Glass Sphere Betaray Concentrates Solar and Lunar Energy
understandsolar.com
understandsolar.com
The article tries to make it sound like a miracle technology that concentrates light "up to 10,000x", but that doesn't mean you get 10,000x more energy out of it, it just means that you can use a much smaller panel since the light is concentrated on a smaller spot by a comparatively large, bulky piece of hardware.
Panels are already pretty cheap, so it's not clear if the cost of a giant glass sphere, plus heavy-duty steel frame, plus tracking hardware will beat just blanketing your roof with stationary panels. It looks cool, sure, and maybe it's a bit more efficient at converting sunlight to electrical energy, but the real figure that's going to matter is the $/kW ratio.
>"Rather than glass lenses, the consumer models will rely on water-filled acrylic polymer lenses and will also be able to handle thermal energy generation in addition to solar energy generation."
Where do you mount this contraption? Solar PV is light enough for any roof - otherwise wasted space. You probably have to mount this on the ground unless you want to spend a ton of money reinforcing everything.
@todd8 is simply stating that the sphere full of water would be too heavy for this to be a serious proposal.
@dghughes is basically replying, "Look, it says so right here. That's their plan."
They're not arguing over the material to construct the sphere. It is merely incidental that there was conflicting information in each of their comments.
And there are much cheaper and more elegant ways to concentrate light than a massive glass/water-blob:
https://en.wikipedia.org/wiki/Fresnel_lens
Just mount a freakin fresnel lens on the tracking device and you have a system with fractional weight ...
https://www.youtube.com/watch?v=drE54ctrHBY
(My guess is that this is originally an art project or maybe a Joke that was misinterpreted by some not-so-technical media)
Get your fresnel lenses e.g. here:
has been a thing for a while and seem to be more expensive than normal PV panels.
If this design really focuses the sun "10000 times", then it'll need complicated cooling to avoid killing the solar cell. I wonder how that is supposed to work.
The one thing that is problematic overall probably is the noise that any steam-based solution will make.
NASA and DOE did some tests with Stirling powered cars in the 70's and 80's. They got up to 50 MPG. In the end, retooling, cheaper fuel and different UX when driving was the negatives that prevented mainstream adoption.
False. You can't reach a temperature hotter than the black body which emitted the light. The moon is a reflector which is as cold as -153 C, not a black body emitter.
Try reflecting sunlight with a large mirror cooled by air to 23 C through a magnifying glass onto an object in the shade. You can still light things on fire.
Moonlight is pretty much partially reflected sunlight. The moon is acting more like a dirty mirror than like a blackbody emitter. This is easily apparent through two simple facts:
1) If the moon was emitting light due to its temperature rather than reflecting light from a higher temperature object, we couldn't see it all. Objects at 120 C don't really emit light in the visible range.
2) The color temperature of moonlight is around ~4000K, about 1000 K lower than sunlight. It's not like we haven't measured this stuff.
So, yes, you could start a fire with moonlight. I leave this as an exercise for the Mythbusters-inspired reader.
[1] https://en.wikipedia.org/wiki/Color_temperature
[2] http://physics.stackexchange.com/questions/244922/why-does-m...
EDIT: After giving TFA another look, I see that they do mention using PV and not just steam engines... so I guess you could use moonlight sometimes to charge a PV, then switch it to the steam engine during the day or something.
I suspect that RM just got a little lost in the weeds on this one. I remember making a similar mistake in undergrad when I was thinking about a problem with two light sources with an optical filter in between. The key insight I needed to make was that the filter was a physical object with its own temperature.
Thinking about things like this is how you develop what physicists call "physical intuition".
That's for efficient electrical generation, which I assume is the point of this thing. As far as pure heat, you're right. You could just have a big curved metal water tank wrapped around the bottom half of the sphere and you might get pretty good water heating capabilities without a complicated tracking system.
That's roughly 500Kg of water, in a glass sphere, and the whole thing would have to cost a couple hundred dollars to beat standard PV, an it STILL needs an active tracking system.
This wouldn't seem to make much sense for individual installations (unless you're wealthy and want something to show off on your roof), but I wonder if the economics would work out in medium-sized arrays, to fill the gap between small residential/commercial installations and huge solar collector operations. Still though, is a 35% efficiency increase enough to justify this particular design? Is it that much better than other concentration methods?
If it is 35% improvement, it would be nice to know what it was an improvement on. One of the linked sources suggests that current maximums on PV efficiency are around 24% of total sun energy converted to electricity out of a maximum of 33.7%. so, if that is the case then does this get us from 24% to 32%, or very close to the maximum solar electricity extraction per area?
Please double check my math or correct me where I'm wrong, but putting everything in marginal terms is very confusing.
This feels enormously wasteful in construction, a huge sphere doesn't feel like the most obvious lens shape. Am I missing something?