Thermosiphon for hot-water solar panels has been around for decades, so it seems plausible it would work here. The main potential obstacle is that you typically don't get water flowing as fast as a pump could drive it, so gross heat output is lower. But if your drilling costs are low enough the total capital cost works out, I guess...

Whoopee! ''They've just reinvented the wheel!''
The earliest water based central heating systems used gravity/thermal feed, in exactly the same way this system works.
They were generally abandoned, for pumped systems, using small bore pipework, due to the much higher cost of the large bore pipes required for the gravity system to operate effectively,
Also, I've been saying for years, to anyone who would listen, that the only sustainable long term power source, is geothermal. Some ''off grid'' adherents are also experimenting with similar systems, but obviously, in a much smaller capacity.

This is significant. I have friends whose home has a geo-thermal setup, but it's true, the heat is not sufficient to produce better thermal energy. Using convection for circulation is brilliantly simple, but how do they drill large bores laterally for such long lengths that are so deep?
And how much heat is hot enough? Shouldn't they be using this method near hot springs or places with volcanic activity? Or at the base of mountains where drilling lateral bores deep enough would be helped by the mass that's already there?
Anyways, this is the way to go. Solar, wind, tidal and hydro could pale in comparison to the energy that's down below.

I wonder if the underground radiator network is difficult to engineer and maintain . If the circulation system has momentum, maybe sporadic pumping powered by renewables on a simpler loop would be cheaper and sturdier.

What a cool concept!

Geothermal power plants known to trigger earthquakes, just like fracking, because they keep pumping so much water into all rocks around!

Would not this design also keep leaking water into bedrock beneath?

IMHO, geothermal power plants need to be designed so that they never leak/pump water into the bedrock all around!

So, how about just 2 very deep pipes, side by side, connected at the bottom, to circulate the water?

Perhaps a cool way to unfreeze those wind farms in Texas?

How much heat is extracted? How much heat would be extracted yearly if this became the planet's primary energy supplier? Way back when some short sighted people thought we would never run out of oil. There was so much. People though we couldn't possibly pollute the oceans , they are so big. Like all our earth bound ressources the core's heat is finite. How much accelerated cooling can it sustain before a catastrophic tipping point is reached?

Dinosaurs trying to justify their existence? Looks to me like free energy until they get invested in it.

@FB36...this is a closed loop system, so no water gets pumped into the bedrock, like in fracking operations.

But now I have another issue. If water is circulated into the loop, that would mean that the heat is limited by the boiling point. If an antifreeze is used it could run hotter. If an oil is used, even hotter. So what exactly are the heat levels at a few miles deep? To generate electricity you need the hot stuff.