Here's the first problem with that Aussie plan: even if it were possible to extract a meaningful amount of heat from that granite rock there virtually no heat recharge capability. There is not a giant nuclear reactor down there pumping out heat. That heat took millions of year to develop that heat content via the incredibly slow decay of a very tiny amount of radioactive minerals. IOW the amount of heat CURRENTLY being generated in that granite rock is the same as is being generated from someone’s granite counter top in their kitchen. I doubt anyone would try “geothermal recover” in their kitchen. LOL.
So once the heat is extracted from that down hole portion of the Aussie wells it has to be replaced by the surrounding rock that’s still very hot. I won’t take the time to go over the details about the thermal conductivity of rocks so go research it if interested:
http://www.gly.uga.edu/railsback/PGSG/T ... rmal01.pdfBottom line: the thermal conductivity is so low that it would take hundreds of years to replace even that very small amount of heat extracted. “Dry rock” geothermal energy, as this would be define, has no significant commercial application as far as I've been able to discover.
As far as existing geothermal projects they are “wet rock” systems. And though they may be in the same regions with volcanic activity they are not getting their energy from volcanos but the heat generated from deep magma chambers which are also the source of volcanos. The most significant geothermal in the US is The Geysers in Ca.
http://www.gly.uga.edu/railsback/PGSG/T ... rmal01.pdfLong ago the Rockman worked for the company that owned the project back then and was given a tour as well as chatting with the geologist that handled drilling ops. In this case the proximity to the magma chamber does allow a relatively rapid recharge of the heat extracted. But even with that heat replacement they eventually lacked a critical component: water. Here’s a short bit from their web site:
“Sustainable power generation at The Geysers is possible today because of two large-scale wastewater injection projects from Lake County and the City of Santa Rosa. Together, these projects provide approximately 20 million gallons of reclaimed water per day for injection into The Geysers reservoir. The vast amount of heat in reservoir rocks efficiently converts the water into steam and supplements the production of original reservoir steam to Geysers power plants. Throughout the 1970s and 1980s, vastly more steam was produced from The Geysers reservoir than was replaced by the injection of power plant steam condensate. By 1989, accelerated development had caused severe steam pressure decreases in the reservoir, resulting in lower steam production rates. This decline threatened the future sustainability of Geysers power generation.
To sustain reservoir pressure and steam production, The Geysers needed a large, reliable supply of water that could be used to augment injection. In 1990 a collaborative effort between Geysers operators, Lake County and the California Energy Commission identified Lake County wastewater from the southeast regional collection system as the preferred source of water.”
Ironic, eh? Critical to maintaining feasibility they need a lot of water from the rather dry (and getting drier) state of Ca.
As far as finding “hidden” sites of vast concentrated geothermal energy that hunt was over decades ago. But there was a source of very hot (300F+) water known for many decades: it’s called S. La below 15,000'. And there was no lack of such heat: trillions of bbls of very hot salt water. And thousands of existing wells already drilled and being drilled into those reservoirs by 1980. A huge chunk of govt money was directed into such projects back then but failed to develop economic projects. The effort even had a boost from recovering some NG from the produced hot water but it didn’t help enough. And when energy prices spiked again less then 10 years ago the idea resurfaced. From 2009:
http://www.houmatoday.com/article/20091 ... /911149941Noticed that a portion of the monies being invested 6 years ago came from the govt:
“Geothermal energy emerging as another alternative - A process that relies on heated, pressurized water to create significant amounts of energy from either natural or manufactured sources continues to gain momentum in south Louisiana. The U.S. Department of Energy awarded $5 million in federal stimulus money Monday to Louisiana Geothermal, an up-and-coming company that boasts it will be able to produce enough energy within the next two years to power all of Cameron Parish. In fact, research suggests there’s enough of the alternative-energy source there to last more than 130 years.
In this case, geopressured energy, one of a group of potential power sources classified under the geothermal umbrella, is derived from hot, pressurized waters trapped deep in the earth’s sedimentary formations. The water, heated by the earth’s natural processes, can be used to generate electrical power. Scientific research, some of it sponsored by the federal government, suggests that the area around Turtle Bayou Gas Field in Terrebonne Parish could potentially hold similar promise as a geothermal energy source. In Cameron Parish, locals have known that a geopressured-geothermal system existed in Sweet Lake since the 1980s, but only recently have investments started to surface to support what’s being called the Sweet Lake Geopressured-Geothermal Project.
U.S. Sen. Mary Landrieu, D-Louisiana, is among the lawmakers pushing the issue in Washington for the Bayou State. “Louisiana may be sitting atop a mother lode of clean, renewable energy if we can successfully harness the earth’s natural heat through geothermal energy,” Landrieu said.”
And how did that company Louisiana Geothermal do? The last post on their Facebook page was Feb 2010:
https://www.facebook.com/Louisiana-Geot ... e_internalI tried their website but it appears to no longer exists. Your tax $’s at work. LOL. Maybe when energy prices triple we’ll see a resurgence of geothermal promises from other companies looking for govt grants. In the meantime I think we can table the geothermal enthusiasm IMHO.