DadBear

Interesting perspective. I didn't hear that message at all, but rather that we need to seriously review who gets the lion's share of our (USA) state and federal taxes. I can see how the message you quoted could be extrapolated from his presentation, but it seems to me that it would be a misunderstanding of the goal of this presentation.

Thanks for the input. I'm largely unaware of his other work outside this Ted talk and one other interview on the same topic.

You're right about rapid transfer out. I guess I wasn't clear about the imagined scenario where the battery may sit untapped for hours or more, and that could definitely cause issues with the metal melting at the upper end of operator temps. Interesting idea for solarpunk story conflict: for whatever reason heat isn't being extracted fast enough so the batteries are overheating and 'slagging' themselves.

From the math I looked at, that doesn't seem to be the case. What we're actually doing is fighting radiative and convective heat loss, basically requiring more energy per second to compensate for increasing heat losses per second. An adequately insulted sand battery would negate a lot of that.

The easiest method is using sand as an electrical resistor allowing the resistance to heat the sand up. I've also wondered about other methods too, such as solar ovens or baking the sand in some way and dumping the hot sand into the battery.

Thanks for the input! I've had several more thoughts:

1. You're absolutely right about the cost, but it could be contained with refractory cement and would not have to rely solely on metal casings. It seems like buying either in bulk has comparable pricing.

2. interest problem. I tried to find some info, but there's a lot of engineeting math (I'm an English teacher who also loves the sciences) I don't have the time to sort out right now. I think that using rock wool and refractory cement (see number 1) could help offset this energy loss.

3. I knew that water could be kept liquid under pressure, but for the purposes of citizen science and making tech more democratic, high pressure systems are a lot of risk and can be devastating when mistakes are made.

4. Absolutely. And that's the goal of my thoughts. Finding a cheap material that can hold high temperatures and remain solid. The transfer to electricity could be done by using the heated mass to heat a hot pumped liquid or using transfer rods made of a solid material with a high heat transfer coefficient.

Good question, not being an expert I don't have a great answer. But maybe doing a composite sand that combined something like copper, iron, it aluminum dust with the sand to increase the ability of the battery to more easily move heat around. Or using the chosen metal in a bar or pipe as heat transfer out of the center. The only issue with that is it lowers the operating temp and would require more active cooling, this negating some of the self-insulating benefits of sand. This could be solved by treating them like control rods, and make them movable so they could be drawn out when extracting energy is not necessary.

Please share! My wife and I are starting a homestead and are always looking for ways to make it more solarpunk. We'd love the inspiration you could provide!

Great connection to old maritime practices. I wonder if by following those routes at altitude could lead to a transatlantic of less than 48 hours? I imagine a big derigible with sails like pectoral fins and a dorsal and tail fin to steer in addition to solar propulsion.

I agree that supplementing with passenger rail is a must, especially to get from terminal to terminal. What you said makes me think of airport terminals, but they're countries away instead of a mile away. However, I do wonder about the impact on fauna that high-speed rail would has while cutting across continents, and if the airships are a way to skip that issue entirely.

As far helium...iirc, helium on Earth is a byproduct of the radioactive decay of certain elements. There definitely would be ecological consequences of helium "mining", if we were to source from the ground as is typical. Perhaps a breeder reactor could be built to produce in a way more cost effective (not monetarily). Another thought is an interplanetary drone that slurps up atmosphere from the gas giants and tows it back here. Keep the helium collection and corresponding pollution off planet (does this even work in a solar punk world)?

I was getting the same inspirational vibes from this!