Pancreas_sl said:
Geo Thermal really doesn't work as a stand alone heating system last I knew. It can bring the ambient temperature of the home to whatever the ground is at the time, usually like 53 degrees F or something like that. Then you must use some other heat source to finish the job. Nice thing about it, is it does double duty in the summer for cooling.
Yeah, it does work as a standalone heating or cooling system with heat pumps. It's just a question of how efficient it is, or rather the return on the electricity it consumes. Basically heat pumps can remove or add heat to the geothermal loop, depending on whether it's heating or cooling. So the geothermal field, wells, or pond acts as a big heat sink that you pull heat from, or reject heat to.
The upfront cost would be much more than going with an electric furnace, but over the long run it would be way the fuck cheaper since you'd be using a fraction of the electricity to run the pumps and the compressor in the heat pump as compared to just using an electric element. I think that good geothermal heat pumps these days have coefficients of performance of something like 6-8, meaning that the net energy gain is 6-8 times the electricity consumed.
The other advantage is that you'd get cooling to go with your heating, as the system works both ways. You can also get them with a domestic water connection, so coupled with a storage tank they can provide your domestic hot water (but the COP will drop when trying to heat water up to 120-130F as opposed to just heating air to 90F or whatever for forced air heating).
Heat pumps sound fancy and/or newfangled, but they've been used in commercial applications for decades. In those applications the heat and cooling source is generally a boiler and/or cooling tower/chiller. The only difference with a geothermal system is that the ground or lake act as your buffer, instead.
Your local climate as well as the soil conditions will determine how big of a field you need if you go horizontal, or how many and how deep of bore holes you'll need if you go vertical. Basically the system has to be designed by a professional to ensure that you don't either freeze up or overheat your system if it's undersized.
No idea how a geothermal system would compare cost-wise over the long run, whether or not you include the initial investment. It would certainly be much, much cheaper than straight electrical heat in terms of operating costs. Pay-off wise, that would depend on how expensive or cheap electricity is in your area. Compared to a natural gas furnace, the initial capital investment would be much higher, and the system would need a lot more maintenance as there's pumps involved. Natural gas is pretty fucking cheap right now and not likely to go up much in the next 5-10 years with the glut of supply coming to market, so I would imagine that it would be tough to beat if you include capital costs for the comparison. However if you have reasonably cheap electricity, then a geothermal system might beat it over the long run.