h a l f b a k e r yRecalculations place it at 0.4999.
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Having an active volcano can be hazardous, but it can also
be lucritive, if you handle the lava just right. For this
idea, only cinder-cone volcanoes need apply. This idea
relies on the viscous "pahoehoe" lava to work. My idea
calls for a converted barge/freighter to be used in energy
production.
A duct that extends from the front would
allow lava to flow directly into the ship (it would
otherwise flow into the ocean). Once in the ship, the lava
is directed into vats, about 1 feet deep. The vats are then
sealed and doused with water, allowing for a flash of
steam to be created which runs a set of turbines,
generating electricity. Because this is a mobile power
facility, it could use the electricity to create
hydrogen/oxygen, which is later burned or converted
through fuel cells into electricity. Once each vat is cool
enough, it is a solid block of cooled lava rock. The vats
are shaped to conveniently eject each cooled block either
into the ocean, or onto another barge to be used for things
such as water breaks, coral restoration, construction, etc.
Land based power facilities have the drawback of zoning
regulations. Usually, volcanoes are converted into nature
preserves, or are otherwise federally protected, providing
enough hassle in any process to try and allow for
geothermal drilling. Geothermal drilling is also tied to
earthquakes (I don't know how). With this barge, the
power production capability can go to wherever the heat
is, and have an automatic supply of water to boil for the
turbines. As well as for power production, this could be
use to provide tourists a close-up yet safe view of a lava
flow. The lava is going to flow into the ocean anyway,
creating large plumes of steam and adding to the island's
land, why not take advantage of this wasted heat? Nothing
survives around the area, so there are little evironmental
issues.
Geothermal Energy
http://www.renewabl...tion-for-the-future
[Jinbish, Sep 21 2010]
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What is the amount of thermal energy available from, say,
1000 tons of lava? Basic numbers? |
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Pahoehoe runs in the range of 1100-1200 C and room temperature Basalt has a specific heat of .2 kcal/kg C (can't find any numbers for the molten state). Assuming the stuff cools to 800 C before it reaches processing, that still give you 700 C of steam production (assuming you use the cooled stuff to pre-heat your water close to boiling). So 1 tonne of Lava is 140000 kcal or 585 MJ. |
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Please note some massive simplifying assumptions, limited available data, and your steam turbine is going to be significantly inefficient, but the numbers appear to be in the useful energy production range. Especially if the end result is cooled basalt blocks in useful sizes. |
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This would require a remarkably robust boat. |
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Why not simply drill a few wells near the lava flow and
pump water continuously through the well network
to produce a constant flow of steam without having
to handle and tranship 1000 tons of basalt between
steam cycles? |
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They need to be thin slabs, almost sheets, otherwise as they cool and crust over they will self-insulate. |
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I was picturing brick sized blocks, or you could preform something like cinder blocks with multiple thins sections. |
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Bricks would be good but don't use them for
fireplaces. Basalt explodes when heated in a fire.
The air bubbles in it make things very interesting
when they expand rapidly. |
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//So 1 tonne of Lava is 140000 kcal or 585 MJ//
//the numbers appear to be in the useful energy
production range. // |
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In other words, 1 tonne of lava would provide the energy
output of a smallish power station (500MW) for about 1
second. |
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Or, to put it another way, processing 1 tonne of lava would
give you as much energy as burning 10 litres of petrol. |
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In what way, then, is this " in the useful energy production
range"?? |
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As [Jinbish] linked and I suggested; Geothermal
power is far more sensible. It doesn't however,
produce a steady supply of stone bricks. |
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However, nor does it require massive amounts of
energy to cart those bricks off to other places. You'd
soon be sitting on a gigantic pile of bricks and blocks
if you implemented this idea. |
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Because you're only processing 60 times as much lava as you would for the same energy from coal, which isn't excessive for a clean power plant. Especially if you locate it where there is a steady supply of lava. |
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Infidel I belive there are only a few plants in the US turning out cinderblocks already. The shipping is already happening, this just does it from a point that produces energy, instead of using it. |
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//Because you're only processing 60 times as much lava as
you would for the same energy from coal, which isn't
excessive for a clean power plant.// |
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It isn't? Then clean energy is surely doomed. I would have
thought that this was a completely hopeless rate of
return. |
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Also, would you be prepared to process 60 tons of coal to
get the energy equivalent of one ton of coal, if that coal
happened to be at 1000°C and located underwater at
randomly changing locations? |
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If you're prepared to accept such low energy returns, then
just start mining some of the less economical coal
reserves, and then devote maybe half the energy
produced toward active sequestration of CO2. Better all
round. |
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I'm picturing somewhere like Hawaii where there is a fairly steady supply of the stuff. And a 60 to 1 ratio isn't bad if you realize the fuel is free. You pay somewhat more in processing for a zero cost fuel. |
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Also the percentage of energy recovered would probably be higher, there's less energy input on the production side, and there's less energy and mess on the output side (especially if the output is usable directly as building materials). Thus resulting in a much higher actual energy return than the same volume of coal |
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//Thus resulting in a much higher actual energy return than
the same volume of coal// |
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Qualitatively, I can't argue with you and you may be right.
However, the statement above needs a bit of thought or,
failing that, calculation. |
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Sorry, I mis-stated, should have been a much higher energy return than the equivalent (meaning 60 to 1) volume of coal, not the same volume. I don't know how it balances out, you'll probably have to handle a bit more lava than coal, just not in the 60:1 range. |
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I dunno. I may be having a bleak day, but most renewables
just depress me. Fundamentally, we want and crave high
power at high density, and have excellent ways of
generating it cheaply. |
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For a lot of alternative energies, I just think they fuck up
the landscape and eat raw materials, and that it would be
more effective (financially and environmentally) to just
remediate the adverse effects of conventional power
generation. |
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Or, to restate and summarize the world energy
situation: |
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There are alternative energy sources.
Unfortunately, they all, so far, fuck up the
landscape and/or use large quantities of raw
materials. It is currently more effective
(economically and environmentally) to use
conventional power and remediate their adverse
effects. |
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Bleak, but concise and accurate. |
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But no bugger calls me "concise" or "accurate" and walks
away. |
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First choice is to figure out more efficient ways to
do something. Eventual universal conversion to
LEDs will probably save more in the same time
period than all the alternative energy sources
combined. |
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Next, implement alternative/renewable where
economically and environmentally feasible.
Desert solar, urban wind (doesn't clutter up the
scenery, minimal transport losses), etc. This may
be one of the above. |
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Then maintain traditional fuel sources where
necessary including much more nuclear (of the
low, short half-life waste variety) and clean up
after it. Of course once you figuring clean-up cost
and the increasing cost of extraction, the EROEI
starts to favor renewable sources more and more
over and time. |
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//But no bugger calls me "concise" or "accurate" and
walks away.// |
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This is on a barge because the lava fields are always
growing and moving. Plus, cooling the lava on its
way to the ocean would cause a clog in the lava
tube, altering its flow. This geothermal energy! It's
just that we don't go down to get the energy, it
comes up to us! |
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This is a brilliant idea. You could keep the rock nice and hot and runny by aiming a huge mirror at it and reflecting sun and moon light at it. That way the rock can be used again and again. |
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Don't be silly! Everyone knows that moonlight is cold. That's why it's warm during the day and cold at night. |
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saedi, that kind of goes against the whole
geothermal concept here. You're proposing some
kind of huge thermal battery, I think. |
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I was revisiting this because I just read an article
that referred to lava hitting ocean. The
temperature it mentioned is about right, but it
doesn't lose as much heat in transit as I allowed. |
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I realized, however, I forgot to allow for heat of
fusion. Again, hard to find exact numbers, but it
appears to be another ~130 kcal/kg. If that's the
case, then you can roughly double the energy
output, or halve the ratio to coal. |
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