91–100 of 108 posts
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No single source has ever provided all electricity for any major region. To pretend otherwise is disingenuous.
Fossil fuels have done that trick, long before gridscale wind and solar ever existed. So really you're the one being disingenuous.
Coal is not natural gas
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I don’t think thermodynamics lets that work. You can’t move heat from something cold to something hot so unless you are preheating your water to a temperature higher than your deep borehole rocks, all you’re doing is putting the first N joules of heat energy into the water you’re going to pump into your steam turbines using excess grid energy instead of geothermal energy.
Of course you can move heat from something hot to something cold, it’s called a heat pump. Though yeah I get what you meant. There are heat pumps that have entered production that are designed to generate the kind of industrial levels of heat required to heat the water to the level required to add heat to such reservoirs. Whether it makes sense, I can’t say. But it certainly makes sense for geothermal well used for d…
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I don't understand what that second sentence means. What do they mean by "capacity" if it's not electricity generation capability?
Capacity is the most they can produce at any given time. Solar only produces power during the day. Geothermal produces power 24 hours a day, without any regard for day or night. Therefore for the same “capacity” geothermal will produce more power per day because it produces for more hours a day at the same rate. (This does not account for any complications such as the cost of that capacity or whether geothermal has o…
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Ideal thermodynamic efficiency is 1-Tcold/Thot in an absolute temperature scale. This means given a perfect mechanism to turn heat into work this is the upper bound of how much of the heat can be turned into useful work. Say ambient air is 20 deg C, with your 90 deg C heat source then you get 1-293/363 which is about 20%. So it's not to say you can't get work out of this system, but it's not great compared to having…
would it be possible to use a heat pump to increase the temperature to a more efficient range? Or would all of the efficiency gained be lost by operating the heat pump?
Make drilling cheaper. This would also help with water access. The biggest cost of small geothermal and water projects is always the drilling. Drill rig time is always a limiting factor.
Drilling is supposed to get cheaper when it is done with microwaves instead of drill bits. But the expense of maintaining the necessary steam turbine still makes it hard for geo to compete with wind and solar. This is also a major factor in the cost of operating a nuke plant, with similar effect on competitiveness. Really big steam turbines cost less to keep than a lot of small ones, but then you generally need to bu…
In summary, a (dumb yet durable) metal waveguide+pipe stretches down, it emits microwaves to vaporize the rock face, and gas pumped down through it is released so that it exhausts back up along with the removed mass of rock-vapor/particles.
> [P]roducing the supercritical steam needed requires drilling to depths of 10 to 20 km [...] rock is capable of both producing superheated steam and destroying the microchips and seals required for directional drilling.
[0] https://jpt.spe.org/microwave-drilling-sounds-like-science-f...
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Drilling is supposed to get cheaper when it is done with microwaves instead of drill bits. But the expense of maintaining the necessary steam turbine still makes it hard for geo to compete with wind and solar. This is also a major factor in the cost of operating a nuke plant, with similar effect on competitiveness. Really big steam turbines cost less to keep than a lot of small ones, but then you generally need to bu…
TIL proposals to drill with microwaves [0]. In summary, a (dumb yet durable) metal waveguide+pipe stretches down, it emits microwaves to vaporize the rock face, and gas pumped down through it is released so that it exhausts back up along with the removed mass of rock-vapor/particles. > [P]roducing the supercritical steam needed requires drilling to depths of 10 to 20 km [...] rock is capable of both producing superhe…
https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...
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we can power it with free geothermal! the deeper the hole gets, the faster the drilling goes. it's power all the way down!
Power's not the issue, labor is. Untill you can replace roughnecks with robots, it's not likely to change.
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I'm trying to imagine the apocalyptic scenario that'd have all of Texas windless and cloudy for a week? Nameplate values for Texas wind & solar will eventually be well above peak required: excess power can be sold for silly things like bitcoin, desalination, fabbing, etc.
Bitcoin sounds like the absolute worst thing to buy with excess electrical production. But desalination sounds like an excellent thing to buy. Silly is not the word I'd use.
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Wow. Have you got a source for that? Waste heat from human power generation and use, not from the Earth cooling? Boil as in bubbles of steam or just slightly evaporate a little? A few hundred as in < 1000 years? And current trajectory as in something like exponential growth which obviously won't happen? I'm sure some part of that makes the idea far less serious than it sounds.
It’s based on extrapolation of current trends, so I doubt it’ll actually happen. Besides, we’d all die before it got to that. But here are some sources that describe it: https://www.youtube.com/watch?v=9vRtA7STvH4 (commentary from Sabrine Hossenfelder, highly recommended) https://www.nature.com/articles/s41567-022-01652-6.epdf https://dothemath.ucsd.edu/2011/07/can-economic-growth-last/
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There are fluids other than water that have usefully different boiling points. Problem is that mature turbines are designed for steam. Turbines for other fluids cannot approach their market volume.
That's not true at all. If any other liquids were more useful they would have been used long time ago, even in places where the cost is not of primary concern, such as nuclear submarines.
Steam is used everywhere despite that it is quite corrosive, mainly because it is cheap.