15 ms·

How to ramp up a factory consuming a lot of energy?

162 points by joebiden2 3y ago

ck2 3y ago
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 3y ago
  > 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.
  - joshfederer 3y ago
    I believe that books continue to hold immense importance in the realm of internet knowledge. While the internet offers a vast array of information, books provide depth, rigor, and expert insights that are often lacking online. They are the repositories of specialized knowledge, offering in-depth exploration of complex subjects. Books provide a tangible, reliable, and authoritative source that withstands the transient nature of the internet. They remain invaluable resources, ensuring a comprehensive understanding of subjects beyond what can be found online.In addition to the significance of books, it is important to acknowledge the value of the internet in knowledge acquisition. The internet provides unparalleled access to a vast amount of information from diverse sources. It enables rapid dissemination of knowledge, facilitates global collaboration, and offers interactive platforms for learning. The internet also offers convenience, allowing individuals to access information anytime, anywhere. Its dynamic nature allows for the dissemination of up-to-date research findings and fosters the exchange of ideas across disciplines. The internet complements books by expanding the accessibility and availability of knowledge in an unprecedented manner.
  - m0n4rch 3y ago
    youtube covers it all :D
  - ramesh31 3y ago
    >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 3y ago
      I wonder if that stuff is available on places like libgen. If it isn't, I really hope someone digitizes it.
      - dredmorbius 3y ago
        Many large academic libraries have extensive digitisation efforts, though the results more often turn up on Hathi Trust (something of a waste of electrons in my view) than anywhere truly useful. Hathi Trust itself grew out of Google's book-scanning initiative, and is shaped (and scarred) by copyright lawsuits. That said, I hope some number of those works also find their way to Libgen and ZLibrary.
  - JimtheCoder 3y ago
    "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...
  - ck2 3y ago
    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 3y ago
      "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 3y ago
        Too late, we already have SciHub.
        JimtheCoder 3y ago
        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 3y ago
        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.
  - TeMPOraL 3y ago
    > 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.
  - ilyt 3y ago
    > 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 https://www.youtube.com/watch?v=3fP0LZMEV5w
  - oivey 3y ago
    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.
  - TillE 3y ago
    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.
- shadowgovt 3y ago
  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.
  - calvinmorrison 3y ago
    That book, well the most enjoyable parts for me of the 1000 pages or so besides the intro (king is great at starting plots) was the whole power station business. Otherwise 900 pages of fumbling with a plot. I should go reread it
- asdfman123 3y ago
  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 3y ago
  And we still have people that think that the earth is flat. Kind of depressing.
- cfn 3y ago
  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) https://pt.wikipedia.org/wiki/Museu_da_Eletricidade_(Lisboa)
shadowgovt 3y ago
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?
- csours 3y ago
  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 3y ago
    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.")
    - generalizations 3y ago
      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 3y ago
        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.
csours 3y ago
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 3y ago
  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.
  - sanxiyn 3y ago
    As a concrete example, if you look at an electric grid map of South Korea (here is one: https://www.e2news.com/news/articleView.html?idxno=236289 https://www.e2news.com/news/articleView.html?idxno=236289), you will find that POSCO, Hyundai Steel, and Samsung Electronics have their own substations.
icyfox 3y ago
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 Manapōuri 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 https://en.wikipedia.org/wiki/Manapouri_Power_Station
- madaxe_again 3y ago
  This is why you’ll often find bauxite smelters next to mountains - this is a common solution for the vast amounts of energy required.
- sidewndr46 3y ago
  Discharging >40% of the freshwater usage in a country to the open ocean is not a 'small' anecdote.
  - Vvector 3y ago
    Instead of discharging into the ocean, could it be used for drinking water?
    - sidewndr46 3y ago
      That was proposed but rejected by the government.
      - rootusrootus 3y ago
        It looks to be a fairly long ways from major cities, is that why?
mkeeter 3y ago
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 3y ago
  That must have been one Bad A*S wind tunnel...
  - dtgriscom 3y ago
    I took a tour of it once, where they started it on low (<= 20MPH) with us inside it. Very cool, and it was fun to imagine it running full bore.
  - ThePowerOfFuet 3y ago
    Either swear or don't, but your comment looks strange in its current form.
- bombcar 3y ago
  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 3y ago
    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.
ilyt 3y ago
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
- Someone 3y ago
  More info at https://en.wikipedia.org/wiki/Droop_speed_control https://en.wikipedia.org/wiki/Droop_speed_control
- isoprophlex 3y ago
  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 ;)
  - HPsquared 3y ago
    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 3y ago
      > 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.
      - isoprophlex 3y ago
        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-clocks-lose-six-minutes-dispute-power-electricity-grid https://www.theguardian.com/world/2018/mar/08/european-clock...
_whiteCaps_ 3y ago
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.
- Glawen 3y ago
  that's a common issue in high power applications, be it in a factory or a train. You need to add special breaker which allow a long current peak and switch on loads in a sequence
schlowmo 3y ago
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.
- londons_explore 3y ago
  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 3y ago
    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.
  - dtgriscom 3y ago
    This is why you never put a laserprinter on a UPS.
thedougd 3y ago
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_Plant 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."
- Hextinium 3y ago
  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.
  - syedkarim 3y ago
    I assume this is for smelting bauxite. Is that correct? Do you have similar numbers for recycling aluminum?
    - jjk166 3y ago
      100% of that energy cost is the electrolysis, recycling has no comparable step. There are additional energy costs for processing the aluminum into useful items on top of this that are roughly the same for primary and recycled aluminum. Overall, recycled aluminum requires only about 5% of the energy that primary aluminum requires.
  - jaggederest 3y ago
    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
baybal2 3y ago
In the past, it was solved this way. A heavy contactor powers on stage 1, stage 1 powers another heavy contactor powering stage 2, stage 2 does the same with stage 3. When mains voltage is too low, the contactor cannot close. This way this allows for tens of milliseconds of separation in between power ons.
Animats 3y ago
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/demand-response-fact-sheet.ashx https://pjm.com/-/media/about-pjm/newsroom/fact-sheets/deman... [2] https://www.pjm.com/markets-and-operations/demand-response/csps.aspx https://www.pjm.com/markets-and-operations/demand-response/c... [3] https://cpowerenergy.com/wp-content/uploads/2018/01/CAISO_DRAM_Full-Download_6.pdf https://cpowerenergy.com/wp-content/uploads/2018/01/CAISO_DR... [4] https://www.peakload.org/ https://www.peakload.org/
ipcress_file 3y ago
I operated the dryers at a coal mine in the 1980s. We had to start the exhaust fans with the dampers closed and then slowly open them, or we'd take out the power for all of Northeastern British Columbia. I know because I knocked the power out by mistake one night. I suspect that high-drawing factories must employ similar strategies to slowly increase the draw.
- Mattwmaster58 3y ago
  I would assume dampers would restrict flow, and I thought motors draw most when stalled. How does this work?
  - andromaton 3y ago
    It's the opposite, contrary to untrained intuition.
kimberly32 3y ago
[dead]
idontwantthis 3y ago
> Each 775-ton flywheel can spin up to 225 rpm and store 3.75 GJ,[47] roughly the same amount of kinetic energy as a train weighing 5,000 tons traveling at 140 kilometres per hour (87 mph). Each flywheel uses 8.8 MW to spin up and can generate 400 MW (briefly) Does that mean that the 775 ton flywheels could come to a complete stop in less than 13 seconds if fully used up?

162 points by joebiden2 3y ago

ck2 3y ago

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 3y ago
> 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.
- joshfederer 3y ago
  I believe that books continue to hold immense importance in the realm of internet knowledge. While the internet offers a vast array of information, books provide depth, rigor, and expert insights that are often lacking online. They are the repositories of specialized knowledge, offering in-depth exploration of complex subjects. Books provide a tangible, reliable, and authoritative source that withstands the transient nature of the internet. They remain invaluable resources, ensuring a comprehensive understanding of subjects beyond what can be found online.In addition to the significance of books, it is important to acknowledge the value of the internet in knowledge acquisition. The internet provides unparalleled access to a vast amount of information from diverse sources. It enables rapid dissemination of knowledge, facilitates global collaboration, and offers interactive platforms for learning. The internet also offers convenience, allowing individuals to access information anytime, anywhere. Its dynamic nature allows for the dissemination of up-to-date research findings and fosters the exchange of ideas across disciplines. The internet complements books by expanding the accessibility and availability of knowledge in an unprecedented manner.
- m0n4rch 3y ago
  youtube covers it all :D
- ramesh31 3y ago
  >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 3y ago
    I wonder if that stuff is available on places like libgen. If it isn't, I really hope someone digitizes it.
    - dredmorbius 3y ago
      Many large academic libraries have extensive digitisation efforts, though the results more often turn up on Hathi Trust (something of a waste of electrons in my view) than anywhere truly useful. Hathi Trust itself grew out of Google's book-scanning initiative, and is shaped (and scarred) by copyright lawsuits. That said, I hope some number of those works also find their way to Libgen and ZLibrary.
- JimtheCoder 3y ago
  "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...
- ck2 3y ago
  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 3y ago
    "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 3y ago
      Too late, we already have SciHub.
      - JimtheCoder 3y ago
        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 3y ago
        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.
- TeMPOraL 3y ago
  > 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.
- ilyt 3y ago
  > 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 https://www.youtube.com/watch?v=3fP0LZMEV5w
- oivey 3y ago
  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.
- TillE 3y ago
  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.
shadowgovt 3y ago
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.
- calvinmorrison 3y ago
  That book, well the most enjoyable parts for me of the 1000 pages or so besides the intro (king is great at starting plots) was the whole power station business. Otherwise 900 pages of fumbling with a plot. I should go reread it
asdfman123 3y ago
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 3y ago
And we still have people that think that the earth is flat. Kind of depressing.
cfn 3y ago
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) https://pt.wikipedia.org/wiki/Museu_da_Eletricidade_(Lisboa)

shadowgovt 3y ago

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?

csours 3y ago
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 3y ago
  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.")
  - generalizations 3y ago
    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 3y ago
      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.

csours 3y ago

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 3y ago
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.
- sanxiyn 3y ago
  As a concrete example, if you look at an electric grid map of South Korea (here is one: https://www.e2news.com/news/articleView.html?idxno=236289 https://www.e2news.com/news/articleView.html?idxno=236289), you will find that POSCO, Hyundai Steel, and Samsung Electronics have their own substations.

icyfox 3y ago

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 Manapōuri 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 https://en.wikipedia.org/wiki/Manapouri_Power_Station

madaxe_again 3y ago
This is why you’ll often find bauxite smelters next to mountains - this is a common solution for the vast amounts of energy required.
sidewndr46 3y ago
Discharging >40% of the freshwater usage in a country to the open ocean is not a 'small' anecdote.
- Vvector 3y ago
  Instead of discharging into the ocean, could it be used for drinking water?
  - sidewndr46 3y ago
    That was proposed but rejected by the government.
    - rootusrootus 3y ago
      It looks to be a fairly long ways from major cities, is that why?

mkeeter 3y ago

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 3y ago
That must have been one Bad A*S wind tunnel...
- dtgriscom 3y ago
  I took a tour of it once, where they started it on low (<= 20MPH) with us inside it. Very cool, and it was fun to imagine it running full bore.
- ThePowerOfFuet 3y ago
  Either swear or don't, but your comment looks strange in its current form.
bombcar 3y ago
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 3y ago
  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.

ilyt 3y ago

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

Someone 3y ago
More info at https://en.wikipedia.org/wiki/Droop_speed_control https://en.wikipedia.org/wiki/Droop_speed_control
isoprophlex 3y ago
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 ;)
- HPsquared 3y ago
  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 3y ago
    > 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.
    - isoprophlex 3y ago
      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-clocks-lose-six-minutes-dispute-power-electricity-grid https://www.theguardian.com/world/2018/mar/08/european-clock...

_whiteCaps_ 3y ago

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.

Glawen 3y ago
that's a common issue in high power applications, be it in a factory or a train. You need to add special breaker which allow a long current peak and switch on loads in a sequence

schlowmo 3y ago

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.

londons_explore 3y ago
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 3y ago
  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.
- dtgriscom 3y ago
  This is why you never put a laserprinter on a UPS.

thedougd 3y ago

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_Plant 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."

Hextinium 3y ago
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.
- syedkarim 3y ago
  I assume this is for smelting bauxite. Is that correct? Do you have similar numbers for recycling aluminum?
  - jjk166 3y ago
    100% of that energy cost is the electrolysis, recycling has no comparable step. There are additional energy costs for processing the aluminum into useful items on top of this that are roughly the same for primary and recycled aluminum. Overall, recycled aluminum requires only about 5% of the energy that primary aluminum requires.
- jaggederest 3y ago
  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

baybal2 3y ago

In the past, it was solved this way. A heavy contactor powers on stage 1, stage 1 powers another heavy contactor powering stage 2, stage 2 does the same with stage 3. When mains voltage is too low, the contactor cannot close. This way this allows for tens of milliseconds of separation in between power ons.

Animats 3y ago

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/demand-response-fact-sheet.ashx https://pjm.com/-/media/about-pjm/newsroom/fact-sheets/deman... [2] https://www.pjm.com/markets-and-operations/demand-response/csps.aspx https://www.pjm.com/markets-and-operations/demand-response/c... [3] https://cpowerenergy.com/wp-content/uploads/2018/01/CAISO_DRAM_Full-Download_6.pdf https://cpowerenergy.com/wp-content/uploads/2018/01/CAISO_DR... [4] https://www.peakload.org/ https://www.peakload.org/

ipcress_file 3y ago

I operated the dryers at a coal mine in the 1980s. We had to start the exhaust fans with the dampers closed and then slowly open them, or we'd take out the power for all of Northeastern British Columbia. I know because I knocked the power out by mistake one night. I suspect that high-drawing factories must employ similar strategies to slowly increase the draw.

Mattwmaster58 3y ago
I would assume dampers would restrict flow, and I thought motors draw most when stalled. How does this work?
- andromaton 3y ago
  It's the opposite, contrary to untrained intuition.

kimberly32 3y ago

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idontwantthis 3y ago

> Each 775-ton flywheel can spin up to 225 rpm and store 3.75 GJ,[47] roughly the same amount of kinetic energy as a train weighing 5,000 tons traveling at 140 kilometres per hour (87 mph). Each flywheel uses 8.8 MW to spin up and can generate 400 MW (briefly) Does that mean that the 775 ton flywheels could come to a complete stop in less than 13 seconds if fully used up?