On Tue, Nov 5, 2013 at 11:17 AM, Henry Spencer <henry@xxxxxxxxxxxxxxx> wrote:
Now THAT would be revolutionary - drill two ~$10 million fracked dry
wells with the right geometry, pump water down one, get steam out of the
other to run some number of megawatts of power plant indefinitely.
The idea is an old one -- I remember seeing it suggested many years ago --
although fracking technology may make it work better. The main problem
in earlier attempts, as I understand it, was establishing a long-lived
network of fine cracks connecting the two wells. In particular, erosion
had a bad habit of gradually concentrating the flow into a few wider
channels, which didn't make nearly as good a heat exchanger.
While this is getting really OT even for arocket, ;) there's a
fundamental challenge with large-scale geothermal problem. It's
discussed in depth here:
http://physics.ucsd.edu/do-the-math/2012/01/warm-and-fuzzy-on-geothermal/
but summed up as: "thermal depletion is a dimensional problem. You can
draw out energy according to volume, but it is recharged according to
area. So the problem is dimensionally stacked to come up short,
leading to thermal depletion."
