There is a fundamental difference between geothermal, or GCHP systems, and other renewable energy technologies. The difference is that wind power, photo-voltaic (PV) systems, biomass systems and hydro-electric produce power. A GCHP system reduces the need for power.
The difference creates a different mindset in how people think about a GCHP system and how we can use energy from the ground. A GCHP uses electricity to move thermal energy to and from the ground to provide heating, cooling and hot water. It doesn't matter how the electricity is created...whether it's produced by burning dirty coal or from a PV system. It uses less power than almost any other fuel used to heat and/or cool your home or building.
I recently heard of a good example of how this can change the way you think about energy. A large PV system was installed on the roof of a large building. The stated purpose was to reduce the use of power from the grid and use renewable energy in the facility. It reduced power consumption by about 40 kW. That's enough power to reduce energy costs for cooling the building by about $4,500 annually (at $0.10 / kWh). The cost of installing the PV system was approximately $220,000.
Another option that, unfortunately wasn't considered, was to change the roof from a conventional dark colored gravel roof to a white roof that reflected much of the sun's heat. Installing this kind of roof was estimated to cost about $150,000. The interesting thing is that it would have reduced the cost of cooling the building by about the same amount - $4,500 annually. It cost less to install and saved as much.
A GCHP does the same thing as a white roof...it reduces the need for power in the first place. There are many other things that can be done to reduce the need for power...efficient lighting, better glass, energy recovery from ventilation air...and these should be done before looking at ways of producing any kind of power.
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.