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.
Presenter is not me, and I claim no credit, but wowzah Scott Galloway really crystalizes and cements some notions I've picked up from the punk side of solarpunk.
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:
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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.
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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.
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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.
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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.
I can't remember if I saw the argument here or on Reddit, but this is my preferred platform so it's going here.
Summary of argument: a user should have been using water for their thermal battery, not sand, because water has better heat capacity (4.18 joules per unit of mass person unit heat - 4.18/gK). Sand's thermal capacity is significantly lower (0.835J/gK).
Looking at these numbers alone in the post I understood why someone would say that; it also made me question why so much research is being done on sand batteries. The user who argued against sand batteries missed a crucial factor: material density. Water has a density of 1000kg per m^3. Dry sand (regular not pure quartz sand) has a density of 1730 kg per m^3. I found no satisfactry response to the argument in that thread, but that thread is now lost to me. I have also been curious about how much better regular sand is for heat batteries than water.
When designing large batteries, the goal is usually energy per volume. Let's compare 1m^3 of each (roughly 3.3ft cube) and how much heat it can hold before the next state change (which matters a lot when managing the pressure from steam).
Total stored energy = mass (g) * thermal capacity (J/gK) * heat (kelvin).
Water: 1,000,000 * 4.18 * 373.15 = 1,559,767,000J Sand: 1,730,000 * 0.835 * 1996.15 = 2,883,538,482.5J
Over 1 billion more joules per m^3. I hope this makes it clearer why sand batteries are such an area of interest lately. It certainly did to me.
Disclaimer: I am not an expert, so there may be mistakes. All the numbers and relevant equations were found on the internet.
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!
Went to a town called Sutton's Bay in Michigan, USA this last weekend. Definitely solar Punk leaning. Solar: a lot of people drive EVs, bike paths throughout the town and connecting other local towns, rain gardens are interspersed throughout the town, some business stops nearby from the local intercity bus network. Punk: residents are encouraged not to mow their lawns until the end of May, the only gas station in town looked pretty closed, their groceries is a mom and pop shop. Obviously, the town has a long way to go (economy is largely tourist/consumerism based, no public ev chargers, housing does not appear affordable, no light rail nearby), but as far as USA cities in the "middle of nowhere" go, it's a speck of hope.
I agree meat is a luxury. If we look historically, farm meat was common at the table of the wealthy, but sparring at the table of the common man. It's often made me wonder about the sustainabity of hunted meats if we were to treat meat as a luxury item reserved for celebrations. It seems like there's quite the potential for carbon offset according to this article: Wild meat consumption in tropical forests spares a significant carbon footprint from the livestock production sector. The article also seems to suggest in this context a necesity of more and larger reforesting/rewilding efforts. I skimmed through this, so if there's contradiction I missed please comment.
Me too! Except I teach middle school (11-14 year olds). I'd love to see how this ideology impacts classroom expectations in a practical way. That and probably would do some volunteering in a large garden or electrical engineering.
Interesting distinction. Could you or another explane it? My Political "chops" aren't that good yet.
It looks like most of this can be grown too. I live in the Midwest region of the U.S., so l'd have to look to see. If i find any helpful planting guides or region guides I'll comment them.
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)?
The blimp, the airship, the dirigible. Whatever you call them, you probably don’t find yourself thinking about them too often. They were an easy way to get airborne, predating the invention o…
Saw this article over on the solarpunk subreddit and wanted to bring it over here with my own opinion attached.
For being a near-zero way to travel in the air it's solar, but the reasons the author criticizes solar-electric propelled airships make it punk. The issues pointed out by the author - slow travel time, lower passenger counts, and windows of time for viable travel, a need for sleepers - could also be seen as its strengths.
For one, slow travel time and lower passenger counts make it a lot easier to meet and connect with strangers with little social risk. They also wouldn't need sleepers. With tight spaces like that, they're less comfortable than economy. My wife and I took a long distance train here in the U.S. (which has its own issues), but we loved the social interaction and actually preferred our economy seats over the sleepers. Two years later, we still like to chat about some of the folks we met and speculate on how they're doing.
The long transit time and specific travel windows would force people to rethink how badly they actually wanted to travel overseas and consider a more local scope. If that's not solarpunk...