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Rice University researchers propose a way to boost solar efficiency

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Re: Rice University researchers propose a way to boost solar efficiency

#71

Post by jfengel »

p1esk wrote: post #66
DoofusOfDeath wrote: post #56

Earlier quoted context omitted.

I'm not infuriated , but having teachers and other adults conflate IR with heat certainly added to my confusion about the physical world when I was a child.

Sorry for a potentially stupid question: why do they need to convert heat into visible light? Why can't we convert heat directly into electricity at the same time as we convert visible light into electricity?

"Light" here is a misnomer. What they're doing is taking the wide array of infrared wavelengths and channeling them into a single wavelength. It's easier to build a solar cell that's tuned to that wavelength.

I don't know why they're calling that "light". It's not clear to me if it means visible light. The paper seems to imply that it peaks in the near-infrared. They appear to be using "light" in the general sense of "photons"... but it's all photons.

They're talking about very high temperatures, the kind that emit significant visible light as well.

Re: Rice University researchers propose a way to boost solar efficiency

#72

Post by PopeDotNinja »

godelski wrote: post #68

On topic of the HN title, there is research being done into carbon nanotube rectennas. Theoretical efficiency is in the upper 90's%. Problem is that they have very narrow bandwidth. Also as far as I'm aware, no one has even built lab samples that do decently.

> there is research being done into carbon nanotube rectennas. Theoretical efficiency is in the upper 90's

I googled optical rectenna.

"An optical rectenna—a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current" [1]

[1] https://www.nature.com/articles/nnano.2015.220

Re: Rice University researchers propose a way to boost solar efficiency

#73

Post by elwell »

Terr_ wrote: post #42
Retric wrote: post #4

That really needs some editing, it reads like gibberish. Just go to the source: https://news.rice.edu/2019/07/12/rice-device-channels-heat-i...

I am especially infuriated by how it repeats a common misconception of infrared light as the epitome of "heat", as if it was some kind of separate particle.

What is the accurate model of infrared light vs. heat?

Re: Rice University researchers propose a way to boost solar efficiency

#74

Post by lukev »

ThomPete wrote: post #53
gmueckl wrote: post #41

Earlier quoted context omitted.

Well, in the grand scheme of things, photovoltaic cells were developed back when nuclear reactors began to appear as well. They are not a new technology, just something that is getting optimized diligently now. In that regard, the parent post is technically correct. But that view is focused too much on big shifts in the market, if you ask me. Smaller, more incremental steps have added up to amazing things around wind…

Oh, it's definitely amazing relative to where it was, just not to where it needs to be to compete. Solar and wind is less than 1% of world energy consumption and is not expected to be more than 3-4% in 2040. Energy is not a product/market problem it's a physics problem and we haven't had any major breakthroughs in that space for a long long time. https://www.iea.org/weo/?fbclid=IwAR3eH1AFcRSPSEit8JINLCMvE_...

This... doesn't have to be the case. Some markets already have way higher renewable penetration. Solar and wind represented about 20% of all generation in California in 2018 (https://ww2.energy.ca.gov/almanac/electricity_data/total_sys...). In the UK this year, solar and wind are almost 25% of generated electricity (https://assets.publishing.service.gov.uk/government/uploads/...)

Incremental improvement and economic forces do matter. Solar is now cheaper than coal in many climates, and we are seeing the effects.

Of course, there are still many problems to be solved. But we're also working on incrementally on solutions to those. For example, battery cost is falling precipitously. "grid scale battery" was not a thing a decade ago, now you see installations popping up regularly.

I'd like to see cold fusion as much as the next guy, but dismissing incremental progress is foolish.

Re: Rice University researchers propose a way to boost solar efficiency

#75

Post by skosch »

p1esk wrote: post #66
DoofusOfDeath wrote: post #56

Earlier quoted context omitted.

I'm not infuriated , but having teachers and other adults conflate IR with heat certainly added to my confusion about the physical world when I was a child.

Sorry for a potentially stupid question: why do they need to convert heat into visible light? Why can't we convert heat directly into electricity at the same time as we convert visible light into electricity?

You're confused – heat isn't being converted into anything. The article conflates the words "heat" and "infrared radiation", which are not at all the same thing.

As a rule, everything around you glows – in other words, it emits photons. Some infrared ones, some visible ones, some ultraviolet (or even higher-frequency) ones. How much of each depends on the temperature of the material. Most things (e.g. you) are too cold to be visibly glowing, but they still emit plenty of infrared radiation.

Now, standard solar cells convert visible photons into electricity. Any incoming infrared photons, however, aren't strong enough to kick any electrons loose, so they go to waste. Here, the researchers used carbon nanotubes to absorb the wasted infrared photons. This heats up the nanotubes, which then emit visible photons, which then increase electricity generation.

There is no way to convert heat to electricity directly, unfortunately. However, you can get small amounts of electricity out of temperature differences: https://en.wikipedia.org/wiki/Thermoelectric_effect

Re: Rice University researchers propose a way to boost solar efficiency

#76

Post by skosch »

elwell wrote: post #73
Terr_ wrote: post #42

Earlier quoted context omitted.

I am especially infuriated by how it repeats a common misconception of infrared light as the epitome of "heat", as if it was some kind of separate particle.

What is the accurate model of infrared light vs. heat?

Hot things glow. Medium hot things (like you) emit lots of infrared light. Really hot things (like lightbulbs) emit infrared and visible light. Ridiculously hot things (like the sun) emit infrared, visible light, and higher-energy radiation (UV etc.).

The exact details depend on the chemical composition of the material, but for a simple model, check out https://en.wikipedia.org/wiki/Black-body_radiation

Re: Rice University researchers propose a way to boost solar efficiency

#77

Post by dreamcompiler »

marshray wrote: post #67
dreamcompiler wrote: post #65

"This light can then be used as electricity." No. One cannot use light as electricity. One can use light to make electricity. This is not just a minor typo; it's flat-out wrong.

If you want to get pedantic, you can't "make electricity" either because 'electricity' isn't a defined concept. Usually when people use words such as "make electricity", they actually mean to refer to energy or power transferred using electromagnetic fields interacting with a conductor. But a purely chemical reaction that charges a battery could be said to "make electricity" without even involving that. More info: ht…

I was going for a simpler idea: Light is photons, electricity is moving electrons. And yeah, if you're talking about electromagnetic fields we're back to photons again. It just struck me as a sentence that was very misleading to lay people.

Re: Rice University researchers propose a way to boost solar efficiency

#78

Post by jfrankamp »

ThomPete wrote: post #57
anchpop wrote: post #31

Earlier quoted context omitted.

Why do you consider cheap solar not a breakthrough? If I 30-year mortgaged some solar cells, I could put them on my house right now and save $20 a month on net because of reduced electricity costs

And you can use them to power your watch perfectly fine too. That doesn't mean it will work at scale for society which is the primary issue. The key thing to look for is energy density as that will be more likely to give society a bang for the buck. Distributing solar cells out with the capacity factor of solar isn't economically feasible for society and neither possible as a main source of energy. Nuclear and Hydro…

Why is it not feasible? I run 32 panels on my roof, in the pacific northwest which is known for its rain, it covers 100% of my residential and electric car usage when considered on an annual basis. If roofs required solar panels we would have a large part of power generation done at a much lower intallation cost and could focus on large scale energy storage projects instead. My payoff period is 11-12 years, system is warranted to 20. No breakthrough required.

Re: Rice University researchers propose a way to boost solar efficiency

#79

Post by lifeisstillgood »

I get the maybes and the caveats, the misleading title but the direction seems clear - solar efficiency is a tractable materials science problem - and "we" should see this as a penicillin moment - invest hugely into the research and development until we find the right processes and approach to make cheap ubiquitous solar. Manhattan project levels of finding is what I mean - because the pay off is humans cutting their carbon output.

Some projects have really big ROI

Re: Rice University researchers propose a way to boost solar efficiency

#80

Post by ngold »

apo wrote: post #61

The title is misleading. The full title is: > Researchers at Rice University developed a method to convert heat into light that could boost solar efficiency from 22% to 80% The conditional tense signals that the researchers didn't actually do so, but that the study might enable it. The article re-iterates that this is speculation: > The implications of their discovery are significant. Research from Chloe Doiron, a Ri…

Maybe speculation should not be presented as a statement of fact in the title.
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