How Do Nuclear Submarines Make Oxygen?- Smarter Every Day 251

I just watched the submarine video on making O2. The remains of the candle is called a "clinker" but the sailor didn't know why. I do. In the olden days (when I was a kid) w burned coal for heat in Chicago. Lumps of coal contain metallic impurities and after the coal burns you are left with all these jagged impurities on the grate (support for the coal) in the furnace. Before you add more coal you must "shake the grate" with an external handle which causes the grate grid to rotate part way right and left which opens up the spacing between the grid of the grate to allow the impurities to fall down into the ash pit along with the ashes. Since the impurities are metallic, they make a "clinking sound"when you do this, hence they are called "clinkers."

United States I discovered your breaking the sound barrier and I loved it. It wasn't just one of those other video," hey look at me, ain't I cool" types but really interesting science information. I've been a pilot for 50 years and I forward that link to all my pilot friends including a guy who flew F-16s for 20 years! "Dead accurate" he said. Keep up the good work.

I watch your videos on YouTube even though I’m a patron. Which way of viewing benefits you most?

I learned about electrolysis 12 years ago, a little dish soap and a grill lighter is a lot of fun. 😁 lighting the bubbles gives a nice little “POP”

That's awesome!

Smarter Every Day

She's a good girl!

Smarter Every Day

I can't get enough of this stuff! Thanks Destin.

As for splitting CO2 back into O2, for space flight, scrubbing is definitely the easiest way to go in terms of mass. Storing enough O2 for sustaining a small number of lives is relatively easy to do. When you have a submarine and mass becomes less of an issue, you can start looking at heavier equipment. The primary methods discussed in Destin's video require very heavy equipment, but very little reagent mass to sustain them - some KOH which is a catalyst (ie not consumed in great amounts) and top up amine (which is a closed cycle, but there is some amine loss due to thermal degradation during the regeneration). The candles and LiOH are your backup if something goes wrong.

James French

High O2 levels are also bad for us, because oxygen is actually fairly nasty stuff and likes to oxidise everything, even tissue. 100% O2 is ok for short term exposure, but is toxic on a timeframe of hours. The early space programs were conducted in 100% Oxygen, but at low absolute pressure such that the partial pressure of oxygen was still fairly close to 0.21 atm. For space flight and other confined atmospheres the immediate risk is rising CO2 concentration. Carbon dioxide becomes toxic at surprisingly low levels, Apollo 13 had more than enough oxygen for the entire return flight. If the crew had not put together the scrubbing solution they would've died from CO2 poisoning long before O2 ever became an issue. Incidentally, humans can breath a CO2 free atmosphere (and keep breathing) because our bodies are always generating some CO2 and blood CO2 never goes to zero.

James French

So the thing that regulates our (and most mammals, except seals) breathing is blood CO2 concentration. Our bodies don't really detect Oxygen levels at all (despite it being the actually important gas). Low O2 levels will lead to hypoxia, which Destin has a video on. It's extremely dangerous because you don't notice it happening. The real risk is when the partial pressure of O2 goes low enough - either because you're in a low oxygen atmosphere or at altitude the absolute pressure is low. In that situation the normal osmosis of oxygen into the blood stream starts happening backwards and your blood starts giving O2 back.

James French

Destin, I’m an active U.S. submariner. I’d appreciate it if I could get your email address. I’m not sure if there is DM on here but you have already sent me a baseball so I assume you have my email. Thanks, Logan

I'm guessing the other gasses, like nitrogen, aren't largely used in our breathing process, that the amount stays pretty constant and it's just the O2 / CO2 that needs regulation. I'd love to hear from someone knowledgeable on it though.

Steve Jones

I am with you. I feel like I am missing something. If we were to refer to space again, throwing away CO2 and creating oxygen does seem wasteful. I am also confused as to where, whether in space or on a submarine, the other elements of air (primarily nitrogen) are regulated. In this video, clearly the sailors on board the submarine can’t breathe 100% O2; they need to breathe a safe combination of air, nitrogen, argon, et al. Just burning for O2 does not include these gases. How are these gasses regulated or reintroduced? Are they just present and never expelled from the submarine?

OriginalGumshoe

Thank him for his service for me.. It takes a special kind of person to do that job - I wouldn't last a day in a sub!!

Steve Jones

Makes me very glad that the only time I ever experimented with electrolysis I was using well water, so there was no CL to kill me! :-)

Steve Jones

I wonder if that's part of the "spraying" process - It could be that it is still at high pressure behind the sprayer, and as it sprays, it gets colder because of the lower pressure, which activates the tendency to accumulate CO2... just a guess - I really dont know..

Steve Jones

This video was great - I hadn't heard of an oxidation reaction that actually creates more O2 than it uses to burn - That is really cool. I do have a question though.. I have always assumed that the CO2 scrubbers were separating the carbon and recirculating the O2 back into the atmosphere, but in this case it sounds like both methods discuss actually take the O2 away as well as the carbon. This makes sense on a sub, where you can just get some more sea water and turn it into O2, but I would think in space flight, that's a serious limitation on the length of flight. You HAVE TO bring enough "candles" to create the O2 for your flight or you'll run out of O2 regardless of the scrubbing. Am I missing something here?

Steve Jones

Wonderful video Destin!

Just showed my coworker. He burst out laughing loving how you introduced your dog but not your significant other.

Barron B

Great video! I did a double take when Dow said where he was from. Apparently he graduated from my small high school (albeit ten years later) which graduates maybe 60-70 people per year

My son is a nuclear technician on a US submarine. I'm glad to know how he keeps breathing down there.

Thanks for including your dog in the video 😍 but the rest of the video was also great and interesting as always 😉

Alexander Scheeben

I'm with you through it all. I know what it's like supporting a family. I use a good bit of your older material for science and engineering examples for the kids to help bolster their curiosity and help show the visual of the concept. Maybe lean back on some of that for a series of basic engineering or science facts for those of us doing school at home with family.

Unfortunately you probably need somewhat regular material rewards (like the baseball) to keep patron numbers up.

Zach Wiggin

I'm guessing that since they had to store them before use, they just put them back where they were stored post-use and then keep them there until the next resupply can take them off their hands.

Michael Lang

Phenomenal series on subs, so cool. All your videos are. Hopefully with the NASA stuff one of these days you can go up to the international space station and go through and film like the sub series 😎. Even space walk 🇺🇸.

David Vinson

I've enjoyed this series so much more than I ever thought I would. Thanks for continuing to create such phenomenally interesting content, Destin! Quick question about this video - what happens to the burnt/used candles?

Still amazes me how much the Navy is willing to let you record! I would have assumed most of the goings on on a nuke would be, at the very least, confidential. So cool. Looking forward to more!

LouisTheLaddah14th

We still use CO/H2 burners!

Ryan Moody

Fantastic video yet again Destin. I was so interested in the video that I didn’t realize it was 30 minutes long till I finished it. I’m a bit sad this series is coming to an end. By far one of the best YouTube channels that exists. Hope you don’t mind, I’m going to start using the saying “this is how the sausage gets made”.

Destin, great video. Back in the '60s and '70s, we had hydrogen/carbon monoxide burners to convert those gases to water vapor and carbon dioxide. Then the scrubbers removed the CO2 and pumped it overboard. Used the same nitrogen for the whole deployment, 75 days or more. At the end of a deployment, we surfaced at the 100-fathom curve, opened the bridge hatch, and the outside air would rush into the boat. The odor was terrible compared to air inside the boat. But it meant we were close to home!

Great job again!

This was fascinating to watch! Ever since as a child seeing a Moody Science Video VHS that featured an electrolysis apparatus, I've wanted to make my own. Unfortunately I personally experienced the fact that attempting to electrolyze salt water creates chlorine gas when I was around 7...

Aidan Boyer

It likely needs to be air-tight... you might be able to seal it after printing and make it work (lots of info available, google it)

Jonathan Murray

Regarding the "preheat" you didn't understand: fella said it's a heat exchanger. I'm speculating here but I figure that after you boil the amine you want to cool it back down in order for it to be able to absorb CO2 again. Probably they use the already boiled, lean amine to heat up the incoming rich amine, which also cools off the lean amine for use again. Conserves energy, reducing the amount it takes to do the whole operation.

This was awesome! I've been going down this rabbit hole for a while learning about life in harsh environments like underwater, underground, and in space. This whole series has been incredible for that. I was watching everything I could about the aquarius reef base and you started making these right after I ran out of resources for that. When learning about oxygen production I realized I have a brother who works in a coal mine and he says they have "scsr's" (a sort of oxygen candle) on their person at all times and caches of them everywhere throughout the mine. It's fascinating stuff!

Thanks again! Good stuff :)

Thanks again for another great video! I love that you mention the analogs to space fight. Each video shows me more and more how these submarines are just spacecraft for under the ocean! Much of this same technology is used on ISS. You continue to remind me how much easier it would be to have a nuclear reactor on station and not needing to deal with the (sometimes) moody solar arrays and batteries.

Nitrogen usually is used in these systems to provide “back pressure” and maintain 14.6 psi or whatever their target is. Since it is inert, I expect they would not need to remove N2, but only add it as spec leakage causes losses. They definitely didn’t go over it in the video but most atmosphere systems will remove other constituents as well through some kind of mass spectrometer filter.

Another great video, Destin! It's a shame with Covid and everything, or I'd be trying to get you a ride on an SSBN so we could do a "crossover" submarine/missile SED! (Fun fact: Tory Bruno, from your ULA videos, used to do some work for the Strategic Systems Programs side of the Navy.) I'll keep my fingers crossed that you'll one day be able to do a submarine-launched ballistic missile video!

Ryan Moody

Where ventilation ducting goes through a watertight bulkhead there is also an associated isolation valve. You're right, unlike all of the "landlubber" HVAC systems, these valves need to have the strength to seal a pressurized environment and can't be just aluminum flappers. In fact, shutting bulkhead ventilation isolations are one of the first things the crew does in response to a casualty (fire, flooding, etc.).

Ryan Moody

Destin, in WY (and elsewhere) where underground burning coal beds bake the surrounding clay beds, the resultant hard baked "ceramics" are called "clinkers" and "clinker beds". It plays havoc with trying to run seismic for oil exploration.

Rick Corbitt

Destin, I am a former sub guy. If you want fee free to email me with questions, or any clarifications. Saltydawgsailing@gmail.com

Awww, yay for the puppers! I've heard the term clinker describing some of the slag in producing iron, as well as referring to burned coal in blacksmithing. I'd be willing to be that is where they got the term clinker for the burned candle remains.

Clifton Ballad

Man, this was my favorite one yet. If someone had told me they made oxygen by burning things, I'd be sure they were pulling my leg. 😆

Awesome video, Destin! Greetings from Chile.

Awesome video! I got smarter today. You only really covered Oxygen and Carbon Dioxide. Do they do anything to ensure the other gasses in the atmosphere stay normal or does it just happen on its own. Nitrogen, for example.

Great video! At the beginning of the video you discuss the importance of ventilation, but I immediately wondered how the heck they make a HVAC system for a sub where they (I assume) want to be able to make every compartment water tight in case of damage or leaks? Maybe it's just a matter of having water tight hatches that can close off the air vents?

Another fascinating installment of this series, it's incredible how we've adapted to our world and made our fragile human bodies go places they should never be going. That's a cute dog you've got there too.

Awesome! Thanks for the STL. Definitely going to print it. Greetings from Poland!

1am in Australia, cant wait to find time tomorrow to watch this. So many questions to be answered.😁

Russell Harris