Quantitative Influence Evaluation to Microorganism Ecosystems by Ground Source Heat Pump System

Abstract

It is important to grasp and evaluate the influences of harnessing the geothermal energy (i.e., the use of Ground Source Heat Pump (GSHP) system) on subsurface ecosystems. GSHP system acts as a heating or cooling system that transfers heat from or to the ground, causing subsurface temperature changes. Though the influences of such temperature changes on subsurface microorganism ecosystems needs to be elucidated, the evaluation methods have not been established yet.

In order to establish a method to quantitatively evaluate environmental impacts of GSHP system in the long term, we performed field tests to analyze how soil temperature changes due to the use of GSHP system affected subsurface ecosystems, especially microorganisms, using the latest analytical techniques.

Microbial and chemical analyses were performed for all the soil samples in the test field (sandy fine grained soils) in two years period. The results showed little or no influences on the subsurface microorganism ecosystem through the heat exchanges caused by GSHP system under operating conditions based on proper design.