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Iceland drills 4.7 km down into volcano to tap clean energy (phys.org)
251 points by dnetesn on May 5, 2017 | hide | past | web | favorite | 163 comments

I'd be careful about getting too optimistic.

Conventional geothermal is about 4-5 cents/kWh, on par with natural gas in the US. The dominant capital cost is drilling a large well (you need volume), and so geothermal plants are generally only built in areas that require shallow (1km) wells.

Well costs are ~quadratic in depth. Given how much money has already been spent optimizing drilling for the oil&gas industry, along with how cutthroat that market is, I don't see the cost coming down significantly. As a result, deep geothermal will likely be limited to niche regions like Iceland. And you need deep geothermal to scale it past the existing locations.

I would love to be wrong, since geothermal checks all the boxes for renewables and is also suitable for base load power, but I don't see an obvious path forward short of a drilling tech miracle.

(source: Climate and Energy R&D group)

Don't bill deep geothermal as any sort of green. There are usually emissions that have health consequences for the population around the power plant. The corrosion of the pipes bringing steam from the drill site to the turbines is massive. Drilling that deep and pumping water into the hole ups the risk of earthquakes.

(source: I live in Reykjavík and have witnessed first-hand the increased stench from the Hellisheiði geothermal plant)

I don't disagree with you—I've been to an 800 MW geothermal facility in northern California and was taken aback by the giant heaps of sulphur everywhere—but other renewables come with their own downsides.

- contemporary photovoltaic panels require all sorts of strange metals to make, which have environmental impacts via mining. This might change with new materials. Solar also tends to have quite high carbon dioxide impacts due to the manufacturing process. These are obviously way less than gas or coal, but about double compared to other renewables and nuclear.

- hydroelectric is notorious for destroying huge ecosystems stretching far above and far below the dam and its reservoir. Hydro is so bad that California doesn't let large projects count in the Renewable Portfolio Standard.

It's tough; there's no perfect energy source.

"contemporary photovoltaic panels require all sorts of strange metals to make"

Certain kinds do (e.g. CdTe and CIGS), but not the kind that you'd put on your house. If modern solar panels required significant amounts of rare earths they wouldn't be as cheap as they are.

"Solar also tends to have quite high carbon dioxide impacts due to the manufacturing process."

About 30g/kwh of CO2 vs. coal's ~900g/kwh, and a lot of that is simply because it is usually currently made without green power (i.e. it will go down).

"It's tough; there's no perfect energy source."

There's a lot of half truths told about really good energy sources.

Yeah, coal is obviously WAY worse than solar vis a vis carbon dioxide. I'm not disputing that. But compared to other renewables, it doesn't do as well as you'd expect:

- wind: 11 g / kWh [1]

- nuclear: 12 g / kWh [2]

- solar PV: 45 g / kWh [3]

- gas: 450 g / kWh [4]

Of course, 12 g vs 45 g is NOTHING compared to 45 g vs 450 g (and coal is another 2x atop gas!), so I'm making a bit of a mountain out of a molehill.

[1] http://www.nrel.gov/analysis/sustain_lca_wind.html

[2] http://www.nrel.gov/analysis/sustain_lca_nuclear.html

[3] http://www.nrel.gov/analysis/sustain_lca_pv.html

[4] http://www.nrel.gov/analysis/sustain_lca_ngas.html

Gas actually contributes more to global warming even than coal does because of the methane (~100x as powerful a warming gas as CO2) also released during extraction:


On the other hand, methane breaks down fast. It's only an immediate problem; if we didn't release more CO2 than could be absorbed, then we'd have a fairly decent methane budget as well.

As it stands, of course, it makes everything worse.

...contemporary photovoltaic panels require all sorts of strange metals to make...

This is not quite right. A few kinds of contemporary PV require exotic elements such as indium, gallium, and tellurium. But the market is dominated by crystalline silicon cell technology (about 93% market share in 2015): https://www.ise.fraunhofer.de/content/dam/ise/de/documents/p...

> Hydro is so bad that California doesn't let large projects count in the Renewable

10 cubic kilometers of water: It's the worldwide-recognized ratio under which hydro is considered renewable, and above which the ecosystem destruction is too important.

FYI, for deep wells you generally have to switch to supercritical CO2 instead of water, for the corrosion issue.

It is, however, extremely low carbon. Wind turbines kill birds and make noise, solar panels need toxic manufacturing processes. But carbon emissions are the overriding problem.

The bird thing is not as big of a deal as some seem to think. Wind turbines kill a couple hundred thousand birds each year [1]. In contrast, cats kill hundreds of millions of birds each year [2]. People still like cats. I also don't think the noise concern is a reason to discount wind turbines.

Of course, dirty alternatives have their own toll on wildlife.

1. http://www.smithsonianmag.com/smart-news/how-many-birds-do-w... 2. https://www.sciencenews.org/article/cats-kill-more-one-billi...

Also, chickens are birds. Not wild birds, but birds. If the concern for birds is some kind of animal rights perspective, chickens are up into the billions per year. If people want to prevent needless bird deaths, that seems like the place to start.

I think the main issue for most people is biodiversity and ecological impact rather than sentimentality. Very few wild animals pass away quietly in their sleep.

"Wind turbines kill birds"

15,000x fewer than house cats do though.

Cats kill exactly zero eagles per year.

DISCLAIMER: I'm not an expert in this and I can be very off concerning this area.

Having said this, I think the risk of man-made earthquakes is exaggerated. I mean, I think it might be possible to trigger small seismic events, but they should not be the destructive kind. I doubt we can trigger massive destructive eathquakes like this. Also, from what I understand, smaller seismic evnts should lower the energy that the bigger ones have.

Tell that to the people of Selfoss and Hveragerði which have now become accustomed to smaller quakes on a more regular basis than usually in the past.

Is it damaging though? That is the question I want answered. I mean, even in my post, I did not question the presence of more frequent small earthquakes, I questioned if these earthquakes are any sort of real issue that produces damages or simply unfounded panic.

Yeah it would seem like frequent small earthquakes are way better than rare devastating ones, so it would even be better to provoke them rather than wait like in SF and Vancouver... If only, it helps rehearsing the response, convincing taxpayers to purchase tge equipment and finding early which buildings are dangerous.

Not being able to trust that the ground you stand on won't shake violently? Are you being serious?

I am being totally serious. Why are earthquakes bad? Because they destroy goods, buildings and kill people. If eathquakes do not destroy goods, buildings and kill people are they that terrible anymore or simply an inconvenience at most?

It might sound alien if you have a certain way of looking at things, but really, is my question not logical?

Spoken from the privileged position of not having to worry about it like it is of little concern to those who do. I'm leaving it as an exvercise for you to think of analogies to other aggrieved groups that would not take kindly to being told their concerns are invalid.

Has the lifetime of deep GeoThermal wells been studied at all? Unlike oil/natural gas drilling, a deep geothermal well should provide energy indefinitely barring collapse or obstruction of the well. I'd venture the cost of shutdown and clearing obstructions is fairly low relative to the initial CapEx of the well.

Dumb question and I'm not trying to be pendantic: if the whole world got their power from geothermal, which must (I assume) extract heat and thus cool the core, at what point is there some effect (on magnetic poles? rotation of earth? tides??)?

I wonder similar things about solar - what effect is there on global weather patterns when enough solar energy to make a difference is extracted from the environment? Like, what would happen globally if the entire state of Arizona was in the shadow of solar arrays?

Think of it this way... the Earth is a rock ~4K miles in radius. Essentially all of it is molten rock. When people try hard we can melt rocks to make metals. But we need special-built furnaces, machines, etc. And these furnaces are maybe 50 feet across.

So the Earth has a heat stored which is (4K miles / 50 feet)^3 times larger than a blast furnace.

i.e. about 7x10^16 times larger.

If everyone on Earth had their own personal blast furnace, we'd be controlling 10 million times less energy than what's in the core of the Earth.

Similar calculations apply to other calculations. A Physics 101 calculation I did (years ago) was how much a tidal plant would slow down the rotation of the Earth. The answer was by less than a second a day, after 100 years of running.

> ke, what would happen globally if the entire state of Arizona was in the shadow of solar arrays?

The plants wouldn't grow. :)

But seriously, the energy has to go somewhere. If it's hitting solar panels instead of the ground, the net effect to the world is essentially zero.

Maybe locally the ground would be cooler because it's in the shade. But that's about it.

There's no way that a tidal plant running for 100 years is going to change the day by 1 second. You're many orders of magnitudes off.

That means that if you built 100 of those plants that in 1 year you'd change the length of the day by 1 second.

The 2011 Tōhoku earthquake and tsunami released 3.9×10^22 joules of energy[1] and changed the day by just over a microsecond[2]. A single Tsar Bomba releases 2.1×10^17 joules, so you'd need the energy of around 200 thousand of those to produce the same amount of energy as the earthquake, and then assuming you can direct that energy you need 1000 times more to shift the day by a second instead of a microsecond.

That means that each one of your proposed tidal plants would need to generate the energy of 20,000,000 Tsar Bombas per year.

That's one Tsar Bomba's worth of energy being released every 1.5 seconds at each one of those 100 plants. Buy stock in sunscreen companies now!

Each one of your 100 plants would satisfy all of current yearly world energy production in just 30 minutes[3][4].

I'm too lazy to calculate what that would do to the surrounding area, but I'd wager that they're going to severely depress local property prices due much of the surrounding beach-side property area now being turned into permanent molten lava.

The good news is you could probably build really good wind power plants now, due to constant hurricane winds not seen on Earth since the K–T impact, but I digress.

I didn't check your molten rock calculation but given how off your tidal plant calculation is I wouldn't be surprised if it's way off as well.

1. https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an...

2. https://www.nasa.gov/topics/earth/features/japanquake/earth2...

3. https://en.wikipedia.org/wiki/World_energy_consumption

4. ((5.67x10^20)/(2.1x10^17))/1.5/60 = 30

> There's no way that a tidal plant running for 100 years is going to change the day by 1 second. You're many orders of magnitudes off.

It was a recollection of a problem from 25 years ago for crying out loud.

Thinking about it some more, it's probably slowing down the rotation of the earth by 1 second over the course of 100 years. Not 1 second per day. Which makes about 4-5 orders of magnitude difference.

> I didn't check your molten rock calculation but given how off your tidal plant calculation is I wouldn't be surprised if it's way off as well.

The point was to get a "back of the envelope" calculation. Not to get a precise answer to 4 decimal places.

What's with the bike shedding? Is the point here to have a discussion, or to prove that you're smarter than everyone else?

> given how off your tidal plant calculation is I wouldn't be surprised if it's way off as well.

he showed his work for his first calculation. Looked reasonable to me.

His numbers look fine, but I think the assumptions are false.

    > And these furnaces are maybe 50 feet across. [...]
    > So the Earth has a heat stored which is
    > (4K miles / 50 feet)^3
This seems to assume that the earth is also cube shaped like a hypothetical 50ft^3 blast furnace, instead of a sphere (or oblate spheroid before anyone out-pedants me).

It also seems to assume that a 50ft^3 blast furnace contains energy equivalent to 50ft^3 of molten mantle. If you look at diagrams of blast furnaces you can see that a relatively tiny part of them is actually molten material.

Not being able to find numbers on the stored joules of industrial blast furnaces, I'm just going to just state that 50ft^3 of mantle has a crapload more potential energy than 50ft^3 of blast furnace, most of which is air, equipment & empty space, not molten material.

He is right that there's at least as much energy stored in the earth as he's saying, but it's going to be a crapload more than that.

The insides of blast furnaces are also significantly colder than the average temperature of the mantle.

The point is that these are "back of the envelope" calculations.

Fermi was known for asking questions like "how many gold balls git into a suitcase". The point isn't to get a perfect answer. The point is to get a reasonable answer.

In this case, the point is to answer the OP question in laymans terms. Using not much more than reasonable assumptions, and grade 5 math.

Or, you can bike shed over details.

> and then assuming you can direct that energy you need 1000 times more to shift the day by a second instead of a microsecond.

Still off by a factor of 1000, a microsecond is one millionth of a second.

Yes you're right. I mixed up micro & milli there. So:

* [...] 20,000,000,000 Tsar Bombas per year

* One Tsar Bomba going off every 1.5ms

* World energy production satisfied in 1.8 seconds

We're also going to need more sunscreen.

Less than a second a day in 100 years is a huge change in earth scale. I'm curious, what kind of tidal plant would even come close? Is it assuming we extract 100% energy from the tidal waves and entirely stop the tides, somehow?

I'm fairly certain stopping the tides would be devastating to the environment since several ecosystems (tidal plains, marshes, riparian zones, etc.) depend upon them.

Doesn't it depend on how much less than a second it is?

You are thinking in linear terms. Humanity's historical energy use definitely doesn't look linear, more like exponential - https://gailtheactuary.files.wordpress.com/2012/03/world-ene...

I imagine that if we were able to tap into deep geothermal energy the continuing exponential growth would eventually pass some sort of geothermal limit point.

This is true, but I know for a fact that US energy use at least has roughly dropped or remained stable for the last decade. Increase in energy use is typically driven by people's increasing incomes and their ability to buy energy for using appliances and such. We can expect energy use to increase significantly globally until everyone is at a base level of income, but after that it should be capped at population growth.

Remember Asimov's city-planet Trantor. It relied in part on geothermal energy (core taps) with huge radiator arrays at the poles.

Like the others said, the earth core is HUGE.

But I am a bit sceptical to the no impact scenario. We know a lot allready about the inside of the earth, but afaik we do not really understand it. There are many flows underneath etc. and small changes can have big impacts. Look for example at the amount of artifical CO2 from humans. It is tiny in comparison with the rest of the atmosphere. And yet it gives us a lot of troubles.

And about geothermal: well, here in germany there have been allready some minor earthquakes, probably caused by geothermal plants ...

(German) http://m.focus.de/wissen/klima/tid-14230/energie-mythen-myth...

I was wondering if anyone else had made the connection to claims (or maybe that's too weak of a word) that fracking causes earthquakes.

Forage indeed can make earthquakes. An experiment was run in Alsace (France) and as far as I know it was stopped due to this kind of problems.

Even if you don't understand French, you can look at pictures of this article: http://www.lefigaro.fr/actualite-france/2013/11/19/01016-201...

Another experiment was stopped in Switzerland for the same reason: https://www.theguardian.com/world/2009/dec/15/swiss-geotherm...

Well according to a professor in canada, fracking definitely causes earthquakes ...


The scale at which humans draw energy from the core is negligible compared to the amount. Think about it, earth has been cooling down through radiating from the surface for billions of years. Given the ratio of the geothermal station and the surface area of earth, I don't think there is anything to worry about.

As for solar, the incoming energy would have been mostly converted to heat. When we use the electricity produced, we convert it back to heat again. If the entire state of AZ were covered with solar panels, and all the energy spent in NY, there would be some localized changes but not much in the global scale. For the foreseeable future, we are not even close to covering up just 1% of the land area of AZ.

Earth's radiation scales as a cube of the radius. Our energy usage is growing exponentially. You can apply big-O analysis to this problem ;)

> Our energy usage is growing exponentially.

Well, with efficiency gains in the latest years energy consumption (not only electricity) actually is constant or decreasing in developed countries. Add to that decreasing population fertility and if you expect that developing countries are going to follow the same trends after a certain threshold then that's not a good assumption long-term.

Japan: https://en.wikipedia.org/wiki/Energy_in_Japan#/media/File:Ja...

US: https://en.wikipedia.org/wiki/Energy_in_the_United_States#/m...

Europe: http://ec.europa.eu/eurostat/statistics-explained/images/thu...

Its a fun question on a Friday, with two possible avenues; "How much heat drain would it take to freeze the Earth's core?", and "What would freezing the earth's core do to life on the planet?"

For me, the more interesting one, which was the 'bad guy' in the forgettable movie "The Core". The earth's magnetic field is created by the motion of the fluid iron (which is conductive) surrounding the solid core[1]. That it is moving and carries charge creates a dynamic dynamo which determines the strength of the magnetic field. Changes in the fluid are why the magnetic poles move around and sometimes change places.

The number 1 feature of the magnetic field (for me at least) is that it deflects the solar wind (those charged particles racing out from the Sun) which would otherwise collide with the gases surrounding our planet and accelerate them outward. Eventually stripping the planet of most of its atmosphere.

One of the less well known ways the solar system could wipe out humanity.

[1] http://www.physics.org/article-questions.asp?id=64

Yes, most wells are productive for about 30 years, and then you have to wait a bit (another 30) to let the rock heat back up. The NPV past 60 years is pretty tiny, so it is hard to amortize capex that far out.

Worst case, you run them continuously at half capacity, but then your cost per kWh is about 2x.

>Yes, most wells are productive for about 30 years

Wait, I haven't looked at geothermal in a long time so I'm not at all up to speed on the current state of the at. But previously you wrote:

>and so geothermal plants are generally only built in areas that require shallow (1km) wells

That sounds like your "30 years" number there is for shallow wells. Intuitively it doesn't seem like this logic would necessarily be identical for deeper wells: obviously at some depth the rock is always extremely hot (or, in fact, molten). The article seems to indicate that they expect a deeper well to produce higher temperatures and pressures, in turn allowing more energy production, and that seems like it'd make sense. Maybe 1km vs 5km makes no difference in lifetime beyond that, but does your analysis include deep wells already in an equivalent area? Otherwise it doesn't seem reasonable to extrapolate past lifetimes of shallow wells to future lifetimes of deep wells, even ignoring that they say they'll be able to achieve far higher energy generation per well.

Yes, you have a point, though the reality is even more complicated.

There are physical limits to the heat capacity of the rock, and the heat flux into the region. Deeper wells are not necessarily hotter. Going hotter adds other costs (drilling mud, water=>co2, casement, etc), so its a big multivariate optimization.

> obviously at some depth the rock is always extremely hot

Not if you keep pumping in water to run a steam turbine.

I assume that's how geothermal energy works, and I'm not going to double check.

>Not if you keep pumping in water to run a steam turbine.

Are you being serious? In terms of known capabilities the Kola borehole shows that even with older tech we can drill down to over 12km in depth, and there have been decades [1,2,3] of efforts drill all the way through the Mohorovičić discontinuity into the mantle (20+km minimum from a continental starting point, 5-10+km from ocean). Lithosphere/mantle boundary tends to be defined by temperature, in that around 1800°F is when the weakest common mineral (olivine) begins to exhibit viscosity. Well before that it'd reach the point where the amount of pressurized water we could pump through it wouldn't be able to keep up with new thermal load. So yeah, at some depth the rock is always extremely hot.

In terms of economics though of course there is some set of balance points for a given level of tech and economics between cost of drilling to a given depth, gains in lifetime/power density, maintenance costs, costs/losses of actually moving working fluid from heat point to generator, reliability advantages, etc etc. Presumably experts go through and consider all of this, it should be tractable within some set of risk bars. If an experienced power company is actually putting down millions on doing a project after evaluation, I see no reason to doubt that they've done the math to their/their investors' satisfaction to a level sufficient for a pilot project.

1. http://www.smithsonianmag.com/science-nature/decades-long-qu...

2. https://en.wikipedia.org/wiki/Chiky%C5%AB

3. https://www.extremetech.com/extreme/247370-drill-baby-drill-...

I'm just making the simple point that however hot the rock is, it will cool down when you pour enough water on it.

I don't know what the Mohorovičić discontinuity is, but I'm sure it doesn't change this physics fact.

The rock will radiate heat sufficient enough to boil the water before it can even come close to coming in contact, so no, basic thermodynamics would like a word with your physics fact....

And the water, in boiling, will remove some of that heat that would otherwise radiate back. The entire premise of geothermal energy is removing some heat from deep down in the earth. Whether that amount is big enough to cause a noticeable difference is was is being debated.

>Well costs are ~quadratic in depth.

Anyone know as to why this is the case? At first pass it seems like your cutting tools should wear out in proportion to depth. But I suppose as things get warmer tool wear becomes faster. What types of tool materials are used for rock boring? Diamond? Tungsten carbide? Is is more of a "conventional machining" process, or an abrasive / water jet? Or explosive like in hard rock mining? What else has an effect on cost for deep holes? Shaft length gets longer, so the twist becomes more of a problem if your are driving rotating bits from the top? Does it have to do with removing the material from the bottom of the hole to the top? Others?

"Anyone know as to why this is the case?"

Think of a telescopic antenna. That structure is similar to what is done to bore a well. You start with large casing diameter and add progressively smaller casings until you reach the target depth. The deeper you go the bigger the casing you must start with. Offshore deep water stuff can be a meter in diameter with 10cm solid steel walls; monstrously heavy and costly materials. And you use kilometers of the stuff.

There are a lot of reasons why costs scale as they do with depth; casing is just one of the more obvious.

Anyone recommend a good pop-sci book on deep hole boring? Seems like it could be an interesting light engineering read.

For deep wells would the need for casing change depending on the material you're drilling into? once your into hard granite bedrock I'd imagine wells of a certain diameter are stable with minimal to no casing.

Yes, geology is a big factor in engineering a well. Pressure is another. Every well is engineered to the prevailing conditions and requirements. Sometimes it is possible to elide heavy casing which can save large amounts of money.

> deep geothermal will likely be limited to niche regions like Iceland

True, but aren't there plenty of such regions around the world? In the US I can think of at least Hawaii and Yellowstone.

Not the greatest population centers, but power lines have a good range. Also, Iceland is making good use of its comparative advantage by doing power intensive production like aluminum smelting and bitcoin mining.

What about the west coast volcanoes in North America?


...how deep do you have to go to get to the 400C temperature level on some of those volcanoes??

The world's largest geothermal energy field is in California, 1½ hour north of San Francisco: https://en.wikipedia.org/wiki/The_Geysers

DuckDuckGo for Cascades Fumaroles. You can hike to vents emitting steam, many through glaciers. http://www.ivm-fund.org/mount-baker-volcano-fumaroles/

Also many hot springs could be potential GeoThermal candidate areas http://www.hotspringsenthusiast.com/USsprings.asp

Imagine the political/public outrage around building an alternative energy source in Yellowstone National Park. People on both sides of the aisle would be losing their minds.

That said, geothermal activity isn't confined to the park borders, and there may be a suitable spot outside of the park. But again, politics. Building a geothermal plant in the middle of natural gas country would be a challenge.

Small note about Iceland- My web host (1984) is located there, and the servers run on 100% geothermal. That, in combination with the stellar privacy laws, make Iceland a nice fit for me.

The plants are relatively humble buildings that just emit water vapor, so they're minor eyesores more than a real danger to the environment.

That said, I agree that it would take a lot to get anything like that built.

It can get pretty crazy the resources consumed by a drill rig during the average week drilling. New bits, roughly 1200 or so liters of fuel every 24 hours, all kinds of sacrificial bits of tube if they are core drilling their holes. Any hundreds of liters of drilling fluids depending on down hole conditions. I was blown away by the consumption when I saw it first hand. The fuel and drilling bits were the craziest. Then all of the maintenance consumables that you go through as a result of running 24/7.

I shudder to consider the quantities of hardware consumed to drill 4km+ you would get all kinds of crazy hard rock down there, not to mention the time it would take for rod pulls.

> geothermal checks all the boxes for renewables


"Although geothermal energy is still preferable to gas, coal and oil, it's not 'completely renewable and without problems... As soon as you start drilling you have issues to it, such as sulphur pollution and CO2 emission...'"

A bit late to the party but i wanted to back this up by linking to the relevant chapter from the fantastic book by David MacKay: http://withouthotair.com/c16/page_96.shtml

The chapter is only 4 pages long and he quickly works out that if done sustainably, even blanketing the entire country with geothermal plants could provide at most 2 kWh/day per person in the UK. Current consumption is about 125 kWh/day per person. So even without the capex argument, it is just not a very efficient source of energy long-term.

Your statement should be qualified with "for the UK region".

> Other places in the world have more promising hot dry rocks, so if you want to know the geothermal answers for other countries, be sure to ask a local. But sadly for Britain, geothermal will only ever play a tiny part.

The additional advantage of Geotermal from an operations standpoint it has 0 marginal cost which guarantees it will be producing on most economically dispatched power grids.

Natural gas use will need to stop because of co2. IOW that "on par" cost of NG unsustainably excludes externalities.

I think the real approach to geo should be more focused on decentralized use, instead of trying to do big arrays of holes, like solar, it's in the combination with localization of other technologies in array themselves that seem to offer the most opportunity.

Wind, solar, geo... they all work together better than as a single unit.

That is sort of true from a grid perspective, but the math doesn't really work out well for geothermal. Geothermal has high capex, low opex, so you need it running 24/7 to amortize the high capital costs.

If you combine it with renewables, you get high fluctuation of demand from the grid, which selects for the exact opposite technology (higher opex, lower capex). Natural gas fits the bill, so that is where the market is going.

And geothermal energy is a too-often-overlooked technology. It's not intermittent like wind and solar. It's more like nuclear but without the emotional baggage. As we try deep decarbonization, we're going to need more things like geothermal (or nuclear) or we'll end up spending like 2 or 3x as much money over-building solar to provide enough power even on cloudy winter days, building many more wind turbines, etc.

The hard part isn't getting to 60-80% clean energy, it's getting that last 20%. Geothermal helps a LOT with that. (As does nuclear, which is why we should be protecting existing nuclear assets until fossil fuels are eliminated... The existing ~20% of our electricity in the US produced by nuclear will make deep decarbonization multiple times cheaper than relying solely on wind and solar alone, plus accelerate deep decarbonization by a decade.)

An interesting idea is to build geothermal and solar at the same site. Consider areas where these two maps overlap in high potential for both: Geothermal: http://www.smu.edu/~/media/Site/Dedman/Academics/Programs/Ge... and Solar: http://www.nrel.gov/gis/images/map_pv_us_june_dec2008.jpg

Places like New Mexico and southern Colorado are good fits for this.

A problem with geothermal is if you draw heat too fast from the ground, the output will decline over the years. If you stop drawing heat, the ground will warm back up and then when you start again, output will be higher than it was when you stopped. So there is some sense in conserving geothermal power when demand for it is low.

So the idea is, you draw from solar when the Sun is shining and draw from geothermal when it's not. By being co-located, you can use the same grid infrastructure and get higher utilization out of your powerlines. You've essentially converted some of your solar energy into a baseload power source. Or you can think about it as enhancing the output and lifetime of your geothermal power source.

(And it's possible that if you have a LOT of extra solar power, you could run a resistive load underground, using the ground as a makeshift thermal battery.)

From what I understand, the big hurdle for 100% renewable is not replacing the power stations that provide base load power, but rather replacing peak load power stations. Hydro is often used for that, but in the Midwest the peaker stations are almost entirely run with natural gas.

Replacing those often involves some way of storing energy that you've generated in a renewable fashion. The issue is that storing large amounts of energy is not easy, especially when you live in an area that could be described as flatter than flat.

Storing energy for a few hours isn't that hard. I have no doubt we can store for 4 or even 8 hours of average load to replace all the peaker plants. It's the multiple-day cloudy spells during the winter when you really need that last 20% of power capability. It's not feasible to store energy like that for 200-1000+ hours (there are ways, but they're very, very difficult and generally inefficient... deep sea hydrogen storage, for instance).

Since we have decent short-term storage tech, it's not the peaker plants I worry about but the constant baseload. Peakers will be replaced by utility-scale storage.

Mr. Musk said that the world would need about 100 gigafactories in order to produce enough batteries to level out solar production off hours.

One factory is producing batteries now, and Tesla is announcing three or four new gigafactory locations by the end of the year.

It's a start.

The first factory is not complete yet. According to Wikipedia:

Tesla held a grand opening on July 29, 2016 of the operational facility, having only three of the final 21 "blocks" of the gigafactory built out, or approximately 14 percent of the final factory size expected by 2020. By September 2016 Tesla had spent $608 million on Gigafactory.

By those numbers it would take only about $425.6 billion to manufacture all 100 factories, which I think is probably an estimate that's off by orders of magnitude in the wrong direction. And of course time and materials are a large factor as well.

I still feel like the reluctance to invest in pumped storage is ultimately going to be what does us in.

Pumped storage at ~$150/kWh (for a large installation) is about half the Musk price of large scale battery storage ($250/kWh).

I think there's room for both, as you can put batteries just about anywhere and at nearly any scale, while pumped hydro works best for large scale. Gigawatt-level for ~10 hours at a time potentially... Largest facility is 3GW for about 10-12 hours, about the same as the yearly battery production the completed Gigafactory will have: https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...

I do think the difference between pumped and battery storage will get closer, however. And battery power has the advantage of option value since you can build it much faster (about 10 times faster) than a big pumped hydro station.

Yes! I've been following various storage technologies for a while and Pumped storage has always been fascinating.

Indeed, we will likely end up using a wide variety of technologies for storage.

Do we even have enough Lithium to supply 100 gigafactories? Recycling Lithium batteries is still quite difficult.

Lithium is one of the most prevalent elements on earth. Spodumene (rocky lithium ore) is likely to be a very important economic source in the future as it is much more common than the brine currently used to manufacture batteries. Brine requires a water pump to extract, spodumene requires mining like any normal mineral. Spodumene is also found in extremely high quality deposits in the US, including single crystals up to 47 feet across. It produces higher quality lithium than brine sources.

Spodumene is found in and with granite and quartz. Granite and quartz make up 75% of the earth's crust. I don't know how much by weight is spodumene but it's certainly extremely common- much more so than any common metals.

Spodumene is ~6-7% lithium by mass and is mined in an open pit, so no worries about soil or water pollution. It's separated from other rocks by grinding, flotation, and then acid. Very few people like acid in their industrial processes but I will note that lithium production uses way less hydroflouric acid than oil refining. The final stage uses sulfuric acid and while again acid is never good, sulfuric acid is one of the most-used and most-produced chemicals. Most minerals require sulfuric acid for extraction. It comes in a bottle of drain cleaner. Mining lithium rock is as economically painless as buying blasting powder and excavators, and as environmentally painless as... well nothing. The pollution is basically negligible.

Yes we do, and no it's not, at least not the way Tesla is doing it. Because they're using a standardized cell and standardized packs, they can easily automate the careful recycling of a lithium cell.

Tesla actually does a single/two step recycling process that incinerates/electrolytically separates the metals from the graphite/hydrocarbons/lithium. The lithium containing fraction is sold as clinker or aggregate. Rocks, basically. Only the steel, nickel and cobalt are really recycled.

I'm talking about the newer process they're developing at the gigafactory. But you're right that lithium is so cheap at the moment (getting it from salty brines) that you don't really need to recycle it. The other metals, sure. But push comes to shove, you could pull it from ocean water. Won't ever be economically competitive with brines, but it's also not too expensive if that were the only option.

copying my other comment:

>Lithium is one of the most prevalent elements on earth. Spodumene (rocky lithium ore) is likely to be a very important economic source in the future as it is much more common than the brine currently used to manufacture batteries. Brine requires a water pump to extract, spodumene requires mining like any normal mineral, but it's found in extremely high quality deposits in the US including single crystals up to 47 feet across. That means higher quality lithium in addition to greater availability.

>Spodumene is ~6-7% lithium by mass and is mined in an open pit, so no worries about soil or water pollution. It's separated from other rocks by grinding, flotation, and then acid. Very few people like acid in their industrial processes but I will note that lithium production uses way less hydroflouric acid than oil refining. The final stage uses sulfuric acid and while again acid is never good, sulfuric acid is one of the most-used and most-produced chemicals. Most minerals require sulfuric acid for extraction. It comes in a bottle of drain cleaner. Mining lithium rock is as economically painless as buying blasting powder and excavators, and as environmentally painless as... well nothing. The pollution is basically negligible.

I didn't know the gigafactory was gonna do component-level recycling, that's pretty cool. I think it should be relatively easy to separate the metals from the SEI and graphite/lithium in a recoverable way, but processing the SEI has to be pretty complex. Maybe acid would do it- at that point it would probably be worth it to recycle the lithium but you'd have to set up an entire process line just to be able to add it to raw feedstock ore. It'll take a LOT of battery recycling before that's more profitable than selling it as clinker.

To enable peak load, one can do pumped hydro (PHES) or molten salt storage when demand is low and the sun is shining or wind is blowing. Only short term storage is needed for peak load. Water can be stored indefinitely but you're probably getting back 70 to 80% of what you used to pump it.

Yeah, but pumped hydro is really hard to implement in the Midwest since we don't even have hills. You can use quarries that are mined to two different depths, but you can't build a quarry large enough to really matter.

Molten salt is interesting though, and I am not particularly familiar with that.

> A problem with geothermal is if you draw heat too fast from the ground, the output will decline over the years. If you stop drawing heat, the ground will warm back up and then when you start again, output will be higher than it was when you stopped. So there is some sense in conserving geothermal power when demand for it is low.

This sounds like a battery to me. Good problem to have :)

People seem to ignore one of the most promissing things for stable load. Solar can actually do it, solar thermal.

It is clean, relativly easy to build, shared tech with gas on the turbine and can have it produce power 24/7.

You just heat up a pot of something and let it cool during the night, still producing energy.

Cheap, green, stable.

Green, but definitely not cheap or stable. Thermal solar is not very efficient and the plants are extremely complicated. They use molten salts that can freeze solid inside the pipes, and are also extremely potent oxidizers capable of starting huge fires.

Ivanpah is expensive and consistently underperforms and has to make up the difference with natural gas. It freezes solid each night and has to be reheated. The nature of thermal solar also means you can't really take advantage of scale, so the problems aren't likely to get any better even if they get built even bigger.

There is essentially zero chance that solar thermal will ever be better than batteries. Ivanpah has 392 MW of capacity @ $2.2 billion, and produces 1.75 GWh per day. Utility scale solar panels are below $1.42/watt[1]- $557 million installed, with land, tax, and inverters. The average price of lithium batteries is below $150/kWh, which would be 788 million for 3 days of storage. Altogether that's 61% the cost of Ivanpah using the average prices from last year. It's also roughly on par with current electricity prices (12.2 cents vs 10.3 cents, but NB residential is 12.6 cents)

Solar city claims panels costing 55 cents per watt and Tesla expects to get below $100/kWh for cells by 2020. If those prices held the cost for a solar plant with 3 days of storage would be 740 million, and the cost of electricity would be 6.8 cents/kWh.

[1]: https://pv-magazine-usa.com/2016/09/29/nrel-u-s-utility-scal...

I think it's possible that geothermal and hydro can get us 20% of our total power (though that relies on very optimistic estimates being correct), but I think that's misunderstanding what we actually need baseload for, which is when wind and solar aren't working to provide either enough, or any, power (for whatever reason). You need to be able to replace all of their power for relatively short periods of time (though to sustain our current lifestyle, probably longer), not 20% of their power all of the time. Being able to ramp up a bunch of normally idle natural gas plants at a moment's notice lets us do that right now, but part of that is that existing natural gas plants don't necessarily all fail at once... whereas wind and solar plans would have pretty correlated failures.

What that 20% does is lets you stretch your storage capacity much more, especially when combined with some demand-response and the remainder of the reduced capacity wind and solar (photovoltaics will basically ALWAYS produce /some/ power during the day, even if it's cloudy).

It helps tremendously. I do think we'll use batteries for immediate power instead of natural gas. And the natural gas plants we DO have (hopefully not many of them!) could be more efficient because we won't have to ramp them up and down quickly, so we can use the much higher efficiency combined cycle plants.

(But this idea of replacing nuclear with renewables and peakers seems really dumb to me... it's clearly a step backwards in emissions when we should be targeting fossil fuel plants for shutdowns. The fact that supposedly "green" people are pushing this is really, really weird.)

> It's more like nuclear but without the emotional baggage.

... and crazy costs (construction, maintenance, decomissioning, waste disposal, much of it obfuscated under general energy budgets, de facto government subsidy, or optimistic amortization).

The maintenance is fairly low. Decommissioning and waste disposal are already included as a small fuel surcharge.

The costs for construction are very high, for one main reason: time. Due to inexperienced contractors, legal battles, etc, it often takes a decade or more to finish a nuclear plant which DRAMATICALLY increases costs and reduces the option value. But all that could be dramatically reduced, in principle, without sacrificing safety or even needing dramatically new designs. Nuclear innovation really needs to focus on the construction process. Get that down to 2 years or less, and the cost problem will be solved.

Decommissioning goes over budget too. Fukushima was partly a result of people not wanting to swallow the decomissioning cost, preferring to extend the nuclear reactor's life beyond what they probably should have. Waste disposal is not a solved problem.

Are you aware of the Westinghouse bankruptcy due to nuclear projects, possibly taking Toshiba under with them?


and the risk that a catastrophic event would bankrupt a large nuclear power plants operator or even an entire state.

If you're interested in tracking the efficiency of your geothermal install, there's an app for that (which I helped build): http://groundenergysupport.com/

I might be interested if you didn't call it "geothermal." :D

(Just kidding, that's a cool app.)

When I was in sixth grade I entered a science contest to invent a new form of clean energy. Mostly I entered because I was getting a B in my science class and needed extra credit to get up to an A.

And the thing I "invented" was literally what's in this article, geothermal power. Pump water down near magma, have it turned to steam, have that steam come rushing back up to power turbines.

The problem with my invention was that the company sponsoring the contest was a geothermal energy company.

I'm still proud of myself though, because I thought of the idea independently and it is a pretty damn cool idea for how to get energy.

Iceland has discussed building a ~7TW (I think?) cable to transmit power to the UK.

At least in Reykjavik, hot water is piped directly into homes and used for heating (radiators) as well as hot water (with attendant sulfur smell). My host there told me "my wife doesn't like the smell so, we use heated cold water instead". I had to think for a few seconds to parse the phrase "heated cold water". Oh, right, that's what I call "hot water" :)

It's so abundant, they don't mind the waste. Just leave the windows above the radiator open, the radiator keeps the room warm, you get fresh outside air inside, and the convective flow keeps the air moving. That chilled water is sent back to the geothermal plant and pumped back into the ground to replace the water taken out. IIRC there are definitely been geological issues (earthquakes) as a result of this whole process.

Most of your comment is wrong. They've been discussing building a 1GW cable. 7000 times smaller than 7TW. A 7TW cable would be enough to transmit Iceland's yearly electricity production 700 times over. It produces ~10GW per annum.

Hot water is not piped directly into the homes in Reykjavík, it's heated up "cold" water, with artificially added sulfur. See another comment of mine here: https://news.ycombinator.com/item?id=14274085

In Reykjavík the water you use is not recycled in any way, it's pumped into a sewer from there into the ocean. It's definitely not pumped the >50 km back to Nesjavellir for reprocessing.

Thank you for the corrections. I was in the datacenter but now I've googled it and found the information about the 1GW cable:


I'm very surprised to find that the hot water is heated cold water. Where is it heated? Offsite, with geothermal plants, I must assume? Otherwise I'd be VERY confused about how my host would not know that he had 2 separate water heaters. Seems quite odd that a local would not know this, but I guess that's how rumors work. Is the hot water in radiators similarly offsite-heated water?

I interpreted your comment as saying that hot water was piped directly into homes from a natural source, but I see now that you may not have meant that.

There are exceptions, but generally hot water is piped directly into homes in Iceland from municipal heating. There's no domestic water heaters. There are dual hot & cold water pipes everywhere. The hot water that comes out of the tap is from the same source that's in the hot water radiators.

In the case of Reykjavík the hot water is initially cold water heated at Nesjavellir[1] and at [2] you can see an article in Icelandic about the pipe. It's 27km of 80x90cm pipe that can transfer 1600 liters of 100 degree hot water per second. Here's the pipe on Street View: https://goo.gl/jFzvYN

The reason they heat up cold water is simply because most of the time when you find an abundant natural heat source it doesn't also come with an abundant natural water source. Therefore you pump cold water in, mix it with the heat, and pump out hot water.

I don't know what fancy technology they use for this at Nesjavellir, but in some rural areas this setup is literally just a coiled pipe dropped into a hot spring.

1. https://en.wikipedia.org/wiki/Nesjavellir_Geothermal_Power_S...

2. http://www.verkis.is/verkefni/veitur/vatnsveitur/nesjavallar...

I did understand the water to be piped directly into homes from a natural source, which is what my original comment reflected. However, in retrospect, that may have been a misunderstanding on my part rather than what my host literally told me. I perhaps combined the concept of municipal hot water and the sulfur smell into a concept where the hot water was actually geothermal water -- rather than normal water heated by geothermal power.

I did see one of the very large geothermal plants, but am having a hard time remembering where it was. Either on my way to/from Thórsmörk, along the golden circle, or on a drive to Snaefellsnes.

Thanks again for your insight!

GW per annum is a unit you would use for the rate of installation of new power production capacity.

Perhaps you meant Iceland's average power production is 10GW?

That's pretty dwarfy! But, can they pump magma to the surface, to defend their rocky fortress?

I just hope that they are being careful not to drill through any adamantine formations. http://dwarffortresswiki.org/index.php/DF2014:Raw_adamantine

Praise the miners!

I firmly believe that the technology to pump water that turns the waterwheel that powers the water pump (and also something else) must be extracting geothermal energy. We just don't see the details. %%

It would be a whole lot cleaner (and friendlier to the framerate) to have a 3x3 geothermal power plant building with a magma reservoir under one tile, and a water reservoir under another, which transmits power to mechanisms or axles touching it, and maybe also pressurized steam to any pipe touching it.

Yes, this seems much better than coal/oil, but isn't there a finite amount of heat under Earth's crust? Have we studied what would happen if we cool Earth's internal temperature by extracting heat in this way?

The Magnetoshpere which protects us from radiation is generated by the magma under the crust[1]. Eventually, if we interfere with the magma currents too much, don't we run the risk of damaging our magnetosphere?

[1] https://en.wikipedia.org/wiki/Earth%27s_magnetic_field#Physi...

> isn't there a finite amount of heat under Earth's crust?

We can't make meaningful change over the next million years which is vastly past any reasonable projections.

The earth is 6 * 10 ^ 24 kilograms. Changing that much mass by 1 degree would take ~2000 Joules * 6 * 10 ^ 24 kilograms, but we don't get 100% efficiency so let's say it's 10% for a nice low estimate to get 1.2e + 27J.

Worldwide energy use is 5.67 × 10^20J / year. So circa 2 million years of total worldwide energy supply for a 1 degree change. Of course it's not a static value as nuclear reactions and tidal friction are also adding energy, while energy also slowly escapes though the crust.

Thank you for this analysis. A 1 degree change over 2 million years strikes me as rather unlikely to meaningfully affect magma currents

The movie The Core, like so many others, are only plausible if your math is really, really wrong.

I would just guess off the top of my head that, because of the sheer volume of the earths interior and the amount of energy stored there as heat, the energy to run our entire civilisation for 1000's of years would be trival compared to it.


The 4.7 km well is still in the earths crust, not even reached the lithosphere. As far as the earths interior is concerned it might just be like an era of slightly increased vulcanism.

The heat in the earths core is actively generated as well, by radioactive decay and viscous friction. It's not all just left over heat. In that way it's kind of like asking if windmills will cause the wind to run out. Heat is constantly moving from the interior to the exterior of the earth, and we are really just tapping into that rather than breaching a dam that does not leak.

No. The total heat energy down there is astronomical. And earth is heated by the sun. And the heat removed from the rock isnt being flung out into space. Much of it will return through the ground. We are just moving it a few km up from where it is. The earth is thousands of kms thick. We are toying with heat within the pond scum atop an immense ocean of hot rock.

Also excuse my ignorance - but does the heat released warm the Earth's atmosphere? I realize it doesn't create greenhouse gases, but wonder if the newly released heat would make a difference to sea & air temperatures, or just gets radiated away.

It actually warms the atmosphere infinitesimally less than other methods of generating power (aside from solar, wind or hydro). Normally when you burn something to generate electricity the excess heat is released into the air. The same process, with the same efficiency (in fact, slightly better), still happens in geothermal but it also very very slightly reduces the amount of heat coming up from the earths core elsewhere.

The short answer is "it depends what they are using as a cold source". They are probably heating the ocean.

"The Institute of Economic Studies at the University of Iceland said in a February report that the country will not be able to abide by the COP21 climate change agreement signed in Paris in 2015.

Greenhouse gas emissions are rising in all sectors of the economy, except in fisheries and agriculture, it said."

This is unfortunate. Given Iceland's cheap & abundant renewable energy (2X Norway's electricity production per capita!), they really ought to be following the example set by Norway and prioritising Electric Vehicles through tax policies, etc.

It would be easy to build excellent charging infrastructure for EVs in this island nation - instead you have hordes of tourists driving around the ring road in smelly diesels.

I do see a few Nissan Leafs around Reykjavik and Akureyri, but there is barely any public charging infrastructure for driving between cities and tourist attractions.

Does anyone know where phys.org has their articles from? I suppose it has something to do with Elsevier. Since a LOT of their articles has to do with students and universities.

Overall, they publish a great amount of "copy-paste" articles, either from other news sites and/or student papers. I am 100% sure their reports don't write original articles, just rewrite from other sources. It looks to me that Elsevier has found something new with the information they are tapping from (students/universities)

PS. The source of their article now is : https://techxplore.com/news/2016-10-geothermal-power-potenti...

PS2. Elsevier seemed my best guess, since a lot of articles discuss research from students. Other articles are a rewrite

Interesting . NZ has had a geothermal plant for decades that is situated in a volcanic area (and right next to tourist hotspots of Rotorua and Taupo). They force cold water down and use the steam to drive turbines. No idea on the efficiency but the fact its been operating for decades would suggest its good enough to be viable.

I'm at a loss a bit, are they directly tapping underground sources of hot pressurized liquid and not using some form of heat exhanger? How would they deal with various minerals dissolved in the water from gumming up their turbines or heavy elements escaping into the environment? IIRC there was one geothermal plant (in one of the nordic countries, i don't recall which) sitting by hotsprings that had to replace their piping every few months due to mineral deposits...

random thought: Could geothermal power be considered nuclear power considering half of the Earth's internal energy comes from decaying radioactive isotopes?

> How would they deal with various minerals dissolved in the water from gumming up their turbines or heavy elements escaping into the environment?

This kind of ongoing, predictable maintenance is usually priced into the project, along with a health margin for error, and is rather easy to predict (except when you're one of the first such power plants using a new technology or exploiting a new geography). According to [1], the upfront capital cost for a geothermal plant is 5-6x that of a natural gas plant ($/kW) and the maintenance cost is over 10x ($/kW-yr) but since geothermal doesn't require expensive fuel it can be cheaper than fossil fuel based power (depending on price of fuel). Replacing pipes every few months isn't any different than buying tons of gas if you're still making profit and since geothermal plants rarely run more than 90% of the year because of diminishing returns, there's plenty of time for that maintenance.

> random thought: Could geothermal power be considered nuclear power considering half of the Earth's internal energy comes from decaying radioactive isotopes?

Technically yes, but nuclear power implies a concentrated sample of radioactive material. Radioisotope thermoelectric generators [2], which generate power from the heat of decaying isotopes, are relatively common nuclear power sources in space exploration. They were used on the Apollo 12-17 missions, they still power the Voyager 1 and 2 spacecraft, Cassini, and many more including, most recently, the Mars Science Laboratory rover.

[1] https://www.eia.gov/outlooks/capitalcost/pdf/updated_capcost...

[2] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

> random thought: Could geothermal power be considered nuclear power considering half of the Earth's internal energy comes from decaying radioactive isotopes?

Only to the extend that all power is nuclear power. Solar power: the sun is a huge fission reactor. Coal: ultimately got its energy from the sun. Etc.

Nitpick: the sun is a huge fusion reactor.

There's an English language summary page from the company itself at https://www.resourcepark.is

This looks like the beginning of the shinra to me

Makes sense, some neighbors in the Midwest have been heating their homes, driveways, etc. with geothermal heat pumps. Same principle, I suppose.

Not at all! Very different principle. "Geothermal" heat pumps are just using the ground as a thermal mass. There's no extraction of the energy from the Earth's interior, with such a heat pump, just using dirt as a thermal buffer (between the seasons).

It's actually super annoying that the same word "geothermal" is used for both. If I were emperor of the world, I'd ensure that the proper "ground-source heat pump" were used instead of the criminally misleading "geothermal."

Ground-source heat pumps are not energy sources, they consume energy.

What Iceland is doing is actually developing an energy source.

Iceland has also been utilizing its geothermal resources for centuries. Currently circa 22% of their electricity and 87% of the heating and hot water needs are met using geothermal energy.

The sulfuric smell in the hot water takes a little getting used to, but it's pretty amazing that it's naturally heated in most places throughout the country (though, a bit easier in such a tiny country).

The sulfuric smell in the hot water has nothing to do with the use of geothermal power. Most tourists think so because they've only been to or near the capital area.

Reykjavík artificially adds sulfur to its hot water to reduce the corrosion of their hot water pipes.

I can't find a source for that in English but there's one in Icelandic, it's the "Vinnslutæknileg vandamál við vinnslu jarðhita" section.

1. http://web.archive.org/web/20160813045634/http://www.samorka...

This seems contrary to most tourism information, and that PDF is pretty much the only source I can find... interesting. So they intentionally make their hot water non-potable to prevent corrosion (the bulk of tourism info recommends not drinking the hot water)?

Seems like Iceland could really use some sort of myth/fact information as they continue look to grow their tourism.

You should never drink hot tap water from any source unless you boiled it yourself using cold tap water in a kettle somehow anyway. There's increased likelyhood of bacteria and trace heavy metals from whatever heating equipment was used. Totally not worth it.

Probably OK to drink if you use a gas or electric califont (zero hot water storage).

Why would they? The Blue Lagoon, aka Icelands largest tourist trap, is completely artificial and is waste water.

They have very little incentive to "correct" people

The Blue Lagoon also publicly posts the information about where the water comes from.

I also know some Iceland natives who actually like it, so I wouldn't completely dismiss it as a tourist trap.

Wow, that's totally contrary to what I thought I learned when I went there, but a number of sources seem to support this.

Centuries? That's a lot of time. What kind of activities were they doing two centuries ago? Smelting iron ore?

Think like tapping hot springs for bathing and keeping your house warm or even cooking. When I was in Indonesia, I saw people would boil vegetables in the hotsprings.

Cool, thank you



If you have an issue with how it's marketed, I'd suggest inquiring against it.

I was going to use "heat pump" but then was sure to get corrected on a traditional heat pump (like in your AC unit) vs a ground-based heat pump.

Air-source vs ground-source.

I need to start using that.

  "If I were emperor of the world..."

Do you want to get firemonsters? Because this is how you get firemonsters.

It would be cool to 3d print rock structures using magma from below

geothermal doesn't use magma, which would destroy the borehole. Its just a hole into very hot rock somewhat near magma. It's still far enough away that water/steam can flow in between the rocks. Steam is what comes up the hole.

Someone more knowledgable than me, please correct me... if they are drilling a hole in the ground and making steam come up from said hole, doesn't that heat up the Earth's crust and atmosphere more than the previous condition without the hole, therefore contributing to higher temperatures (and climate change), making it not that "clean" after all? Maybe cleaner than carbon/petrol, but not ideal for the current context.

>doesn't that heat up the Earth's crust and atmosphere more than the previous condition without the hole, therefore contributing to higher temperatures (and climate change)

It's irrelevant when compared to the amount of energy from the sun. World energy consumption is roughly 5.4 * 10^20 Joules per year. This is 86% of the total energy from the sun that hits the Earth in an hour.

It's like worrying over putting a single drop of poison into the ocean.

> It's irrelevant when compared to the amount of energy from the sun. World energy consumption is roughly 5.4 * 10^20 Joules per year. This is 86% of the total energy from the sun that hits the Earth in an hour.

Man, every once in a while you remember the scale of energy when you're talking about the sun. Good lord.

And that's just what hits us, a tiny spec 8 light minutes away.

It outputs our yearly energy usage in about a microsecond, and converts 4 million tons of mass to energy per second.

However, per unit volume, it's putting out energy about the same as a compost heap.

Global warming isn't really about heat per se, it's about heat retention. It's the green house gasses reflecting back the latent infrared energy preventing it from escaping to space.

Adding more heat doesn't change the equation, it's how much we retain.

And mostly, it is heat retention of solar radiation rather than heat caused by consuming fuel on earth.

I'm probably no more knowledgeable than you in this area, but I have a free morning, and this is interesting. My hypothesis, is that the heat that we produce or release to generate usable energy, is an insignificant factor in global warming, compared to the solar heat that we trap with greenhouse gases. Let's find some quick simple stats and do some arithmetic, to figure out how much we are directly heating the surface of the Earth.

According to Wikipedia, the global energy production for 2012 was about 5.616e+20 joules, or 156 petawatt-hours. The Earth has about 1.386e+21 liters of water on it, and I will assume that that water represents the bulk of the relevant thermal mass, when considering weather patterns and sea level.

Now, let's estimate the heating caused by that energy. According to www.bickfordscience.com/03-05_State_Changes/PDF/Specific_Heat.pdf, 4,184 Joules of energy applied to 1 KG of water will raise its temperature by 1 degree Celsius, and this scales linearly with mass. Assuming that Earth-water averages out a density of 1 KG per liter, our 5.616e+20 joules, applied over a year to our 1.386e+21 liter water mass, would heat that water by 1.036e-38 degrees Celcius.

It has been a while since I've done a dimensional analysis, and the scale here are so extreme that I can't tell if my result is sensible. However, if my assumptions are reasonable and my math is correct, and the processes that I have chosen to ignore are insignificant (i.e. radiation into space over one year), then all of the heat that we release in the generation of the global energy supply, has a negligible impact on the temperature of the planet.

You multiplied instead of dividing somewhere, the result should be : dT = 5.616e+20 / 1.386e+21 / 4,184 = 9.684e-5, or about 1 ten thousandth of a Kelvin. So still insignificant.

Thanks for doing the math!

Overall, the warming effect of greenhouse gases is 100x the warming effect of waste heat: http://www.cgd.ucar.edu/tss/ahf/

It doesn't matter what they use. There is a lot of heat byproduct. Read this:


I imagine any pipes down into the hole will be insulated however there was some work looking at the changes in bacterial make up of soil surrounding these access lines. I can't find reference, but it was mentioned last time this idea was brought up on HN.

I don't know if it's a matter of absolute temperature, as much as one of rate, ie that we need more rays to be reflected than are now.

Relatedly, though, won't this cool the core?

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