BLOG

The Earth is a (Geothermal) Battery!

May 24, 2013 by Woolpert

Yes, the earth can literally charge and recharge energy, using it to heat and cool facilities via a thermal reservoir. The process of using the earth’s soil to store energy results in what is known as a geothermal system, and it depends largely on the geography and type of soil.

Our Fort Campbell client is ideally located for this type of green building strategy. With well-suited soil that has good thermal capacity and transfer rate, and a climate that is suitable based on mild spring and fall temperatures, Fort Campbell quickly realized the benefits of a geothermal system. As a result, they have implemented this green strategy on two projects so far: the Unaccompanied Enlisted Personnel Housing (UEPH) Barracks and Barkley Elementary School.

The process of heating and cooling a facility is fairly simple. According to Renewable Energy World, “Geothermal heat pump systems consist of basically three parts: the ground heat exchanger, the heat pump unit, and the air delivery system (ductwork). The heat exchanger is basically a system of pipes called a loop, which is buried in the shallow ground [or in the case of Fort Campbell, in deep wells] near the building. A fluid (usually water or a mixture of water and antifreeze) circulates through the pipes to absorb or relinquish heat within the ground.” An area known as a geothermal well field provides a home for these pipe loops.

Woolpert worked with Fort Campbell to use an emerging technology from geothermal software providerGreensleeves to help better monitor and control the heating and cooling loads going to the soil. This allows Fort Campbell to use a well field at the most optimum time and under the best conditions, which in turn helped reduce the size of the well field significantly, saving upfront costs associated with installing the well field, while also reducing operational costs over time.

By making geothermal energy a component of the overall efficient designs of Fort Campbell’s UEHP and Barkley projects, we were able to help them reach 56% and 59% more efficiency respectively over the ASHRAE-required 90.1-2007 baseline.

This ‘earth battery’ is becoming more popular, too. Geothermal energy will be the first step in the U.S. Army’s $7 billion renewable energy effort to power its installations. Fort Campbell is a great example of how successful this approach can be.