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Rice University researchers propose a way to boost solar efficiency
- chovy 7y agoThis is what we need before we're all fucked.
- pstuart 7y agoprobably too late but we should never give up.
- kevin_thibedeau 7y agoBest that we prepare a smooth transition for our robot overlords.
- garysahota93 7y agoa day late and a dollar short I'm afraid, bud.
- qntty 7y agooriginal article: https://news.rice.edu/2019/07/12/rice-device-channels-heat-into-light/ https://news.rice.edu/2019/07/12/rice-device-channels-heat-i... Sounds like 80% is a theoretical prediction for this method, not an experimental result: Naik said adding the emitters to standard solar cells could boost their efficiency from the current peak of about 22%. “By squeezing all the wasted thermal energy into a small spectral region, we can turn it into electricity very efficiently,” he said. “The theoretical prediction is that we can get 80% efficiency.”
- Retric 7y agoThat really needs some editing, it reads like gibberish. Just go to the source: https://news.rice.edu/2019/07/12/rice-device-channels-heat-into-light/ https://news.rice.edu/2019/07/12/rice-device-channels-heat-i...
- Terr_ 7y agoI 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.
- DoofusOfDeath 7y agoI'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.
- p1esk 7y agoSorry 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?
- jfengel 7y ago"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.
- skosch 7y agoYou'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 https://en.wikipedia.org/wiki/Thermoelectric_effect
- epistasis 7y agoWhile this is a very interesting and ingenious development, what's needed for greater deployment are lower costs per unit of energy. Increasing efficiency will reduce the cost of land, but land isn't typically a huge factor in solar deployments. In this NREL analysis, land acquisition gets put into "Other Soft Costs" along with permitting, inspection, interconnection, sales tax, engineering, procurement, construction, developer overhead, and net profit: https://www.nrel.gov/docs/fy17osti/68925.pdf https://www.nrel.gov/docs/fy17osti/68925.pdf And that broad category is ~25% of costs.
- teej 7y agoWe shouldn't discourage progress just because it doesn't fit exactly into todays model of the world.
- epistasis 7y agoI certainly didn't mean to discourage this at all! But I think it's important to point out that even though people often disparage solar photovoltaic for having low "efficiency," that metric is not an impediment to its broad deployment or great utility to us.
- caymanjim 7y agoSure it is. Lower efficiency means you need more panels, larger panels, and more support infrastructure. It limits where it can be deployed and makes it less competitive.
- epistasis 7y agoAnd the need for more/larger panels and support structures will only be a win if overall, the costs decrease. The cost is what makes the decision for deployment, not the efficiency. Perhaps this efficiency makes 2-axis tracking economical enough to justify, and then it gets deployed, but in the end the efficiency wasn't as important as the improved costs.
- m3kw9 7y agoNano tubes are super expensive
- pacala 7y agoThey have no use at scale yet. Expect prices to drop exponentially once a use at scale is found.
- deleted 7y ago[deleted]
- blunte 7y agoThis sounds great, but for some years we hear of various discoveries that will greatly increase solar panel efficiency. Why are we still at 22%-ish?
- Ancalagon 7y agoUsually the materials to get higher efficiency are prohibitively expensive or dangerous to use at scale.
- ThomPete 7y agoThe primary issue with everything in this category is that plenty of things are possible in the lab or in theory which just isn't possible when applied in reality and at scale. Blame journalists for hyping this because of the climate change focus. I am involved in actively looking for better materials and better sources of energy. The reality is that there are no fundamental breakthroughs since oil and nuclear. No matter what you hear we just haven't had anything that fundamentally changes the game. So instead of actual breakthroughs in the fundamentals, we get marketing, branding, and communication. But this is not something that can be fixed with that, it's physics, not product innovation We will most likely get fusion (far out) fuel cells (even further out) before we get any fundamental breakthroughs here.
- anchpop 7y agoWhy 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
- gmueckl 7y agoWell, 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 and solar power.
- i_am_nomad 7y agoInteresting work - seems like this could also be used to create a thin film that could yield thermal vision, if indeed the nanotubes upshift IR frequencies to visible light. But I’m not a physicist.
- ryanmarsh 7y agoThis is essentially the same principle behind current night vision tech.
- xendo 7y agoI wonder if the process of changing heat into light can be used for transferring heat more efficiently than current AC units.
- ___karim 7y agoI doubt it would work similar, since generating heat is always a byproduct.
- ryanmarsh 7y agoThis has been discussed in several previous threads on HN. From what I’ve been able to gather, creative ways to reduce the energy consumption of A/C will require a change to building designs, and/or increase the cost and complexity of new buildings. Whereas the cost of running the A/C is up to the future tenant(s). This is why you see some companies applying eco friendly tech to some new buildings (Apple) but not in general commercial development. Again this is just what I’ve surmised from reading threads like this. YMMV
- mikepurvis 7y agoInteresting to contemplate what could be done to shift those incentives around. Obviously there are certifications (LEED), and there's straight-up regulation, but would there be a way to mandate that a builder or landlord is responsible for a portion of future HVAC expenses such that they are motivated to get this right upfront?
- ryanmarsh 7y agoI’m sure if some energy saving tech was commercialized and reasonably cost effective local municipalities could update building codes. LEED standards could be updated as well. What goes into a building isn’t entirely up to the developer. But right now most of this stuff is just in a lab. Frankly the tall cooling towers you see on some buildings weren’t in widespread use until at least the 50’s even though they were invented at the turn of the century.
- mruts 7y ago
- Terr_ 7y ago> turning heat into light > channel mid-infrared radiation (heat energy) into light energy > absorbs thermal photons and emits light. Goddamnit, no! None of this is "heat", it's just one range of light being converted into another! This is shitty "science"-journalism parroting a common misconception. After all, the only reason we associate infrared with "heat" in the first place is that it's useful for detecting things which happen to be at a range of temperatures, temperatures which just happen to be slightly warmer than the operating state of self-reproducing bags-of-mostly-water on a small rocky planet.
- infogulch 7y agoYeah it seems more like it.. fluoresces (?) around the infrared spectrum. Fluorescence might actually the right term for what is happening.
- amluto 7y agoAs far as I can tell, this is functionally just a coating with low emittance in the IR outside a narrow band. A matched PV device that is kept cool can, in principle, approach the Carnot efficiency for the temperature difference between the emitter and the PV junction. If the emitter is the sun, then the source temperature is very high and the Carnot efficiency isn’t a major limit. If the source is a solar panel, I’m having a hard time seeing how this is useful. I can see this being somewhat useful as a no-moving-parts heat engine for something like a solar concentrator, but there’s another relevant thermodynamic limit: even if this magic material has emissivity 1, it won’t radiate at a greater power per unit area than the blackbody spectrum predicts. At non-crazy temperatures, this is not very high, which will limit output for small things like solar concentrator targets. So I can see this being useful to convert waste industrial heat, or maybe as a bottoming engine for a combined cycle plant, but I am having trouble understanding how it could be useful for solar.
- kazinator 7y agoFor solar, it somehow has to integrate with the solar panel, so that the same square meter is used both for direct photovoltaic generation of electricity, and for this IR capture, so energy is obtained from a wider band. I understand your point that it can't just be driven by a secondary IR emission from a warmed-up solar panel; that's not hot enough to be that useful. In a more detailed article, there is talk about the carbon nanotube device being useful because it can withstand high temperatures: https://news.rice.edu/2019/07/12/rice-device-channels-heat-into-light/ https://news.rice.edu/2019/07/12/rice-device-channels-heat-i... They of course understand that they need a big temperature differential.
- TTPrograms 7y agoOne sketch of such a system is to physically mate an effective high T solar absorber to an effective narrow spectrum photon emitter (as described in this work). Then that can be coupled with a typical solar cell with bandgap matched precisely to the emitter wavelength. So your solar cell is near ideally efficient for the photons it receives. As I understand the emissivity of these materials can exceed blackbody radiation in the near-field but not the far-field (or something like that? Search "Superplanckian emission"). The devices as I am familiar are often called thermophotovoltaic cells: https://en.wikipedia.org/wiki/Thermophotovoltaic https://en.wikipedia.org/wiki/Thermophotovoltaic See eg http://xlab.me.berkeley.edu/pdf/259.pdf http://xlab.me.berkeley.edu/pdf/259.pdf for a great overview, esp section 3.3. I saw this video recently that I found accessible from an undergrad physics background and got me interested: https://www.youtube.com/watch?v=XnVVyTD7CzM https://www.youtube.com/watch?v=XnVVyTD7CzM
- ejz 7y agoVery cool! Let's see if it reproduces experimentally, and then let's see if it scales.
- anewguy9000 7y agoive always wondered why leaves all generally evolved to be green instead of black. wouldnt black be more efficient?
- outside1234 7y agoThe short answer is that absorbing a narrow band of energies is more efficient than a wide band. See: http://scienceline.ucsb.edu/getkey.php?key=4979 http://scienceline.ucsb.edu/getkey.php?key=4979
- quote 7y agoBecause other wavelengths were probably already taken. https://en.m.wikipedia.org/wiki/Purple_Earth_hypothesis https://en.m.wikipedia.org/wiki/Purple_Earth_hypothesis (Black is not a wavelength but rather the absence of visible light, e. g. it has all been absorbed)
- darksaints 7y agoI'm really curious as to what this will do for waste heat from other processes.
- sovnade 7y agoFor anyone curious: Carbon Nanotubes, so this will likely not see the outside of a lab any time soon.
- clouddrover 7y agoWhy not? Nawa's ultracapacitors are based on carbon nanotubes and they're going in to production: https://newatlas.com/nawa-nanotube-ultracapacitor-production/59684/ https://newatlas.com/nawa-nanotube-ultracapacitor-production... Vantablack is based on carbon nanotubes and you can buy it now: https://www.surreynanosystems.com/vantablack/science-of-vantablack https://www.surreynanosystems.com/vantablack/science-of-vant...
- inxdz 7y agoIs Rice University located in Asia?
- deleted 7y ago[deleted]
- apo 7y agoThe 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 Rice graduate student, revealed that 20% of industrial energy consumption is wasted through heat. It could also mean an increase in the efficiency of solar cells, which are currently only 22% efficient at their peak. Recycling the thermal energy from solar cells using carbon nanotube technology could increase the efficiency to 80% according to the researchers. ...
- ngold 7y agoMaybe speculation should not be presented as a statement of fact in the title.
- colechristensen 7y ago"invent" is the key misleading word
- silentrob 7y agoperhaps "hypothesize" would fit better.
- dang 7y agoOk, we swapped invent for propose above.
- elif 7y agoI hope this means that my computer fans will be replaced by a laser show
- dreamcompiler 7y ago"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.
- marshray 7y agoIf 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: http://amasci.com/miscon/elect.html http://amasci.com/miscon/elect.html
- dreamcompiler 7y agoI 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.
- marshray 7y agoIt's only simpler because "electricity is moving electrons" is not a meaningful claim. What is the physical unit of 'electricity'? There's not one, because it's not a thing.
- godelski 7y agoOn 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.
- PopeDotNinja 7y ago> 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 https://www.nature.com/articles/nnano.2015.220
- GeorgeTirebiter 7y agoThese guys are trying: http://NovaSolix.Com http://NovaSolix.Com
- lifeisstillgood 7y agoI 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
- natermer 7y agoThe penicillin moment happened because penicillin actually came into existence and became widely available pretty rapidly. Research and speculation is awesome stuff, but the hard part isn't discovering new concepts. It is actually making those concepts into a marketable and affordable good. The evidence for this is that even though there is essentially a new 'breakthrough' discovery every other week for solar panels, or electric motors, or batteries.. We are still using what amounts to cutting-edge tech from the late 90's. In the modern era this means we generally have to wait till the patents expire and market competition kicks in in order to get the price low enough and the product perfected enough to see widespread usage. If it goes anywhere at all. It's also worth noting that Florey, the man who is largely responsible in making penicillin practical drug, refused to patent his early innovations to make it widespread as possible.
- afarrell 7y ago> wait till the patents expire If this is the case, then wouldn't "buy a bunch of patents and (with great fanfare) make them open-source" be a relatively low-complexity way for a billionaire who feels like making a name for himself to accelerate progress on fighting climate change?
- lifeisstillgood 7y agoPenicillin had to undergo decade long R&D to go from Fleming's petria dish to a cheap practical drug - I cannot find the article now but I believe the investment levels from the US Military were compared to Manhattan (obviously poorly compared) but the point is this was not the "gosh what luck" story it is in mass media. Having made that first breakthrough, world class teams across the globe fought to bring the efficiency up from "froth on the top of a brew" to "gallons of the stuff" Florey was a big part of the story but so were teams in US and Europe and then the US military scaled it up beyond belief. We spent money, targeted money, on the best teams globally and then put serious industrial might to it once they found the answers. That exact approach is what I am calling for again. And as for patents - if enough global effort is put in, with enough government funds, the pressure to put the results "in public hands" rather than hold out for patents is really strong https://en.m.wikipedia.org/wiki/History_of_penicillin https://en.m.wikipedia.org/wiki/History_of_penicillin
- michaelcampbell 7y agoIs solar efficiency the new "battery breakthrough" that will transform our lives "in 10 years", for 25 years straight now?
- deleted 7y ago[deleted]