One of the problem with geothermal is that you simply can't just stick a geothermal plant anywhere you want to, so it's potential is limited by geology, and in fact, there are more places in the United States where you can't put a geothermal plant than there are where you can simply due to the geology. Now, that's not to say that we shouldn't pursue geothermal in areas where it is practical, but there are also other factors that need to be considered.
For instance, you can forget about building any geothermal plants virtually anywhere along the coastline of the Gulf of Mexico, and in most places for up to 100 miles inland, as all of that land is sedimentary, and is slowly sloughing off into the Gulf. For instance, New Orleans is expected to be IN the Gulf of Mexico in the next 200 years, not from erosion, but from the fact that the land is sloughing off into the Gulf. Access to any rock formations necessary for geothermal plant operation are too deep to easily access, and even if the bore holes were lined, the casings would eventually become so deformed that they would break, thereby necessitating a new hole to be drilled.
There is also the expense of drilling through igneous rock, as in much of the East Coast, and specifically in the area around Atlanta, in the Black Hills, in West Texas, and other similar locations, thereby making the location of a geothermal plant in those locations economically untenable.
Another example, if you're going to build them along geologic fault lines, you need to be prepared to have your source of energy shut off in an earthquake, possibly forever. Building geothermal plants in western California would be risky to say the least, as it's very tectonically activity, while making it relatively easy to access, could also result in a severe economic loss, not due to the destruction of the plant itself, that's easy enough to engineer for, but from tectonic shifting, which could easily cut off the source, which would require re-drilling the shafts.
Geothermal plants should ideally be places where the crust is thinnest, as the heat source (the core of the Earth) can more readily be replenished, whereas in areas where the crust is thicker, the plant will eventually cause the crust to cool to the point where it can no longer produce, for decades, if not centuries. Ideally, geothermal plants would be placed where known natural wet vents occur, many of which have been located by the very oil industry many seem hell bent on disparaging.
One other point that needs to be made is that the Oil Industry is NOT responsible, in any way, for the efficiency, or inefficiency of a geothermal plant. That responsibility lies solely with the Engineers who designed it. If, in their efforts to keep costs down, they used existing "off the shelf" technology, of course it's not going to be as efficient as it may have been by specifically designing a system from the ground up, but doing specific design is expensive, and the CUSTOMER may not have wanted to, or possibly been able to, afford the additional expense, deciding instead that it was more cost effective to have a less efficient system in place. You have to remember that energy companies, regardless of the source of that energy, are PRIVATE BUSINESS ventures, and they are in the business of generating a profit, as well as energy. Now, if you have a few hundred million laying around, need one hell of a tax write off, and want to help mankind in the process, by all means, build a geothermal plant and give the power away, otherwise, quit being obsequious, and stick to reality.
