Potential for Geothermal

Over here at Damn Interesting, there's an article on the deepest hole ever. It's something like 12.5 km deep and there's all sorts of interesting stuff that they found out. What i found interesting however was that this was a Russion effort that started at the same time as the space race and it's still the best effort to date!
Next time someone bugs you about "it's CO2 or nuclear - make a decision", feel free to point out that we haven't even begun to get serious about extracting energy from sustainable sources - i mean, for crying out loud, you'd think in the 21st century we could dig a 10 km hole with a fair chance of success, chuck in a working fluid and hey presto, it's turbine time. Plenty of technological problems of course, but come on, it's not nuclear physics (which is literally the alternative!).