
Heliogen, backed by Gates, says it has achieved a solar breakthrough - solarengineer
https://edition.cnn.com/2019/11/19/business/heliogen-solar-energy-bill-gates/index.html
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Jamwinner
Am I missing the breakthrough? This just reads like boilerplate tech
marketing, replete with questionable ai usage. I suspect without its well
known backer anyone would notice.

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jccooper
They seem to be using computer vision techniques to dynamically aim the
mirrors. Presumably static or open-loop techniques don't focus as precisely,
and using a closed loop also allows them to reduce the stiffness (and this
material use) in their mounts and/or fewer mirrors.

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sanxiyn
Closed loop enables higher temperature. I doubt material saving is worth it.

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mlyle
Pointing hundreds of mirrors is expensive. Requiring a lot less rigidity for
the motion system is notable.

I don't doubt you could have done this open loop with a very rigid (expensive)
platform before (including solving problems of ground subsidence). But now you
can do it with a reasonably priced platform closed loop, which is what makes
it actually possible.

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core-questions
Could you expand on what closed/open loop mean in this context?

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lifelongUU
Open loop means that they’re just using a mathematical prediction of where to
point the mirror at a specific time, given the relative position between the
heliostat, the target and the sun. adjustments to the mirrors are typically
done every 10 to 15 seconds, which is sub optimal. Closed loop means that
they’re actually using Computer vision to dynamically sense the specific
angles between the sun and the target and then adjust the mirrors accordingly,
no mathematical model required, and the adjustments can be done tens of times
per second.

~~~
core-questions
Thanks!

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solarengineer
Excerpt: A secretive startup backed by Bill Gates has achieved a solar
breakthrough aimed at saving the planet.

Heliogen, a clean energy company that emerged from stealth mode on Tuesday,
said it has discovered a way to use artificial intelligence and a field of
mirrors to reflect so much sunlight that it generates extreme heat above 1,000
degrees Celsius.

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The article describes a bit about the role the AI is playing, and Heliogen
didn't seem to me to have used "AI" as a buzzword

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Waterluvian
I fundamentally cannot perceive where AI plays a role. Isn't it just a
solvable geometry problem?

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splittingTimes
"Heliogen uses computer vision software, automatic edge detection and other
sophisticated technology to train a field of mirrors to reflect solar beams to
one single spot."

In principle I think you are right, but that would mean for each plant you
build you need the exact position of each mirror, the oven chamber and the
motion of the sun through the day and year. I think the "AI" approach scales
better, as it is rather simple "AI" application.

~~~
amelius
Can't you then solve this by having a bunch of photodiodes under the edge of
each panel, indicating if the panel is placed correctly?

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kjeetgill
From my reading of the article, one of the big issues to overcome was cost of
CSP vs Photo Voltaic . They're even using smaller flat mirrors that are less
sophisticated since per panel costs add up fast. One of the advantages is that
this takes 4 cameras across the full plant, not a per panel cost.

That's just my reading of it, not asserting anything myself.

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trickstra
How many photodiodes it takes before you reach the cost of 4 cameras?

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jws
One of my discarded project ideas was exactly this, but on a smaller scale. A
steerable mirror on a mount with a camera for targeting. The idea was to place
one on the ground outside a north facing window. The device would then busy
itself reflecting the sun up into the room making a nice sunny patch on the
ceiling to light the room. They could also be used to deliver extra light to
windows with plants in them to grow plants which require more light than is
available or to modulate the daily light to fake a different season.

Sitting in 2020 the technology is near trivial. The problem is that some
knucklehead would point a bunch of them at the same window and set curtains
and pigeons on fire. (You’d do this because you had a large room with few
windows, so dispersed mirrors would give you multiple dispersed lighting spots
in the room… and incinerated pigeons.)

I was unable to make the leap to what happens if you are a deliberate and well
reasoned knucklehead! In a controlled situation a megawatt of light might be
just the thing.

Addendum: The mass field of mirrors introduces a _lot_ more work. Some of the
immediately interesting problems:

• you need a “everyone stop shining at the target” mode for emergency stop,
but the mirrors need to move away from the target in such a way that they
don’t create convergences elsewhere. Obviously sweeping your portal to hell
down the tower would be a bad idea. So you have a collection of autonomous,
free thinking mirrors, but when commanded to stop hitting the target they need
to not make the same decisions.

• your camera probably needs to be able to stare into the heart of a thousand
suns (literally). But it also needs to see in ordinary daylight. Maybe a
pinhole filter that moves over the lens would be appropriate.

• with 999 mirrors shining on the target, you will not be able to see your own
contribution to aim. There probably needs to be a “hey! Everyone else look
away for a second” command for unit to aim and calibrate itself. See
complexities from the first bullet and not incinerating things you like.

So yeah, they could have started with my garden heliostats, but then it would
be a crack the knuckles, bring in the eggheads, and get to work operation to
solve all the hard problems.

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hirundo
Add similar software to a swarm of drones each carrying mylar film stretched
on a lightweight rigid frame with a vertical tilt actuator, and you have a
seriously dangerous weapon system on sunny days.

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mlyle
It's hard to point what's basically a giant sail on an airborne drone.

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dmurray
Add a second sail and use the AI magic to move it to roughly counter the force
on the first one, helped with the rotors for fine control.

I don't really know if this would be possible, but sailing ships can rig their
sails to propel them against the wind.

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ben509
Another interesting problem this might solve is birds.

Yes, domestic cats kill orders of magnitudes more birds, but that argument a.
depends on relative scale that people don't grok, and b. coming from an energy
company reinforces the preconception that they're callous.

Add radar and a sufficiently smart AI, and they could turn a PR problem into a
marketing pitch by showing birds flying through unscathed while the mirrors
shift to avoid them.

~~~
pbhjpbhj
If you can track individual birds like that I'd have thought you could do
targeted scaring to deter the birds before they get fried. Moving mirrors
quickly enough seems like it would require quite significant adaptation of the
apparatus?

~~~
beatgammit
I worked with a security company that did essentially that with air canons and
radar. Unfortunately, scared birds aren't the most predictable creatures, but
it seems to work pretty well.

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oschrenk
I think the article is overplaying the promise of CO reductions.

Around 60% of CO2 (see 1) emissions during cement manufacturing are just a
byproduct of the chemical process converting calcium carbonate to lime (see 2)
- nothing that solar power can help with.

1) [https://precast.org/2013/05/concrete-and-
co2/](https://precast.org/2013/05/concrete-and-co2/) 2) [https://www.ipcc-
nggip.iges.or.jp/public/gp/bgp/3_1_Cement_P...](https://www.ipcc-
nggip.iges.or.jp/public/gp/bgp/3_1_Cement_Production.pdf)

~~~
sanxiyn
Cement is 8% of global CO2 emission. 40% of that is still greater than air
travel (about 2.5%).

~~~
stkdump
I thought that the problem with air travel is not (just) the amount of CO2
emitted, but also the altitude, which makes the green house effect bigger per
ton of CO2.

~~~
Confiks
It's not about CO2 emissions, but rather the high-altitude NOx that
contributes more to climate change than low-altitude emissions. However, it's
debatable whether the amount is very significant, at least compared to other
sources of NOx.

[1]
[https://en.wikipedia.org/wiki/Environmental_impact_of_aviati...](https://en.wikipedia.org/wiki/Environmental_impact_of_aviation#Carbon_dioxide_\(CO2\))

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meggar
Cool, an Archimedes Death Ray with AI.

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janpot
I'm wondering, where does AI come into play? Isn't this achievable with just
basic geometry.

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sanxiyn
I wouldn't call closed control loop "AI", but you need some control to deal
with unpredictable ground heave/subsidence.

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seshagiric
Is the company backed by Bill Gross or Bill Gates or both?

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Stierlitz
Just how much AI is required to keep a mirror aligned with a target. If I see
another article on AI, cloud or blockchain then I'll eat my keyboard :]

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mads
Just barely enough so it can make it into the marketing material without
seeming like a total scam.

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jerry292
@elonmusk please work with integrating battery tech with these guys!!

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edhelas
Backing up solar production with batteries is pointless. Except for a really
specific cases. The costs are too high, the stress on the grid is too high,
the grid need to be overscaled, the batteries need to be changed each 15 years
the solar panels need to be changed each 20 years.

And even if we overcome this, we will need so much solar panel and batteries
that we simply don't have enough raw materials to do so (to replace a 1GW
nuclear core you need to cover half of Paris with solar panels, source
[http://www.assemblee-nationale.fr/15/rap-
enq/r2195-t1.asp](http://www.assemblee-nationale.fr/15/rap-enq/r2195-t1.asp)).

In France, 95% of the stored electricity is done using reversible-damns (you
pump water up to store, you empty the water and generate electricity when you
need it), only 2% using batteries. We basically put damns everywhere we could
on the territory. We have 2 days max of storage. How can we now store
weeks/months of solar-panel/wind electricity we don't need to use it when we
need it?

Batteries are inefficient for grid storage, oversized, heavy and too short
term. That's it. We now know for decades that damns are the easiest way to do
it and we can't do more than a few days of storage.

At one moment we simply have to face the maths and physics. Trusting the "next
big thing" in battery storage/solar production, even if we do 5x more energy,
even if we develop long lasting ones, will not work in the end. Our needs are
too big and the amount of minerals and other raw materials we need is way too
big. That's it.

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jerry292
Yeah true. I heard of another Bill Gates backed startup that actually stored
the energy in a form of potential energy which was way more cost effective.
Keep in mind though dams are super catastrophic to the environment as far as
water flow which can be detrimental to moisture and animals that depend on
water in certain areas

~~~
beatgammit
I'm sure you could do it with a closed system, e.g. pump water up a cliff, and
when you need power, bring it back down. I'm guessing using dams on existing
rivers is just more convenient than building a closed system from scratch
since it can double dip on hydro infrastructure.

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analognoise
Again, we've been able to do this with four photodiodes for something like 30
years.

Of course it worked the first time they turned it on - they were using 4
photodiodes. The "AI" and "computer vision" is just to get funding and hype.

I'm going to start taking solved problems and applying BS "AI" to them to get
funding, sheesh.

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anonuser123456
I somehow doubt Gates gets fooled by hype. Do you think he just stumbled his
way to success? Maybe there is a little more complexity to the problem than
you anticipate.

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analognoise
There isn't.

"Bill Gates is smart, therefore he can't be fooled or wrong" is not a strong
argument.

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agumonkey
Actually being smart would be leveraging all the hype for maximum coverage,
granted the actual product has actual value/benefits.

