Heliogen targets 1500°C solar thermal

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.)

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.

Even if the surface temperature of the solar collector focus point is 1500C, the molten salt flowing on the other side of that wall must be at a significantly lower temperature in order to transfer heat quickly enough from the small area. Then you will have a thermal profile in the wall, say from 1500 to 1200 C, and furthermore a thermal boundary layer in the fluid, say from 1200 to 800 C.

> 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.

>mostly photogrammetry - being able to tell the position and orientation of your mirrors from a video stream - in a feedback loop with motor controllers and temperature sensors.

This. Modern photogrammetry uses computer vision techniques like deep neural nets.

It's an amazing advancement.

Imagine this problem: having to place a ground vehicle like a wheeled robot at an arbitrary coordinate in a room. The mirror positioning problem can be reduced to this one. Traditionally, you'd do it by building a very nice wheeled robot with non-slip wheels, wheel rotation angle sensors, fraction of a degree stepper motors, all very nice to work with, precise, and expensive. You could even solve this in an open-loop system with good enough actuators.

Today, just stick a camera on the ceiling - or on the robot, if want a more challenging problem - and use CV to move a cheap RC car where you want.

The Terminator will jangle and jiggle, instead of being built like a precise Swiss watch. But you'll get ten of them for the same price!

Many years ago, I implemented star tracking for telescope alignment for auger.org. An actual basic version using libnova et al was pretty straightforward and a matter of days to prototype if I recall correctly (it was a project for a master student, so I had to do most of the work over a longer period of time). I think the accuracy was around a decimal fraction of a degree then. But the cameras of that thing have only 440 1.5° pixels (photomultipliers that sample at 5-20M samples/s). A higher resolution camera could probably do much better assuming you have a very accurate computer model of the optical properties of your telescope/lenses/camera.

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.)

You can replicate this behavior with four solar panels mounted on a motorized platform. The panels should be at a slight angle, with a peak in the middle... then a voltage differential top-to-bottom activates the vertical motor, likewise the horizontal motor.

I'm not sure how to make such a simple system for mirrors pointing at targets, but I suspect "AI" and "cameras" are overkill.

They could be said to be naturally intelligent, yes. However they only have to point at one target, the sun, while the mirrors have to point halfway between two targets, the sun and the tower.

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

That is solved problem with vr reduction in high quality lenses.

Gyroscopes drift. Every system using gyroscopes that needs precision has some external tracking system as another reference (e.g. GPS, star tracking). In this case, that external system is a camera on top of the tower.

> what they have is machine vision as a novel input into a conventional control loop

Control loops are everywhere, but CD-ROM drives do not use machine vision. That's why op said that's the novel part.

Sure, thought needs to go into the location of these things; avoiding migration routes and habitats of endangered birds. Using scarecrows and possible trained predator birds (presuming these can be trained to avoid the danger zone!) etc.

Of course conventional industry doesn't get a free pass here either, treatment and storage ponds, climate change, habitat destruction etc.

But aren't most larger birds predators that are highly habitat/food supply constrained? That kind of population could be quite resilient to moderate increases in mortality.

(I might be assigning far more importance to predator-Peru cycles than is warranted though, I was reading about what I now found is called https://en.wikipedia.org/wiki/Lotka%E2%80%93Volterra_equatio... at a very young age and the concept stuck for life)

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