Heliogen targets 1500°C solar thermal • Hacker News Board

Re: Heliogen targets 1500°C solar thermal

#71

Post by newnewpdro » Thu, Nov 28, 2019, 9:49 PM UTC

giarc wrote: post #67

newnewpdro wrote: post #59

Earlier quoted context omitted.

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.

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

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.

Re: Heliogen targets 1500°C solar thermal

#72

Post by brohee » Fri, Nov 29, 2019, 10:56 AM UTC

baybal2 wrote: post #62

thinkcontext wrote: post #61

Earlier quoted context omitted.

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 re…

> 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…

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.

Re: Heliogen targets 1500°C solar thermal

#73

Post by rasz » Fri, Nov 29, 2019, 11:22 AM UTC

rrss wrote: post #68

rasz wrote: post #55

Earlier quoted context omitted.

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

> 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.

The point is you dont need machine vision to focus and track, just 2-4 photo cells.

Re: Heliogen targets 1500°C solar thermal

#74

Post by masklinn » Fri, Nov 29, 2019, 6:59 PM UTC

baq wrote: post #6

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.

yeah the only problem is the useful heat is contained in a very small area/volume, so this is only a research facility.

It's a solar furnace / oven not a solar power tower.

Odeillo's purpose is to heat things very high and very quickly, not to produce power. It's a tool for materials research not a solar power demonstrator.

There is a solar power research site nearby: https://en.wikipedia.org/wiki/Themis_(solar_power_plant)

Re: Heliogen targets 1500°C solar thermal

#75

Post by masklinn » Fri, Nov 29, 2019, 7:05 PM UTC

astrodust wrote: post #53

arcticbull wrote: post #40

Earlier quoted context omitted.

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.

> 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.

Re: Heliogen targets 1500°C solar thermal

#76

Post by masklinn » Fri, Nov 29, 2019, 7:16 PM UTC

tempodox wrote: post #30

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.

> Inertia must be incredibly strong. Otherwise, why did it take so long to come up with something that strikingly simple?

It didn't? There are both solar ovens and solar power plants in active use.

The issue's mostly that it's historically been fairly inefficient and expensive (compared to other electricity production sources). Prices have been coming down through improved efficiency and economies of scale, the plants being built these days are bid under $75/MWh and construction has been ramping up a lot especially in high-irradiation locations e.g. Morocco onlined their first station in 2017 (510MW CSP, 72MW PV) and is already building a second one, and Dubai is apparently aiming for 5GW installed by 2030.