Pretty interesting comparison. Arguably airplanes can coast down and nuclear reactors (especially Gen-IV low-pressure ones like sodium metal or molten salt) can passively cool their nuclear decay heat post shutdown without external power. But it is true that TMI and Fukushima were not chain reacting, they were both decay heat cooling problems. For those unfamiliar with this, a chain reactor immediately drops to about 7% of full power after shutdown and then exponentially decays to 1% after a day and half a percent after weeks. Turns out 1% of a gigawatt is still a lot.
On the nuclear topic, I'm annoyed that natural gas accidents that cause deaths get way lighter media treatment than nuclear accidents like TMI that cause no deaths.
Just to be pedantic, nuclear plants generate electricity at about 33% efficiency. So to get 1000 MW of electricity, you start with about 3000 MW thermal.
Turns out 1% of three gigawatts is even more. :)
It's definitely a lot. But nothing naturally-circulating sodium metal through 4 redundant NaK-air dump heat exchangers can't handle.
While there are some pure air cooled engines, lawn mowers, motor cycles, etc. A typical car engine is also considered air cooled since it gives off its heat to atmosphere even with assistance of a coolant radiator system.
Most marine engines, some power plants and some industrial equipment is considered liquid cooled since the coolant passes through a fluid to fluid heat exchanger and then that cooling water gets put back into the ocean/river. An example would be some ABB drives come in a LC liquid cooled or AC air cooled package. The motor drive lineups are the same with primary coolant going through all the drive bays the difference is at the end if they put an liquid to air or liquid to liquid heat exchanger.
We just have different definitions then. In car circles your typical car is definitely water cooled. I had never seen your definition but it also makes sense. The typical one is describing what fluid contacts the hot parts and yours is describing what mass the heat is transferred to.
My late 90s era Ducati is considered my most people to be "air cooled", but it has oil galleries that circle around the cylinder walls and an air-oil radiator. (Pedants might call it "oil cooled", but those are mostly the same people who "well actually" you when you call it a V Twin. "Well, actually, it's an _L_ Twin..." - just because it's a 90 degree V Twin rolled forward so the front cylinder is roughly horizontal and the read is mostly vertical...)
(And to further complicate matters, the 900cc two valve "air cooled" Ducati motors have those cylinder cooling oil galleries, but the 750cc motors also have oil coolers, but do not circulate the oil in the cylinder walls. The 600cc motors use the same oil galleries as the 750s, but do not come with the oil cooler...)
The problem the author points out is that you cannot "pause" to think about what information may be correct and which instruments to follow. You have to react immediately, which is much harder than considering the same decisions sitting at a desk reading the NTSB report.
If the low speed indication/alert is correct you need to push the nose forward immediately to keep the aircraft out of a stall, if the high speed indication/alert is correct you need to pull power to flight-idle and nose up carefully but immediately to avoid overspeeding the aircraft and risk structural failure.
I'm not sure how easily a regular airline overspeeds or stalls if the controls are close to a middle position. They should be aerodynamically stable (if loaded correctly).
For a fighter jet it's a different situation.
The report highlighted training, which I guess is always possible to point out, but looking at the event I think they could have made more conclusions regarding how the control system performed counterintuitive by emitting stall warnings at the time they actually did the right thing, and provides little feedback when it drops into alternate law making a standard full pullback into a potentially dangerous move.
Since nuclear power plants are so expensive to build, even just the loss of plant itself is in the billions.
To put it in perspective, the prediction for the number of climate refugees vary, but papers seem to put the number somewhere between 150 and 300 million by 2050.
That's about one Fukushima every five to eleven days, starting from now and continuing until 2050.
Think about it.
 https://orbi.uliege.be//bitstream/2268/136972/1/11-1188-mr7-... (Table 1, page 5) - Disclaimer: this was the first link from Googling "climate refugee prediction".
That's one Fukoshima every day.
Apparently the US felt that hundreds of thousands dead, millions displaced, and democratic governments overthrown was an acceptable price for slightly cheaper oil. I fully expect that calculation to come out the same when climate refugees are considered.
The lengths we'll go to for cheap energy and car culture, right?
Since I can't find it anymore I'll say that my number is very likely wrong and your's is right.
Sadly can't edit my post anymore though.
Reactors are circa gigawatt electrical. Nukes usually have a thermodynamic efficiency around 1/3rd, so a 1GWe reactor will produce 3GWt at the core. That's the heat they have to deal with when uncooled.
Why this annoyance? I'd prefer the media for the most part shut up about energy accidents in general, considering how damaging their outcries have been for nuclear power. A few sober reports are fine. It's probably a minor miracle the natural gas industry hasn't suffered like the nuclear one.
In the mean time, we’ve had Exxon Valdez, Deepwater Horizon, Andover, San Carlos, CA, plus oil trains burning down entire towns, coal mine explosions, two Gulf Wars, and sea level rise due to global warming.
Pick your poison.
The list of accidents is so large that the US has to create separate wikipedia pages for every 25 year span.
Actually it has a separate list page for each year since 2000. And the 25-year lists before ("List of pipeline accidents in the United States (1975–1999)" etc.) are huge lists.
Do you want to put some money Fukushima being fully decomissioned by 2028?
The difference is many tens of thousands of smaller sites affected by fossil fuel pollution and accidents as compared to a couple of large incidents.
For one, they rarely mention the amount of US government subsidies ($hundreds of billions) poured into getting the early plants up and running. For another, the unwillingness of insurers to take an interest in those operations.
When Rocky Flats spilled a little Pu dust into the Denver suburbs, they just raised the 'safe' exposure by a factor of 10. Easy peasy.
Do you have numbers for this comparison?
"When Open Loop Detection is enabled L.dE, the controller will look for the power output to be at 100%. Once there, the control will then begin to monitor the Open Loop Detect Deviation L.dd as it relates to the value entered for the Open Loop Detect Time L.dt. If the specified time period expires and the deviation does not occur, an Open Loop Error will be triggered. Once the Open Loop Error condition exists the control mode will go off and an Open Loop message will be display. If the process value goes in the opposite direction, a Reversed Loop message is display. The sensor is likely wired in reverse polarity."
If this crew was replacing an old cast iron gas main, it probably predated such controllers. That's not necessarily a bad thing. A mechanical controller can work for many decades. It's hard to get that level of uptime from microprocessors.
The real problem here is "maintenance induced failure". Especially on a system which is not fully shut down.
The videos are well produced and, apart from those accidents that involve injury or death, they are quite entertaining if you happen to be in a forensic frame of mind.
Here’s an example of one of their videos: https://youtu.be/_icf-5uoZbc
The report will be thorough, but we may not get a great video out of it :(
It also allows the market to decide what risks justify the cost and which ones don't via the insurance market. These advisories are front and center in lawsuits when dealing with repeat occurrences so the pressure comes from economic forces. Thankfully, there are limitations to what the market is allowed to decide so this may eventually become a regulation through public pressure or agency review.
Is any of your work available to read online?
Seriously, this sounds like a very interesting subject. Best of luck with your thesis writing and submission (mine's still a couple of years away).
> The cause of the accident was not a leak or an equipment failure or a design flaw or a worker turning the wrong valve. The pressure didn’t just creep up beyond safe limits while no one was paying attention; the pressure was driven up by the automatic control system meant to keep it in bounds. The pressure regulators were "trying" to do the right thing. Sensor readings told them the pressure was falling, and so the controllers took corrective action to keep the gas flowing to customers. But the feedback loop the regulators relied on was not in fact a loop. They were measuring pressure in one pipe and pumping gas into another.
The author is not alone. Over a decade ago, there was a theater piece called "Charlie Victor Romeo" that consisted solely of actors re-enacting cockpit voice recordings of aircraft that crashed. http://charlievictorromeo.com/
As for your bad actor: what would he pressurize your lines with? An air compressor? He'd have to dig up the lines or disconnect them first and gas from the line would likely escape in quantities large enough to discourage such tricks.
Just like in theory you could disconnect the mains from a house and then send a high voltage pulse down the feed lines, in practice pranksters and miscreants tend to avoid doing stuff that might get them killed instead.
On the gas meter on my house anyway, the underground pipe mates at a valve. It doesn't seem hard or particularly dangerous to shut that valve off, disconnect the meter, connect whatever, then open the valve again.
Anyway, if you want to destroy someone's house there are much quicker, less obvious and easier ways to do so.
The real determining factor is not age but whether the installer was lazy and hand tightened it all (which you can get away with at 1/2psi, but not much more).
Yeah, natural gas tech is old and over time has been worked into a multi-layer system that is close to "inherently safe". I remember years ago trying to light an old heater the most stupid way possible and only singeing my eyebrows in the resulting explosion.
But these events just show that if a company skimps enough on needed maintenance, ignoring constant smaller leaks and the similar despicable maneuvers done by this gas company, then the overall potential of piping an explosive gas into a city can be realized and people die and are injured, building are destroyed and so-forth.
In this context, it seems pretty obvious this isn't a "technological tragedy" but a "people doing bad things tragedy" and I hope it's obvious people deserve to go to jail for this and if they don't then other problematic aspect of this society are then to blame.
I think our political process has completely lost touch with science and pragmatism.
Essentially, it follows the logic that the only way to keep corporations from devastating the environment is giving them some positive market incentive to not do so. But of course, given zero regulations or morality, there's always going to be an economic incentive to toss some poisons in lakes and some pollutants in the atmosphere - because some things just aren't useful and if you have zero-cost disposal, that the (amoral) path of least resistance.
I'd go the opposite rout. Polluting in whatever form should be illegal. Polluters should be fined or go to jail, whatever is appropriate. "I could make money with my stuff so I tossed it/burned it/whatever" should never an acceptable explanation or excuse.
Billions of cubic feet of gas is not a reasonable disposal problem - there's no place to put it, that isn't worse than burning it. Except a pipeline, where it would be ultimately burned anyway, but now yielding energy.
Unfortunately, programmers seem often to be isolated from this really complex part of engineering, so this interplay might not be appreciated properly.
Aha, looks like there's a new version (dated 2013).
Why after switching to new pipe nobody checked/could check the pressure in it?
Why there were no other kind of speed sensors on a plane, simpler, less accurate, slower but not that vulnerable to icing?
Why in Three Miles Island incident why people couldn't double check if reactor has water in it or not?
There's a reason some houses went bang and some houses didn't.
I know it's fashionable to blame the megacorp (and it sure looks like they have plenty of blame in this case) but there's plenty of blame to go around here. There's a reason some houses went bang and others didn't. I've worked residential construction in MA and plumbers as a group have a pretty bad reputation (well earned, at least based on my experience, you should see some of the corners these guys will cut). I would wager that the houses that went bang weren't the ones that had their gas pipes done by the apprentice who still does everything by the book but the "seasoned professional" who knows exactly what you can get away with when your work only needs to hold 1/2psi.
Like any large accident there are many dominoes that need to be lined up before they can all be knocked down at once. I think it's foolish to act like some contractor dutifully carrying out Colombia Gas's faulty work order is the only cause of this.
> you should be very suspicious of any conclusion that requires you to assume that all the world’s experts have missed something extremely basic.
It seems to me most likely that the answer is simply that releasing natural gas into the air is an even more dangerous failure mode than overpressure - natgas is not air in a compressor. But regardless I'd bet you dollars to doughnuts that, for one reason or another, blow-off valves are a bad idea in the context.
This is hugely mistaken. If you're an expert in compliance in one field, often your insights are valid in another field.
For example, anybody who has certified a data center knows that Fukushima was both in the wrong location and had wonky power distribution.
Anybody in aviation knows the Tyndall F-22s were in the wrong location after Kermit Weeks' collection was destroyed in Florida in 1990.
Expertise and common sense are always in short supply. It's 2018 - we've collected enough hindsight for the next 100 years.
Use a pilot light to ensure it can always function after the release valve/disc blows.
They have, the problem here was that the relief valves vented way too much gas - they're in the houses of people... and one spark with the right amount of oxygen and stuff goes kabooomm. Gas fires are no joke, gas explosions even less.
A blow-out disk isn't going to fail to operate. My pressure-cooker has one. It's just a piece of material that will catastrophically open the vessel to the atmosphere before massive overpressurization.
Its design hasn't changed since 1977.
It's not a tube that a bean could get into. Maybe you're thinking of the vent pipe? When that gets clogged, the overpressure plug is what blows away to release all the pressure.
Looking into RAPEX, I see multiple recalls for this specific issue (pressure buildup leading to uncontrolled blowout); all for brand names that are unfamiliar to me.
1 depended on the rubber gasket itself as the blowout valve. Several could be opened while under pressure, and some were deemed structurally deficient, which I take to mean that the vessel wasn't (consistently) built to withstand the design pressure (and a margin of safety).
 1 did reach 290kpa (42psi), nearly triple the typical pressure cooker. Not sure what happened on that one.
Next year we may see the first models without a
steering wheel or a brake pedal—there goes the
option of asking the driver (passenger?) to take
You can stop yourself from posting selfies on social media, under your real name. You cannot stop other people from taking pictures, which your acquaintances discover and tag with your real name.
This is kind of horrific. At least as horrific, or moreso than, current traffic statistics, because the moral hazard in play is abysmally worse.
There was an effective arms race that took shape with SUVs and road rage in the late 1990's. I think something similar will take shape, as self driving cars ramp up. It may surprise some, to find that a self driving incident won't be accepted as blameless, glitchy software errors. Owners may see themselves villified directly, for things a car they chose to own, had subsequently carried out.
I think there are three turns of consequence to a botched self driving car deployment.
One: some will choose harm the legal owner as an individual, lawfully or lawlessly.
Two: others will harm dealerships, mostly through sabotage.
Three: overt action against the manufacturers. At all levels, and not limited to ordinary civil disobedience.
These consequences are nothing to be sniffed at. Aviation shows us that spotty disasters don't result in civil unrest, but with a human in the loop survival was incentivized. Automotive deployments like this will be a fire and forget scenario, and the corporations loosing the reigns, have a demostrable history of neglect. I wonder if they anticipate, in the rush to market, just how severely the general public might react to finding their roads on the receiving end of software glitches that kill their firends and relatives like deer?
For cooking, induction, for heating, heat pumps.
You can take my gas stove over my dead body. I'll happily pay whatever it takes for carbon neutral methane to come through my pipes. (Natural gas is mostly methane.)
The flame just makes everything taste better, and methane is pretty easy to produce without fossil fuels.
For installation. For ongoing costs, gas wins by a mile.
Meaning, running an electric oven / stove (edit: with appropriately-matched grid-tied solar panels) costs about the same as running a natural gas oven / stove.
The difference is that my loan never increases in cost, but the cost of natural gas is probably going to go up.
Anyway, I pay about $9-11 a month for natural gas to run my stove and grill. That's much less than the monthly premium to eat organic.
(Water heaters are odd. Where I live, there are no highly efficient gas-fired tank water heaters because no one makes one that meets the NOx rules. You can get highly efficient tankless heaters as well as indirect fired heaters. And you can get heat pump water heaters.)
I know grid electricity is usually about 1/3rd efficient. (Rough numbers.)
(I’ve seen swimming pool heaters with heat pumps that quote a COP of 6 in mild weather. In appropriate climates, you can get a heat pump that pumps heat from your house to your pool, which can be extremely efficient.)
They are definitely better in appealing to first time buyers who may not know or care about their shortcomings. They look great and are easy to clean. But if you are into cooking, gas wins.
With induction, ~90% of the energy from the electricity is used for cooking while only 40% of energy is used using a gas cooktop. Induction is more efficient, and you can use a wok if one is purchased that is designed for use with induction. Induction units can also regulate themselves based on feedback from the cooking device on the receiving end.
Induction is arguably superior to cooking with gas.
> On almost all counts, induction is faster, safer, cleaner, and more efficient than either gas or electric. And yes, we've done exhaustive oven testing in our labs to support that claim.
Yes induction is efficient if you only look at the part inside your house. But most of the losses are outside your house.
If you live in a place with advanced wind or solar power like South Korea then electric probably is more efficient.
It's wasteful to spend money on gas infrastructure when it's clear electrical distribution is the future of home energy use. Infrastructure dollars are already in short supply. Just my two cents.
EDIT: You can stockpile energy with batteries, which is the likely outcome based on how much battery manufacturing capacity is coming online to build hundreds of thousands of EVs a year (which are also a great buffer for renewables and electricity in general).
Maybe for cooking with a wok. But around here most homes are heated with natural gas. And that takes a lot more energy then heating chicken and vegetables.
New natural gas furnaces are up to 97% efficient. They're no longer allowed to sell furnaces that are less than 78% efficient.
To your point, you can purchase very efficient gas furnaces, but they're more expensive and require a retrofit of the flue pipe to PVC due to corrosive properties of high efficiency furnace exhaust (not a concern in new construction).
Air source only heat with a heat pump is a slam dunk anywhere south of the 36°30′ parallel, and all of California.
We can stockpile natural gas, which is mostly methane. And we can figure out how to make methane without fossil fuels.
They're none of that, although they are less flexible than gas.
> They are definitely better in appealing to first time buyers who may not know or care about their shortcomings. They look great and are easy to clean.
They're safe, efficient and convenient for people who want to make food.
> And if you want to use a wok, well, you can't. […] But if you are into cooking, gas wins.
If you're one of the people who believes they need gas to survive, you can buy bottled gas for your range.
I also wonder if the utiliy’s connection between the sensor and controller is on the internet.