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Iceland Seeking 'Supercritical Steam' For Power Source (bbc.com)
New submitter FatdogHaiku writes: Already getting over 25% of its electrical power from geothermal sources, Iceland hopes to break new ground using "supercritical steam" from a 5 km deep borehole. Is it just me, or does this sound like the start of a movie where everything that can go wrong does in fact go wrong? It's not like they are new to the tech, but working with geologic sources at 450C to ~600C is a new ball game for anyone. It should be noted that Iceland also uses direct geothermal for most of its space heating. "In this area at Reykjanes, we typically drill to 2km or 3km depth to harness the steam, to run power plants and produce clean, renewable electricity," explained Asgeir Margeirsson, CEO of the Iceland Deep Drilling Project (IDDP). "We want to see if the resources go deeper than that." The "supercritical steam" holds more energy than a liquid or a gas. The team wants to bring it up to the surface to convert into electricity, as they believe it could produce up to 10 times as much energy as the steam from conventional geothermal wells.
We've hit magma before (drilling at Krafla) - only the second time in the world that it happened. Totally by accident. The magma backed a couple dozen meters up the borehole, then stopped.
The first time anyone ever accidentally drilled into a magma chamber was in Hawaii; they immediately sealed up the borehole as a result. Here they just decided "what the heck..." and started pumping water down it to see if they could turn it into a production well. And the performance turned out to be superb.
Sometimes I doubt your commitment to Sparkle Motion.
Most power plants (natural gas, oil or coal) run on supercritical steam anyways, at least in their designed power level. The technology is neither new nor rare. The need to run on "dry" steam for efficiency is known at least from steam locomotives. The only modern power-generating subcritical steam systems I know of are some nuclear power plants where the reactor expects some of the cooling water in it to stay liquid (read: dense) because it serves as neutron moderator as well.
Also, even the most hardcore anti-nuclear people wouldn't generally have a problem knowing that there's a ,ulti-kilometer thick radiation shield in place.
Even if they did object it's not going to stop the process, no matter how much they protest.
Did you know your decaf latte probably used supercritical CO2 to decaffeinate the beans? Supercritical CO2, also at very high pressures, is a very good solvent and used in many industries.
Have some fun videos about the latter.
https://www.youtube.com/watch?...
https://www.youtube.com/watch?v=-gCTKteN5Y4
Silence is a state of mime.
Or not.
"supercritical steam" just means steam at above the boiling point of water at whatever pressure applies. More specific heat than "saturated steam" (steam at the boiling point of water at the applicable pressure), but otherwise pretty much the same as any other steam....
That would be superheated steam as opposed to saturated steam. Supercritical steam would be steam that is at pressure higher than water can exist as a vapor and temperature higher than water can exist as a liquid. For water this is above 3200 psia and above 705F.
I assume you mean wind turbines? Here you go.
The higher you go, the higher the figure you can harvest. Effects at the surface are generally rather minimal, although there are some small effects. It's a shame, honestly, as I think most people in windy areas (at least speaking for myself) would like more of a reduction on surface wind speeds.
Geo is generally locally, temporarily depletable. Over broad regions or over long periods of time, it's renewable. Nuclear decay inside the earth yields an average of 0.06W per square meter heat input. While that's far less than solar (even accounting for night, angles, inefficiencies, etc), it's particularly useful because it concentrates and stores. So if you drill a well into a particular hot water reservoir, you're harnessing the heat that flows up through that entire reservoir, not just immediately at the point of the borehole. And even if you're depleting it faster than it's being added (which is generally anticipated to be the case by significant margins, although these things are surprisingly difficult to assess), there's always other areas to move into; over somewhere between dozens and thousands of years (depending on the reservoir), the old site will reheat.
Note that this isn't always the case; sometimes you have "fossil heat". For example, in some places we tap heat from old lava flows or dikes. They're hot because they represent heat from another location (deep magma sources). They're hotter than their surrounding rock, and if you take the heat from them, they're never again going to be hotter than their surrounding rock.
Climate does not work that way. Planet surfaces very rapidly equalize to their equilibrium temperature, as radiation increases relative to the fourth power of temperature. The only way to have a meaningful difference in the surface temperature is to change the radiation balance (which can happen in a wide range of factors, affecting both incoming and outgoing radiation), and thus the equilibrium. Simply having "something hot at points on the surface" is virtually meaningless.
Sometimes I doubt your commitment to Sparkle Motion.
what kind of pipe they use for this kinda thing, im thinking some kind of ceramic metal hybrid??
A few articles I've found on it, state it's 6-layered titanium. Makes sense when you think about it, since titanium has a very high rating against corrosion, buildup resistance against materials on the surface and inside of it and very high resistances to temperatures depending on the "mix" that's used when the tubing manufactured.
Om, nomnomnom...
You appear to think that most of the heat at the earth's core is residual, in which case presumably tapping this heat would "let it out" and we would eventually run out. This is not the case. The vast majority of the heat (90% or more) is from the decay of radioactive elements. Thus, the heat is being produced continually and is renewable until the radioactive elements decay (should be a good source of heat for at least a few billion years, probably much more). This means that tapping into the earth's core is not going to ruin the insulation of our crust and cause all the stored up heat to get out, because the core isn't really hot because of residual heat – regardless of what people are taught in grade school.
Saying geothermal heat like this is not renewable is ultimately like saying that hydropower is not renewable because at some point the sun will expand and the earth will get so hot that all the water in all the rivers evaporates – which
Have they done anything to address the issue of the earthquakes this can produce? Earthquakes (especially large numbers of microearthquakes) are why geothermal energy is off the table because it damages all of your buildings and infrastructure. To make things worse, the effects of lots of earthquakes on wildlife isn't well understood.
It's Iceland, They have volcanoes and lava and new islands forming, and earthquakes all the time anyway. You could shoot every evil hoomin, appoint some pond algae prime minister, and they'd still have all of the above.
Perhaps a lawsuit against the Mid-Atlantic Ridge is in order.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
Tapping geothermal energy is a great idea, but it's not precisely renewable.
You are correct. There are no precisely renewable energy sources. The wind? Nope, Solar? Nope, pretty clear that stars have a finite lifetime, and are not precisely renewable. But on a human time scale, from when homo has been around, to our likely extinction, it will fit a non-pedantic definition of renewable.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
But these days we do have metallurgical solutions.
During 1979-1980 I was involved in the testing of steam wells near the Vesuvius volcano in Italy.
The tapped reservoirs were between ~1200 and ~1800 meters deep and the bottom hole temperature was close to 350degC, on full flow around 250 degC at the wellhead..
Producing them caused a hellish noise and a lot of steam, we calculated the gross output of a single well was around 50MW.
After a while the measurements showed a rather serious problem, lot's of sulphur, heavy metals and other nasty minerals were included in the steam and eventually in the condensed water.
Cleaning this up would leave around 15MW of energy but it would be hugely expensive.
Although the wells still exist they have never again been produced.
Back to your question about the pipes used, in the day they were some Chrome alloy suitable for the expected temperatures and pressures but any serious corrosion would have a time factor.
I found it interesting that starting up the wells (very slowly and controlled) caused the wellhead to rise some 3 meters due to the heat driven expansion of the pipes. Shutting them down required the same kind of care.
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
In real world units around 375 degC and 220 Bar.
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
This is not correct. Combustion temperatures can reach these temperatures, but boiler water circulates by convection fast enough that the heat is conducted away before the boiler tubes reach those temperatures. The superheater tube bundles must be carefully designed since they are cooled only by steam (less heat carrying capacity than water) and are often exposed directly to the radiant heat. Typical properties for high temperature steam for coal or natural gas plants is 1000F-1050F (538-566C) at 2400psi (measured at the turbine inlet). Plants do exist at up to 1100F steam with some designs using up to 4200psi steam, but these designs are less common due to extra costs of using thicker pipes and pressure vessels, requirement for superalloys and more frequent maintenance.
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.