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Scenario: The character (myself in this case) wakes up to a world where almost all humans disappeared (about 100 left in the US) in February 2022. A go-kart-like vehicle is used instead of having the risk of driving a larger vehicle such as a car without any experience.

As mentioned before, power plants are mainly ran by computers. What would happen to non-automated systems such as stovetops in residential areas if left running? There may be a chance that pressure regulators may fail and allow high-pressure gas to enter low-pressure lines, what would happen then?

edit for clarification: Humans were removed from the planet instantaneously by an unknown force, the character finds out about this after discovering CCTV footage. Because of this, vehicles were strewn everywhere as there was no more control over them.

CTCL
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    Regulators are designed to fail safe. I'm not sure what you're asking here. You want a sort of Mythbusters episode recounting of what happens if you blow up a stove? Please take our [tour] and read-up in the [help] about our ways. Could you then [edit] to tell us your worldbuilding problem to be solved. – Escaped dental patient. Nov 03 '21 at 01:24
  • Please remember that one of the reasons for closing a question is asking more than one question (click the "Close" link and read "Needs More Focus"). You've asked two questions. Please keep that in mind when you ask future questions. Thanks! – JBH Nov 03 '21 at 03:03
  • BTW, your link about power plants simply goes to Stack Overflow. That's an odd place to find a reference to most power plants being run (ostensibly, automatically) by computer. Can you [edit] your post to change the link to the actual question you were referring to? Go to that post in SO, right-click over the "Share" link and copy the link. – JBH Nov 03 '21 at 03:11
  • Sorry, but this question is based on multiple fallacies. Rethink, recheck your assumptions. – PcMan Nov 03 '21 at 03:36
  • Driving a car is no problem if there are no other humans on the roads. – user253751 Nov 03 '21 at 09:40
  • @JoinJBHonCodidact They don't have the closing privilege; As such, they cannot click the close button as there's none :). – Tortliena - inactive Nov 03 '21 at 16:53
  • There are a lot of unknown conditions which make your question hard to answer without setting our own premises. What do you mean by "disappear"? Is it instant and magical in a night, over the span of a few months (a bit like some typical zombie infected world), or many years? In other words, what people could do before they vanish? What's the relationship with the kart and your question (it's confusing regarding your intentions as of now)? – Tortliena - inactive Nov 03 '21 at 17:03
  • @Tortliena Oh, dang. I didn't notice their rep.... – JBH Nov 03 '21 at 23:35

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I agree that the 'supply-side' of electricity generation and gas reticulation is generally fairly fail-safe. Such industries don't require people, poised over switches or dials, ready to turn things down/off if they get too hot etc.

On the other hand, if almost everyone 'disappears' over one night then all those pots of oil left heating on the stove, electric heaters placed too close to clothes racks etc will present a significant risk. So expect a lot of domestic fires - probably enough to set whole neighbourhoods alight.

After your edit that confirms that people disappeared 'instantaneously' I would add that there would be numerous plane crashes. There are approximately 10,000 planes in the air at any one time and they would all come down. It is a little difficult to calculate exactly, as the density of planes in the air varies from place to place as a result of the routes they take and how their auto-pilot works. I presume a lot of them would fly to somewhere near their destination airport and then either crash in the vicinity (if they flew on till they ran out of fuel), or crash on or near the runway if teh auto-pilot is smart enough to land them without assistance (but nopt taxi off the runway).

If the disappearance occurs during a period of busy traffic flows, the cars wouldn't just be strewn about - many of them wouuld collide with eachother and/or surrounding buildings and other road-side objects. So downed power-lines, the ocasional gas-station catching fire, and more local (but possibly spreading) fires from crashes etc.

...And fully laden oil tankers careering round the seas until they hit something and spread their oily load around local shorelines.

Penguino
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  • Yes, in a certain movie where half of Earth's population suddenly disappeared there was one helicopter crash in the background, but no real examination of the greater casualties among the "survivors" due to suddenly absent drivers, pilots, medical staff, and the blocked streets preventing emergency services getting to all the domestic fires etc – KerrAvon2055 Nov 03 '21 at 23:33
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If you want drama, have drama... but in reality, it would just peter out.

Natural gas has a lot of safeguards. Oh, houses might burn down if people were using a gas stove and suddenly disappeared, but that wouldn't cause massive explosions or major catastrophes.

Even in major metropolitan areas, most gas delivery systems use large tanks as baffles between the supply inlet and the users. Large metropolitan areas may have pipes sourcing the tanks. Smaller areas use trucks.

But once the sourcing went away, the clock is maybe a month... at best... before all the liquified gas in the tanks is gone.

No drama. No big booms. Unless an earthquake (or something similar... big, abrupt...) severs a trunk line, it'll just go away due (if for no other reason) to the many legacy water heaters and furnaces still using pilot lights and furnaces still in operation.

One day the gas is working. The next day it won't.

JBH
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Older gas appliances relied on pilot lights. Usually, a person who lived in the home would soon notice that the hot water was cold, or that their stove wouldn't light up... and a quick relight corrected the issue.

However, if there was no one left to notice, then presumably some residences might fill up with with enough NG to be explosion hazards. This would take at minimum days, but possibly weeks/months.

Though there would be no one left to light up a smoke and set this off (and really, if there were, they've asphyxiated from the NG anyway), if electrical power is still on then any number of other appliances might spark/arc and set those off. Boom. These sorts of explosions aren't self-sealing, so a hundred feet away in the alley there's a hissing pipe there.

I can't find statistics for how often this results in fires that could spread. It's neither 0% nor 100% of the time though. The explosion itself can extinguish any fire, but this isn't a sure thing (or even good odds, I would guess). Spreading fires could of course, set off other houses in a distant part of a neighborhood.

The catch here is that many modern gas appliances no longer have pilot lights, but instead use electric ignition. So the risk slowly decreases. Only slowly though since, with the exception of water heaters, the appliances last for decades and so rarely need outright replacement.

Unlike water plumbing, all of these fittings and valves are brass, which won't quickly corrode or fail. Not even on the scale of decades.

John O
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