[HN Gopher] Why geothermal isn't ubiquitous and how it might get...
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Why geothermal isn't ubiquitous and how it might get that way
Author : Osiris30
Score : 84 points
Date : 2021-07-08 18:24 UTC (4 hours ago)
(HTM) web link (austinvernon.eth.link)
(TXT) w3m dump (austinvernon.eth.link)
| Animats wrote:
| _Most current efforts need a lot to go right just to reach
| mediocrity._
|
| Right. It may be do-able, but unlikely to be cost effective in
| deep hard rock.
|
| One of the deepest drilling projects got down 31,400 feet, but
| instead of hitting something saleable like natural gas or oil,
| they got liquid sulfur.
| eloff wrote:
| I think you're referring to the hole drilled in Oklahoma back
| in the seventies: https://en.wikipedia.org/wiki/Bertha_Rogers
| curtis3389 wrote:
| Hug of death?
|
| https://web.archive.org/web/20210707172539/https://austinver...
| blakesterz wrote:
| This seems to be all about Geothermal HEATING, which seems pretty
| tough in most places. I thought Geothermal Cooling is
| easier/cheaper in many areas? Heat from Geothermal seems really
| difficult because you have to drill so deep almost everywhere,
| but that's not the case for cooling, is it?
|
| Iceland seems to have some decent heat there:
| https://en.wikipedia.org/wiki/Geothermal_power_in_Iceland
|
| Five major geothermal power plants exist in Iceland, which
| produce approximately 26.2% (2010) of the nation's electricity.
| comicjk wrote:
| Ground-source heating/cooling is quite different from
| geothermal heat or power. With ground-source, you just have a
| heat pump like an ordinary air conditioner, but using the
| ground as the heat sink instead of outside air. A couple of
| meters is deep enough. It's nothing like prospecting for the
| rare resource of accessible hot rock or natural steam, as in
| Iceland.
| maxerickson wrote:
| The systems used for cooling work just as well for heating.
| Really heating is probably the reason most of them are
| installed, and then, hey, why not also use it during the
| summer.
| abrowne wrote:
| Keep in mind Iceland's population is under 400k. That's less
| than the city proper of Minneapolis, for example.
| oscardssmith wrote:
| That said, Iceland does in effect export a ton of power by
| importing bauxite and turning it into aluminum.
| y04nn wrote:
| Indeed, in 2011, 71% [1] of the electricity production of
| Iceland was used by the aluminum industry!
|
| [1] https://en.wikipedia.org/wiki/Electricity_sector_in_Ice
| land#...
| abrowne wrote:
| True, although I think that's hydropower? At least that's
| what I remember from when I studied there ~15 years ago.
| [deleted]
| wffurr wrote:
| To heat a home with geothermal, you use a heat pump. It works
| better than an air source heat pump most places because the
| ground doesn't get as cold as the air does.
|
| More widely deploying ground source heat pumps for home heating
| seems more promising than pursuing geothermal electricity
| generation. The problem with ground source heat pumps is that
| the lifecycle of the equivalent if 30-50 years, well outside
| the typical homeowner's planning or payback horizon.
| a1371 wrote:
| Same heat transfer dynamics apply to cooling as well. Earth is
| a really good insulator, that's why it has a steady temperature
| in the first place. If you dump too much heat in it, it will
| warm up. That's seen as an advantage when you can harvest the
| same heat in the colder months using geothermal heat pumps.
|
| Some buildings that have access to the ocean or a lake can use
| that for heat rejection because those take the heat away.
|
| None of these applications require going too deep in the
| ground. This article is all about going deep.
|
| Iceland has access to very hot water in shallow ground. They
| are unique that way.
| russellbeattie wrote:
| I've wondered if there could be a way to use the Earth's heat by
| drilling a small hole in your back yard a few km deep and somehow
| embedding a tiny generator down there to take advantage of the
| heat differential between various layers of rock. Maybe a
| Stirling engine? I'm thinking like a long thin tube filled with
| liquid that boils at low temps. The liquid would boil, expand,
| rise up through an insulated tube, condense at a cooler layer and
| circulate back down. A little generator could use the constant
| motion to power a house.
| comicjk wrote:
| Deep holes are expensive. Oil drilling, the cheapest kind of
| drilling since it's very common and in soft rock, costs
| $100-$200 per vertical foot.* A 2 km hole would cost $650,000 -
| $1.3M. It would not be economical to do this for one house.
| Then there are operating costs: operating a power plant on the
| surface is very likely to be cheaper than operating one
| underground, and temperature difference is bigger. All in all,
| a traditional geothermal plant (utility scale, at the surface)
| looks like that for good reasons.
|
| *https://www.oilgasequity.com/resources/drilling-
| completion-f...
| turtlebits wrote:
| IMO, geothermal doesn't really make sense. It's expensive, and
| the heat gradient isn't huge- you have to drill or dig huge
| trenches to make up for it.
|
| Solar water heating is extremely efficient (and less
| complicated), but I have never seen it in the US.
|
| As for cooling, if it's hot out, the sun is probably out- solar
| PV with AC/heat pump should be fine.
| olivierlacan wrote:
| I've seen solar water heaters routinely on roofs in Florida and
| other U.S. states that get sufficient heat (Arizona, etc.).
|
| I'm not sure either of our observations are useful to determine
| how prevalent rooftop solar water heating is.
| berlincount wrote:
| The first geothermal wells in Germany have exhausted their heat
| gradient; after less than 30 years ... so, unless you're actually
| in Iceland or the Canaries or something similar, this might not
| even sustainable for even one full generation ...
| fatsdomino001 wrote:
| What I find most fascinating is that this is an .eth link.
| Starting to see them everywhere.
|
| Does anyone know why there's a ".link" after ".eth"?
| erulabs wrote:
| A legitimately useful blockchain application - who knew!?
| hanniabu wrote:
| It's a decentralized site using ENS so you'd need to run an ETH
| node and IPFS to view it. Cloudflare was generous enough to do
| the hard part and host those and serve the sites though the
| .link TLD to support casual browsing.
| mcguire wrote:
| See also https://eth.link/.
| kristopolous wrote:
| Ucs, the controversial organization, has an interesting analysis
| of geothermal.
|
| https://www.ucsusa.org/resources/environmental-impacts-geoth...
|
| The takeaway
|
| > Enhanced geothermal systems, which require energy to drill and
| pump water into hot rock reservoirs, have life-cycle global
| warming emission of approximately 0.2 pounds of carbon dioxide
| equivalent per kilowatt-hour [11].
|
| > To put this into context, estimates of life-cycle global
| warming emissions for natural gas generated electricity are
| between 0.6 and 2 pounds of carbon dioxide equivalent per
| kilowatt-hour and estimates for coal-generated electricity are
| 1.4 and 3.6 pounds of carbon dioxide equivalent per kilowatt-
| hour.
|
| Nothing is really truly zero carbon currently. Solar has
| manufacturing and maintenance. Nuclear has construction, mining,
| refinement, containment, etc. It's nice to see the full lifecycle
| being looked at.
|
| We can't pretend that something essential for the process doesn't
| matter because we do a classification handwaving. It all counts
| siddboots wrote:
| Life-cycle emissions accounting is useful if we're considering
| technology options or feasibility assessment for a specific
| project. But the linked article isn't talking about any
| specific project. It's talking about whether geothermal is a
| good tech in general.
|
| In that context the lifecycle emissions stats are less useful
| because the calculation assumes a rate of indirect emissions
| (due to construction, mining, refinement, containment, etc.)
| based on the incumbent power generation tech.
|
| In other words, if geothermal power was more ubiquitous, then
| the indirect emissions for a new geothermal project would be
| lower.
| emtel wrote:
| Yes, but carbon costs come from burning fossil fuels. If you
| don't burn fossil fuels to drill wells or build PV panels, then
| those don't have an embodied life-cycle carbon cost.
|
| I'm being a bit pedantic, but I think its an important point:
| The life-cycle carbon cost of renewables isn't a fact about
| renewables. It's a fact about our current energy production
| mix, which renewables themselves will change over time.
| kristopolous wrote:
| > The life-cycle carbon cost of renewables isn't a fact about
| renewables. It's a fact about our current energy production
| mix, which renewables themselves will change over time.
|
| Sure but we are talking about right now. Things will
| eventually be swapped out. That's a different conversation
| though, it's an advocacy and not a descriptive one.
|
| People tend to use things that are marginally adequate way
| longer than anyone intended. For instance, the ancient Roman
| gravity dam of Proserpina is still doing its job.
|
| Even if we had say a sleek $1,000 self driving solar car that
| never needs charging and goes for a million miles without
| maintenance, there's no guaranteed adoption curve, production
| capacity, distribution and logistic timeline, consumer
| acceptance, these are all hard unknown realities regardless
| of how silvery the bullets are.
| imtringued wrote:
| You can probably do "time" arbitrage here. The CO2 price is
| low today so CO2 intensive construction is still viable today
| but it won't be in the future. Thus your geothermal plant
| will end up becoming more profitable over time.
| goda90 wrote:
| So we should be doing calculations of "what percentage of its
| lifetime power production is required to sequester the carbon
| it took to create and use it?"
| kristopolous wrote:
| That's almost a peak oil approach, which was both
| insufficient and the most accurate possible.
|
| We can only state things in terms of stuff which currently
| exists. The future will yield different results because new
| techniques and technologies will come along. But we can't
| rely on or predict them.
|
| There's a lot of "pons and fleischmanning" when talking about
| future energy use - mass scale geo-engineering or sucking
| carbon out of the atmosphere technology, it has to be
| avoided. The technologies don't exist yet. We have to use
| real-world stuff.
|
| Using current reality for future projections is inherently
| defective because of the innovation factor and routinely
| leads to bad predictions (such as peak oil[1]), but it's the
| only reality we have and is sadly as good as we're going to
| get. Anything else (such as say next-gen nuclear) has to be
| regarded as a fiction in the calculations until it actually
| exists.
|
| It's messy, sloppy, and requires a large trashcan but the
| alternative is to get to results that rely on things that
| literally do not actually exist. Kinda like how the people
| planning Operation Downfall (the land invasion of japan
| during ww2) weren't told about all the other things in the
| works (backroom deal to get Russia to declare war on Japan
| and the Manhattan project), they had to assume those things
| would continue to not happen.
|
| [1] - The Hubbert peak was essentially that the amount of
| energy to extract and refine oil would surpass the energy
| from the oil and thus make it unsustainable so the operations
| for oil extraction would cease. New techniques have been
| developed (such as fracking) which have changed this math,
| but in 1956, using 1956 knowledge, this was the best
| prediction possible. It's somewhat Malthusian - who was also
| as "correct as possible" with the best science that 1798 had
| to offer. He couldn't factor in, say, the Haber-Bosch process
| from 112 years in the future in his food growth computations.
| scarby2 wrote:
| > Using current reality for future projections is
| inherently defective because of the innovation factor and
| routinely leads to bad predictions (such as peak oil[1]),
| but it's the only reality we have and is sadly as good as
| we're going to get. Anything else (such as say next-gen
| nuclear) has to be regarded as a fiction in the
| calculations until it actually exists.
|
| but are certain that at least one of these fictitious
| scenarios will come into being. We just have no certainty
| as to which.
| jandrese wrote:
| The first step in this is inventing a scalable way of
| sequestering the carbon from atmospheric CO2. We have been
| talking about carbon markets for over three decades now and
| still have not solved the supply side of the equation. It's
| frankly embarrassing.
| abraae wrote:
| > We have been talking about carbon markets for over three
| decades now and still have not solved the supply side of
| the equation.
|
| Talking, but never actually doing.
| jandrese wrote:
| Carbon Credits are a thing, but the fundamental problem
| is that one 1 of carbon credit isn't used to pull 1 ton
| of carbon out of the atmosphere. Instead they're like
| brownie points that politicians arbitrarily set the price
| on.
|
| If there were some large scale way to scrub carbon out of
| the atmosphere then the market could work, but in their
| current state they are a joke.
| Dylan16807 wrote:
| > If there were some large scale way to scrub carbon out
| of the atmosphere then the market could work
|
| We don't need to wait for that to set up an impactful
| system. At the simplest, have a serious tax and dump a
| bunch of the resulting money into research grants and a
| big reverse auction for capture.
| rapind wrote:
| Is it embarrassing? Maybe it's a shortage of market
| incentives or maybe it's just a really difficult problem?
| We shouldn't assume we'll have innovative solutions for
| everything.
|
| I think a healthier futuristic perspective would be one
| that considers only some percentage of problems will be
| solved through innovation, at least in the near term. That
| way we accept we still could be screwed and need to work
| harder!
| jandrese wrote:
| It's embarrassing that we are still using fossil fuels
| without any plan to deal with the pollution it causes. It
| isn't like people weren't aware of the problem either, I
| remember talks in the 80s about the Greenhouse Effect and
| how we needed to act quickly before the problem got out
| of hand.
|
| We're already well past the point where if we just
| stopped emitting we will be ok. We now need carbon
| capture as part of the solution and thus far nothing has
| panned out. Nor is there much political will to actually
| push for solutions. They're just seen as pure cost that
| will make your country less competitive so nobody wants
| to be the only country who goes for "truth" in this
| prisoner's dilemma.
| swiley wrote:
| The "free energe" is moving the heat from the hot rock to the
| atmosphere. The difference is that it's not doing that by
| oxidizing carbon to CO2.
| SEJeff wrote:
| I just priced out HVAC for a large home in central KY. It worked
| out to 3 of the highest efficiency American Standard/Trane units
| (Central Heating and Air) for around 50k or a touch over 70k for
| Bosch Geothermal. The big caveat for geothermal was the 70k price
| was guaranteed _only_ if they didn 't hit rock when digging. They
| couldn't give me a guaranteed price if they did hit rock so the
| choice was obvious. I picked Central Heating and Air.
|
| For horizontal or vertical geothermal loops, the biggest cost is
| always going to be digging for the loops. Until they make that
| more affordable, they're going to have a hard time making it more
| ubiquitous.
| lnwlebjel wrote:
| Did you look into horizontal, such as with a backhoe? It's hard
| to see how that would cost an extra 20k if viable.
| SEJeff wrote:
| Unfortunately, due to the topology, it wouldn't be very
| viable. I don't want to cut down the hardwood (white oak,
| maple, walnut, and cherry) forest around the home just to
| install hvac when there are alternative options.
|
| The real killer was knowing full well the house sits on or
| around a ton of limestone and the best quote I got told me it
| would cost a lot more if they hit rock.
| fghorow wrote:
| There are two classes of systems that go by the name
| "geothermal".
|
| The article is opining about the deep "High Temp" thermal
| systems that are found in places like the Geysers field in
| California, in Iceland, and in New Zealand. Those use heat in a
| primary way to power heat engines to generate electricity.
|
| You are talking about the other class of geothermal. That class
| is also known as "ground source heat pumps" for HVAC. Just like
| a reverse-cycle air-conditioner can heat as well as cool by
| exchanging heat with the outside air, ground source heat pumps
| do the same by exchanging heat with relatively shallow
| underground media. Typically, those have much higher heat
| capacities than air, which is the competition. Nobody attempts
| to run heat engines with such Low Temp resources as encountered
| in ground source heat pump applications...
| turtlebits wrote:
| For 50k+, you're probably better off improving your thermal
| envelope (insulation/air tightness) and going with a smaller
| HVAC unit.
| cshepher wrote:
| Improving the envelope is particularly important for geo
| heating and cooling. It makes sense to include that in the
| budget for a geo install.
|
| I had a geo system installed last December (GeoComfort with 3
| 200 foot wells for a 120 year old, 1600 sqft house).
|
| The system works great except that the point where the aux
| heat kicks in for my house is 25 degrees F. I am working this
| year to improve the envelope to reduce the need for aux heat.
| SEJeff wrote:
| It is 4 zones with (effectively) 5 floors and a lot of square
| footage. Anderson gave us a great deal on high efficiency
| triple pane argon gas filled windows and I walked the home
| with a wireless thermometer to check for obvious insulation
| problems. What else could I do to improve the thermal
| envelope?
|
| I've followed much of the advice in this cleantechnica series
| on this exact problem:
| https://cleantechnica.com/2020/10/08/home-
| efficiency-101-app...
| taneq wrote:
| What counts as a "large home" here? 50k USD for aircon seems
| insane!
| SEJeff wrote:
| ~6,500sqft / 4 stories with a basement.
|
| The price a year ago would have been more like 20k, but with
| the crazy price of lumber and all building materials going
| up, the HVAC companies followed suit :(
| codingdave wrote:
| Please tell me this is a full build-out of not only the
| HVAC system, but all ductwork and construction as well?
| Otherwise, you are getting royally ripped off.
| DannyBee wrote:
| A few things:
|
| 1. I'm not sure what "if you hit rock" means there.
|
| In general, you _want_ to hit rock, and should hopefully hit it
| very quickly (40-50ft), because rock generally has much better
| thermal conductivity than stuff like clay.
|
| 2. You hopefully got a loop design report that has real details
| on the load of your house and the design of the loop and how it
| meets them. The loop design should hopefully tell you they are
| mostly drilling in rock :)
|
| Hopefully it all does not look like nonsense (I'm happy to look
| at it if you like, as are the folks over at forums like
| geoexchange)
|
| 3. The only units you should consider are waterfurnace,
| climatemaster, and maybe bosch.
|
| Trane, for years, was using rebadged waterfurnace units At
| least browsing, it looks like they still are.
|
| In any case, you want someone who does this for real, and Trane
| ain't it.
|
| Bosch is an okay unit, but they are newer at this, and not
| obviously better in any meaningful way.
|
| 4. The price for single family residential drilling is high in
| part because it's not what the drillers want to be doing.
|
| The rig setup takes them quite a while, the actual drilling is
| not that bad.
|
| For multi-family residential (or commercial), where they are
| drilling 100 holes, it's much more cost effective.
|
| So you are right in that sense - the current way of drilling is
| not going to bring the cost down.
|
| On top of that, keep in mind you are probably paying
| significant markup on the drilling because it's being
| subcontracted.
| SEJeff wrote:
| By "hit rock" I mean the 3 hvac firms I spoke with didn't
| want to dig through rock, but couldn't nail down a cost if
| they hit it, which is basically a certainty.
|
| Bosch as a general rule has pretty solid engineering. I've
| used their kitchen appliances for years and am quite happy
| with them. Unlike some of the korean vendors (I'm looking at
| you Samsung and LG, it is easy and fast to get parts when
| things break).
|
| You're right that they're new at this, but all of the
| existing major appliances in the home are Bosch. If you buy
| more than three major Bosch appliances, they'll give you a
| fairly sizable discount.
|
| When I said American Standard/Trane, I meant for the Central
| Heating and Air, not for the Geothermal. They're the same
| hardware and come off of the same assembly line with
| different stickers on them.
| DannyBee wrote:
| Honestly - you had the conversations and i didn't, but if
| they really said they don't want to dig through rock, i'd
| probably run away.
|
| I've got a lot of experience in this, and what you are
| being given sounds like a bunch of nonsense, and yes
| sometimes you will get a bunch of nonsense from more than 1
| HVAC firm. Lots do not specialize in geothermal, and see it
| as a way they can make additional profit off some people.
|
| Concretely: At the price you are being given, the drill
| price should be fixed and included, excepting them hitting
| lots of water.
|
| The driller certainly gave a fixed price, based on the
| local geography and what they are gonna hit. The know
| exactly what they will hit in terms of rock/etc.
|
| The variable cost thing is not drilling rock or whatever,
| it's controlling water and sediment.
|
| If they hit lots of water (IE 100+gallons a minute),
| controlling and remove it can be expensive and unexpected -
| most cities/etc have strict rules on this (so they can't
| just run it into the street). This is the thing that is
| hard to tell for them - it's rare to have good enough data
| to know exactly whether and where you will hit water, and
| it can even vary from hole to hole in the same job.
|
| Otherwise, be careful - unlike regular HVAC, Geothermal
| requires people who really know what they are doing, and
| not just doing the kind of "finger in the wind" HVAC you
| can often find for folks doing heat pumps/furnaces. At a
| minimum, make sure you are using IGHSPA/etc certified
| folks.
|
| If you want to get more into this, there are lots of
| knowledgable drillers and installers over in places like
| the geoexchange forums, and they won't steer you wrong.
|
| As for Bosch, the units they are offering in residential
| are _super_ basic units last i looked.
|
| They are neither variable-speed pump or variable speed
| compressor.
|
| They are simply 1-2 stage geothermal units. They appear to
| at least offer variable speed blowers on some of them, but
| that's very basic stuff.
|
| This is the kind of unit you would have seen 20 years ago.
| I would not pay what you are paying for them.
|
| Nice geothermal units (say, the waterfurnace 7-series)
| these days have variable speed pumps and compressors. They
| match themselves exactly to the load needed by the house
| over time, and run continuously at part-load, modulating up
| and down as they day goes on, and end up being both silent
| and _very_ high efficiency.
|
| They are also much longer life - parts like scroll
| compressors (and most forms of rotary compressors) are
| _much_ happier if you modulate load rather than start
| /stop.
| SEJeff wrote:
| I basically followed your advice and ran far away. That's
| why I'm getting Central HVAC, which I'm sad about as I
| like the idea of Geothermal, but it is what it is.
| usefulcat wrote:
| My house was nearly burned down by a cheap Bosch tankless
| water heater that failed to turn off the flame when the
| flow of water stopped. You would think that would be a
| pretty obvious failure mode. Needless to say, we went with
| a different brand when we replaced it.
| hourislate wrote:
| This cost seems high to me. Installed a horizontal loop
| geothermal system over an acre of land in Northern Ontario. Had
| the trench dug out with an excavator (approx 12 + ft deep) and
| the same guy lay all the pipe and back filled for about less
| than 10k. If you look in the classifieds you can hire an
| excavator/operator for about $1k a day. The guys did it all
| over a week. Our whole system came in under $30k. It was a few
| years back but I don't think it would cost 70k today.
| SEJeff wrote:
| Not sure if you were aware, but the cost of building
| materials such as wood and also hvac has went up massively.
| The same central heating and air units a year ago would have
| cost maybe 20k with a full install. We got three quotes for
| three different firms that do geothermal.
|
| And as I mentioned elsewhere, if I installed a horizontal
| loop, I'd have to cut down a ton of beautiful 100 year old
| trees surrounding the home. I'd rather not do that when there
| are viable alternatives. The cost of higher electricity usage
| isn't a big deal as I've got 48 bifacial solar panels on the
| barn that run to the home.
| hourislate wrote:
| Consider closed cell spray foam and you will probably make
| out better with a traditional high efficiency system than
| you would with geothermal and regular insulation. If you
| went with geothermal and spray foam your heating and
| cooling/comfort costs would be less than someones Starbucks
| habit but I can understand the initial cost might not make
| sense for some folks.
| SEJeff wrote:
| I've got a looooot of solar panels, so the electricity is
| "effectively" free. This is good advice though, thanks!
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