geothermal Energy?
There are three main parts within a GeoExchange system: pipes that are buried
within the ground, a heat exchanger and ductwork to distribute
(or remove) the heat throughout the building. The series of pipes buried in the ground near or under the building are called a 'loop', and are
available in many different patterns ( including vertical and horizontal). The size of the loop depends on the size and demands of the building
that requires heating or cooling. On average, one loop (400 to 600 feet) will transfer 3.5 kilowatts worth of heat energy. To put it in context,
the average home would require 10 to 18 kilowatts and would thus require 3 to 5 loops of underground piping.
The heat transfer goes into effect when a liquid (water or a mixture of water and antifreeze) circulates through the underground loops and either
absorbs heat from or releases heat into the ground. As a basic rule of heat, high heat gravitates towards areas of lower heat, so in summer months,
the liquid absorbs heat from the building and follows the pipes out of the house into the loop, where the extra heat transfers into the cooler
surrounding earth. In the winter months, the effect is reversed when the liquid absorbs extra heat from the ground and delivers it into the
building. As the liquid enters the building, it is required to pass through a heat exchanger which is the transfer point for the heat before
the liquid cyles through the loop again. A heat pump is located within the heat exchanger and is responsible for temperature control. There are
also specialized 'hybrid' heat pump models that not only allow the use of GeoExchange to regulate the temperature of the building, but also
provide hot water heating functions.
 
How would I benefit from Geothermal Energy?
Electricity Savings-
GeoExchange systems will dramatically drop your electricity requirments ( and more importantly-- your bill). GeoExchange systems out-perform even the most efficient gas technology, and gas heat pumps, by an average of 36 percent in heating mode and 43 percent in cooling mode. Energy costs with GeoExchange typically are 25 to 70 percent less than other HVAC systems and energy requirements.
This 3,000 sq. ft. house in Oklahoma City has a verified average electric bill of $60 per month - using a geothermal heat pump.
Investment Payback-
GeoExchange systems also have an long expected equipment lifespan (systems are often warranteed for 25 years and the ground pipe often will last over 50 years).
Tailored Comfort-
Due to the 'zone' conditioning functionality that allows specific areas or rooms to be heated or cooled independently from each other, GeoExchange systems are highly advantageous in Schools and other similar buildings.
Flexibility -
-GeoExchange systems typically take up much less space than traditional HVAC systems, and particularly suitable for situations where space is at a premium and/or for aesthetics purposes.
-Geoexchange systems are optimal for commercial buildings as they provide the architect with optimal design flexibility because the roof and landscape are free of chillers, air handlers and other outdoor equipment. In addition, with geoexchange systems, boiler rooms can be eliminated and the size of mechanical rooms can be reduced.
-Due to the design flexibility, a GeoExchange system can be implemented in both new and retrofit situations.
Eco-friendly Benefits-
-If every school district in North America that needed to replace a heating and cooling system in the next 10 years decided to install geoexchange systems, the total energy savings over that time frame would exceed $11 billion.
-The electricity required to power one million homes for one year would be saved if every North American school that could use geoexchange did so.
-GeoExchange qualifies as a renewable energy - a typical two bedroom house-sized installation is equivalent to taking two cars off the road or planting one acre of trees.
References:
http://www1.eere.energy.gov/geothermal/overview.html
http://geothermal.marin.org/GEOpresentation/
http://www.marshallutilities.com/residential/geothermaldiagram.gif
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