Why not tap the energy in volcanoes
Question:
Great job Randy. But melting is not the only way to dissolve the pipe. I know a lot of metals, if hot enough anyway, can be attacked by the kind of mixture of super heated scud in the lava. The same sort of reason that glasses melt at temperatures way below the melting point of silicon oxide. So it would take some research to be sure that one would actually survive immersion in lava.
… – Hide quoted text — Show quoted text -> A *really* quick google search for "magma temperature" > turns up temperature estimates from 700 – 1300 C. > More googling tells me that 15% platinum-iridium > melts at 1821 C, osmium at 2700 C, molybdenum at > 2625 C, titanium at 1664 C. > I don’t know about the strength of all of those or > their suitability for making into pipe, but it’s > at least plausible that you could stick a metal pipe > into magma without it melting. Moly sounds like a > potential choice for instance. Isn’t moly already > used for extra-strong machine parts? > Of course, even your materials that don’t melt might > get kind of gooey at these temperatures. > – Randy
Response:
> Do all rocks melt at the same temperature?
Volcanic magma is highly variable in temperature. It can also be moving with considerable velocity, and accompanied by nasty solid projectiles. I doubt anything could survive even a modest eruption, no matter what it was made out of.
Response:
(irrelevant newsgroups deleted) > Its also not renewable. You can only extract the heat once. (well, the > supply does *slowly* replenish via radioactive decay, but thats > probably not relevant at human timescales.)
Uh no, the heat creeps back from the hot magma below. Radioactive decay is the engine that drives the entire heat reservoir of the earth, but is not relevant locally. The rate at which heat transfer occurs depends entirely on the structure you are dealing with. Of course, if there is flowing magma in the vicinity there will be greater heat transfer, but also greater danger of an eruption. The best geothermal sources are where you have water circulating down from the surface, contacting the magma and boiling back up (such as in Yellowstone Park). But these are rare situations, particularly stable ones.
Response:
> What about asbestos , or that new industructible material > starlite demonstrated on Tomorrow’s world
Volcanic magma is molten rock. Asbestos is rock fibre. Why don’t you get a little bit of basic scientific knowledge before posting?
Response:
>> What about asbestos , or that new industructible material > starlite demonstrated on Tomorrow’s world >Volcanic magma is molten rock. Asbestos is rock fibre. Why don’t you get a >little bit of basic scientific knowledge before posting?
Do all rocks melt at the same temperature? — "Is that plutonium on your gums?" "Shut up and kiss me!" — Marge and Homer Simpson
Response:
Why not the stuff the Russians used for the space landing on Venus 400c Volcanic magma is molten rock. Asbestos is rock fibre. Why don’t you get a little bit of basic scientific knowledge before posting?
Response:
> What about asbestos , or that new industructible material > starlite demonstrated on Tomorrow’s world > Volcanic magma is molten rock. Asbestos is rock fibre. Why don’t you get a > little bit of basic scientific knowledge before posting?
Asbestose’s meting point varies depending on the type. 1,200 to 1,500 degrees C is about right. Some magmas will melt some asbestose. Claims for Starlite include resisting 10,000 degrees C. Regardless, if you pump significant amounts of water into a magma pocket, it will solidify the magma around the pipe. Karl Johanson
Response:
> (irrelevant newsgroups deleted) > Its also not renewable. You can only extract the heat once. (well, the > supply does *slowly* replenish via radioactive decay, but thats > probably not relevant at human timescales.) > Uh no, the heat creeps back from the hot magma below.
Correct, but the heat is non-renewable. Once used it cannot be reused. Now how fast will it collect back in? Shall we look at thermal conductivity? http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatra.html Assuming that you had a magma repository at 1000c seperated by 10 meters of aluminum with ice at 0C on the other side, what would the thermal conductivity be? Well, if it is aluminum, 200 W/K/m. (Silver is twice this). This is only 20kW/M^2. Average continental heat flow is .06W/m^2. To equal one nuclear ractor (good for about 3GW of heat, 1GW of generation), it would need to have a surface area in excess of 600,000 m^2, or most of a square kilometer. Now lets look at energy density of that magma. If heat were extracted at a rate of 3GW, then [http://www.geo.ua.edu/volcanology/lecture_notes_files/additional_phys...] about 3 tons of magma would have to be solidified and cooled to 0C each and every second. So each year, 30e6 seconds, about a hundred million tons of rock would be cooled to uselessness. This is enough to cool the 600,000 square meter patch from 1000C to 0C to a depth of 40 meters, in one year. Thats to generate as much electrical power as one single nuclear reactor. Thats not exactly renewable, and unless the flow rate is at least 40m/year, the heat won’t creep back in at anywhere near that rate. Nor would it take that long to for 10GW of electrical generation (about 3% of US electrical generation) to cool a 10km^3 resivor; about 25 years. Geothermal is alternative, but is by no means renewable; although its fuel supplies may be larger. Also above I give the constraints of *physics* on the system, not of engineering. Scott
Response:
> >> What about asbestos , or that new industructible material >> starlite demonstrated on Tomorrow’s world >Volcanic magma is molten rock. Asbestos is rock fibre. Why don’t you get a >little bit of basic scientific knowledge before posting? > Do all rocks melt at the same temperature?
A *really* quick google search for "magma temperature" turns up temperature estimates from 700 – 1300 C. More googling tells me that 15% platinum-iridium melts at 1821 C, osmium at 2700 C, molybdenum at 2625 C, titanium at 1664 C. I don’t know about the strength of all of those or their suitability for making into pipe, but it’s at least plausible that you could stick a metal pipe into magma without it melting. Moly sounds like a potential choice for instance. Isn’t moly already used for extra-strong machine parts? Of course, even your materials that don’t melt might get kind of gooey at these temperatures. – Randy
Response:
– Hide quoted text — Show quoted text -> >> What about asbestos , or that new industructible material > >> starlite demonstrated on Tomorrow’s world > >Volcanic magma is molten rock. Asbestos is rock fibre. Why don’t you get a > >little bit of basic scientific knowledge before posting? > Do all rocks melt at the same temperature? >A *really* quick google search for "magma temperature" >turns up temperature estimates from 700 – 1300 C. >More googling tells me that 15% platinum-iridium >melts at 1821 C, osmium at 2700 C, molybdenum at >2625 C, titanium at 1664 C. >I don’t know about the strength of all of those or >their suitability for making into pipe, but it’s >at least plausible that you could stick a metal pipe >into magma without it melting. Moly sounds like a >potential choice for instance. Isn’t moly already >used for extra-strong machine parts? >Of course, even your materials that don’t melt might >get kind of gooey at these temperatures.
Or dissolve. Carbon has a high melting point, but I’m sure that would dissolve right into molten iron, at least. But a coolant might be circulated inside the walls of the pipe. — "Is that plutonium on your gums?" "Shut up and kiss me!" — Marge and Homer Simpson
Response:
- Hide quoted text — Show quoted text – > (irrelevant newsgroups deleted) > Its also not renewable. You can only extract the heat once. (well, the > supply does *slowly* replenish via radioactive decay, but thats > probably not relevant at human timescales.) > Uh no, the heat creeps back from the hot magma below. Radioactive decay is > the engine that drives the entire heat reservoir of the earth, but is not > relevant locally. > The rate at which heat transfer occurs depends entirely on the structure you > are dealing with. Of course, if there is flowing magma in the vicinity there > will be greater heat transfer, but also greater danger of an eruption. > The best geothermal sources are where you have water circulating down from > the surface, contacting the magma and boiling back up (such as in > Yellowstone Park). But these are rare situations, particularly stable ones.
Geothermal power is nothing new. In iceland they have been doing it for years, and Scott was right. Before they locate and construct a plant, they evaluate the site for: low probability of further violent activity, total expected energy availible, best method of extraction, best rate of extraction. They do not locate in still active areas for obvious reasons.
Response:
… > Regardless, if you pump significant amounts of water into a magma pocket, it > will solidify the magma around the pipe.
Not sure I agree with that. First off, that can be one absolutely huge flow. Second the pump rate needed is a function of the magma characteristics and it’s convection rates. Third, the moving magma exerts very large forces on the little pipe and it’s great sail of partly solidified rock. You would have to do some slick work to punch/drill/melt a hole in the wall of this chamber, while at the same time cooling the pipe fast enough to keep the magma from dissolving it right away. You may be right that it can be done, but I think it is no easy process.
Response:
Good analysis, but I think you missed two factors. First, I think that a number of areas over these hot spots have layers of permeable broken rock that can be used as very large heat transfer regions. So a few square KM of collection area is not always impractical. Second, I am not so sure of how it affects your evaluation, but many of the hot spots come from friction in the subduction zones. This friction generates heat in the immediate region of the magma, so it doesn’t have to flow anywhere. In fact, if we cooled the magma to solidity, we would probably increase the rate of heating, since that is what caused it to reach molten in this area anyway. – Hide quoted text — Show quoted text -> (irrelevant newsgroups deleted) > > Its also not renewable. You can only extract the heat once. (well, the > > supply does *slowly* replenish via radioactive decay, but thats > > probably not relevant at human timescales.) > Uh no, the heat creeps back from the hot magma below. > Correct, but the heat is non-renewable. Once used it cannot be reused. > Now how fast will it collect back in? > Shall we look at thermal conductivity? > http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatra.html > Assuming that you had a magma repository at 1000c seperated by 10 > meters of aluminum with ice at 0C on the other side, what would the > thermal conductivity be? Well, if it is aluminum, 200 W/K/m. (Silver > is twice this). This is only 20kW/M^2. Average continental heat flow > is .06W/m^2. To equal one nuclear ractor (good for about 3GW of heat, > 1GW of generation), it would need to have a surface area in excess of > 600,000 m^2, or most of a square kilometer. > Now lets look at energy density of that magma. > If heat were extracted at a rate of 3GW, then
[http://www.geo.ua.edu/volcanology/lecture_notes_files/additional_phys... rop.html] – Hide quoted text — Show quoted text -> about 3 tons of magma would have to be solidified and cooled to 0C > each and every second. So each year, 30e6 seconds, about a hundred > million tons of rock would be cooled to uselessness. This is enough to > cool the 600,000 square meter patch from 1000C to 0C to a depth of 40 > meters, in one year. Thats to generate as much electrical power as one > single nuclear reactor. > Thats not exactly renewable, and unless the flow rate is at least > 40m/year, the heat won’t creep back in at anywhere near that rate. Nor > would it take that long to for 10GW of electrical generation (about 3% > of US electrical generation) to cool a 10km^3 resivor; about 25 years. > Geothermal is alternative, but is by no means renewable; although its > fuel supplies may be larger. Also above I give the constraints of > *physics* on the system, not of engineering. > Scott
Response:
The magma chamber tens of miles wide is only 2km below , so why not tap it and supply Italy with all the power it needs . Water sent cascading down in a pipe will come back up as superheated steam. scientific american jul 03
Response:
The huge magma chamber of MT Etna is only 2km from the surface. Some South African gold mines are more than ten km deep
Response:
Unfortunately, if you contact the magma chamber directly, the pipe will also come rushing back up the pipe as molten metal.
– Hide quoted text — Show quoted text -> The magma chamber tens of miles wide is only 2km below , so > why not tap it and supply Italy with all the power it needs . Water > sent cascading down in a pipe will come back up as superheated steam. > scientific american jul 03
Response:
> The magma chamber tens of miles wide is only 2km below , so > why not tap it and supply Italy with all the power it needs . Water > sent cascading down in a pipe will come back up as superheated steam. > scientific american jul 03
That’s geothermal energy and it is tapped. Unfortunately there are issues of pollution, hydrogen sulphide, sulphur dioxide and other noxious substances in the steam. Foul water needs to be handled and desposed of. There are extreme corrosion problems because of the acidity of the fluids and dissolved solids like calcium and magnesium carbonate and sulphate, silica, and other minerals foul and plug pipes and erode turbine blades. There’s lots of energy but it is a bitch to handle. It’s much easier to burn oil or coal. Icon
Response:
> The magma chamber tens of miles wide is only 2km below , so > why not tap it and supply Italy with all the power it needs . Water > sent cascading down in a pipe will come back up as superheated steam. > scientific american jul 03 > That’s geothermal energy and it is tapped. Unfortunately there are issues of > pollution, hydrogen sulphide, sulphur dioxide and other noxious substances > in the steam.
Including radioactives. I think the amounts of radioactive materials are trivial, but their more significant than the releases from nuclear. – Hide quoted text — Show quoted text ->Foul water needs to be handled and desposed of. There are > extreme corrosion problems because of the acidity of the fluids and > dissolved solids like calcium and magnesium carbonate and sulphate, silica, > and other minerals foul and plug pipes and erode turbine blades. There’s > lots of energy but it is a bitch to handle. It’s much easier to burn oil or > coal. > Icon
Response:
You can tap the energy of a volcano far away from the lava but still at temperatures hot enough to power a turbine by drilling into the rock. A company in Hawaii has already built a unit which has a water chamber and turbine and can be drilled into the rock, allowing the heat to boil the water out and drive the turbine. There are still problems with this technology, but companies have been using geothermal energy from deep in the earth to generate electricity for a long time. http://www.eere.energy.gov/geothermal/geoelectprod.html
Response:
The huge magma chamber of MT Etna is only 2km from the surface. Some South African gold mines are more than ten km deep
Response:
What about asbestos , or that new industructible material starlite demonstrated on Tomorrow’s world
Unfortunately, if you contact the magma chamber directly, the pipe will also come rushing back up the pipe as molten metal.
Response:
> The magma chamber tens of miles wide is only 2km below , so > why not tap it and supply Italy with all the power it needs . Water > sent cascading down in a pipe will come back up as superheated steam.
Here’s something to puzzle out: What is the potential Joules (of heat) in a cubic km of lava? Assume that about 30% of the heat energy will be turned into electricity, now compare that to the yearly electrical energy needs of an industrialized country. Its surpisingly low, and such a calculation only takes 20 minutes to estimate. I did it once on a post here 6-8 months ago. You repeat the work and tell me the longest such a supply of magma would last. This is a sci.* newsgroup, I’m sure you can answer this question. For a look at the pressent, worldwide installed capacity is about 8.1GW[1], with about a third in the United States. I’ve not found numbers about actual generation, but [2] claims that 1000 EJ is available. (1EJ = 10^18 J) Running the numbers however, 1000 EJ is only enough to run the US’s yearly electrical use of 3.6 T kW*h for 77 years. The 80,000 MW of installed capacity they talk about being realistic, worldwide, is about 1/4 the US’s electrical usage. An interesting idea, but doesn’t scale to be a foundation of the world. Lets look at a hypothetical electrical ‘green’ energy policy for the USA for 2020: % of electrial production by source. 7% Hydroelectric. (current generation) 25% Geothermal. (worldwide *potential* generation) 12% Wind. (25x current, from AWEA assuming an ‘really aggressive policy’) [3] 55% Magical fairies produce it? That other >55% can only come from either uranium or coal. I’d rather it not be coal; burning a billion tons a year doesn’t seem right. Scott [1] http://geoheat.oit.edu/pdf/powergen.pdf [2] http://www.bgr.de/b1hydro/index.html?/b1hydro/fachbeitraege/a199801/e… [3] http://greennature.com/article98.html
Response:
> The magma chamber tens of miles wide is only 2km below , so > why not tap it and supply Italy with all the power it needs . Water > sent cascading down in a pipe will come back up as superheated steam.
Iceland does that already, in a way. You can’t get too close to an actual volcano, because it will sooner or later destroy your installation in a very spectacular fashion. However, in a volcanic area there are often more stable hot-spots near the surface which can be tapped in more reliable fashion. Look up the information available on the Web on Icelandic ground heat power and building heat production. There are lots of interesting sites in English. In general, one problem is that rock is not a very good transmitter of heat. So one can exhaust the heat in a spot fairly quickly if it is extracted too quickly.
Response:
> In general, one problem is that rock is not a very good transmitter of heat. > So one can exhaust the heat in a spot fairly quickly if it is extracted too > quickly.
Its also not renewable. You can only extract the heat once. (well, the supply does *slowly* replenish via radioactive decay, but thats probably not relevant at human timescales.) A few weeks ago someone claimed (without citation) that in california, some geothermal plants are already down to 50% of the production they had 30 years ago. Scott
Response:
> > In general, one problem is that rock is not a very good transmitter of heat. > So one can exhaust the heat in a spot fairly quickly if it is extracted too > quickly. > Its also not renewable. You can only extract the heat once. (well, the > supply does *slowly* replenish via radioactive decay, but thats > probably not relevant at human timescales.)
We use hot water here in Iceland, the water circulates through the hot areas in the ground and is thus renewable. – Hide quoted text — Show quoted text -> A few weeks ago someone claimed (without citation) that in california, > some geothermal plants are already down to 50% of the production they > had 30 years ago. > Scott
Response:
Related Posts