[HN Gopher] How to ramp up a factory consuming a lot of energy?
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How to ramp up a factory consuming a lot of energy?
Author : joebiden2
Score : 126 points
Date : 2023-06-19 15:53 UTC (7 hours ago)
(HTM) web link (electronics.stackexchange.com)
(TXT) w3m dump (electronics.stackexchange.com)
| thedougd wrote:
| A fact in this Wikipedia article shocked me into understanding
| how much juice an aluminum smelter plant requires.
|
| https://en.wikipedia.org/wiki/Shearon_Harris_Nuclear_Power_P...
|
| "The Shearon Harris site was originally designed for four
| reactors (and still has the space available for them), but
| cancellation of an aluminum smelter plant in eastern North
| Carolina in the 1970s resulted in three of the reactors being
| canceled."
| nurple wrote:
| I grew up next to a hydroelectric dam on the Columbia River in
| Oregon where a large amount of the power went to smelting
| aluminum. That industry was a huge part of the industry in our
| small town that otherwise primarily produced cherries. I went
| on a tour there with my scout group and it made a serious
| impression on me, it was erie how you could literally feel the
| enormous amounts of current in the air.
|
| There was so much current that the free-air magnetic field in
| the plant was literally palpable, the engineer giving us the
| tour did a demonstration similar to this video[1] which blew my
| young mind.
|
| A portion of the land, and the substantial power-handling
| infrastructure (and proximity to the river for cooling) now
| powers a Google datacenter.
|
| [1]: https://www.youtube.com/watch?v=HsuSo7aFGhk
| Hextinium wrote:
| A kilo of aluminum contains about 55 kw/h of embodied energy, I
| like to think of aluminum smelting as pretty much the direct
| conversion of electricity to metal.
|
| That means that each MW/hr of production only makes 18 kg/hr,
| so a 900MW/hr nuclear plant only makes 8 tons of aluminum a
| hour. Its insane.
| dmurray wrote:
| To illustrate this: aluminium costs about $2.25 per kilo
| wholesale [0], so that's about 4c per kWh or $40 per MWh.
|
| There aren't many places where electricity can be produced
| close to that. Iceland is one and it's unsurprisingly the
| world's major bauxite importer and aluminium exporter.
| Wholesale electricity there goes for around $42/MWh [1].
|
| OK, the smelters can do a bit better than the average
| wholesale rate, but not much - Iceland's electricity supply
| is not highly variable like solar or wind.
|
| So the rest of the expenses of the process - mining, shipping
| half way around the world twice, capital costs - are all
| basically free compared to the electricity cost.
|
| [0] https://markets.businessinsider.com/commodities/aluminum-
| pri...
|
| [1] https://www.datacenterdynamics.com/en/opinions/time-for-
| an-i...
| jaggederest wrote:
| First, a clarification: a kilowatt-hour is not a kilowatt per
| hour (1 kwh = 3.6 * 10^6 joules). Same goes for megawatt-
| hours. There's no such thing as a "900Mwh" reactor - it's a
| 900 megawatt reactor. During an hour, it'll produce 900Mwh*
| (3.24e+12 joules) and can smelt 16363 kg of aluminum. Behold
| the power (pun intended) of dimensional analysis.
|
| Secondly, you're not wrong, the way that aluminum is smelted
| is by melting e.g. bauxite or another aluminum compound, and
| then electrolyzing the resulting fluid to extract pure
| aluminum. Usually the same electrodes are used for both
| operations. It's the very grandest scale of electrochemistry,
| and the reason that aluminum smelting plants are nearly
| universally located near cheap and highly available power
| sources.
|
| * Something close to 900Mwh, anyway, given that reactor
| nameplate capacity is not always the actual running power or
| peak possible output, plus an allowance for maintenance.
| Other power sources have different capacity factors that
| would result in something below 900Mwh, but a typical fission
| plant is "up" continuously for our purposes
| syedkarim wrote:
| I assume this is for smelting bauxite. Is that correct? Do
| you have similar numbers for recycling aluminum?
| ilyt wrote:
| Other interesting fact is how grid uses frequency to communicate
| the load demand.
|
| Load drops, the big spinny generators stop having so much
| resistance and accelerate.
|
| Load increases and the big spinny generators have more load,
| synchronously slowing down.
|
| So in simplest system just feeding your generator more when
| frequency is below nominal and less when it is above is enough
| isoprophlex wrote:
| Whoa, ever since learning about this, I randomly tell people
| about this. Noone ever seems to understand my fascination with
| this distributed grid of spinny things interacting.
|
| I'm glad there's at least two of us ;)
| jupp0r wrote:
| There is a whole world of nerds who do this in their job
| every day. They are fun people.
| yannyu wrote:
| I studied electrical engineering, but power engineering isn't
| a course that I took. The most enlightening quote I've heard
| about this was a response to a question:
|
| "What happens when I turn on an electric device in my house?"
|
| "A turbine in a power plant spins more slowly for just a
| moment."
| HPsquared wrote:
| Before quartz oscillators, clocks would use the grid as their
| time reference. It can be done mechanically via a small
| synchronous motor and some gears. I'm not sure if it's still
| the case today, but the grid frequency used to be managed
| through the night so those clocks were most accurate in the
| morning (for peoples' alarm clocks)
| michaelt wrote:
| _> Before quartz oscillators_
|
| Some systems still use grid frequency for timekeeping.
|
| If you own a mechanical rotary timeswitch, it's got a
| synchronous motor spinning 50 or 60 times a second, then a
| series of gears, gearing it down to 1 rotation per day.
| throwaway173738 wrote:
| A switch such as would be present in an older clothes
| dryer or washing machine. The newer ones use
| electronically controlled relays but I could see the
| designers skipping the quartz oscillator because the time
| difference comes out in the wash.
| isoprophlex wrote:
| Yeah. Some years back there was a structural underfreq
| event for a couple of weeks on the European grid. My
| microwave phased out of time by several minutes, and then
| phased back. Was fun to observe.
|
| https://www.theguardian.com/world/2018/mar/08/european-
| clock...
| cesarb wrote:
| Interestingly, my country (Brazil) doesn't seem to
| regulate the grid frequency for use as a time reference,
| at least as far as I could find. So if this happened
| here, and if the microwave used the grid frequency for
| its clock, the clock would stay wrong.
| bri3d wrote:
| This isn't just a "before quartz oscillators" thing; it's
| still in extremely widespread use today since quartz
| oscillators still cost some fraction more than $0. And,
| it's not always mechanical, there are a lot of all-in-one
| timekeeping/clock chips that use AC as the reference
| frequency for their internal oscillator/PLL.
|
| Almost all cheap / "simple" consumer mains appliances,
| including non-"smart" microwaves, ovens, alarm clocks, etc.
| still use mains frequency as their time reference.
|
| Due to the growing complexity of power grids and in Europe,
| international power-grid politics and infighting, the grid
| frequency is becoming less stable and you see these devices
| fluctuate badly more often than they used to.
| https://hackaday.com/2018/03/09/europe-loses-six-minutes-
| due...
| bsder wrote:
| > Almost all cheap / "simple" consumer mains appliances,
| including non-"smart" microwaves, ovens, alarm clocks,
| etc. still use mains frequency as their time reference.
|
| I find this _incredibly_ hard to believe. Crystals are
| _incredibly_ cheap and _waaaaaay_ more accurate than
| anything that the grid does.
|
| If you're not an actual motor, sensing the grid is both
| an engineering challenge and a non-trivial expense.
| AdamH12113 wrote:
| To my understanding, the grid is managed to have a fixed
| number of cycles per day, which would make it perfectly
| accurate. A cheap crystal can easily lose a few seconds
| per day. And given how hard it is to keep 60 Hz noise
| _out_ of circuits, I can't imagine the sensing would be
| difficult.
| pixl97 wrote:
| Heh, it's easy to model when you have a few generators,
| especially when one is much bigger than the others on the grid.
| But what's fun these days is you can have an absolutely huge
| number of generators. Keeping things in phase just seems insane
| to me.
|
| Practical engineering has a great video about power black
| starts that give some insight into this complicated machine.
|
| https://www.youtube.com/watch?v=uOSnQM1Zu4w
| HPsquared wrote:
| It's a bit like they are all connected together by gears. All
| the generators are in phase.
|
| The most difficult bit for an operator is to make sure the
| generator is synchronized before they actually connect it.
| Only after it's synchronized can they start actually feeding
| power in.
|
| You can't just turn these things on and off at will like a
| regular motor. To extend the gears analogy, gears need to be
| synchronised before they can engage - just like synchronous
| AC generators.
| fbdab103 wrote:
| During the Texas blizzard power outages, the state was
| supposedly minutes away from a black start scenario[0].
| Estimates are that it would have taken weeks to restore power
| to the state owing to the complexity of syncing everything
| back together.
|
| [0] https://arstechnica.com/tech-policy/2021/05/texas-power-
| outa...
| binbag wrote:
| As another commenter says, it's actually easier the more
| generators you have because the rotational inertia of all the
| spinning masses is larger. This (and the storage problem) is
| one of the reasons that wind and solar destabalise grids -
| they are interfaced to the rest of the grid by converters
| that create ac sources - but there's no real rotating mass
| there, so the inertia is tiny. The result is that as we add
| more renewable power to the network, it becomes less able to
| 'roll with the punches' of loads coming on and off line.
|
| PS One of the answers in the SO thread mentions JET in the
| UK. I spent a few summers there as an electrical engineering
| student (it's home to the MAST and JET fusion reactors). When
| the JET tokamak ignites a plasma, it can't sustain it for
| very long (we are not yet at the point of extracting enough
| energy to sustain the reaction). As a result they need to
| ignite the plasma and keep it hot. They can't do it for more
| than 1-10 seconds. During that time, they draw massive
| amounts of power - they're permitted to draw up to 1% of the
| UK's capacity for a short period, whilst they simultaneously
| dump all the energy stored in two gigantic flywheel
| generators housed in a nearby building. I've never been there
| when the flywheels are running but I've climbed around
| beneath them. There's nothing quite like massive engineering
| :)
| ilyt wrote:
| > Heh, it's easy to model when you have a few generators,
| especially when one is much bigger than the others on the
| grid. But what's fun these days is you can have an absolutely
| huge number of generators. Keeping things in phase just seems
| insane to me.
|
| The difficulty is not "keeping them in phase", that just
| happens (aside from initial connection), it's the whole load
| prediction and handling, when to tell which plant to start
| producing more or less energy, with variety of plants having
| shorter or longer ramp-up/down periods
| jnsaff2 wrote:
| It's not hard to keep it in phase. Once it's synchronized it
| is actually rather hard to not keep it in phase.
|
| Generator spins at 50hz Motor spins at 50hz
|
| Add load to the motor, it starts slowing down both itself and
| the generator. Generator governor increases input energy,
| frequency goes up. Both are in phase all the time.
|
| Remove load, both start spinning faster. Reduce governor to
| regulate it to 50hz again.
|
| It's a bit harder with inverters but the idea is similar, you
| follow the grid phase and if you want to send energy to the
| grid you will be slightly early to the grid phase and if you
| want to take energy from the grid your phase will slightly
| lag.
| Someone wrote:
| More info at https://en.wikipedia.org/wiki/Droop_speed_control
| madaxe_again wrote:
| I do this at home - I'm off-grid, but have a picogrid here as
| we're distributed over a fairly large area and have a few
| structures separated by up to a kilometre, and we've multiple
| PV arrays, a hydro generator to be installed later this summer
| when the river is low, and a few wind turbines.
|
| By far and away the easiest way to control production - i.e.
| brake/feather turbines or dump PV, is frequency shifting, as
| I've batteries and inverters in several locations and while
| networking them would be possible, it's unnecessary. It's
| typically intended for grid-tie operations, but here I use it
| to control our tiny isolated grid.
|
| It's a pretty small range (50.2-53hz) over which they shift,
| but it's more than enough.
|
| https://www.victronenergy.com/live/ac_coupling:fronius
| baybal2 wrote:
| [dead]
| shadowgovt wrote:
| One question about the grid I've never wrapped my head around:
|
| So the entire grid is in phase, by which I mean every generator,
| load, &c is operating on the same AC pulse ( _handwave-handwave_
| ignoring smaller loads, transformations, etc.). But that phase
| isn 't instantaneous; it's near-light, and the grid is long
| enough for that to matter in places.
|
| So every point in the grid can't be perfectly in phase with every
| other point, right? Because we have both lightspeed delays and
| loops, so even if point A is receiving power from two substations
| in-phase, point B (with different lengths of wire to those two
| substations) should be receiving it out-of-phase, right? How do
| we balance that in the grid?
| camtarn wrote:
| You could introduce a back to back HVDC link [1] on one of the
| two incoming legs, allowing you to alter frequency and phase
| freely.
|
| [1] https://en.wikipedia.org/wiki/High-
| voltage_direct_current#Ba...
| itzworm wrote:
| I think it's more like doing the wave at a large sports
| stadium.
|
| Everyone isn't always in phase with every other station's phase
| at that exact moment in time. They're just in phase with their
| local part of the grid's phase. Though amount that is different
| is milliseconds, not seconds as in the stadium wave example.
|
| This mostly came from reading this:
| https://electronics.stackexchange.com/a/291328
| Someone wrote:
| Others answered your question. A related, but different problem
| is "how do you make sure a new power source you add to the grid
| is in sync with the grid the moment you connect it?".
|
| That's described on https://en.wikipedia.org/wiki/Synchronizati
| on_(alternating_c....
|
| Firstly, you design your generator to have the same wave form
| and phase sequence as the grid.
|
| Then, you power up your generator and make sure the voltage,
| frequency and phase angle of the electricity it generates
| matches that of the grid.
|
| The moment that's (more or less) the case, you connect the
| grids, preferably on a zero crossing. That Wikipedia page
| describes a setup with incandescent bulbs that can be used to
| manually detect that moment, but nowadays, it's done using
| electronics.
| ars wrote:
| I looked this up once, and the answer is: They basically just
| ignore it.
|
| If everything is in a line, you just sync to your local phase,
| but if you have wires in a triangle that's impossible, and they
| basically just ignore it, in practice it doesn't happen often
| enough to cause any problems.
| asdfman123 wrote:
| You can think of electrical phases like any other kind of wave:
| maybe like shaking a slinky. The power plant sends the phases
| downstream to consumers, and once it leaves the factory it
| doesn't know what consumers do with it (beyond detecting
| voltage drops, etc.).
|
| So the grid doesn't need to balance it, no.
|
| And from the receiving end's perspective, power will be exactly
| one phase out of sync if the cables differ in length by 5000
| km. I'm assuming that isn't really a problem people have to
| worry about, but my background is in physics and not
| engineering (i.e. maybe there's some industrial applications
| that I'm not thinking of).
| cesarb wrote:
| > So every point in the grid can't be perfectly in phase with
| every other point, right? Because we have both lightspeed
| delays and loops, so even if point A is receiving power from
| two substations in-phase, point B (with different lengths of
| wire to those two substations) should be receiving it out-of-
| phase, right? How do we balance that in the grid?
|
| As far as I know, in your example, one of the two circuits will
| be transmitting more power from the substations to point B than
| the other. There's a device called a phase-shifting transformer
| (https://en.wikipedia.org/wiki/Phase-shifting_transformer)
| which can be used to adjust the phase angle of the circuits,
| and that way, adjust how much of the power is carried by each
| circuit.
|
| (The following sentence from that article probably goes to the
| core of the answer for your question: "For an alternating
| current transmission line, power flow through the line is
| proportional to the sine of the difference in the phase angle
| of the voltage between the transmitting end and the receiving
| end of the line.[1]")
| csours wrote:
| You just synchronize to wherever you are on the wave. Your
| offset will not be the same as your neighbors offset, but
| that's fine.
|
| Maybe imagine a line of buoys in the ocean as a wave passes.
| shadowgovt wrote:
| But if I have power from two sources coming into my facility,
| they wouldn't be in phase with each other, right? How do I
| use both?
|
| (Perhaps the obvious answer is correct here: "Grids don't
| work that way; you'd never do that.")
| asdfman123 wrote:
| Imagine you've got two cables coming into your factory. One
| is 500 meters longer than the other. That would mean that
| the sine waves are 0.01% out of sync.
|
| I'm pretty sure for home electronics the phase difference
| doesn't even matter that much. Everything sensitive seems
| to be converted to DC anyway.
|
| Maybe it matters in large industrial applications, I have
| no idea. But I also imagine in their situation it's
| probably pretty straightforward to clean up the power
| supply.
| londons_explore wrote:
| In reality, the phase difference is always small, and it
| ends up not mattering.
|
| But... If you had a worldwide electricity grid running at
| 60Hz, it would start to matter, and you would make sure to
| use local capacitors/inductors to make phase shifts to make
| sure that you didn't have big circulating currents in loops
| (they just are wasting energy)
| csours wrote:
| Napkin math: Speed of light is 300,000 kilometers/second.
| At 60 hz, the wavelength would be 5,000 km. 1% of that
| would be 50 km.
|
| Imagine a triangle with 2 generators 100km apart, and a
| factory almost due south of one generator:
|
| ga ......... gb
|
| __f
|
| I think the offset would be something like sin(gb.f) -
| sin(ga.f)
|
| But really this comment is bait for an EE to school me.
|
| Here's a video of old school mercury arc rectifiers as
| payment: https://www.youtube.com/watch?v=YhaQqgXrMMU
| generalizations wrote:
| I wonder if the solution is similar to routing traces on
| PCBs where there's high-frequency stuff going on - you add
| and subtract length from the line pairs until the phases
| match up. Sometimes the dumb solutions are the best ones?
|
| Weird how all the replies so far misunderstood your
| question.
| marcosdumay wrote:
| There's a lot of high-frequency stuff going on, but the
| line length is so much that most of it irradiates away.
| You don't go adding more line to compensate anything, but
| you do add filters at some places.
| applied_heat wrote:
| An airport or hospital might be fed from two different
| nearby substations. The substations are probably fed from
| the same transmission lines with parallel circuits. The
| substations will have transformers with the same winding
| configuration for a consistent phase shift from
| transmission to distribution level voltages.
|
| The airport or hospital will procure transformers that have
| the same winding configuration and impedance so the phase
| shift and voltage drop across them will also be the same.
| The low voltage windings of the transformers at the
| hospital can be paralleled so they both feed the load.
| Reverse power protection would be implemented so the
| hospital can't back feed the distribution line.
|
| What phase difference do you expect in this case? What
| effect would it have?
| londons_explore wrote:
| The sum of two sine waves of differing phase is a sine wave
| with some phase between the two.
| sidewndr46 wrote:
| you would have to be in a location to straddle synchronous
| grid. There may be some places that allow that. Otherwise,
| the two sources are already in approximately in phase
| anyways. To put it simply though, you put some devices on
| one feed and some devices on another feed. So it is a non-
| issue.
|
| If you have local generation you want to combine with grid
| power you usually just sync your local generation to the
| grid. If you don't want to do that you can just use a DC
| intertie that is local. Basically you'd have two AC -> DC
| converters and a single DC -> AC converter.
| ilyt wrote:
| In most cases where you do have more than one source (say
| datacenter for redundancy) you don't just tie them together
| directly, in simplest config you'd just switchovered from
| one to another if one failed.
| michaelt wrote:
| So what happens if you've got three power plants in different
| states, connected in a triangle?
| KaiserPro wrote:
| > So every point in the grid can't be perfectly in phase with
| every other point, right?
|
| not in phase as such, but in sync.
|
| because you only have to match your 60hz(or 50hz) to what you
| receive locally, so long as the waveform is reasonably stable
| its not that much of an issue.
|
| Because everything is effectively a bunch of elastically linked
| pendulums, you tend to reach equilibrium, so long as the load
| doesn't act too much as a dampener
| amenghra wrote:
| random guess: the entire grid is huge but the difference in
| lengths between those two substations is tiny and doesn't
| matter?
| ilyt wrote:
| 50Hz wave length is at ~6000 km so it frankly isn't a problem.
|
| You'd have to have 2 different routes from same power source
| that differed in hundreds of kilometers in length and that just
| doesn't really happen. And small phase difference would just
| cause uneven loading
|
| Also that power would be "used up" closer to the power source
| and you'd be sucking off power from closer sources.
| ck2 wrote:
| Collective human knowledge just blows my mind sometimes.
|
| Consider how many obscure but useful, necessary even, things
| we've learned over the past thousand years.
|
| Before the internet it would all be hidden away, only quickly
| available to specific experts in their fields.
|
| You'd have to go to a university library and dig for hours.
| ars wrote:
| > You'd have to go to a university library and dig for hours.
|
| If it's not online it doesn't exist. /s We really need more of
| these obscure pieces of knowledge put online because people
| don't go to the library as much as they used to.
|
| There's so much specialized knowledge out there, but often
| you'll only learn about it from someone else, or a highly
| technical book.
|
| Like, say you want to frame and build your own house - there's
| bazzilions of YouTube videos about the beginning process. But
| very very few about the more advanced details you need to know.
| TillE wrote:
| I've been lamenting for many years that the dream of an
| "information superhighway" has basically failed.
|
| There is _so much_ deep information available in any large
| university library that is simply not on the internet at all.
| If you 're researching any historical topic, there are at
| least a few solid books (and possibly hundreds) that draw
| from primary sources, compared to a couple pages of text on
| Wikipedia and very little else. You mostly won't even find
| ebooks.
|
| Somehow the best, most extensive free digital resource is a
| podcast like Age of Napoleon, which synthesizes information
| from many books.
| TeMPOraL wrote:
| > _If it 's not online it doesn't exist._
|
| Even if it _is_ online, it probably doesn 't exist either -
| see today's threads about communities moving from Reddit to
| Discord. The "cozy web" is undoing a lot of progress of the
| past decades. Might be that we'll all need to go to the
| university libraries and dig for knowledge ourselves, hoping
| any of the more recent experiences and discoveries end up
| being published as books, instead of dying in private
| Whatsapp groups.
| ramesh31 wrote:
| >There's so much specialized knowledge out there, but often
| you'll only learn about it from someone else, or a highly
| technical book.
|
| I remember my mind being blown by the Cal engineering
| library. Endless stacks and stacks of dense foundational
| knowledge from the 1950s-1990s you would never find on
| Google. Books are massively underrated these days.
| generalizations wrote:
| I wonder if that stuff is available on places like libgen.
| If it isn't, I really hope someone digitizes it.
| ilyt wrote:
| > Like, say you want to frame and build your own house -
| there's bazzilions of YouTube videos about the beginning
| process. But very very few about the more advanced details
| you need to know.
|
| That's an interesting factor of online knowledge - the most
| readily available one is the one that masses are interested
| the most because the views give the budget for people to
| care. It's also weirdy trendly, like how pandemic spawned a
| lot of woodworking channels coz people cooped up in their
| homes found a new hobby.
|
| To add to the point this [1] random video is an example, it
| does go into terminology and reasoning behind each element
| but won't tell you what kind of lumber to get, how climate
| would affect that decision, how to isolate the house and a
| bunch of other things. You might look for them and probably
| find some info but at some point just looking for a dedicated
| book might be the saner option.
|
| And uh, if someone knows a good one covering how to build and
| isolate your own shed I wouldn't mind recommendation...
|
| - [1] https://www.youtube.com/watch?v=3fP0LZMEV5w
| JimtheCoder wrote:
| "Like, say you want to frame and build your own house -
| there's bazzilions of YouTube videos about the beginning
| process. But very very few about the more advanced details
| you need to know."
|
| Advanced? All I need is some TooBa Fours and a Larry Haun
| book...
| oivey wrote:
| Undergraduate electrical engineers learn this fact. It's
| technical but in the scheme of things not all that obscure.
| That's some of the value of a formal education.
| ck2 wrote:
| At some point someone is going to figure out how to feed
| every scientific paper into an AI, including all measurements
| and formulas, and I have to imagine that is going to really
| make some progress towards less-than-obvious connections in
| knowledge.
| JimtheCoder wrote:
| "At some point someone is going to figure out how to feed
| every scientific paper into an AI"
|
| I'm sure the scientific publishers that charge $50 to view
| a single journal article will do everything in their power
| to prevent this...
| arcanemachiner wrote:
| Too late, we already have SciHub.
| JimtheCoder wrote:
| Yes, I know that site very well.
|
| This does bring up the issue of actual legal protections,
| though.
|
| If you are training an LLM on the open web, or things
| posted for everyone to view for free, than that is OK I
| guess when it comes to legal ramifications. (Definitely
| not a lawyer)
|
| When you start using data that you really don't have the
| rights too...and somehow someone finds out that their
| protected data is included in the dataset...then what?
| withinboredom wrote:
| It might be protected if you are doing it yourself, for
| personal (non-commercial) use. Just like you can build
| any patent you want for fun, but the second you try to
| sell it, you need permission.
| cfn wrote:
| You are forgetting museums. Before the internet was widely
| available I visited the Electricity Museum in Lisbon which is a
| repurposed power station. They had a simulator of a power
| station with operating instructions and, according to the
| staff, it was realistic. I spent quite a few hours trying to
| startup the damn thing but it was too complicated. It was a bit
| like a game but with very low tolerance and a long list of
| steps which gave me quite an insight into how complex that
| field is.
|
| https://pt.wikipedia.org/wiki/Museu_da_Eletricidade_(Lisboa)
| shadowgovt wrote:
| And one challenge (as is so often true in software) is knowing
| _what_ to know. It 's not particularly intuitive that grid
| balance is necessary if one's entire experience with
| electricity is "I plug in a machine and the power comes out of
| the wall."
|
| It's actually a minor plot point in Stephen King's "The Stand"
| that after a viral apocalypse wipes out most of humanity, the
| survivors try to restart the electrical grid in a town.
|
| The first attempt proves fatal because they haven't properly
| isolated the circuits throughout town, so when they connect the
| plant to the main grid the plant's generators explode from
| trying to support the load of every home where someone died
| spontaneously while running a hair dryer.
| asdfman123 wrote:
| The internet has made "random fact retrieval" much faster for
| sure. In fact, I notice movies seem... less dumb than they were
| a few decades ago, and I have a theory that that is why.
|
| But to really know something, you have to have studied it, even
| in the modern era. I can read an instantly-available wikipedia
| article about power generation, but I'm only scraping the
| absolute surface.
| BonoboIO wrote:
| And we still have people that think that the earth is flat.
| Kind of depressing.
| icyfox wrote:
| A small - and somewhat related - anecdote.
|
| New Zealand had to build an aluminum plant in the 1960s and
| figured out it would be more efficient to bore miles underground,
| build turbines, install a huge power station, and wire it tens of
| miles to the smelting plant. It relies on a vertical drop between
| Lake Manapouri and the open ocean to create the gravitational
| potential to turn the turbines. When the smelting station doesn't
| use the full capacity the power station has to immediately reduce
| output, otherwise it can overload the transmission lines to the
| rest of the grid.
|
| Manapouri Power Station is the name if anyone is interested in
| reading more. It has an interesting history.
| https://en.wikipedia.org/wiki/Manapouri_Power_Station
| sidewndr46 wrote:
| Discharging >40% of the freshwater usage in a country to the
| open ocean is not a 'small' anecdote.
| Vvector wrote:
| Instead of discharging into the ocean, could it be used for
| drinking water?
| treis wrote:
| Can't do that and generate power. You'd spent all (or at
| least a lot) of the generated energy pumping the water
| where it needs to go.
| sidewndr46 wrote:
| That was proposed but rejected by the government.
| rootusrootus wrote:
| It looks to be a fairly long ways from major cities, is
| that why?
| below43 wrote:
| That is correct. It's located in one of the most remote
| areas of New Zealand, and a very long way from cities
| with a decent population.
| ComputerGuru wrote:
| What percentage of a non-negligible amount of fresh water
| pumped/dumped into the ocean is returned to the freshwater
| ecosystem/loop given, say, 10 years?
| colechristensen wrote:
| Plenty of places can do this with essentially zero
| environmental impact. If it rains a lot and the rain came
| from ocean evaporation and the natural water route was a
| big river quickly back to the ocean, you can pretty
| harmlessly divert a portion through hydroelectric.
|
| Not everywhere is the American west where it doesn't rain a
| lot and water sources are being used way past their
| capacity.
| rdlw wrote:
| It's a large amount of water but the anecdote itself is only
| ~32cm2 on my screen :)
| codetrotter wrote:
| > the anecdote itself is only ~32cm2 on my screen
|
| This comment reminded me of a cute tool I used to have
| installed back in the WinXP days called "Screen Calipers".
| It was a super sweet tool. 100% skeumorphic :D
|
| http://www.iconico.com/caliper/
| phire wrote:
| The lake is in a reasonably remote part of the country, in an
| area with exceptional high rainfall. Plenty of other sources
| of water. Most of that fresh water was going to flow out into
| the ocean anyway, this just sends it via a more direct route.
|
| The longer route (which actually flows next to the farm my
| mum grew up on) doesn't even go near a major population
| centre. The largest town (Tuatapere) has a population of 500
| people.
| madaxe_again wrote:
| This is why you'll often find bauxite smelters next to
| mountains - this is a common solution for the vast amounts of
| energy required.
| dendrite9 wrote:
| Oh Cool, there's a very similar setup in northern BC. The
| Nechako reservoir drains through tunnels drilled under the
| Coast Range and generates powers in Kemano. Most of the power
| goes to a smelter in Kitimat.
|
| https://en.wikipedia.org/wiki/Kemano
|
| https://en.wikipedia.org/wiki/Kenney_Dam
| nurple wrote:
| Thank you for sharing, I grew up next to a hydroelectric dam
| and the time I spent on top of it for general tours and special
| tours with our scout group is something I will always remember.
|
| My brain however has in the past created incredible nightmares
| based on the scale of what I experienced there. I just _had_ to
| see what the tailrace output looked like and was not
| disappointed by this nightmare fuel:
| https://www.youtube.com/watch?v=qlhSzs4JXE0
| withinboredom wrote:
| Why is the video nightmare fuel? I have zero context, but I
| assume it's nightmare fuel because they could suddenly let
| out a crap-load of water through there and you'd get smashed
| to smitherines?
| lostlogin wrote:
| A slight aside, Tiwai is now now owned by Rio Tinto. Every few
| years Rio Tinto claims the power is too expensive and they may
| have to closed down. Then they get a discount and carry on.
|
| They are at it now. That place closing down would lose 1000+
| jobs if n a region that doesn't have a ton of options, the
| world would lose a greenish supply of aluminium and I would
| potentially get a discount on my power bill when I stop
| subsidising that massive company (that smelter uses a bit over
| 10% of NZs electricity).
|
| Oh, and Rio Tinto have dumped toxic waste in various places
| too.
|
| https://www.powercompare.co.nz/n/tiwai-point-aluminium-closu...
|
| https://www.rnz.co.nz/news/national/468066/tiwai-point-toxic...
| dpc050505 wrote:
| Rio Tinto is always extorting the Quebec government for
| preferential rates on power to make aluminum. I don't
| understand why governments let companies hardball them like
| that. The c-suite and the trademarks can leave, the factory,
| the expertise and the market will still mostly be there,
| governments could invest and rebuild something they/the
| people actually have ownership of.
| chongli wrote:
| _I don 't understand why governments let companies hardball
| them like that_
|
| Moral hazard [1]. Government officials make these decisions
| because they can win political points by doing so. Usually,
| they get to take credit for being "job creators."
| Opposition politicians who try to raise the issue of risks,
| potential debts, environmental degradation, etc. can be
| quickly branded as anti-jobs and their valid criticisms
| dismissed.
|
| Down the road, when the chickens come home to roost, the
| politicians who approved the deal are nowhere to be found.
| Since there's no law allowing the public to hold those
| politicians financially accountable for their past
| decisions the effect of moral hazard has run its full
| course, leaving the public holding the bag.
|
| As for why (even new generations of) politicians would
| continue to cave to these companies' demands: no one wants
| to be left taking the blame for job losses.
|
| [1] https://en.wikipedia.org/wiki/Moral_hazard
| colechristensen wrote:
| If they actually throttle them during peak usage aluminum
| plants _should_ get a discount. Because much of the
| electrical part is more or less the equivalent of charging
| a shitty battery, it can be throttled really easily and
| being able to eat up extra capacity during low electrical
| usage is really environmentally friendly, as is aluminum as
| a material for making stuff being infinitely recyclable.
| csours wrote:
| Ew, you mean they have to talk to a human on the telephone?
|
| ---
|
| We built a whole application to manage a certain workflow between
| multiple systems, and our users kept using email instead, because
| it turns out that the users on the other end don't check the
| system, but they do check their email.
| CaliforniaKarl wrote:
| For critical stuff that is not instantaneous, it's good to have
| both automated and human communication/confirmation. In this
| case, the automation is equipment throughout the grid that can
| disconnect a line if it falls too far out of compliance (for
| example, frequency drops too low, due to a sudden increase in
| load). As mentioned elsewhere, huge consumers get their own
| substation, and such equipment can be placed there.
|
| You also have people who are drilled in following procedures,
| especially when failures in process become very public.
| schlowmo wrote:
| This is no powerplant-level story, but sometimes there are high
| startup currents were you didn't expect them:
|
| On one of my first IT jobs at a big manufacturing company my team
| was tasked to find out why there are regular power outages in
| some printer rooms (there were rooms with shared printers on each
| floor of the office building). There were always some tripped
| circuit breakers and the facility management had to dispatch
| someone to put them back on. Between those incidents were always
| some weeks were nothing happened, but when it happened it
| affected a lot of printer rooms.
|
| In the end we found a monthly cronjob on a central printing
| server which triggered a testpage print on all connected
| printers. Took us quite some time since no one ever saw those
| test pages. Never underestimate the needed current for a room
| full of colour laser printers coming to live all at once.
| hinkley wrote:
| I've heard of people hacking system startup procedures so 15
| hard drives didn't try to spin up at the same time.
| 13of40 wrote:
| There was some home computer - either an original Apple II or
| a Commodore PET, I don't remember - where if you splurged for
| the fancy second disk drive, the computer could be destroyed
| by a rogue program spinning up both drives at once. And since
| every program ran at the same protection level as the OS
| (because there were none), it was either two MOVs or two
| POKEs to the hardware registers to make it happen.
| taddevries wrote:
| This was a feature on SCSI disk controllers. I remember one
| controller that had dip switches to set the spin up sequence
| number, and then you would configure the controller to wait
| for all the drives to be spinning before it tried to bring
| the array online.
|
| I'm going from memory here but each Ultra 320 SCSI HDD had a
| startup current of almost 2 Amps so if you had a disk shelf
| with 24 drives and stack a few shelves in each rack you could
| do some serious power damage if you didn't plan the startup
| sequence right.
| unregistereddev wrote:
| On a per-machine basis, many server motherboards have out-of-
| the-box BIOS support for this feature. At least they used to.
| It's been a long time since I've built a server and
| mechanical hard drives are less common than they used to be.
| h2odragon wrote:
| I had a home hacked 1TB+ server, using 5.25in 23GB 8lb
| monster drives salvaged from a long life as a TV video bank
| (long, long ago, when dinosaurs walked the earth). There was
| 60+ actual spindles as i recall.
|
| The drive array was powered by 6x, 400W ATX server supplies
| with my own wiring harness. This was enough to keep them
| running but they had to be sequenced carefully to keep from
| overdrawing the power supplies.
|
| This was all on an UltraSPARC 6k so there was plenty of
| support for that; bringing up the system always sounded like
| multiple jet takeoffs tho. Took 15min. When the rack of 10k
| RPM "quick cache" disks spun up it was like a chorus of the
| whines of the damned.
| forgotusername6 wrote:
| In our office we were so over the rated current for the
| building that after the breaker tripped (which it inevitably
| did) it wasn't possible to just switch it back on. The moment
| you did all the servers and PCs went back on and it tripped
| again. You'd have to go around and pull out plugs all over the
| office then switch the breaker, then switch them all back on
| one by one. We also had regular electrical fires. Those were
| the good old days.
| rootusrootus wrote:
| Having enough inrush current to trip a breaker doesn't seem
| so terrible or entirely unexpected, but electrical fires?
| That's certainly bad news, the breakers are supposed to be
| sufficient to protect the wiring.
| cesarb wrote:
| > Having enough inrush current to trip a breaker doesn't
| seem so terrible or entirely unexpected
|
| It should still not happen, since breakers are supposed to
| deal with inrush currents. A quick look at a random circuit
| breaker manufacturer page tells me that this particular
| breaker model is meant to instantly trip once the current
| is 3 to 5 times larger than the nominal current; less than
| that, it should take several seconds to trip, giving enough
| time for the inrush current to cease. So either the breaker
| (and the wiring) is underdimensioned, or the device is
| using too much power.
|
| (IIRC, the trick is that most breakers have two independent
| trip mechanisms: a thermal one which has a built-in heat-
| dependent delay, and a magnetic one which is instant.)
| Nextgrid wrote:
| Most server BIOSes have an option for a random delay on power
| loss recovery to prevent this exact scenario.
| KeplerBoy wrote:
| A single black and white laser printer made the lights in my
| dorm room dim for a fraction of a second. So yeah, that thing
| must've pulled quite a few amps.
|
| Also: don't put a laser printer in your bedroom. It's
| unhealthy. Only learned about that after the fact.
| jstarfish wrote:
| > Also: don't put a laser printer in your bedroom. It's
| unhealthy.
|
| 3D printers are even worse, depending on the filament type
| (ABS is worst?). Always ventilate!
|
| A few papers printed over the course of years won't kill you.
| What will are the conditions of working adjacent to the
| office copier, 8-10 hours a day, for years.
|
| Get an air purifier to capture particulates. (Supposedly,
| houseplants help too.)
| KeplerBoy wrote:
| That's why i keep my 3D printer next to my toilet these
| days. The joys of living in a small apartment.
| londons_explore wrote:
| Laser printers use a lot of power for a few seconds when coming
| out of standby.
|
| Part of the printing process involves passing the paper covered
| in toner through a hot roller, to fuse (melt) the powder toner
| (ink) onto the page. That roller has to be up to temperature to
| print. It is normally heated by a powerful (ie. 1 kilowatt)
| light bulb inside a hollow roller. Sometimes if you peek
| through the vents in the printer, you can actually see the
| light it makes.
|
| The light bulb is pulsed on and off to maintain the right
| temperature - but when coming out of standby it is solidly on
| for ~10 seconds. Manufacturers want their printers to warm up
| from standby quickly, so they put very powerful heaters in
| them, even though the steady state heat requirement isn't
| awfully much while printing.
| actionfromafar wrote:
| Id THAT what that light is?! It always bothered in the back
| of my mind. It didn't look very laser-y to me. Especially
| since the laser was supposed to be infrared.
| Animats wrote:
| PJM, the grid operator for the northeastern US, has a "demand
| response fact sheet".[2] There are various ways to buy large
| amounts of power. Big users will have a connection to the pricing
| system, getting better prices during low demand periods, higher
| prices during high demand periods, and shutoffs during very high
| demand periods.
|
| Big power consumers usually pay for power at grid market rates,
| which vary from hour to hour. So they're tied into both the
| market system and the control system. This is done via a
| Curtailment Service Provider.[2] Some of those are power
| distribution companies, and others are just brokers.
|
| Here's one in California.[3] There's a phone app, a web page, a
| connection to your meter, and an API for your own load's control
| system. Large power consumers connect to them, and they connect
| to the grid operator, which is CAISO for California. Once
| everything is connected, they can remotely tell your systems to
| reduce their load and verify that has happened, for which you get
| a price break.
|
| There's the Peak Load Management Association, which you can join
| if you buy power by the gigawatt.[4]
|
| [1] https://pjm.com/-/media/about-pjm/newsroom/fact-
| sheets/deman...
|
| [2] https://www.pjm.com/markets-and-operations/demand-
| response/c...
|
| [3] https://cpowerenergy.com/wp-
| content/uploads/2018/01/CAISO_DR...
|
| [4] https://www.peakload.org/
| mkeeter wrote:
| Relevant story: back in grad school, I did a few experiments in
| the (old) MIT wind tunnel, now torn down.
|
| Before starting up the fans, the guy running the control booth
| picked up the phone and had a short conversation, roughly
|
| "Hi, this is [name] at the wind tunnel; can we turn it on?"
|
| [someone on the other end replies]
|
| "Great, thanks."
|
| I asked who he was calling, and he explained that he had to check
| with the power company before powering it on. This was mid-
| winter, so grid demand was low; apparently during the summer
| (when everyone has ACs on), the start-up load could cause
| brownouts!
| JimtheCoder wrote:
| That must have been one Bad A*S wind tunnel...
| bombcar wrote:
| I was touring a datacenter and they got the reverse call;
| California was experiencing some power issues so the local
| electric company would call them and say "switch to the back up
| gens, we need to cut you off".
| fbdab103 wrote:
| I believe this is a somewhat common arrangement for
| industrial users. The power company gives a discount if you
| agree to be first in line to be cut when reserves are at a
| minimum.
| _whiteCaps_ wrote:
| Another anecdote to share: at my dad's office, while doing a
| disaster recovery exercise, they realized that their startup
| power requirements exceeded what their electrical system could
| supply.
|
| Systems had been slowly added over the years, but because the
| power system is pretty reliable around here, they'd never had to
| start things up from a complete power failure.
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