How Long Would The Lights Stay On?

[zev_steinhardt]

Just a hypothetical question:

I live in New York City. Suppose I were to wake up one morning and find that I was the only person in the city. All the infrastructure is still in place -- there are just no people anywhere except for me. Assuming that I did not interfere with the electrical equipment and no one else came to the city to fix things, how long would the lights stay on?

And, just out of curiosity, how long could I expect to have running water/toilets/showers, etc.?

Zev Steinhardt

[Shagnasty]

I don't know the answer but we have talked about this before a few times over the years. IIRC, the answer was just hours to days for major utilities. They all require some degree of manual intervention and they are are somewhat inter-dependent. For example, a total electrical failure will cause havoc with other services in short order.

[Si Amigo]

Not sure about NYC, but I did see a special the other week about this very scenario. They claimed that Hoover Dam would be capable of keeping the Vegas strip lite up for several years. At least until the dynos coolings lines clogged up and it went into an automated shutdown mode.

[VernWinterbottom]

I saw that Life Without People show, too. The Hoover Dam would keep running for years, but its power source is naturally flowing water. The time for more conventional power was far shorter, but I don't remember how long. Only days, I think.

[RickJay]

Originally Posted by VernWinterbottom

I saw that Life Without People show, too. The Hoover Dam would keep running for years, but its power source is naturally flowing water. The time for more conventional power was far shorter, but I don't remember how long. Only days, I think.

I've been to the Hoover Dam, and other hydroelectric facilities, and there is just no conceivable way the power would flow for years, absolutely not a chance in hell. A LOT of labour goes in to keeping those plants running. The turbines cannot run for years without constant maintenance; they're perpetually being brought down to have parts replaced. Even if the turbines continue to run, which they wouldn't, that also does not mean that the power will continue to be delivered from the dam to Las Vegas (or any other city that gets power from Hoover.) The electrical transfer stations also require a lot of intervention to run properly.

[VernWinterbottom]

Originally Posted by RickJay

I've been to the Hoover Dam, and other hydroelectric facilities, and there is just no conceivable way the power would flow for years, absolutely not a chance in hell. A LOT of labour goes in to keeping those plants running. The turbines cannot run for years without constant maintenance; they're perpetually being brought down to have parts replaced. Even if the turbines continue to run, which they wouldn't, that also does not mean that the power will continue to be delivered from the dam to Las Vegas (or any other city that gets power from Hoover.) The electrical transfer stations also require a lot of intervention to run properly.

This wasn't idle speculation. On the show, they went to Hoover Dam and interviewed an engineer and workers there. It was determined that what would stop the dam from providing power was the eventual clogging of the water intake pipes.

I guess they might build a little bit of automatic backup and redundancy in there so that if nobody shows up in the morning the whole thing doesn't go to hell.

Actually getting the electricity to Vegas is another thing, but the people who worked at the dam said that it would be running on its own for a very long time.

[Arjuna34]

I haven't seen Life Without People, but here's one excellent article on how long the lights would stay on:

When the zombies take over, how long till the electricity fails?

[jimmmy]

Wiki on Life Without People

Fossil fuel fired power plants, which are largely automated, would remain running for a few hours until their fuel supplies are depleted. Within hours, lights begin going out all over the world as electrical systems start failing.

Subway systems like the New York City MTA require pumps to keep the groundwater at bay and without humans to turn them on, most subways will be flooded within 36 hours.

After 48 hours, nuclear power plants will enter a safe mode automatically due to reduced power consumption and will not meltdown. Wind turbines will cease operation once their lubrication fails.

I'll back Vern. The program definitely flat out said that Hoover Dam would keep functioning without people & Vegas would keep lit for about 2 years (in the same cite above) & would likely be the last place on earth to lose power. And, the program showing an unseemly and odd emphasis on Hoover Dam, implies the Dam might be the last vestige of our civilization left on earth - lasting ~10,000 years (same cite)

[Cerowyn]

Originally Posted by jimmmy

I'll back Vern. The program definitely flat out said that Hoover Dam would keep functioning without people & Vegas would keep lit for about 2 years (in the same cite above) & would likely be the last place on earth to lose power. And, the program showing an unseemly and odd emphasis on Hoover Dam, implies the Dam might be the last vestige of our civilization left on earth - lasting ~10,000 years (same cite)

Una's Mailbag report, linked above, suggests otherwise:

Originally Posted by Una

My guess is that within 4-6 hours there would be scattered blackouts and brownouts in numerous areas, within 12 hours much of the system would be unstable, and within 24 hours most portions of the United States and Canada, aside from a rare island of service in a rural area near a hydroelectric source, would be without power. Some installations served by wind farms and solar might continue, but they would be very small. By the end of a week, I'd be surprised if more than a few abandoned sites were still supplying power.

Unless Las Vegas is off the grid when the operators disappear, I doubt it would fall into Una's definition of an "island of service in a rural area."

[jimmmy]

Well, I certainly don't have the chops or inclination to say that Una is mistaken overall. Perhaps she was speaking generally or perhaps she didn't check deeply into Hoover-as-exception or perhaps things have changed since the report was written.

Being GQ I can offer that the Life Without People program spoke to the Engineers at Hoover. The guys actually running the place said all this on camera. They said that it is all automated and doesn't require people on a day to day basis to run. What is written in wiki is an accurate reflection of what these guys-who-would-know said: i.e.. What would likely ultimately shut down the power at Hoover was clogged water pipes in about two years. They showed Vegas as one light on on a darkened globe.

[Si Amigo]

I beleive that they focused on Hoover Dam because it's A) HUGE, B) fairly remote from everybody to start with and C) Vegas is a fairly straight shot from Hoover and it's possible that there is only one sub-station between the two. But I too tend to think that there esimate may be a bit to optimistic. Vegas would need to be taken off of the main grid and only supply Vegas itself for there senario to work IMO. Even then Vegas would most likely burn to the ground in an uncontrolled fire before two years was up.

But as for the damn itself and the on going maintance that causes temporary shutdowns, this is what makes it likely to keep on going, a good preventaive maintance schedule. It gets shut down for maintanance not becuase they have too, but because they are continuously upgrading and replacing valves, controls and plumbing.

But as of course, as we know from The Stand Vegas is going to be where all of the evil people flock to serve Satan in the end of days. Satan does likes his bright lights and AC controlled casinos after all.

[jimmmy]

Here is the first 10 minutes of Life after People.

At 3:00 they talk about the OP and the answers here (and Una's answer) all play out as pretty much right.

At 4:40 they talk to Hoover Dam Facilities Manager Mr. Brungia and he first talks about Hoover. That first introduces the idea that Hoover will be able to stay on-line generating power for up to two years without people. There is more detail later in the show. All I can say is that is what these guys say on camera. YMMV.

[Si Amigo]

Thanks for the link. You got to love the History Channel. But is does appear that the engineer was making a best case senario for the plant going on for two years. At first he states weeks, then says months and then possibly years. You really can't blame the guy for dramitizing it up for TV, this was his big break and he got a chance to show the world what he does for a living; working on a very impressive /complicated project. One so impressive and complicated that it will be running two years after we are all dead, damn I'm good.

[Si Amigo]

Looks like the National Geographic Channel has there own show called Aftermath Population Zero that covers the same subject. They stated that even hydroelctric power would be down after less that a day.

[CalMeacham]

This question has been addressed in the past by various folks writing end-of-the-world scenarios. One of the more convincing (and I can't recall which it was) had hydroelectric failing when the lubrication to the various bearings ran out, and things froze in place. The timetable was relatively short -- weeks or months.



As for water, it depends on how the water system was left. If all the faucets were shut off, and you had a good head of pressure, and you were the only one using the water, the pressure would stay until you'd exhausted the local tank. If the automatic refulling system was on, you'd have water until the power failed, and then some. I suspect, though, that depending on your EotW scenario, somebody would leave a pipe open somewhere, and when your power failed that would be it for that particular water supply.

[Spoke]

Originally Posted by jimmmy

After 48 hours, nuclear power plants will enter a safe mode automatically due to reduced power consumption and will not meltdown.

That's interesting. National Geographic Channel's similarly-themed Aftermath: Population Zero (which ran last night) postulated that nuclear plants would eventually have meltdowns (after diesel-powered backup generators failed).

I wonder which is correct.

[Mangetout]

Originally Posted by Si Amigo

Thanks for the link. You got to love the History Channel. But is does appear that the engineer was making a best case senario for the plant going on for two years. At first he states weeks, then says months and then possibly years. You really can't blame the guy for dramitizing it up for TV, this was his big break and he got a chance to show the world what he does for a living; working on a very impressive /complicated project. One so impressive and complicated that it will be running two years after we are all dead, damn I'm good.

Or to put it another way, he got a chance to show the world what he does for a living, and eloquently declared himself more or less redundant.

[robby]

Originally Posted by spoke-

That's interesting. National Geographic Channel's similarly-themed Aftermath: Population Zero (which ran last night) postulated that nuclear plants would eventually have meltdowns (after diesel-powered backup generators failed).

I wonder which is correct.

My wife made the same observation as you after watching the show, which is an easy conclusion to come to for someone not familiar with nuclear power. As a former Navy nuclear operator, I wondered how the show could come to that conclusion. For an operating reactor, you obviously need cooling water. After a reactor automatically shuts down, the residual decay heat would be a concern, but only for a relatively short time. (Decay heat is what led to the Three Mile Island meltdown). Decay heat immediately after reactor shutdown is equal to about 6.5% of the operating power, subsequently decreases to about 1% of operating power within 1 hour of shutdown, then continues to decrease asymptotically over the course of a few days. However, automatic cooling systems should be able to handle the decay heat.

So anyway, I finally watched the show myself last night, and actually, they did NOT say that the nuclear power plants would melt down. Instead, their concern was with the spent fuel in holding pools.

I'm not an expert regarding spent nuclear fuel, but my initial reaction is that the show's concern is greatly overblown. I find it hard to believe that that much residual decay heat would be produced from spent nuclear fuel. After all, the point of the Yucca Mountain storage facility is to encase spent fuel in glass containment with no cooling water at all. It's my understanding that spent fuel repositories do not depend on active cooling (which would require sustained backup power), but instead use passive cooling (such as some type of natural recirculation).

Anyway, the show's repeated emphasis on the supposed aftereffects of spent nuclear fuel somehow resulting in catastrophic meltdowns makes me think that someone involved with the show has an anti-nuclear power agenda.

[chorpler]

In reality, of course, we surviving Boulder City folk would chop the power lines to Vegas and move our civilization to a small cluster around the dam. Then we'd continue to defend the dam from the zombies / starving hordes / cannibalistic armies and fix whatever turbines failed until we could spread civilization to the rest of the world again. (See also Lucifer's Hammer.)

Sadly, we'd have to take out all the Colorado River dams upstream of us to ensure a steady flow of power. Sorry, Lake Powell ... that's just the way it goes.

ETA: On a more serious note, isn't Una's report saying that the plants would go down because when part of the grid fails it forces the plants that are still online to shut down lest they try to supply too much power and overload? So if you could isolate power plants from the grid (like Cerowyn mentioned), they should still be able to produce power as long as things in the plant are running, right?

[Si Amigo]

Originally Posted by chorpler

In reality, of course, we surviving Boulder City folk would chop the power lines to Vegas and move our civilization to a small cluster around the dam. Then we'd continue to defend the dam from the zombies / starving hordes / cannibalistic armies and fix whatever turbines failed until we could spread civilization to the rest of the world again. (See also Lucifer's Hammer.)

First you are going to have to take it away from the Decepticons.

[mwbrooks]

Originally Posted by chorpler

ETA: On a more serious note, isn't Una's report saying that the plants would go down because when part of the grid fails it forces the plants that are still online to shut down lest they try to supply too much power and overload? So if you could isolate power plants from the grid (like Cerowyn mentioned), they should still be able to produce power as long as things in the plant are running, right?

The power grid is a sort of balancing act. There is no significant power storage capability, so power plants have to continuously adjust their output to match the demand.

As I understand it, past regional blackouts have occurred when a plant or transmission line shut down for some reason, causing the load to exceed the remaining plants' capacities, so all those plants shut down to protect themselves. Supposedly steps are taken after each blackout to prevent this kind of thing. There's always another blackout, but maybe the next one isn't as big as it would have been.

Also as I understand it, a plant can't just "disconnect itself" from the grid and keep generating, because it will also be damaged if it continues to operate without a load. So while Hoover dam could conceivably continue operating, someone or something would have to be doing a quickstep to keep its output matched to the remaining load. The smaller the remaining grid, the harder this is. This might be easier with hydroelectric than with other power sources, I don't know.

I've read about steps being taken to put some storage capacity into the national electric grid, but I gather it'll be a long time, if ever, before there's any significant amount.

[Spoke]

Originally Posted by robby

Anyway, the show's repeated emphasis on the supposed aftereffects of spent nuclear fuel somehow resulting in catastrophic meltdowns makes me think that someone involved with the show has an anti-nuclear power agenda.

I kinda got that vibe, too.

They also seemed weirdly obsessed with poisonous gases, given that even if there were a leak of such gases, the effect would be short-term and localized.

[chorpler]

Originally Posted by mwbrooks

Also as I understand it, a plant can't just "disconnect itself" from the grid and keep generating, because it will also be damaged if it continues to operate without a load. So while Hoover dam could conceivably continue operating, someone or something would have to be doing a quickstep to keep its output matched to the remaining load. The smaller the remaining grid, the harder this is. This might be easier with hydroelectric than with other power sources, I don't know.

No problem -- we'll keep a bunch of big ol' resistors in the lake and cycle a new one in when we shut off the microwave.

[tracer]

Originally Posted by zev_steinhardt

I live in New York City. Suppose I were to wake up one morning and find that I was the only person in the city.

You can rest easy in that case. New York City gets plenty of its power from power plants outside the city -- and you didn't say anything about the OTHER cities being deserted!

[mwbrooks]

Post deleted by poster out of sheer embarrassment.

[si_blakely]

Originally Posted by robby

So anyway, I finally watched the show myself last night, and actually, they did NOT say that the nuclear power plants would melt down. Instead, their concern was with the spent fuel in holding pools.

I'm not an expert regarding spent nuclear fuel, but my initial reaction is that the show's concern is greatly overblown. I find it hard to believe that that much residual decay heat would be produced from spent nuclear fuel. After all, the point of the Yucca Mountain storage facility is to encase spent fuel in glass containment with no cooling water at all. It's my understanding that spent fuel repositories do not depend on active cooling (which would require sustained backup power), but instead use passive cooling (such as some type of natural recirculation).

Initially, the spent fuel generates a lot of heat. After most of the shortlived radionucleotides have decayed, the cooling requirements fall off (allowing noncooled longterm storage). And while passive cooling is sufficient at this stage, the water does get hot. And if it evaporates away in the absence of human monitoring, the spent fuel is not longer cooled or moderated, and a disaster is waiting to start.

Of course, there is no-one around to worry about the situation - this is a posthuman world, after all

Si

[robby]

Originally Posted by si_blakely

Initially, the spent fuel generates a lot of heat. After most of the shortlived radionucleotides have decayed, the cooling requirements fall off (allowing noncooled longterm storage). And while passive cooling is sufficient at this stage, the water does get hot. And if it evaporates away in the absence of human monitoring, the spent fuel is not longer cooled or moderated, and a disaster is waiting to start.

Of course, there is no-one around to worry about the situation - this is a posthuman world, after all

Si

Perhaps you could elaborate a bit more on this?

First off, it seems to me that the lack of moderation is a good thing, not a bad thing. After all, the point of moderation is slow down the fast neutrons (which have little tendency to cause subsequent fissions) down to thermal neutrons (that are much more likely to cause a chain reaction).

Secondly, if passive noncooled storage is sufficient for the spent fuel, what difference does it make if the fuel is surrounded by water or not?

[Nuke]

I hate to tell you this, but when the Diesel Generators run out of fuel and there's no offsite power, the cores will melt. Also, the water in the spent fuel pools will eventually boil and evaporate, making even more of a mess. Better to keep some folks around.....

[si_blakely]

Originally Posted by robby

First off, it seems to me that the lack of moderation is a good thing, not a bad thing. After all, the point of moderation is slow down the fast neutrons (which have little tendency to cause subsequent fissions) down to thermal neutrons (that are much more likely to cause a chain reaction).

In the context of a nuclear reactor, you are correct. However, the radioactivity from spent fuel is not fission generated neutrons - it is mostly alpha, beta and gamma radiation from radioactive decay. There may be some slow decay neutrons as well, but the surrounding water will slow them even more. And the spent fuel rods are no longer fissile - they are spent, full of neutron absorbing fission products and a bit of residual Pu and U. If all the spent fuel melted together, it would be a mess and there may be some additional fission, but probably not much. The bigger problem is the whole mass catching fire, because then you have radioactive combustion products spewing into the air.

Originally Posted by robby

Secondly, if passive noncooled storage is sufficient for the spent fuel, what difference does it make if the fuel is surrounded by water or not?

For the same reason cars are mostly water-cooled - water (even just from internal convection) is a better heat transfer medium than air, needed during the initial decay period when the fuel is much hotter thermally than later, when all the 'hot' radioactive material has decayed away and the temp has fallen away. Only then can the spent fuel be processed into passively cooled storage (and by using deep underground storage, they are using the surrounding rock as a massive heatsink). One proposed disposal scheme was to place enough waste in a massive heatproof container, drop it down a shaft in a granite slab, and let the heat melt the rock so that the container just kept on going slowly down through the mantle. Eventually, it would melt, but it would be deep enough not to matter at that point. The risk was that a volcano could force back up the descent tube, adding radioactive lava to the localities problems.

Si

[rocking chair]

did any of the shows mention hydro power that is run off of falls? niagara, for example.

[Una Persson]

Originally Posted by jimmmy

Well, I certainly don't have the chops or inclination to say that Una is mistaken overall. Perhaps she was speaking generally or perhaps she didn't check deeply into Hoover-as-exception or perhaps things have changed since the report was written.

I was speaking of hydro plants in general, but even then I challenge that Hoover could stay running and generating fully unattended for anywhere near 2 years. "Alarms" happen all the time at power plants, even the hydro ones I've worked at, and they very often require a human response to allow the plant to continue running. Unless Hoover is set up with something like sextuple-redundant intelligent systems and such, I just can't see it. Remember that the folks programming the plant systems are not setting them up to run unattended - they're setting them up with the expectation of running reliably, but with human oversight. While I won't speak for Hoover in specific, IME even a worthless BS alarm that actually means nothing can shut down a plant if it's ignored long enough, simply because someone put in the code "if this warning about gate position sensors is still going on after 2 days, and no one's noticed, then something is seriously fucked up, so start shutting that gate."

Hoover probably could be set up to run unattended for months or years (until it lost connection and tripped...), and that may be what they really mean to say, but I would bet that it is not currently set up to do that.

Like mwbrooks says - the whole system is a very delicate balancing act in some places, and it can fall prey to very sudden and unexpected weaknesses - witness the latest blackout in south Florida, cascading from a relatively simple issue at a single point.