Pennsylvania is a four season state, which is one of the reasons it is a great place to live. Even though the temperatures fluctuate above ground, the temperature about 8-10 feet below the surface stays around 50°F (http://extension.psu.edu/energy/geothermal-energy). While 50°F sounds cold in actuality it is 50 degrees of heat energy that geothermal systems move to heat or cool your house. One unifying theme that I try to burn into my science students’ heads is that “energy” likes to move from area of higher concentration to lower concentration, this same concept is what drives the really complicated and hard to explain condensers, loops and heat pumps. The simplified explanation is that the heat is moved from the ground into your house in the winter, and from your house to the ground in the winter. I was going to try to write a post that was all scientific and sexy to get folks really excited about geothermal but instead I think the easiest way to explain it is to check out these awesome graphics Mike Armstrong created for Morrison Inc. Tomorrow I will have information about what tax breaks and incentives are available for people who install this type of system. Anyone have any experience with geothermal? What do you think the pros and cons are?