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Diesel, iron or aluminum, from your parent post, are difficult to explode… (personally, no clue about magnesium); and the point of the latter two is that you ca
by harperlee 1y ago
Diesel, iron or aluminum, from your parent post, are difficult to explode… (personally, no clue about magnesium); and the point of the latter two is that you can “store” energy by upstreaming its consumption when power is available, you don’t necessarily need to produce an actual reversible energy store.
- trillic 1y agomagnesium is the most explody of all those
- Retric 1y agoBut still not explosive at scale. It’s a surface area issue, a small strip of magnesium explodes when dropped in water but a 100t cargo of magnesium sinking in a harbor would be a huge fire.
- pfdietz 1y ago> a small strip of magnesium explodes when dropped in water No it doesn't. Magnesium metal burns because the boiling point of magnesium is just 1091 C, so extremely reactive vapor is readily produced. But it would be very hard to heat it that high in water unless it was ignited first. It will then continue to burn under water.
- Retric 1y agoMaybe I should have clarified burning, as in “Why does burning magnesium explode when sprinkled with water?” https://physics.stackexchange.com/questions/33167/why-does-burning-magnesium-explode-when-sprinkled-with-water https://physics.stackexchange.com/questions/33167/why-does-b...
- kragen 1y agoYes, safety is a significant disadvantage of the use of magnesium as portable stored energy, but if your ship's payload is already on fire, in most cases the shipment will not be very successful anyway, and loss of the ship is a serious possibility. If a hypothetical ship full of magnesium sinks without catching the magnesium on fire first, the magnesium will probably not catch fire from exposure to water. Perhaps if it's sufficiently finely divided, which seems like a bad idea.
- Retric 1y agoI agree, the point is you’re not risking something like: https://en.wikipedia.org/wiki/Halifax_Explosion https://en.wikipedia.org/wiki/Halifax_Explosion “At least 1,782 people, largely in Halifax and Dartmouth, were killed by the blast, debris, fires, or collapsed buildings, and an estimated 9,000 others were injured.” “Nearly all structures within an 800-metre (half-mile) radius, including the community of Richmond, were obliterated.[3] A pressure wave snapped trees, bent iron rails, demolished buildings, grounded vessels (including Imo, which was washed ashore by the ensuing tsunami), and scattered fragments of Mont-Blanc for kilometres. Across the harbour, in Dartmouth, there was also widespread damage.[4] A tsunami created by the blast wiped out a community of Mi'kmaq who had lived in the Tufts Cove area for generations.”
- kragen 1y agoNot with magnesium ingots or dry magnesium, no; but, because the water–magnesium reaction is exothermic, spontaneous, and gas-producing, I'm pretty sure there's a range of ratios where wet magnesium does constitute an explosive if it's finely divided, at least a low explosive like gunpowder, so such an accident could happen. It seems unlikely to happen by accident because at stoichiometry you need more water than magnesium, and I don't think spontaneous explosion is a real risk with magnesium. The International Magnesium Association's safe handling guide https://cdn.ymaws.com/www.intlmag.org/resource/resmgr/safety/Safe-Handlling-of-Mg.pdf https://cdn.ymaws.com/www.intlmag.org/resource/resmgr/safety... does mention that magnesium swarf can spontaneously combust in the presence of water, but I think swarf is too coarse to explode. It recommends keeping wet magnesium swarf under water to prevent it from heating up enough to spontaneously ignite. But presumably you'd be shipping the magnesium in the form of plates, ingots, or rolls rather than powder, swarf, or loose foil.
- horsawlarway 1y ago> and the point of the latter two is that you can “store” energy by upstreaming its consumption when power is available Are you sure the parent isn't referring to something like a rust (iron-air) battery? Aluminum, Iron, and Magnesium are all viable battery chemistries. Side note - I'm pretty certain you don't actually need to make contents of a ship explode to easily sink it with explosives. I'm actually somewhat concerned that between drones and smart mines - we've never had a better chance of completely ruining our ability to do ocean based shipping during combat.
- kragen 1y agoYou may have seen that Colombian drug cartels are already using Starlink-piloted "sea drones" to do ocean-based shipping through blockades. The US Coast Guard estimates that 90% of crewed narcosubs get through: https://www.youtube.com/watch?v=5aPLXdtbLZ0 https://www.youtube.com/watch?v=5aPLXdtbLZ0