[creativeSlumber]

what happens if that large enclosure fails and the CO2 freely flows outside?

That enclosure has a huge volume - area the size of several football fields, and at least 15 stories high. The article says it holds 2k tons of co2, which is ~1,000,000 cubic meters in volume.

CO2 is denser than air will pool closer to the ground, and will suffocate anyone in the area.

See https://en.wikipedia.org/wiki/Lake_Nyos_disaster

Edit: It holds 2k tons, not 20K tons.

[jaggederest]

CO2 is in general less dangerous than inert gases, because we have a hypercapnic response - it's a very reliable way to induce people to leave the area, quite uncomfortable, and is actually one of the ways used to induce a panic attack in experimental settings.

If it were, say, argon, it would be much more likely to suffocate people, because you don't notice hypoxia the way you do hypercapnia. It can pool in basements and kill everyone who enters.

That being said it is an enormous volume of CO2, so the hypercapnic response in this case may not be sufficient if there's nowhere to flee to, as sadly happened in the Lake Nyos disaster you cited.

[Gud]

CO2 is extremely dangerous in high concentrations because the body reacts and switch off the breathing.

[Hnrobert42]

The last section of TFA is called "What happens if the dome is punctured?". The answer: a release of CO2 equal to about 15 transatlantic flights. People have to stand back 70m until it clears.

It would not be good, but it wouldn't be Bhopal. And there are still plenty of factories making pesticides.

[creativeSlumber]

Comparing it to X flights maybe correct from a greenhouse emissions standpoint, but extremely misleading from a safety perspective. A jet emits that co2 spread over tens of thousands of miles. The problem here is it all pooled in one location.

Also that statement of 70 meters seem very off, looking at the size of the building. What leads to suffocation is the inability to remove co2 from your body rather than lack of oxygen, and thus can be life threatening even at 4% concentration. It should impact a much much larger area.

[epgui]

It's a gas in an open space, it diffuses very quickly.

[to11mtm]

Yep. When I had to fill CO2 tanks at a paintball shop yes there were times that I had to open a door (I mean we were talking a lot of fills in short time, btw fills had to start with draining the tank's existing volume so I could zero out the scale) but even indoors a door+fan was enough to keep even the nastiest of sale days OSHA compliant.

Also a 'puncture' is very different from the gasbag mysteriously vanishing from existence; My only other thought is that in cold regions (I saw wisconsin mentioned in the article) CO2 does not diffuse quite as fast and sometimes visibly so...

[ben_w]

https://en.wikipedia.org/wiki/Limnic_eruption

I don't know the safety limits for this quantity, I hope the "70 meters" claim was by someone who modelled it carefully rather than a gut check.

[apparent]

Seems like it would depend if there was a small tear or a massive breach.

[jojobas]

It also deflates pretty slowly. I'd guess any breeze would remove the hazard altogether.

[Animats]

> People have to stand back 70m until it clears.

How did they calculate that evacuation distance? CO2 is heavy. That little house about 15m from the bubble needs to be acquired.

The topography matters. If the installation is in a valley, a dome rip could make air unbreathable, because the CO2 will settle at the bottom. People have been killed by CO2 fire extinguishing systems. It takes a reasonably high concentration, a few percent, but that can happen. They need alarms and handy oxygen masks.

Installations like this probably will be in valleys, because they will be attached to wind farms. The wind turbines go in the high spots and the energy storage goes in the low spots.

[cycomanic]

The distance is likely calculated based on the stored volume and the area you cover until the height is significantly below head height (because as you point out CO2 settles to the bottom). Regarding the little house 15m from the bubble, they are not planning to build this in residential areas, so it's very unlikely that there would be a house within 15m just for operational purposes already.

[Hnrobert42]

Again, from TFA, the install needs 5 hectares of flat land. I thought it was odd when the article mentioned "flat" land, but I assumed it was more about accommodating the bubble. Now I am thinking it is specifically to avoid the valleys you are describing.

[kumarvvr]

Company says safe limit is 70 meters, about 200 feet.

Easy to build infra and other stuff that far away, especially in locations where this is meant to be used.

There are many aspects of safety

1. If the puncture is due to hurricanes, etc, the danger is non existent. The hurricane will blow away the co2 in no time.

2. If the puncture is due to wear and tear, then the leak will be concentrated and localized. It could naturally diffuse.

CO2 meters can be installed around the unit for indication.

Oxygen masks can be placed around the facility for emergency use.

The dangers are very much mitigatable.

[microtherion]

Yeah, I was also immediately thinking about the Lake Nyos disaster. But that one released something like 200k tons of CO2 in an instant, whereas this facility has 2k tons, which would more likely be released more gradually.

[pjc50]

So .. significantly less dangerous than a corresponding volume of natural gas, which is also unbreathable but also flammable/explosive?

[andrewflnr]

Why is that a relevant comparison? Is anyone gathering natural gas in giant balloons near habitations or workplaces?

[evan_]

Yes https://en.wikipedia.org/wiki/Gas_holder

[andrewflnr]

...huh, yeah, I don't love that either. Seems sketchy.

> putting houses around gas holders was discontinued in the UK.

[ben_w]

Phased out during my lifetime. I grew up with them as part of the suburban architecture, e.g. https://www.google.com/maps/place/DUNHAM-BUSH+LIMITED/@50.86...

[tonfa]

> People will also need to stay back 70 meters or more until the air clears, he says.

[SoftTalker]

Good luck running 70m in a CO2 dense atmosphere. And CO2 hugs the ground it does not float away. It will persist in low areas for quite a while.

Anyone in the local vicinity would need to carry emergency oxygen at all times to be able to get to a safe distance in case of rupture. Otherwise it's a death sentence, and not a particularly pleasant one as CO2 is the signal that triggers the feeling of suffocation.

[cycomanic]

It's unlikely that the thing will burst and disperse all CO2 immediately. It's just slightly higher pressure than the outside (that's the whole principle). So you have a slow leak of CO2 to the outside. You don't have to run that fast (or run at all).

The way I understood the quote, the safety distance is when they have to do an emergency deflate (e.g. due to wind). The way they calculate the 70 m is probably based on the volume and how large of a area you cover until the height is low enough that you can still breath.

Generally, because it's leaking to the outside, where there is going to be wind it will not stick around for long time I suspect.

[andrewflnr]

> It's unlikely that the thing will burst and disperse all CO2 immediately.

This requires the people running this facility, and all the facilities based on it built by unrelated organizations in the future, to not cut engineering corners on the envelope. I don't take this for granted anymore. But as long as you don't get a big rip, then yeah, it'll be hard to build up a dangerous amount. I wonder if a legally mandatory cut and repair trial on the envelope would reduce risk significantly.

Speaking of wind, I also worry about whoever is downwind if there's a big release. I bet 70m is not quite far enough if it's in the wrong direction.

[quotemstr]

I wonder whether it'd be possible to augment the CO2 with something that would make it more detectable visually and aromatically, like we do natural gas.

Natural gas is naturally odorless and colorless. Therefore, by default, it can accumulate to dangerous levels without anyone noticing until too late. We make natural gas safer by making stink, and we make it stink by adding trace amounts of "odorizers" like thiophane to it.

I wonder whether we could do something similar for CO2 working fluid this facility uses --- make it visible and/or "smell-able" so that if a leak does happen, it's easier to react immediately and before the threshold of suffocation is reached. Odorizers are also dirt cheap. Natural gas industry goes through tons of the stuff.

[amelius]

I suppose the people working at the plant will be wearing detectors and/or these will be placed at strategic locations in the area.