Greening up America: Ground sourced heatpumps

Since not everyone knows what a heatpump is, it is exactly what it sounds like. All kidding aside it is an air conditioner that can run backwards in the winter. An AC unit only moves heat around, via the compression and expansion of a gas. In the summer a heat pump uses energy to move heat out of a building to the hotter outside. This is not a violation on the laws of thermodynamics since it uses energy to compress a gas making it much hotter then the outside temp. Then by cooling it with additional energy it can be reexpanded inside to remove heat inside. In the winter a heatpump does the opposite. It cools the hot compressed gas inside and warms the very cold expanded gas outside. This allows it to move or pump ~4 units of heat in for every unit of energy consumed. The issue with AC units and heat pumps is they have a range where they are best able to move heat. This ranges from 35 to ~80 F. Just outside that range they use a lot of energy, which makes them inefficient.
This why in the summer during the day there are brown outs. All the AC units are working hard but not efficiently. I once heard more than half the electricity us in the US goes to climate control. If the outside temp goes too far beyond the range AC/heatpumps simply can't move heat and cease to function. There is another option and it is below you feet. In most parts of the country below 6 feet down the ground temp is a steady ~60 year around. (This is way caves and basements are cool.)By burying a long coil in the yard or if space is limiting deep it is possible to ensure the heatpump or AC unit operates at peak efficiency, which reduces the running cost and ensures optimalcomfort. In new construction the hole for a buildings foundation can be dug over sized and the coils installed around the perimeter. Yes a ground sourced heatpump costs ~$7k but with oil and gas prices where they are and where they will likely remain for the next few years, it is likely the pay back period will be short enough that the risk will be low. As of this writing oil futures for 2016 delivery are selling for >$100 a barrel. If there was a tax benefit, it would really encourage adoption, and reduce the demand for oil and gas.The problem with a heatpump is they are power hungry (30 A at 240 V). This is actually a huge power savings, versus traditional AC units or hydrocarbon fueled heaters, but in many cases installing one will require upgrading the power system in the building. In some areas this will also require upgrading the power grid. (Which is needed anyways.) The upside is that the load increase will largely be base load, which is the cheapest power to generate.