Heliogen Awarded Exclusive Right to Lease Brenda Solar Energy Zone for Green Hydrogen Production 2

[cmoreride]

https://heliogen.com/heliogen-award...ar-energy-zone-for-green-hydrogen-production/

 

[IRstuff]

I would disagree the notion that the maintenance is automatically higher; rotating machinery comes with its own required maintenance, not to mention the logistics of fuel for the gas turbine.

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[itsmoked]

"unicorn farts" I had not heard of those before.

I'm amazed they've left such huge gaps between the mirrors. Why?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[IRstuff]

The spacing might be tied to the accuracy of the pointing mechanism sensors, which might have limitations on how close together the mirrors can be in angle space.

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[JoshPlumSE]

"unicorn farts" is a term I use to depict the irrational hope of a "magical" technology that will suddenly solve our energy problems.

 

[JJPellin]

I have never understood the fascination with hydrogen. It burns very cleanly. That is true. But, it is difficult to produce it efficiently. It is complicated and expensive to transport and store. There are inherent safety risks. Under current conditions, I cannot imagine how it could be advantageous to produce hydrogen in this manner. Solar panels are so cheap and efficient, it should always have more environmental benefit to simply install solar panels and use the produced electricity to back out more environmentally destructive sources elsewhere. The cost to build and maintain this facility would be much, much greater than a simple solar farm. There are inefficiencies at every step of producing hydrogen this way. Solar panel go directly from sun to electricity, so the overall efficiency will always be better. And since battery storage has become cheaper and better, one of the main arguments against solar (we need power at night) is not as impactful as it once was.

Johnny Pellin

 

[EdStainless]

A PV farm is more expansive than one of these. At least based on the studies that I have seen.
One big reason to make hydrogen is that you can store it. And I can simply replace many fossil fuel with it without converting all of those systems to electrical power.
The way that they get evening generation is that the salt system includes storage tanks.
When they start up in the morning they don't circulate through the cooler tanks, just start making power.
As the system heats up they gradually bring the tanks up to temp.
By dusk the tanks are hot enough to continue providing power for a couple of hours.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[rb1957]

I thought ammonia was a good source of H2 ... and safer to store.

another day in paradise, or is paradise one day closer ?

 

[itsmoked]

rb: "Ammonia is fatal in small and varying amounts", so sez the chemical safety handbook.

JJ; Batteries are not there for things like long-haul trucking. They still need a chemically dense stored energy source. I believe they want some batteries fed by fuelcells fed H[sub]2[/sub].

Keith Cress
kcress -

http://www.flaminsystems.com

 

[JoshPlumSE]

A PV farm is more expansive than one of these. At least based on the studies that I have seen.

Agreed. I don't know where JJPellin got his information about the relative cost / efficiency of solar panels to these other types of solar plants. There is, of course, lots of misinformation out there from companies (and groups) that promote solar panels.

However, those cost almost always include the following:
a) A very generous estimate of the "life span" of solar panels.
b) Overly generous estimates for the power output of the solar panels..... especially considering that the power output drops precipitously with age.
c) Not considering the effect of government subsidies to the solar power companies directly and to the homeowner who installs them. This includes the home owner being able to "sell back" excess power at the end user price rather than the "whole sale" price.
d) Not considering the cost of installation, maintenance and manufacture of solar panels when compared to including ALL of those in the comparison to natural gas.
e) Using solar cost / efficiencies that ONLY consider the areas where solar is most efficient (i.e. the southwest (CA, NV, AZ, NM). And, pretending that these efficiencies could be replicated in other areas (like Seattle) or the north where you have to worry about ice, shorter days, more frequent rain (and clouds).

Put another way, why in the world would PG&G or Edison or whatever power company we're talking about not choose to create a mega plant of solar panels is these were indeed more cost effective than other methods of generating power. If this were actually the case we would have solved our CO2 / climate change issue already. And, we would only have some smaller natural gas facilities as "backup" for cloudy days.

Now, I'm not saying that solar panels don't have their place. They're just not scalable in the same way that these other types of power generation are.

 

[EdStainless]

Ammonia is far easier to transport and store than hydrogen.
There is already a significant infrastructure in place to handle it.
It is one of the most common industrial chemicals produced.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[JJPellin]

I was never attempting to compare solar panels to all other forms of power generation. I was comparing it to the system in the original post.

Johnny Pellin

 

[IRstuff]

Insofar as the first image posted is concerned, that might have been artistic license in the animation; most of Heliogen's other materials show much tighter mirror spacings, consistent with previous solar arrays.

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The spacing might be tied to the accuracy of the pointing mechanism sensors, which might have limitations on how close together the mirrors can be in angle space.

That makes sense. Be interesting to know how the mirror tracking system works.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

I have never understood the fascination with hydrogen. ... But, it is difficult to produce it efficiently. It is complicated and expensive to transport and store.

In hydro generation, efficiency is not as important as time-flexibility. If you can make the H2 off-peak and burn it on-peak you have added substantial value (in the same way pump storage hydro economics is justified despite lower turbine efficiency up and down). So in this scenario H2 acts as a storage medium. Zero-emissions and low maintenance costs weigh in its favour. A straight-to-electricity PV farm is more efficient, but cannot easily match peak production to peak demand.
H2 transport and storage in large quantities are indeed problematic, but a turbine-generator could be built near the solar farm, and not more than a day's worth (or a few days, depending on strategy) needs to be stored.
But a comprehensive 'hydrogen economy'? Can't see it happening, but H2 can be a piece of the puzzle.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[IRstuff]

Heliogen's patent shows 4 sensors outside of the target that look at the reflected sky from each mirror and tries to balance the measured sky radiance from each sensor to center the reflection of the sun to the centroid of the sensors. Because the sun itself is never imaged, it does make for a more challenging optimization problem

https://www.freepatentsonline.com/11017561.pdf

if anyone is interested


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I suppose you could program the tracking movement of each mirror based on the known precise astronomical position of the sun over time. That approach would just need initial calibration.

How big is the target relative to the reflected beam width?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[IRstuff]

I suppose you could program the tracking movement of each mirror based on the known precise astronomical position of the sun over time. That approach would just need initial calibration.

That's a blind control (conventional) approach, since you have no direct feedback whether the mirror is warped and caused the sun to be pointed off-target; Heliogen's approach uses the mirror reflection directly, although not of the sun, per se, which ostensibly improves the pointing accuracy. Heliogen's approach does not require calibration and is tolerant of post-installation misalignments of the mirror relative to the control system

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[JoshPlumSE]

IRStuff -

Thanks for the summary, I knew they were "doing something better" with the mirror alignment, but I didn't know the details. Yours is a good enough summary that I feel like I at least understand the concept for why it's better than the ones at Ivanpah or such.

For what it's worth, it's clear that Ivanpah had some serious mirror alignment problems as they damaged one of their turbines severely once due to misalignment of mirrors. Ergo, this is a serious issue and is one of the reasons why Heliogen's technology is getting good publicity.

 

IRStuff,
Thanks for the details, and I agree, any programmed approach (blind control) will inevitably drift off target eventually.
With the sensor-based system, would it be possible to use only a limited number of mirrors, with surrounding neighbours working off the sensored mirror in a sort of master/slave arrangement? One sensor for each mirror seems extremely busy.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[JoshPlumSE]

In hydro generation, efficiency is not as important as time-flexibility. If you can make the H2 off-peak and burn it on-peak you have added substantial value

I think time flexibility is an excellent point and one of the major things to address when making "solar" (of any kind) more viable. Another reason why Heliogen is getting more positive press and is viewed as having the potential to be a significant improvement over the Ivanpah's type plants. I look at it as the same basic concept, but with incremental improvements in a number of key areas.