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Heliogen targets 1500°C solar thermal

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Re: Heliogen targets 1500°C solar thermal

#51

Post by rrss »

analognoise wrote: post #46
pjc50 wrote: post #23

Earlier quoted context omitted.

The difficult problem is not knowing where the sun is but knowing where the ground is. Since all the panels are separate structures not on a single rigid slab, ground "settling" can tilt them fractionally in unpredictable ways. It sounds like what they have is machine vision as a novel input into a conventional control loop. For one panel at a time, wiggle it about and look how the light spot changes. Find the local…

You don't need machine vision for that, you can do it with four photodiodes. That's how it's been done for like 40 years. No vision or "AI" required.

How do you align an array of hundreds of mirrors to a single spot with four photodiodes?

Re: Heliogen targets 1500°C solar thermal

#52

Post by astrodust »

agumonkey wrote: post #43
Juliate wrote: post #7

Earlier quoted context omitted.

Granted. Size and lightweightness are definitely a point - that could be emphasized as a major argument - even the ratio with size & power capacity & heat intensity.

I wonder how security is handled there

Oh man what if someone stole the sun.

(In all seriousness, the security risks are pretty low here. This isn't like stealing nuclear fuel.)

Re: Heliogen targets 1500°C solar thermal

#53

Post by astrodust »

arcticbull wrote: post #40
aj7 wrote: post #39

Very skeptical that this is a practical means to supply 1500C to an industrial process. Do they plan on piping heat via liquid metal, or what? Do you shutdown on cloudy days and sen everyone home?

Just store some molten salt in a really big thermos

Since thermal energy is only lost at boundaries, the larger the amount you have, the smaller the net surface area per unit of volume.

This is how you can store huge blocks of ice well into the summer (e.g. https://en.wikipedia.org/wiki/Ice_house_(building)), but also how a giant underground mass of molten salt that's not in physical contact with the surrounding ground could store a lot of heat for a long time.

Re: Heliogen targets 1500°C solar thermal

#54

Post by nanomonkey »

I'd love to see something like this put into use for smelting titanium. We really need to start embracing it as a building material as it doesn't corrode or break down like wood, steel, aluminum does...plus it's light and strong which would allow moving houses and vehicles made from it much less energy intensive. It would be great to invest the energy into building materials that can last instead of continuously having to fight corrosion.

Re: Heliogen targets 1500°C solar thermal

#55

Post by rasz »

pjc50 wrote: post #23
ReptileMan wrote: post #10

Earlier quoted context omitted.

What exactly do you need AI for except for buzzwording? It is not as if the sun/earth trajectory or rotation speed is random. You can precalc with ease at every point which is the best position for each mirror.

The difficult problem is not knowing where the sun is but knowing where the ground is. Since all the panels are separate structures not on a single rigid slab, ground "settling" can tilt them fractionally in unpredictable ways. It sounds like what they have is machine vision as a novel input into a conventional control loop. For one panel at a time, wiggle it about and look how the light spot changes. Find the local…

CD-ROM laser pickups have been doing it in the 70s without AI.

Re: Heliogen targets 1500°C solar thermal

#56

Post by baybal2 »

thinkcontext wrote: post #38
Juliate wrote: post #3

https://en.wikipedia.org/wiki/Odeillo_solar_furnace "started operating in 1970", "Temperatures above 3,500 °C (6,330 °F) can be obtained in a few seconds". See also https://en.wikipedia.org/wiki/Solar_furnace Not dismissing this press release, but at least some scale of progress should be used to compare against. Or state where the economical/industrial/regulatory innovation stands.

Here's a better article which explains the advantages over traditional CSP. https://www.vox.com/platform/amp/science-and-health/2019/11/... TL;DR Traditional CSP is aligned once, Heliogen aligns continuously. This allows them to correct for individual panel changes in warping, settling, weather, dust, etc. This approach also allows them to use cheaper hardware.

Well... no.

Motors and circuitry on each mirror instead of a simple screw drive are certainly not making the setup cheaper

It smells to me like a second Solindra in making

Re: Heliogen targets 1500°C solar thermal

#57

Post by mirimir »

rrss wrote: post #51
analognoise wrote: post #46

Earlier quoted context omitted.

You don't need machine vision for that, you can do it with four photodiodes. That's how it's been done for like 40 years. No vision or "AI" required.

How do you align an array of hundreds of mirrors to a single spot with four photodiodes?

Just align one mirror at a time. The one being aligned vibrates at some frequency, and detectors around the target just measure that modulated signal. So just keep cycling through all the mirrors.

Re: Heliogen targets 1500°C solar thermal

#58

Post by chrisbrandow »

Beltiras wrote: post #21
ginko wrote: post #19

Earlier quoted context omitted.

Not sure which salts would be used here, but I 1500C+ is pretty hot even for many salts. Sodium chloride boils a bit below that(1465C) for instance.

Molten salt towers don't heat above 800 iirc. If they were designed for storing more energy it would come from more mass. It goes without saying that the benefit of salt is reduced once it becomes gasified.

In a technical sense, that would depend in part on the salt. If a salt with a higher melting point existed then it could be stored at a higher temperature.

I’m not meaning to “correct” your statement, because the actual practicalities of these systems Is not my expertise and there may be other much more significant factors to consider

Re: Heliogen targets 1500°C solar thermal

#59

Post by newnewpdro »

giarc wrote: post #33
kwhitefoot wrote: post #20

Earlier quoted context omitted.

Is 6000 birds a year a lot? It's a serious question, I have no idea what fraction of birds in the area that is. Is it comparable to the normal fluctuation in bird mortality in the area or is it so large that it has a disturbing effect on the population? Of course fewer bird deaths would be good, and zero would be better. But these bird deaths are noticed because of where they occur. What is the 'background' level, th…

I recall seeing a chart one day that showed bird deaths by source. Death by domestic cats were magnitudes higher than any other source.

The Mojave desert wilderness areas are not overrun with domestic cats.

6000 sounds like a lot to me. I have five acres near joshua tree, and while there is wild life the only stuff that seems to be abundant are some rodents, rabbits, and reptiles. It's a fragile ecosystem. There used to be tortoises supposedly, but the roads wiped them out.

Re: Heliogen targets 1500°C solar thermal

#60

Post by [deleted] »

baybal2 wrote: post #56
thinkcontext wrote: post #38

Earlier quoted context omitted.

Here's a better article which explains the advantages over traditional CSP. https://www.vox.com/platform/amp/science-and-health/2019/11/... TL;DR Traditional CSP is aligned once, Heliogen aligns continuously. This allows them to correct for individual panel changes in warping, settling, weather, dust, etc. This approach also allows them to use cheaper hardware.

Well... no. Motors and circuitry on each mirror instead of a simple screw drive are certainly not making the setup cheaper It smells to me like a second Solindra in making

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