201–210 of 222 posts
I love how every Tom, Dick & Harry with a bit of math & engineering thinks he can "dispel the myth" of HN Idea X with two minutes of off-the-top-of-his-head equations. Read about these two: http://www.gravitricity.com/#people Do they seem like complete morons? Do you think they haven't studied this just a little bit more than you have? It doesn't mean their idea is good or will work - just that you aren't going to ri…
Let's do out the math on this... A subway tunnel might have a diameter of about 6 meters, so cross section = 3 * 3 * pi = 28 square meters. Digging subway tunnel through rock costs about $100M per kilometer. On the one hand, these holes would be vertical, which is harder than horizontal; on the other hand, they wouldn't need ventilation and train tracks and stuff. Let's handwave and say it's $100M for a 1 km deep hol…
http://www.solarserver.com/solar-magazine/solar-energy-syste...
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I don't understand why they need to dig holes to do this. Why not build something equivalent onto the side of a cliff?
The depth requirement is 500m to 1500m. Though cliffs can be much taller than this, they usually are not totally vertical and cannot accomodate this much depth. Disclaimer, not a geologist.
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You just need more mass. Have a look at this concept: http://eduard-heindl.de/energy-storage/index-e.html (unfortunately the english version is very sparse, the german version has some more images and videos: http://eduard-heindl.de/energy-storage/ ) The idea is to cut a 1km diameter cylinder into the ground (solid rock), and then lift it up up to 500m by pumping water underneath it. The power stored can power a coun…
But presumably you'd need more than a day's worth of power to lift the damn thing? That's probably doable, but still, I suspect that'd be the main problem.
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2nd Avenue subway [0] requires about 8.5 miles worth of tunnels (several hundred feet of which were already dug back in the 70's) and it's budget is $17 billion. Of course that whole cost isn't just for digging tunnels, but it's a clear indication that digging tunnels (especially in dense urban areas) can be extremely expensive. [0] http://en.wikipedia.org/wiki/Second_Avenue_Subway
There is a very large difference between building complex tunnels and a simple hole in the ground. The cost for drilling a straight exploratory/mining hole was 10 Million/km in the 70's and 80's[0]. I can easily imagine this being cheaper by a factor of 2-5 with current advances. Not to mention this concept has a lot of synergy with mining companies. [0] http://facstaff.gpc.edu/~pgore/geology/geo101/interior.htm
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The picture they're drawing isn't very straight, as many have demonstrated. Until these "experts" provide evidence otherwise, it's useless to berate readers for pointing out the obvious.
Bduerst, I have almost never downvoted anyone over anything. But I must say you have no right to put "experts" in quotation marks. Given their bio, they are experts. Which makes your comment a troll comment. (Unheard-of on HN.) Really, what do you think the definition of an expert is? "Just because he teaches the stuff at the University of Edinburgh, has sold a company to Siemens that created the world's only install…
As it is, this website reads like they did the napkin math for the idea and are using only their credentials to legitimize it. Its an appeal to authority.
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The majority of humanity's great inventions didn't have basic physics saying "this isn't brilliant" long before a prototype got built. Most of humanity's great inventions were things that were difficult because human beings thought they were difficult, or complicated or intricate or whatever. On their webpage they say " The biggest single cost is the hole, but it is expected that firstly this will have a very long li…
The hole for this has different requirements than holes for water and petroleum: you'd not want to drill one of these holes into an aquifer, because then it would fill up with water. Oil and gas wells have to be drilled in specific places where the oil and gas are, naturally. In this case, you'd want nothing but a dry, empty hole. A dry, empty hole would be the kind of hole least likely to interact with anything unde…
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The majority of humanity's great inventions didn't have basic physics saying "this isn't brilliant" long before a prototype got built. Most of humanity's great inventions were things that were difficult because human beings thought they were difficult, or complicated or intricate or whatever. On their webpage they say " The biggest single cost is the hole, but it is expected that firstly this will have a very long li…
Sadly what you say is true. Despite the fact that humanity has been drilling holes into various types of soil for over 8000 years, we don't really have a good way to do it. The situation is not quite as bad as you're describing though. It is not $50k per day, more like $5k. That is for machines that can only do soil, not rock, and aren't as much drilling as they're making a hole. But in places where you can do agricu…
The problem with going shallower is that the system capacity is directly proportional to depth and weight. Too shallow and you have to have huge weight and that means a large diameter hole and really big cables and such.
But going deeper requires drilling through rock, and aquifers which are located within the rock. That means big regulatory hurdles because nobody wants to poison the aquifer on accident. Plus the large costs of drilling through rock.
I really like the idea from a theoretical standpoint. It's very elegant. But it doesn't seem practical from an economic or regulatory standpoint. If there are places where you can get the diameter and depth for free, it's clearly genius. But I don't think purpose-drilled holes for this will become a thing -- at least barring some kind of immense breakthrough that I can't even imagine.