[HN Gopher] Why steam rises from San Francisco streets
___________________________________________________________________
Why steam rises from San Francisco streets
Author : kaycebasques
Score : 71 points
Date : 2023-04-23 15:08 UTC (7 hours ago)
(HTM) web link (secretsanfrancisco.com)
(TXT) w3m dump (secretsanfrancisco.com)
| elcomet wrote:
| This article actually never answers the question, why does this
| steam network releases steam in the streets?
| [deleted]
| [deleted]
| randyrand wrote:
| bad pipes
| mikeryan wrote:
| Is this a guess?
|
| I'd think there would be some sort of safety system for
| venting pressure. Or even condensation around the hot pipes
| (which seems to be why the same thing happens in New York
| which also has a steam network)
|
| All of the above could work too.
| wongarsu wrote:
| So what's up with maintenance? The leaks seem trivial to
| locate and visibly waste both heat and water.
|
| How is it more economical to have enough leaks that people
| start talking about it instead of doing proper maintenance?
| Especially since this situation seems fairly unique, I've
| never seen this outside the US, and could only name San
| Francisco and New York as places where this happens. So what
| discourages maintenance in those places compared to
| everywhere else?
| sidewndr46 wrote:
| As long as a service provider can pass those costs onto
| customers and there is no alternative service, it can't be
| economical to make repairs. You'd be expending capital to
| decrease revenue.
| wongarsu wrote:
| But everyone is facing roughly the same forces here. You
| either spend money on maintenance, or you lose money in
| leaks. It's a tradeoff, but any place outside SF and NYC
| seems to determine that the best place in that tradeoff
| produces barely any leaks that a pedestrian would notice.
| Scoundreller wrote:
| Water distribution works the same way. Large systems lose
| like 10% of their supply through leaks in the system but
| just pump more through the system to make up for the
| losses. Just like drug smugglers.
| kevincox wrote:
| This doesn't make sense. Price isn't set by the cost of
| service. You could fix the leaks and still raise the
| price to increase your profit margin.
| zamnos wrote:
| The energy market in California is highly regulated and
| the prices consumers pay are fixed by the California
| Public Utilities Commission (CPUC), and are designed to
| cover the utility's costs, plus a "reasonable" profit.
| toast0 wrote:
| Steam leaks is a big indication that you've made it as the
| downtown of a metropolis. I've witnessed it in Seattle,
| pretty sure in Chicago and not sure about Milwaukee.
|
| Doing proper maintenance requires opening the streets,
| which is expensive and causes confusion and delay, so
| there's some amount of acceptable leak before it's a good
| idea to fix it. There's always a chance of finding unmapped
| critical infrastructure when you dig, which adds more risk.
| Plus, when you fix it, you lose the street cred.
| wirrbel wrote:
| I live in a town with teleheating, frankly I never saw it
| steem. I would say the upkeep in the US of the
| infrastructure is just bad.
|
| This reminds me that in Paris you can pretty often see
| water flowing on the street, it seems that the Paris
| water supply has a tendency to leak that I just don't see
| in other towns (but then, i am really walking for
| kilometers through the city when visiting paris so maybe
| I just have more opportunities to spot leaks).
| Scoundreller wrote:
| Paris regularly cleans its streets with the non-potable
| water supply of its two-stream h2o distribution system.
| Probably an antiquated practice back from when not
| everyone had sewer connections and would dump their waste
| pots on the road, but they still do it.
|
| https://parisianfields.com/2012/03/11/a-most-unusual-
| water-s...
| greysteil wrote:
| If it's the same as NYC then the steam you see is generally
| from water evaporating off the outside of the pipes ( _not_
| steam escaping from the pipes). The pipes are very hot, so any
| outside water that touches them quickly turns to steam.
|
| https://web.archive.org/web/20160811170408/http://www.coned....
| jwr wrote:
| That means the whole thing is incredibly wasteful. I always
| wondered why nobody seems to care about the huge amounts of
| energy being wasted in NYC in this way.
| lukeschlather wrote:
| There's an invisible component which is the efficiency of
| the furnace used to create the heat. Suppose every building
| uses a small furnace which is 30% efficient, then there's
| no visible waste heat in the streets. On the other hand,
| suppose a bunch of buildings use a single furnace which is
| 50% efficient and pipe the heat with 10% waste from piping.
| You're still substantially less wasteful to use the central
| furnace. There's no such thing as a system that doesn't
| generate waste, and the visibility or invisibility of the
| waste doesn't tell you how wasteful the system is.
| thaumasiotes wrote:
| What does it mean for a heating furnace to be less than
| 100% efficient? Efficiency is normally measured in terms
| of how much waste heat you generate. If your goal is to
| produce heat, it isn't possible to produce any waste
| heat.
| quesera wrote:
| A lot heat is lost as exhaust into the air.
|
| This can be a large portion, e.g. in older systems from
| the days when fuel was cheap, and pollution wasn't a
| topic.
|
| Modern systems attempt to recover exhaust heat, and can
| be 90-ish% efficient.
| thaumasiotes wrote:
| Releasing heat into the air is the entire point of the
| building furnace. For the heat to get lost, it would have
| to leave the building.
|
| There's a more obvious argument that leaking steam into
| the _streets_ is a waste of heat, but that still depends
| on your goals. You might like having warmer streets.
| quesera wrote:
| > Releasing heat into the air is the entire point of the
| building furnace
|
| You're thinking of forced hot air systems, but these do
| not vent combustion exhaust into living space. There are
| fuel remnants and combustion byproducts in the exhaust
| which would smell bad, and kill people.
|
| Combustion exhaust, and all of the heat it contains, goes
| up the chimney and is lost. The living space air is
| heated by proximity to the combustion chamber, but
| circulates in a separate closed loop.
|
| Also, in a forced hot _water_ system, there is no air
| circulation at all. 100% of the air involved is heated
| and goes straight up the chimney.
|
| Aside: Some people call FHW systems "boilers" instead of
| "furnaces", but this seems to vary by region. Where I'm
| from, "boilers" are steam systems only -- which seems
| reasonable, since water is not _boiled_ in a FHW system.
| tommoor wrote:
| In NYC the steam is from co-generation facilities which
| produce electricity first, so the steam is essentially
| waste product to begin with - in most coal plants for
| example you'd just have giant steam stacks to condense the
| water again. But yes, it's all very normalized waste.
| [deleted]
| the_mitsuhiko wrote:
| That however is not a natural "feature" of district heating.
| Vienna uses it too and I have never seen steam leaks.
| wolfgang42 wrote:
| This post is basically a less-detailed blogspam of Cordia's
| marketing page: https://cordiaenergy.com/our-networks/san-
| francisco/
| barbazoo wrote:
| Thanks Google for making the internet shitty!
| azinman2 wrote:
| Curious - what would you do differently if you were google?
| willcipriano wrote:
| > plants produce steam and pipe it to approximately 180
| customers for space heating, domestic hot water, air
| conditioning
|
| Had no idea you could make a steam powered air conditioner.
|
| https://en.m.wikipedia.org/wiki/Steam_jet_cooling
| sbierwagen wrote:
| You can run a refrigerator off of any heat source: burning
| propane, solar heat, etc
| https://en.wikipedia.org/wiki/Absorption_refrigerator
| bloomingeek wrote:
| I'm about to retire from this very trade, so here's my 2 cents.
|
| In my city the boilers run at 600psi.(Not near any salt water,
| however if we decided to use it if we could, removing all the
| impurities from the feed-water would be to expensive. At our psi
| the feed-water must be clean and deaerated to protect the boiler
| tubes.)
|
| I'm a plant operator so I don't fix leaks in the field, these
| steam leaks are just that, small leaks that develop in the steam
| supply piping or the condensate return piping. (True, some lines
| aren't insulated properly in the maintenance boxes, so you do get
| some pulverized condensate.)
|
| The steam generated from the main plant is used for all kinds of
| applications. Heating of course, whether live steam or heating
| water using a heat exchanger. Also it is used to power steam
| turbine chillers to create chill water, which cools a significant
| amount of office buildings and manufacturing plants. (These
| chillers use refrigerant, usually 134a, to cool down the water
| being pumped through them, which is then pumped to where the
| cooling process is needed. Sometimes these pumps are steam
| driven, but are usually electric motor driven. Water temp leaving
| the chiller is usually 38 degrees, but may be around 42 by the
| time it arrives to where it is used.)
|
| My plant uses natural gas to create steam. Many electrical
| generating power plants still use coal or nature gas to heat
| treated water to create the steam to spin the turbines which spin
| generators to create the electricity. (Sorry, I'm not a very good
| writer.)
|
| There are many other applications for steam boilers, and no
| matter what they are, there's always the threat of leaks. The
| cleaner the system, whether steam of water, the better the
| chances of not corroding the piping. This is done by using
| chemical treatments to destroy the oxygen or rust inhibiters.
| schoen wrote:
| > This is done by using chemical treatments to destroy the
| oxygen
|
| I couldn't help thinking of the fictional weapon used against
| Godzilla:
|
| https://godzilla.fandom.com/wiki/Oxygen_Destroyer
| tedunangst wrote:
| Because steam is warmer than the surrounding air, and thus rises.
|
| Anyway, https://en.wikipedia.org/wiki/District_heating.
| maxbond wrote:
| I have a fun tangential story about when steam doesn't rise.
|
| In college I would walk past a steam stack on campus every day,
| because I could see it was always on the verge of making rings
| (pretty much any cylinder with steam or smoke passing through
| it or around it is, I've seen rings from incense, boiling rice
| [the cylinder here is the column of steam bubbles], dropping
| food coloring into water - if you look for them you start
| finding them. The craziest example I've seen, which works much
| like the food coloring, is an airplane contrail.). I thought if
| I kept it up, one day the wind would blow in just right right
| way and there would be a beautiful train of rings.
|
| I never did see it. But on a hot day[1], I saw the steam settle
| into the narrow alley next to the building. It formed into a
| tiny roll cloud, about six feet long. I watch it stunned for
| about fifteen seconds, and then it dispersed.
|
| [1] I'm pretty sure it was a hot day, what I remember clearly
| was that it was an unusual temperature. I surmise the air was
| very warm and so the steam was denser than the air. But it may
| have been a cold day and the steam cooled and then sank,
| unfortunately I can't say for sure because I didn't write it
| down.
| fulafel wrote:
| Other parts of the world with district heating don't leak
| steam. Is it just because they use (liquid) water and not
| steam?
|
| The water is still plenty hot enough for steam to form in
| leaks, so there's perhaps some factor that makes leaks more
| tolerable in steam systems? Different corrosion concerns
| perhaps, air leaking in is less corrosive?
| tedunangst wrote:
| I think it's an American thing. Our pipes are just that much
| freer. New York and Philadelphia systems leak steam, too.
| mangecoeur wrote:
| Steam based systems are just obsolete, steam under pressure
| leaks easily unless you do plenty of maintenance. Most
| district heating systems use liquid water in a closed loop.
| In fact most operators today are looking to further reduce
| temperatures to reduce losses and improve efficiency. You
| only let this much steam escape if you really dont care about
| saving energy/money
| bobthepanda wrote:
| The issue is generally for these large historic systems,
| the capital cost of replacement is larger than the savings.
| Because the streets of New York had many utilities laid out
| very early, there's poor mapping and everything underground
| is haphazard, and disrupting somebody else's utility system
| will get them to sue you.
| wongarsu wrote:
| Our smallish city has district heating with hot water, and no
| steam rising from the streets.
| [deleted]
| arbuge wrote:
| In NYC also:
| https://www.bloomberg.com/news/articles/2015-10-23/why-steam...
| ginko wrote:
| >Critics of the system point out that the system produces heat,
| but also wastes nearly 250,000 gallons of water per day,
| according to a 2015 story by CBS Bay Area.
|
| Any reason why they couldn't use ocean water?
| throwaway173738 wrote:
| Salt water ruins everything it comes in contact with.
| Scoundreller wrote:
| As someone that maintains two vehicles located in the rust
| belt/salt belt, I concur.
| PeterisP wrote:
| Saltwater corrodes all the metal parts, and you simply can't
| use it for a steam cycle as the salt would pile up as the water
| turns to steam.
| donalhunt wrote:
| Google's datacenter in Hamina, Finland uses salt water for
| one of the cooling loops. aiui it was not trivial to
| incorporate the salt water loop (corrosion was an issue) but
| they've made it work.
|
| https://www.wired.com/2012/08/google-finland-data-center/
| toast0 wrote:
| Water in a datacenter cooling loop is almost certainly not
| heated to the same temperatures as water in a (steam)
| heating loop. Corrosion is temperature dependent.
| ville wrote:
| And on top of that, the Google datacenter in Hamina
| doesn't use ocean water with 3.5% salinity, but water
| from the Baltic sea, which in that part of the Gulf of
| Finland only has roughly 0.3% salinity - a tenth of ocean
| water.
| Scoundreller wrote:
| Sounds like less of a Baltic sea thing, but more of being
| in a fjord or bay that's fed by fresh water keeping a lot
| of the salty sea water out.
| mikeryan wrote:
| Building a system from the ground up to use saltwater is a
| whole different ballgame then trying to retrofit an
| existing legacy network though.
|
| It would probably be cheaper to just convert to another
| heat source all together.
| justsomehnguy wrote:
| Even without reading TFA it's surely not the loop what is
| actually cooling the hardware.
| jldugger wrote:
| Google also has a 30 percent profit margin, even after
| accounting for boondoggles like that.
| Etrnl_President wrote:
| You can get basalt-lined pipe, for chemical stability.
| deepsun wrote:
| Would be way more efficient if that was an power plant
| (electricity generation), that just made use of its waste heat.
| There were plenty of those in USSR, but I guess not everyone
| likes a power plant in the neighborhood.
| ElfinTrousers wrote:
| tl;dr: leaky steam pipes in district heating in downtown SF. Same
| reason you get it in NYC.
| mokarma wrote:
| Yup, we have it in Detroit too.
| https://www.hourdetroit.com/community/whats-the-source-of-th...
| ElfinTrousers wrote:
| Not only is district heating energy-efficient, it's great for
| setting a real film noir atmosphere.
| grogenaut wrote:
| One time walking past union square I saw smoke and flames coming
| out of the cable car slot. There was just a cop watching it and
| waving people around. Pretty sure just waiting on the repair
| crew. Totes normal.
| nharada wrote:
| Meanwhile over in Chicago this is called "working as expected":
| https://www.cnn.com/2019/01/30/us/chicago-train-tracks-fire-...
| babyshake wrote:
| It's tempting to make a joke about how in that neighborhood,
| you're lucky if the worst thing you see is flames coming out of
| the ground.
___________________________________________________________________
(page generated 2023-04-23 23:02 UTC)