3 ms·

This is interesting, but isn't the challenge with "deepest holes ever" that they frequently cave in on themselves? And wouldn't you need multiple levels of wate

This is interesting, but isn't the challenge with "deepest holes ever" that they frequently cave in on themselves? And wouldn't you need multiple levels of water storage while pumping upwards since there are practical limits to how high water can be pumped? (rough citation on that: https://www.theurbandeveloper.com/articles/how-water-works-worlds-tallest-skyscraper https://www.theurbandeveloper.com/articles/how-water-works-w...)

runnerup 4y ago
These types of holes don’t cave in because they’re drilled through solid rock. But they do get very very hot where the drilling is done (and by design for geothermal, they want to reach hot geology). This heat melts the drill bit quickly.
lazide 4y ago
1) the issue is not usually that the hole ‘caves in’, but rather that at some point everything is hot enough and under enough pressure that it doesn’t act like a solid anymore. Think playdough. Casings make it doable for awhile, but then at some point it’s so soft and hot it’s more like pudding. 2) you’re thinking of limits on vacuum suction (aka ‘sucking’ water up), which yes is very limited. Deep bores of any kind are almost always submerged pumps, and they don’t have this issue (‘pushing’ water up). Typically there are strings of submerged pumps in the borehole for deeper wells. For geothermal, usually they can just push cooler water down, and don’t even need to pump it back up - the heat expansion/steam pressurizes everything and does the work for them, as it’s a closed aquifer.
marcosdumay 4y ago
> there are practical limits to how high water can be pumped? Well, no. The problems you see on your article really doesn't apply to their situation. (And it's a really small limit on the article, if it applied, we wouldn't be able to extract most of our oil or even water from some aquifers.)

runnerup 4y ago

These types of holes don’t cave in because they’re drilled through solid rock. But they do get very very hot where the drilling is done (and by design for geothermal, they want to reach hot geology). This heat melts the drill bit quickly.

lazide 4y ago

1) the issue is not usually that the hole ‘caves in’, but rather that at some point everything is hot enough and under enough pressure that it doesn’t act like a solid anymore. Think playdough. Casings make it doable for awhile, but then at some point it’s so soft and hot it’s more like pudding. 2) you’re thinking of limits on vacuum suction (aka ‘sucking’ water up), which yes is very limited. Deep bores of any kind are almost always submerged pumps, and they don’t have this issue (‘pushing’ water up). Typically there are strings of submerged pumps in the borehole for deeper wells. For geothermal, usually they can just push cooler water down, and don’t even need to pump it back up - the heat expansion/steam pressurizes everything and does the work for them, as it’s a closed aquifer.

marcosdumay 4y ago

> there are practical limits to how high water can be pumped? Well, no. The problems you see on your article really doesn't apply to their situation. (And it's a really small limit on the article, if it applied, we wouldn't be able to extract most of our oil or even water from some aquifers.)