[HN Gopher] Is TfL losing the battle against heat on the Victori...
___________________________________________________________________
Is TfL losing the battle against heat on the Victoria line?
Author : zeristor
Score : 66 points
Date : 2025-05-25 09:01 UTC (13 hours ago)
(HTM) web link (www.swlondoner.co.uk)
(TXT) w3m dump (www.swlondoner.co.uk)
| Y_Y wrote:
| > Historically, the Underground infrastructure offered a respite
| from warm weather, indicated in Austin Cooper's 'It is cooler
| below' poster, issued in 1924 by the Underground group to promote
| a more comfortable experience of travel during warm weather.
|
| A century of burrowing commuter-worms unfortunately managed to
| bake all the beautiful wet clay that kept the tunnels tolerable
| when the sun was shining about.
|
| It seems straightforward to me that it would be enough to
| rehydrate the ground. Just need (approximately),
| 400km of track * 25m average depth * 3m tunnel width * 20%
| moisture content of wet clay = 6 billion litres of water
|
| Sounds like a lot but it's only about 1/300th of the yearly flow
| of the Thames.
| lloydatkinson wrote:
| Have you thought of suggesting this to TfL? There has to be
| something here.
| thyristan wrote:
| Unfortunately, hydrating clay is extremely hard to do. Clay
| is what you use as a water-tight material in dams, artificial
| lakes, waste dumps and stuff like that, because water doesn't
| really pass through it.
| rjh29 wrote:
| Yes, people whose day job is to explore all possible options
| have surely missed this extremely obvious idea.
| heisenzombie wrote:
| <man walks into sauna room> Ooh, it's a bit hot in here! I
| better throw some water on these rocks to cool them down.
|
| Joking aside, I actually don't know how dry it is in the
| underground, and therefore whether adding water for evaporative
| cooling would work. I would have assumed it was quite humid,
| but maybe not?
| ajb wrote:
| It seems implausible to me that the clay is dehydrated. The
| Victoria line was only built in the 60s and has a waterproof
| lining. (It's also built with asbestos cement, unfortunately,
| which is no doubt a problem when they need to cut it for
| whatever reason)
| avianlyric wrote:
| I don't think the hydration of the clay is the important
| element here. Rather I suspect it's simple just the sheer mass
| of clay, wet or otherwise, that's involved.
|
| There's a reason why ground source heat pumps work so well.
| It's because the ground is such a fantastically huge heat
| sink/source that in most scenarios we consider it capable of
| sinking or sourcing a practically unlimited amount of heat.
|
| Unfortunately one of the scenarios where this breaks down, is
| when you stick a bunch of tunnels in the ground, then pump a
| crap ton of energy into those tunnels years round, and expect
| the ground to sink all the heat away. Turns out, if you do
| that, the ground itself starts heating up, and given that clay
| is a reasonable good insulator, it's like wrapping all those
| tunnels in wool jumpers.
|
| I would point out as well that all these tunnels are "deep
| level" tunnels running at an average depth of 24 meters and
| getting as low as 67 meters. The heat of the sun on the ground
| surface will have approximately zero impact on the tunnel
| temperatures. 24 meters of clay is a lot of insulation to work
| with.
| azernik wrote:
| "The average temperatures on the Victoria line have risen by
| almost seven degrees since 2013 - nearly a *30%* increase.
|
| Conversely, the increase in the average annual temperatures
| across all Underground lines from 2013 to 2024 was merely *seven
| percent*, placing Victoria's temperature rise vastly above that."
|
| Using percentages to talk about changes in non-Kelvin
| temperatures is crazy.
| OJFord wrote:
| It would definitely be crazy in Fahrenheit, but in centigrade I
| think it makes some sort of intuitive (if not scientific)
| sense. (Together with the sea-level assumption we always make
| in casual temperature discussion anyway.)
| azernik wrote:
| It makes just as much intuitive sense in Fahrenheit as it
| does in centigrade.
| perching_aix wrote:
| Why? The slope of the Fahrenheit scale is different to the
| Celsius and Kelvin scales, but the slope of the latter two
| does match.
| meindnoch wrote:
| Ok. Then please explain what % does the temperature rise
| when going from 0 Celsius to 5 Celsius!
| stephencanon wrote:
| Or -1 to 1 Celsius, for that matter.
| chihuahua wrote:
| Obviously it's -200%, which means that going from -1C to
| 1C is a drastic decrease in warmness!
| azernik wrote:
| The slope of the Fahrenheit scale matches that of the
| Rankine scale.
|
| I would still say that the in the Rankine scale
| percentage increases make sense, and Fahrenheit changes
| to not.
|
| The thing that matters isn't the slope, but the zero
| point; "X% farther from absolute zero" is a useful
| measurement, "X% farther from an arbitrary zero point" is
| not. Especially when negative or zero temperatures are
| involved.
| lolinder wrote:
| The slope of the scales has no bearing on whether
| percentages are meaningful here. The problem with both
| systems when it comes to percentages is that neither
| system has 0 set to a natural 0. This leads to an
| entirely arbitrary point on the scale where decreases in
| the unit will approach a 100% difference and then
| suddenly start decreasing again.
|
| If anything Fahrenheit should be less insane because at
| least the artificial 0 is likely to stay much further
| away in the data they're quantifying so the percentages
| stay reasonable.
| perching_aix wrote:
| Ah right, okay, that makes sense.
| detourdog wrote:
| Early measurements were done by individuals and they were
| idiosyncratic to the process of discovery/calibration.
|
| Kelvin is refined measurements used to relate to a wider
| scale of temperatures. Celsius is a metric human scale
| subset of Kelvin.
| detourdog wrote:
| Reading this quote made me finally realize why the name
| centigrade exists. It's a gradient scale of 100.
| tailspin2019 wrote:
| Reading this comment about the previous quote made me
| finally realize why the name centigrade exists.
| tim333 wrote:
| Maybe because I was brought up with centigrade it makes
| more sense to me. The centigrade number is how far you are
| from water freezing. If it goes up 100% then you are twice
| as far away. I'm not aware that doubling the fahrenheit
| number has a similar easy to understand meaning?
| ars wrote:
| > The centigrade number is how far you are from water
| freezing
|
| The Fahrenheit scale is how far your are from your own
| body temperature. It was designed that 100 is the
| temperature of a human. (Adjusted later to 98.6 due to
| inaccuracies.)
|
| 0 was designed to be as cold as you can get with ice and
| salt (also ended up being slightly inaccurate).
|
| > Maybe because I was brought up with centigrade it makes
| more sense to me.
|
| Yup. People brought up on Fahrenheit think it is
| superior. For temperature neither argument is objectively
| better. (In contrast to imperial distance measurement
| with non-powers of 10 and factions, where there are good
| arguments against it, with temperature both scales are
| ultimately arbitrary.)
| strken wrote:
| In both it makes a sort of intuitive sense. 7% of the way
| from freezing to boiling is a meaningful way to visualise
| temperature; 7% of the way from ice melting in a bath of salt
| to slightly above Mrs Fahrenheit's armpit temperature is also
| meaningful, although perhaps a little idiosyncratic.
|
| Edit: this comment was deeply stupid for obvious reasons and
| I regret trying to interact with other people when I should
| be asleep.
| movpasd wrote:
| The issue is a percentage of a Celsius value is not that.
| For example, an increase from 1degC to 2degC is a "100%
| increase", but is only 1 percentage point from freezing to
| boiling.
| OJFord wrote:
| You could say things like that with anything in
| percentages? 100% increase in your pension from 100k to
| 200k is only 10% (increase, to 20% total) of your target
| 1M, or whatever.
| eCa wrote:
| But in your example, the 10% has nothing at all to do
| with the increase of 100%.
|
| If your "whatever" target instead was 50k, is the
| argument that going from 100k to 200k would be 400%?
| casenmgreen wrote:
| I logged in just to give this an upvote :-)
| Y_Y wrote:
| Feynman was complaining about this error appearing in textbooks
| back in the sixties[0].
|
| The trouble (of course) is that Celsius properly is not a
| proper unit, but a "scale", or a "unit of difference" (equal to
| kelvin), or even torsor[1].
|
| The trouble with the kelvin here is that if you see the 7
| kelvin increase as a proportion of the 295K starting
| temperature the you only get a 2% increase. Nobody is going to
| buy your newspaper if you're putting up weak numbers like that.
|
| [0] https://mathematicalcrap.com/2024/03/05/the-feynman-story/
| [1] https://math.ucr.edu/home/baez/torsors.html
| azernik wrote:
| Then just don't use percentages, and rely on people realizing
| that a 7 degree difference is big!
| buran77 wrote:
| To make matters worse, not all ranges and percentages on that
| scale are equal, whether they're the same in absolute or
| relative terms. Humans have a narrow relevant "operational"
| temperature band. Even 20 degrees between 10-30C feel like
| nothing compared to the 5 degrees between 37-42C.
| hnlmorg wrote:
| You're right in principle but that's probably the worst
| example you could have given. So bad an example that I
| think it could easily be argued to disprove your point.
| paganel wrote:
| For us people not living in Arabia or South Texas the
| difference between 37 and 42 Celsius is indeed quite
| important. 37 feels pretty hot, but yet livable, while 42
| (and even 40 for me) means that nothing non-urgent should
| bring me out of the house.
| pdpi wrote:
| And, inversely, the five degree drop from, say, 3C to -2C
| represents means water can and will freeze, which is
| another massive change in livability.
| nkoren wrote:
| Indeed. At 3C in London, the humidity seeps into every
| pore and settles into your bones. Riding a bike at 3C,
| unless you're wearing a balaclava and a ski mask, is an
| exercise in pure pain, as the wetness sublimating off
| your face has approximately the same effect on your
| facial nerves as being flayed.
|
| Ok the other hand, -2C in London is crisp and
| invigorating and entirely preferable in every possible
| way.
| VBprogrammer wrote:
| Not to mention that wet bulb temperature, measuring the
| effect of humidity, is actually the most important measure
| in those temperature ranges.
| robocat wrote:
| Humidity in London is also awful as the temperature gets
| closer to freezing. I found the damp cold in London to be
| common over the year and truly horrid (a reason to never
| live there).
|
| At home (Christchurch, NZ) we often get dry cold which
| can be pleasant: however when we do get the occasional
| vile damp cold I personally call it "London cold" because
| it made so much impression upon me in my 20s.
| moomin wrote:
| I don't know if I'm worried about it. While the measurement
| makes little scientific sense it makes intuitive sense, and,
| importantly, the intuitive implications are the scientific
| implications.
|
| It's a huge increase, if not for the reasons they describe.
| nelgaard wrote:
| And they manage to make it even more crazy by also comparing it
| to average external temperatures.
|
| == The Victoria Line average temperature in August last year
| was 60% higher in temperature than the average external
| temperature that month, measured at 19.5 degrees. ==
|
| Certainly for January it must have been hundreds of percent
| higher.
|
| And what would the numbers be for e.g., the Moscow metro in
| winter months where the average outside temperature is
| negative?
| StopDisinfo910 wrote:
| Is it? I think it puts the Victoria rise in perspective to the
| other lines quite effectively.
|
| Everyone knows where the zero is in Celsius using countries
| anyway and days in the negative are so rare in the UK you can
| discount them (plus they are none inside the tube).
| zeristor wrote:
| Yikes. I posted this, and I missed that, something I realised
| soon into my first year physics degree lab. I learnt more than
| just dipping calculators in liquid nitrogen for fun.
|
| I apologise.
| brookst wrote:
| Yep. That 30% is a bad use of statistics.
|
| 28 degrees Celsius is not 30% warmer than 21 degrees Celsius.
| This same stat rendered in Fahrenheit would say 70 degrees ->
| 82 degrees, or 17%. In kelvin it would be 294 -> 301, or 2.3%
|
| Or we could invent a new measure indexed to Celsius but offset
| by 20 degrees, and declare a 1 -> 8 change, a whopping 700%.
| AStonesThrow wrote:
| So how many decibels louder is it now?
| chiph wrote:
| Looking at the temperature chart and the significant drop in 2020
| during the pandemic, the source is certainly the trains and
| people themselves. (fewer trains moving, less heat added back
| then). At this point I expect the infrastructure is heat soaked
| and will need a prolonged period of cooling to bring temps down.
| i.e. don't expect instant results.
|
| Moving more air through the tunnels, adding A/C systems - both
| have a problem of needing room up on the surface for blowers and
| compressors, something that is hard to do in modern London. Tough
| problem.
| meindnoch wrote:
| This. Brake friction pumps heat into the ground at a higher
| rate than it could dissipate away.
| eternauta3k wrote:
| Aren't they using regenerative braking?
| Zigurd wrote:
| Some parts of the London underground use passive energy
| recovery by locating stations nearer to the surface than
| most of the tunnel between them. Trains start by rolling
| downhill and when they approach a station, uphill.
| blipvert wrote:
| Yes.
|
| https://tfl.gov.uk/corporate/transparency/freedom-of-
| informa...
| altairprime wrote:
| > _If the line is unreceptive, braking energy is
| dissipated in on-board resistors_
|
| How many watts are dumped into onboard heat-generating
| resistors on the trains in the most heat-affected lines
| per week?
|
| Should regenerative braking be disabled in aboveground
| trains when heat impacts reach uncomfortable levels in
| belowground tunnels?
|
| > _Regenerated braking energy is transmitted to the
| London Underground high voltage distribution network_
|
| If regenerative braking oversupply is inducing higher
| temperatures belowground through on-train resistors, then
| only an operational change to aboveground mode would be
| required to minimize that induced heating during times of
| thermal need.
|
| (Obviously longer-term solutions with non-zero capital
| expenditure exist that could be pursued in parallel.)
| cranky908canuck wrote:
| To me, 'disable abovegound regen' feels like not likely
| to solve the problem, just from a feeling that those
| systems are not that closely coupled. Otherwise, it seems
| easy to just keep on doing regen and set up (maybe not
| even need to: run a cable up to) aboveground dissipation
| grids.
|
| I will guess that the limit is how much regen current can
| be passed back from the train into the supply system
| through the power supply rails / pickup shoes.
|
| If I were making (confess, yes, untrained outsider)
| suggestions, I'd add water tanks to the trains, use the
| resistive braking to heat the water (not ambient air)
| during the trip, then change out the now-hot water for
| cold at the destination layover points. Not thinking this
| is a particularly creative solution, sounds like the
| "pull trains full of ice" already noted. Also this is
| off-the-cuff, so welcoming critiques!
|
| Speculate: district level heating (wikipedia entry:
| https://en.wikipedia.org/wiki/District_heating) using
| heat pumps to draw out the tunnel heat; not sure if that
| is too complex altogether, maybe it would work as a
| longterm maintenance process but not as a 'fix the
| current problem' one...?
| zeristor wrote:
| Believe regenerative breaking is used to supplement Oxford
| Circus' electricity supply
| avianlyric wrote:
| The trains in London can be up to 50 years old at this
| point. Where the technology was available during the
| building of the trains, you can generally expect
| regenerative breaking. But it's far from universally
| available unfortunately.
| netsharc wrote:
| I wonder if they can carry hundreds of opened barrels of ice on
| open-bed trains through the tunnels at night, go slowly and let
| them melt to water (but kept in the buckets, because you don't
| want to flood the tunnels)...
| thyristan wrote:
| They could flood the tunnels with an appropriate amount of
| liquefied air.
| Andys wrote:
| Ice blocks were trialed in the past. https://en.wikipedia.org
| /wiki/London_Underground_cooling#cit...
| euroderf wrote:
| Big fans to pull surface air down into the tubes when the tubes
| are warmer than surface ambient ? Cool the tunnels, warm the
| surface.
| avianlyric wrote:
| Where there's space, this has already been done.
| Unfortunately for many lines there simply isn't space.
|
| Just about every abandoned station, elevator shaft, and
| maintenance tunnel on the network is already fitted out with
| huge fans where possible.
|
| TfL also runs a semi-continuous works project that looks a
| custom and novel one-off cooling solutions that can be
| retrofitted into whatever space is left. Including
| complicated hydronic systems that pump around huge quantities
| of water where the infrastructure allows for it.
| randallsquared wrote:
| > _Temperatures hiked as high as 31.1[C] degrees in August 2024
| [...]_
|
| So, I can imagine that this is a long-term problem, but it seems
| odd that the panic is setting in already, when some platforms in
| the NYC subway regularly exceed 40C / 104F every summer? This
| article seems in a similar genre to the breathless advice to
| remain inside in Britain when the outside temperature might get
| above 27C / 81F, otherwise known as a not-particularly-warm
| spring day in much of the US in most years.
| masklinn wrote:
| > This article seems in a similar genre to the breathless
| advice to remain inside in Britain when the outside temperature
| might get above 27C / 81F, otherwise known as a not-
| particularly-warm spring day in much of the US in most years.
|
| It's really not breathless, because high temperatures and how
| to handle them is completely absent from the cultural baggage.
| I don't live in the UK, but in a place which similarly does not
| have much in the way of high temperatures historically and low
| AC penetration, and during heat spikes I see a significant
| fraction of my neighbours with windows wide open at 4PM.
|
| Habituation is also a significant factor. The UK does not get a
| smooth transition into higher normals, it gets heatwaves.
| tim333 wrote:
| I live in the UK and a lot is down to the tabloid newspapers
| trying to get some sales with 'Horror Heatwave!' type
| headlines when it's 27C. Brits go on holiday to Spain, we are
| familiar with heat.
| tialaramex wrote:
| Statistically we know that humans who live somewhere that
| you'll just die in the regular environment due to climate
| behave _very differently_ from humans who live in a
| temperate climate like the UK when the actual temperature
| warrants the same behaviour. If you live in Nunavut or the
| Iran / Pakistan border you already _knew_ that you can
| just die from temperature extremes and so you need to
| ensure you stay at a survivable temperature, in Wales it 's
| quite unexpected.
|
| As a result you actually get many _more_ deaths from
| extremes in countries where the usual climate is temperate
| like Britain, even when the actual temperatures aren 't as
| extreme as in countries where that would be more common.
| gambiting wrote:
| I'm only in London occasionally but I can confirm that some
| lines are unbearably hot, in the summer I have no idea how
| people commute in that heat every day. And I'm originally from
| a much hotter country than the UK.
| philjohn wrote:
| I commute on the northern line 3 times a week ... it's not
| fun, but it's bearable ... just.
|
| The trick is, if the window at the end of the carriage isn't
| open, make a beeline and open it, as the air moving past does
| help keep you cooler.
| hnlmorg wrote:
| Surely that says more about how NYC than it does about London?
|
| If I had to suffer overcrowded trains with standing room only,
| people's armpits in my face and all, at 40C temperatures
| everyday in the summer, then I wouldn't be laughing at London
| for trying to avoid the same fate. I'd be complaining that my
| own city isn't taking their problems seriously enough.
| cherryteastain wrote:
| > tunnel ventilation installations, chiller systems pumping
| chilled air into mid-tunnel shafts and regenerative braking to
| reduce heat generated by trains breaking
|
| The hoops TfL jumps through just to not extend AC to the rolling
| stock in more lines are baffling. At least we finally got some AC
| in the new Piccadilly rolling stock.
| pitaj wrote:
| AC will only make the problem worse in the long term. Picadilly
| got AC because it has above-ground sections.
| cherryteastain wrote:
| You can redesign the signalling systems etc to work at even
| 40C, plenty of countries do it. You can't redesign humans to
| feel comfortable inside a stuffy carriage at 35C.
| crote wrote:
| Sure, but that means the stations will _also_ have 40C air.
| Can the humans handle that? And it 's going to be 42C the
| next year, 44C the year after, and so on...
| raattgift wrote:
| What do you do if some incident halts full trains (possibly
| depowering them but for things like emergency lighting)
| near the midpoints of longer sections of 40 degC deep
| tunnels?
| thyristan wrote:
| You can survive a few hours at that temperature, so not
| an immediate catastrophe. You should be still able
| (though not comfortable) to walk to the next emergency
| exit or station.
| Aachen wrote:
| Isn't heat free energy in a place like London? I know very little
| about metro systems so please correct me if this is insane:
| wouldn't the people living above the tubes be happy to get a heat
| exchanger (passive) or heat pump (active, but takes more of the
| heat) that prewarms their hot water supply? People still take
| warm showers and boil tea and rice/pasta in summer, and in winter
| the purpose should be obvious. If the water comes in at 30
| instead of 10 degrees C, you need to add only a few degrees for
| showers and floor heating
| joshlk wrote:
| What do you do in the summer when the homes don't want the
| heat?
| jairuhme wrote:
| People still take hot showers and use hot water
| crote wrote:
| That doesn't have to be a problem in practice.
|
| The entire issue is that the earth surrounding the tubes is
| acting as a giant buffer. Enough heat has been dumped into it
| over the years that it has _permanently_ warmed up. Draw heat
| from it during the winter to warm up homes, and it 'll be
| able to absorb more heat from the tunnel air during the
| summer.
| TheOtherHobbes wrote:
| And because it's _permanently_ warmed up, the long term
| consequence is the line becomes a health hazard and has to
| be closed for increasingly long periods.
|
| When wet bulb > body temp people start getting heat stroke,
| which leads to fainting and potentially death - a bad look
| for a public transport system.
|
| The likely remedy is to install gigantic refrigeration
| units in the ventilation shafts and pump in cold air. This
| will be hugely expensive to build and run.
|
| But the alternative is a tube line that can't be used. So
| there may not be much choice.
| Aachen wrote:
| It won't be zero so spreading it across enough people might
| already solve it. If that still leads to insufficient demand
| during the hottest weeks, idk, it's energy, surely there's
| something useful you can do? Store it for next week, pre-heat
| water for the nearest steam engine (e.g. gas power plants are
| steam engines running on methane, so if they have to heat the
| water by fewer degrees.. The problem will be finding a steam
| engine close to the heat source), supply it to an industrial
| process that needs temperatures above ambient (egg breeding
| for vaccine production? Idk), create electricity from the
| temperature differential between this system and the Thames
| water using the Peltier effect
|
| I've surely got a too naive view of economics but if the goal
| were to not waste resources then there will be things you can
| do before dumping it into the hot summer air
| metalman wrote:
| Your are correct in principal, though implimenting your idea,
| now, is essentialy impossible as installing the plumbing after
| the fact might cost more than just starting over with a whole
| new line, and would in fact make things much worse durring the
| many years it takes to find out if the added systems even work.
| Given that there is only clay under London, it is by far better
| to start over and build a whole new line, and/or go all in on a
| mega high tech ,high pressure refrigeration systems for the
| human occupancy areas, and hope that there are no break downs
| in the "hot zones" orrible mess
| tobylane wrote:
| There is at least one on this line (north of Kings Cross) and
| one on the Northern line (north of Moorgate). It's for district
| heating or electricity generation.
| gruez wrote:
| >wouldn't the people living above the tubes be happy to get a
| heat exchanger (passive) or heat pump (active, but takes more
| of the heat) that prewarms their hot water supply
|
| Ground source heat pumps are expensive to build, even more so
| in a dense area like London. So even if everything you said is
| true, I suspect the juice isn't worth the squeeze.
| cranky908canuck wrote:
| I think you are correct.
|
| In this case, though, the excess heat is a major burden, so
| there is room to negotiate with a district thermal provider
| that pays that provider to absorb and redistribute the heat,
| as long as it's less than the cost to pump it out to the
| environment.
|
| I'm not saying it's easy (it will likely be a bespoke
| solution). Given the organizations, I expect the difficulty
| to be as much business (setting the prices) and political
| (defending the prices set) as technical.
| hnlmorg wrote:
| The problem isn't so much finding uses for the heat, it's
| getting the heat out of the tunnels to begin with.
|
| These are some of the deepest tunnels going under some of the
| most built up parts of the UK.
| BJones12 wrote:
| I wonder if an extremely tall subterranean windcatcher [0]
| with its bottom at the top of a tunnel could passively cool
| the tunnel.
|
| [0] https://en.wikipedia.org/wiki/Windcatcher
| jodrellblank wrote:
| A problem is the clay surrounding the tunnels insulates them -
| it traps heat because heat flows through it very slowly. So you
| drill down and put a heat exchanger pipe down there, you pump
| heat from 3cm of clay around the pipe and now no heat flows
| through the clay to your pipe even though there's a lot of heat
| still down there.
|
| Your pipe becomes a tiny worm of cold pipe in a big lump of hot
| clay and you've done very little to cool the underground or
| warm your water. That is, if heat moved easily through the
| stuff then the problem of heat buildup would be easy to solve
| but in that case heat wouldn't build up so there wouldn't be a
| problem; and vice-versa.
| philshem wrote:
| In case you also couldn't guess the "f" in TfL, it's Transport
| for London.
|
| https://tfl.gov.uk/
|
| https://en.wikipedia.org/wiki/Transport_for_London
| moomin wrote:
| You can blame Blair, I think, for the fashion of putting "for"
| into the names of administrative organisations.
| devnullbrain wrote:
| In case you missed the 4 places it's made explicit in the
| graphs, or 'London' in the URL.
| pfdietz wrote:
| This problem is also an illustration of the potential of
| geological thermal energy storage.
|
| The thermal time constant of a lump of matter scales as the
| square of its linear dimensions (for a given geometry). This can
| easily reach many years for large enough chunks of underground
| stuff. This is why geothermal energy works at all; the heat
| energy flowing up from the deep earth is stored for many
| thousands of years at reachable depths and can be mined. And, if
| one has excess energy, it could be reinjected underground as heat
| and later recovered.
| zeristor wrote:
| I had an idea, perhaps a weird fantasy.
|
| Of a special tube train with blocks of ice. You'd need to have
| various pits dug in, and pumps to drain the water. Yes water and
| power electronics is "fraught".
|
| I just like the idea of trains trundling along, blocks of ice
| being carted out and gradually melting.
|
| Another idea is to move mechs-bots via Underground in a post-
| apocalyptic scenario, but that's not so relevant here.
| laurencerowe wrote:
| This was actually tried:
| https://www.theguardian.com/uk/2007/jun/05/transport.world
| LeoPanthera wrote:
| This would also increase the humidity to swamp-like levels.
| Havoc wrote:
| Is there a reason why they can't drill a couple bowling ball
| sized holes at strategic intervals and put some high speed
| extraction fans in?
|
| Stations entrances are open to outside so if you create enough
| negative pressure the hottest parts in the tunnels it'll pull in
| air. Do that long enough and presumably ambient & clay cools?
|
| Presumably engineers dismissed this already, but why?
| CorrectHorseBat wrote:
| They have added ventilation to the tunnels, it's mentioned in
| the article. It's more than just a couple bowling sized holes,
| but apparently still not enough
| thyristan wrote:
| Unfortunately, hydrating clay is extremely hard to do. Clay
| is what you use as a water-tight material in dams, artificial
| lakes, waste dumps and stuff like that, because water doesn't
| really pass through it.
| CorrectHorseBat wrote:
| I think you replied to the wrong comment?
| thyristan wrote:
| Yes, sorry.
| philjohn wrote:
| Yep ... know people who commute on the Victoria and it doesn't
| sound fun. I've had to get it when my usual commute on the
| Northern line was impossible (only once, thankfully) and it was
| horrendous.
|
| And the Northern line is no picnic either.
| gilbertjolly wrote:
| This is a generational buildup of heat, being tackled seasonally.
|
| TfL must run its cooling operations in the winter as well as the
| summer.
|
| It's about net energy difference over the whole year.
|
| Finding cold air in the winter will also be substantially cheaper
| MichaelZuo wrote:
| I dont quite understand what's stopping them from just buying
| hundreds of chillers, putting them on the surface close to each
| station, and running chilled water loops down. Other than cost
| of course.
| mnw21cam wrote:
| They're running trains. Trains use a lot of electricity, and
| they turn almost all of it into heat. You'd have to have as
| much chilling capacity as the current electricity demand of
| the entire tube line, which is quite a lot.
|
| However, if the buildings above were to sink ground source
| heat pump loops into the warmed ground to heat the buildings
| in winter, this would basically be what you just suggested,
| and would be a win-win situation.
| MichaelZuo wrote:
| Huh? Modern modular air cooled chillers go up to 800 tons
| each and can remove multiple MW of heat load continuously
| pretty much 24/7.
|
| 500 of them could remove 1.4 GW of heat.
|
| Of course there are many ways to improve efficiency, but
| even assuming the worst case it's still technically
| feasible to remove many times more heat than the line
| generates.
| lysace wrote:
| Using the London subway is an adventure.
|
| https://www.bbc.com/news/articles/cy9xxlky2pno (2024)
|
| > Phone signal goes live on 25% of underground Tube
| isaacremuant wrote:
| Losing the battle or not even trying to fight? It's
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