
Heliogen targets 1500°C solar thermal - nclzz
https://www.vox.com/science-and-health/2019/11/19/20970252/climate-change-solar-heat-heliogen-csp
======
Juliate
[https://en.wikipedia.org/wiki/Odeillo_solar_furnace](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](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.

~~~
thinkcontext
Here's a better article which explains the advantages over traditional CSP.

[https://www.vox.com/platform/amp/science-and-
health/2019/11/...](https://www.vox.com/platform/amp/science-and-
health/2019/11/19/20970252/climate-change-solar-heat-heliogen-csp)

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.

~~~
baybal2
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

~~~
thinkcontext
You didn't bother to read the article.

> Rather than assembling large, complicated, curved heliostats (mirrors) on
> site, eSolar used small, flat, prefabricated heliostats of only about a
> square meter. They were cheaper, faster and easier to set up, more modular,
> and easier to replace.

> Gross’s key insight was that he could replace a lot of the material and
> labor involved in CSP with computing power. (Or, he could replace stuff with
> intelligence.) Rather than make bigger, more complicated mirrors, he made
> small, simple ones and controlled them with software, so they stayed aligned
> more precisely and produced more power.

~~~
baybal2
> You didn't bother to read the article.

I did, their entire premise is invalid. They are either very bad at math, or
engineering, or both.

The metal part, screw drive, and simple pulleys and etc are nor hard, nor
expensive. Saying it otherwise is purest bs.

The limits of precision of theodolite are more than enough position for
precise initial reference.

Existing solar thermal farms were not designed for generation of process heat
in mind to begin with, so them saying that they suck at that because of their
"design" is a PR trick.

Existing thermochemical processes are profitable enough to burn oil for them,
and if one minds anything cheaper, they will first consider CHP colocation
before thinking of anything as weird as this.

~~~
brohee
The precisely curved mirrors are expensive, and likely dominate the BOM.

And tanks to economy of scales, electronic systems are now often cheaper than
mechanical ones.

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new299
Bill Gross, Heliogen’s current CEO previously founded eSolar. eSolar proposed
using an array of Heliostaticly controlled mirrors to direct light toward a
solar cell:
[https://en.wikipedia.org/wiki/ESolar](https://en.wikipedia.org/wiki/ESolar)
So... that part of the eSolar approach is carrying over into Heliogen.

Last time this was posted the “AI” component of the play was less clear... But
with an array of mirrors, in particular being to generate heat in some volume
I guess a more complex feedback/control system may be required.

~~~
ReptileMan
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.

~~~
pjc50
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 maximum for tightest spot. That's
now "locked" in the PLL sense and should stay locked for days or weeks.

~~~
JshWright
From my comfy armchair, with zero experience in this field, it seems like you
could use star tracking to very accurately predict the angle of the sun (since
the sun is effectively fixed in position relative to the background stars over
the timescales you'd care about). Spotting the target is a little harder, but
the same measurement could be made by sticking some reflectors in known
positions around the target.

I'm sure there are tons of considerations that aren't occurring to me (for
instance, thermal expansion likely contributes substantially to making it a
moving target (literally)), but I really don't see where "AI" comes into it...

~~~
dreamcompiler
Figuring out the sun's location is the easiest part of the problem. The hard
part is that each mirror is a big, floppy slab that moves with wind,
temperature, gear backlash, mechanical wear, rain/hail, and ground settling.

The so-called "AI" here is really just a clever way to use closed-loop control
so that the above factors don't matter much.

(Side note: A large amount of "AI" these days just amounts to changing open-
loop mechanisms to closed-loop, often by using computer vision as the state
sensor. 3D printers, for example could become much more precise with no
mechanical improvements if they did this. Probably some have already done so.)

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honopu
I think the point of calculating using imaging vs a model that requires layout
and flat land etc is this would be cheaper to build. You have to build one
collection tower/ target, and the mirrors can aim themselves. This greatly
reduces the grading, measurement etc and makes installing on existing land
without needing to flatten at all, or to some crazy tolerance, much easier. I
can see this used in rolling hills, with less impact etc possible.

------
aj7
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?

~~~
arcticbull
Just store some molten salt in a really big thermos

~~~
astrodust
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)](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.

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

You do need to do the initial melting work though. It took two months for
Crescent Dunes to melt its 32 tons of salt.

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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.

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Tangokat
I wonder who Heliogen hired to do their PR. Must be a really good (or
expensive) campaign. There is nothing new in high temperatures and the AI part
is pure buzzwords.

~~~
epistasis
I imagine that being able to throw around the name Bill Gates is as big an
advantage as a good PR firm.

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tempodox
Inertia must be incredibly strong. Otherwise, why did it take so long to come
up with something that strikingly simple? The last time someone allegedly had
an idea like that was around 212 B.C., in the defense of Syracuse.

~~~
trickstra
Because of oil lobby mostly. The idea is nothing new, it was just easier to
burn oil instead of building new industry from ground up and going against all
existing oil companies.

~~~
nradov
That "oil lobby" conspiracy theory is such nonsense. There are several
developed countries with minimal oil reserves and no domestic oil companies.
If alternative energy industries were really practical before then those
countries would have built it.

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zubspace
Another similar project in the mojave desert incinerates 6000 birds a year
[1]. I wonder, how they handle that..

[1] [https://www.sciencealert.com/this-solar-plant-
accidentally-i...](https://www.sciencealert.com/this-solar-plant-accidentally-
incinerates-up-to-6-000-birds-a-year)

~~~
kwhitefoot
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, the death rate in the same place without the solar plant?

The Ivanpah installation is on a known migration route, presumably most other
such installations will cause fewer bird deaths simply by not being on such a
heavily used route. The article was a bit light on background information and
I don't know how to find it.

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

~~~
newnewpdro
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.

~~~
giarc
The devils advocate view is that climate change will kill them all, so what's
really that bad about 6000 birds?

~~~
newnewpdro
It's not like this is the only method for harnessing the sun's energy.

PV fields for example don't cook the local fauna.

