Citation

http://www.ianswer4u.com/2012/02/geothermal-energy-advantages-and.html#axzz3JvaY0r29
http://www.dougrye.com/advantages-disadvantages-geothermal-energy.html
http://www.conserve-energy-future.com/Advantages_GeothermalEnergy.php
http://www.cooltoday.com/blog/article/florida-geothermal-heat-pumps