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Lightcell: An engine that uses light to make electricity
- snakeyjake 2y ago[dead]
- slipperybeluga 2y ago[dead]
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- megaman821 2y agoI find the bandgap tuned cell interesting. It reminds me of a TPV https://www.nature.com/articles/s41586-022-04473-y https://www.nature.com/articles/s41586-022-04473-y which is tuned for infrared instead of yellow light.
- ggm 2y agoless moving parts means it could work in contexts where moving parts demand lubrication, maintenance. I felt it was a bit light on putting the system energy efficiency/losses up front. I am sure they're stated but it was hard to work out how it compared to normal PV efficiency, or steam turbine efficiency. Heat exchangers are applicable to lots of things. I am skeptical that this is significant because almost any heat energy process does reclaim and preheat, and so the size of the thermal mass and efficiency here would be exceptionally well studied and if they have made improvements, they may be as, or more valuable as IPR overall. So while it looks amazing, unless they are spinning it out into wider industry it will be a small increment over things in deployment.
- detourdog 2y agoI read their statement of 40% efficiency would be compared to the currently available photovoltaics were generally 20% efficiency is normal.
- enragedcacti 2y agothe 40% efficiency is a claim about how much energy contained in the fuel can be converted into electricity*. It would make the most sense to compare this against either combustion engines or hydrogen fuel cells. Compared to those 40% is not breaking any records but could be extremely useful given the size, flexibility, weight, power output, etc. Basically big if true, but this thing's 40% and photovoltaics' 20% aren't comparable efficiency numbers. * They say wire to wire, IDK exactly what that means, but if it includes the losses from green hydrogen production then it seems like pretty wild efficiency. This doesn't line up with the numbers though, as H2 with 1250Wh/L * 0.4 = 500 Wh/L claimed density.
- cryptonector 2y agoI agree that 40% "wire-to-wire" seems wild. But if it was 40% nat gas to wire that'd be quite nice considering how simple such a generator would be, and it might be more efficient (perhaps significantly more) than traditional internal combustion generators. I.e., if you ignore the green aspects of this it sounds quite nice. Though you have to supply sodium. Hmmm.
- enragedcacti 2y agoI don't think they are claiming an efficiency breakthrough on their heat exchanger, just that they've made a competitive heat exchanger that also blocks light very effectively.
- ggm 2y agoIn context, an important innovation. Perhaps this technology can retrofit into hot gas heat exchangers like in steel works, but they use the thermal energy directly so it may be robbing Peter to pay Paul. Thanks for a clarification which makes sense.
- DaniFong 2y agowe're not aiming to break records with the absolute heat exchanger efficiency, which can get into the high 90s (%) if you're willing to devote a lot of space and mass, but we are innovating in the heat exchanger area. to capture more of the waste heat up to a higher temperature, and preheat the incoming air and possible fuel to a higher temperature, we have to exceed 1000 C and want to drive towards the 1600-1800C maximum working temperature of the high alumina 3d printed material we're using. Thankfully Formlabs has already done some of the preliminary development on the material, but it's bleeding edge both as a material and in use in heat exchangers.
- skykooler 2y agoI suspect this needs some moving parts to function - without a turbine's suction, you need some sort of a fan to pump air into the thing, and also a fuel pump. Most things with internal combustion require some kind of active cooling as well.
- cryptonector 2y agoIf using compressed natural gas you might not need a fuel pump at all.
- DaniFong 2y agoyou need at least valves/regulators, but for self pressurized fuels like propane, butane, or even natural gas (CNG or LNG) you can probably get away with only that, and fans for air intake and cell cooling.
- larodi 2y agoAmazing idea. BTW, following Danielle on X, very insightful and bright minded person.
- jandrese 2y agoBottom line: 40% efficiency, which is better than I expected but the competition is batteries at 80+% efficiency. It's a hard sell, especially as continual improvements in battery storage will continue to eat away at their niche. 5,000 W/kg sounds great on paper compared to 150 W/kg for batteries and is even in the same ballpark as gasoline at 12,000 W/kg, but I think that's just the figure for the fuel. I don't think it includes storage, the solar panels, the burner, etc... The cost is an open ended question as well. Maybe this will pan out for aircraft?
- VBprogrammer 2y agoIf that is 40% efficient as in 40% of the theoretical energy input comes out as electricity then it's quite incredible but I find that hard to believe. It would put it in the same range as diesel engines.
- jandrese 2y agoThe 40% figure is supposed to be "wire-to-wire", but they do list that as the "target efficiency" which suggests it may be somewhat aspirational. It presumably doesn't include the energy needed to extract and refine the oil into whatever kind of burnable fuel you are using, nor the energy necessary to extract and then blend in the sodium additive.
- kube-system 2y agoAnd at the bottom they seem to indicate they are still in the "proving feasibility" stage. I read this all as: "this is a POC we have, and if we can get it to 40% efficiency than it might make sense (otherwise who cares, just use a conventional generator)"
- deleted 2y ago[deleted]
- amluto 2y agoWhat does "wire to wire" even mean? The input isn't a wire! (Do they mean they think they can synthesize fuel and burn it at 40% overall efficiency? If so, that's pretty good.)
- finnh 2y agoThe energy densities listed are flagged as approximate, so grains of salt etc, but the numbers on the page aren't entirely consistent. The stated energy density is "> 500 watthours/liter". But higher on the page we see a relative-energy-density bar graph shows lightcell at 5x the energy density of lithium batteries, and (38/5 =) 7.6x less dense then petrol. This implies an energy density for lightcell of 1250 Wh/liter, as (according to Google) petrol clocks in just under 9500 Wh/liter, and (again according to Google) lithium batteries can reach 300 Wh/liter so let's call it 250 for the math to work out. I'm curious which number is closer to truth: 500Wh/liter, or 1250? Is 1250 the theoretical max and 500 the current output in a test rig?
- enragedcacti 2y agoI believe the bar graph is showing relative energy densities of the raw energy sources so the 5x bar is just the energy density of hydrogen as H2. Your 1250 Wh/L number is right for compressed gaseous hydrogen so The 500Wh/L lines up with burning H2 at 40% efficiency. The "use fuel for extended duration" implies that they believe they can achieve a much higher Wh/L with other fuels.
- Someone 2y agoI would think the energy density varies with that of the fuel they put in. They mention hydrogen, natural gas, gasoline, ammonia, butane, propane, alcohols, syngas…. That’s about anything that is or can easily be turned into a gas that burns. also, “/liter”, for gases such as hydrogen, can be made larger by using higher pressures in your tank. On the other hand, they also say “target efficiency: ≥ 40% wire to wire”, and 40% of 1250 is 500, so it may be that.
- DaniFong 2y agothat's correct. the mass of the power related systems are a moving target based on what we're developing. but we are aiming for a medium term target of > 1 kW / kg for e.g. DC power to a drone or a hybrid drone power system
- debo_ 2y ago
- tekno45 2y agoforbes to prison pipeline?
- josefritzishere 2y agoThe solar panel conversion of sunlight to usable energy to around 20%, with a theoretical max of 30%. So it's better than that.
- qayxc 2y agoThat can't be true. The current record for non-concentrating cells is 39.5% efficiency using triple junction cells [1] Concentrating cells are at 47.6% [2] [1] https://www.cell.com/joule/fulltext/S2542-4351(22)00191-X https://www.cell.com/joule/fulltext/S2542-4351(22)00191-X [2] https://publica-rest.fraunhofer.de/server/api/core/bitstreams/ec4fb182-ed3e-4aa1-886e-4d67978cd456/content https://publica-rest.fraunhofer.de/server/api/core/bitstream...
- sroussey 2y agoIsn’t that for sunlight though? I imagine if you have a source that only radiates a single wavelength, you could make a collector for that specific wavelength that’s more efficient than some general case one. Could be wrong though.
- choilive 2y agoThe innovation here is you have a system that emits monochromatic light, and you have solar cells tuned specifically for that bandgap, plus the system is also "naturally" concentrating because the light output is incredibly bright. 3000 suns vs 500-1000 suns in typical CPV, plus they also do waste heat recycling. End-to-end efficiency of 40% is definitely feasible as advertised.
- DaniFong 2y agocorrect
- selimthegrim 2y agoSo you’re recycling the waste heat and reducing the operating temperature to normal solar cell levels as opposed to thermoelectrics?
- jasonjmcghee 2y agoI've periodically seen lightcell and danielle fong in various news / reddit /forums over the last few years and it always seems to be steeped in controversy. I know next to nothing about the field / tech, but a portion of folks seem to be like "incredible visionary etc. etc." and the another portion like "fringe science / complete bullshit / this is as realistic as cold fusion" kind of thing. Very interested to hear from folks more in the know of like, high level long term viability / what the implications are etc.
- thot_experiment 2y agoIt's a very good idea that is worth pursuing, they are pursuing it. There are many many many problems that need solving between here and "this is a better way to make energy from heat at scale than turning water into steam and spinning a turbine". The science is fundamentally sound but we're nowhere near economic viability.
- sesm 2y agoIt's not like cold fusion, the lightcell is based on well-understood physics. The author may be too optimistic with efficiency claim, but those are relatively easy to verify independently.
- brian-armstrong 2y agoIt probably doesn't help that the website looks like an American Science & Surplus catalog
- randomcatuser 2y agoMy initial thought about this was that it's using fuel to make electricity, right? Rather than using sunlight/hydro/etc -- kinda like a generator, but without the mechanical aspect?
- qayxc 2y agoTo my limited understanding yes, that's what they claim. Basically burning fuel (any fuel, really) with added sodium to create very bright monochromatic light that can then be converted into electricity using very high efficiency solar cells.
- DaniFong 2y agocorrect
- sesm 2y agoIt's a different way to capture energy stored in fuel. Normally to produce electricity from fuel you would spin a turbine, either with a mechanical engine or using vapour. But here the energy is captured through a photo cell, and the author claims that mixing sodium into certain fuels leads to a very significant part of fuel energy going into light at specific wavelength.
- cryptonector 2y agoFrom the "wire-to-wire" mention it seems that they're proposing using electric power to generate and store hydrogen till it's needed, then burn it to get electric power back. But they say other fuels work, in which case it wouldn't be "wire-to-wire", and then it'd be more appropriate to compare this to a power generator fueled by natural gas or gasoline. A generator with no pistons or turbines, just a fuel pump, sounds fantastic, if they can make it work. But you'd have to supply sodium.
- card_zero 2y agoOften I imagine storing light as fuel. Compared to hydrogen, it doesn't weigh much at all, and you can fit a lot in the same space. (Yes, I know where the halfbakery is.)
- waveBidder 2y agoJust be careful or you might make a Kugelblitz
- metalman 2y agothis was done by a company in Alberta,late 90's early 2000's, except burning diesel, same idea of tuned photovoltaics outside a quarts cylinder,where a flame was buring @ one specific coulor temperature, they were marketing an initial model for sailboats, and had working devices in service. published efficiencies wrre also 40%+ lost track of them and could not find again this effort uses excited sodium,though there will be a number of other possibilities
- DaniFong 2y agolet me know if you can remember the name or a reference, thanks!
- nialv7 2y agoTwo questions I have: 1. How much of the fuel's energy is released as heat? They have a heat recapture device, but that's only used to preheat air/fuel, and not used to generate electricity. Is the energy in the heat simply discarded? 2. Can this be made to work without the process of burning? i.e. can it function purely from heat? If it can, it might be able to replace steam turbines in, for example, nuclear plants or CSP plants. That could be hugely beneficial.
- mppm 2y ago1. The countercurrent heat exchanger achieves exactly that: exhaust gases are cooled while the inflowing fuel mixture is heated up. 2. Thermophotovoltaics in general can operate with any heat source, though this device is clearly optimized for combustion. However, the efficiency is far too low to compete in the large-scale power generation segment. This is almost certainly aimed at light aviation, heavy drones, military applications, etc., where there are not a lot of alternatives that combine small size, high power density and good efficiency.
- EA-3167 2y agoI suppose for aviation at least this is no less efficient than a gas turbine or a piston, and it's certainly a good deal quieter, has fewer moving parts, and requires less precision engineering than a jet engine. This feels tailor-made for attritable low->medium performance aviation, aka loitering munitions and drones. Strip away the "green" talk, and you're left with something that can burn just about anything (including hydrocarbons like avgas) without the complexity of a turbine.
- DaniFong 2y agomaybe so. i don't know about attritable for the first applications though. may long range or duration oversight. a large % of the cost is these specialty cells which have not been scaled up to mass production. in the denominator is the intensity of light we can produce, which is based on how high a temperature we can drive, there's a very nonlinear brightness vs temperature. but at 100 suns or so we can get near to $1/W on the cells at startup scale
- idiotsecant 2y agoThis seems like a hydrogen fuel cell with extra steps.
- DaniFong 2y agofuel cells have trouble being cheap, lightweight, high efficiency, and long lasting, all at the same time. I think this could have better scaling on all those dimensions, plus could use natural gas or propane or other fuels for when you don't have hydrogen
- cryptonector 2y agoThis seems possibly not crazy. If you can have one of these powered by natural gas and scale it to 20 kW then you have a nice home generator that is "whisper quiet" according to TFA and also: simple, easy to maintain, with few moving parts, perhaps even durable. The hydrogen aspect of this is not as interesting as the other fuels, though it'd be nice to know the efficiency numbers for different fuel types. That said, having to supply sodium might be a problem.
- adrianmonk 2y agoI wonder if they recover the sodium and run it back through the process. For that matter, could you maybe put sodium in a sealed container and then heat the whole container? Like a sodium vapor lamp but causing it to glow by throwing heat at it instead of passing electricity through it.
- DaniFong 2y agoindeed yes; the sodium is added as sodium chloride. in molten form, it wicks along sapphire and alumina surfaces, similar to a candle. it reforms into sodium chloride as the temperature drops below its boiling point -- 1400 C. we're exploring fully sealed experiments, but, you have to get the heat into the sealed cell somehow. https://patents.google.com/patent/US12136898B2/en?oq=US12136898B2+++ https://patents.google.com/patent/US12136898B2/en?oq=US12136...
- lodovic 2y agoaha, i was wondering how that worked. Creating pure sodium using the Downs process requires a lot of electricity and I doubt this engine would be economic if that was required. But it looks really promising, >= 40% efficiency is a great goal.
- cryptonector 2y agoIf such a generator were powered by nat gas rather than being a battery of sorts, then even being a bit less efficient than an ICE would be attractive if the generator were simpler and had a lower TCO than the ICE equivalent.
- fraggleysun 2y ago[dead]
- amluto 2y agoThis burns fuel at very high temperature, and I wonder how they plan to deal with NOx production. They could attempt to burn the fuel in pure-ish oxygen (with an oxygen concentrator?), but that would increase the complexity of the design and compromise the "quiet" part.
- DaniFong 2y agooxygen works and might be worth it for a stationary application like a powerplant for an AI data center. but NOx breaks down exothermically. so our approach if you hold the flame at >1300 C for less than a second or so you can destroy most of the NOx. This doesn't happen in a Diesel because the pulse stays that hot for only a short time, locking in the NOX that is produced. this is a matter of sizing the heat exchanger / flow rates correctly. we have to validate all this though. good question
- corysama 2y agoA couple video interviews with the inventor: https://www.youtube.com/watch?v=aMQYAqIxK1s https://www.youtube.com/watch?v=aMQYAqIxK1s https://www.youtube.com/watch?v=1U_KbgF-sAc https://www.youtube.com/watch?v=1U_KbgF-sAc
- bilbo-b-baggins 2y agoReminds me of the TimeCube page…
- DaniFong 2y agowe'll have to fire the web dev (me)
- palmfacehn 2y ago1.6mb, mostly images. A reasonable and to-the-point use of resources. Very few "modern" sites achieve this page weight.
- DaniFong 2y agohey! this is the inventor, danielle fong. thanks to curl-up who posted this, whoever you are. since it came up, "wire-to-wire" efficiency is what I intended to coin a synonym for electrical to electrical efficiency, with hydrogen storage. for example, an 80% electrical to hydrogen efficiency, and a 50% hydrogen to electrical efficiency, would yield a 40% wire to wire (electrical to electrical) efficiency. of course, people are working on 95% electric to hydrogen efficiency, and 50% fuel to electrical efficiency is a target. here's an illustrative energy flow diagram for us trying to hit 60% -- even more aggressive. https://x.com/DanielleFong/status/1775595848887677138 https://x.com/DanielleFong/status/1775595848887677138
- curl-up 2y agoHey, thanks for jumping into the thread! I stumbled upon Lightcell a couple of days ago after seeing the episode of First Principles [1] podcast, and found it really interesting, so decided to share what you're doing with HN. [1] https://www.youtube.com/watch?v=1U_KbgF-sAc https://www.youtube.com/watch?v=1U_KbgF-sAc
- mhb 2y agoDoes the tube become less transparent because of contaminants? Over what time scale? Is this issue exacerbated before the system is operating at full temperature (e.g., coking)? Is the sodium vapor kept in the closed cavity or is it a consumable? If a consumable how much is needed? How is it stored and dispensed?
- DaniFong 2y agowe don't see any degradation in sapphire tubes, though quartz, which is more convenient to work with because it almost completely resists thermoshock, does degrade slowly. there is a layer of salt on the tube which becomes transparent when melted, above 800 C. sodium vapor is provided to the reaction tube via direct evaporation -- melted sodium has a high surface tension and surface affinity for alumina, and wicks into the chamber. after combustion as it cools, it reforms into sodium chloride. for all fuels we've explored, sodium-chlorine is the maximum bond energy, but you can have some swaps if you have for some reaction alkali or fluorine in your fuel (don't!), the sodium chloride condenses from 800-1400C in the heat exchanger, and then wicks itself back along the surface to where it is evaporating. We hope to drive this process to some number of 99.99..% recovery, and just add granular salt (or could be a solution) to replenish. There is only a few % of salt needed in the flame, and if you recover 99.9% of the salt then you would have hundreds of total refuelings before you need to replenish a salt vessel of about 1%.
- PaulHoule 2y agoWhy would I use this instead of a fuel cell?
- DaniFong 2y agofuel cells have trouble being cheap, lightweight, high efficiency, and long lasting, all at the same time. I think this could have better scaling on all those dimensions, plus could use natural gas or propane or other fuels for when you don't have hydrogen https://news.ycombinator.com/item?id=42745109 https://news.ycombinator.com/item?id=42745109
- worik 2y ago> fuel cells have trouble being cheap, lightweight, high efficiency, and long lasting, all at the same time. Flow batteries? Not light weight (for stationary batteries, does that matter) but tick the rest of the boxes
- dang 2y agoWe detached this subthread from https://news.ycombinator.com/item?id=42745018 https://news.ycombinator.com/item?id=42745018.
- guerrilla 2y agoHey Dani, do you have any videos of prototypes in operation?
- george_rsa 2y agoDid you also consider a thermionic setup before settling for thermovoltaics? I assume it would be trickier to design and run.
- ninalanyon 2y agoHow much sodium is used? In what form is the sodium stored?
- Developerx 2y agoMoney laundering continues
- mharig 2y ago[dead]
- bythreads 2y agoIsn't "hot" sodium: Super corrosive, Highly reactive (goes booooom with water or oxygen) Expands incredibly when heated For those efficiencies i would recon you'd need temperature in excess of 1500k right? That does not sound like anything that is easily "safe" or "reliable"
- ggreer 2y agoTheir patent[1] says they use sodium chloride as the source of sodium ions. I don't know how they'll deal with the hot salt corroding stuff. Probably ceramics, superalloys, and/or special coatings. Like other types of engines, there are tradeoffs between unit cost, maintenance cost, and unit lifetime. Some applications will prefer a high unit cost with a long lifetime and low maintenance (generators at construction or mining sites). Others will prefer cheaper engines that require more maintenance (drones). And others will prefer very cheap engines that only need to work for a few hours (cruise missiles). If I had to bet, I'd say this idea is not likely to succeed. But the upside of success is so high that it's worth pursuing. 1. https://patents.google.com/patent/US12136898B2/en?oq=US12136898B2 https://patents.google.com/patent/US12136898B2/en?oq=US12136...
- nabla9 2y agoCorrect me if I'm wrong, but I don't see this being viable even if you reach your target efficiency. The problem with hydrogen is the storage cost. Improving wire to to wire efficiency can help only so much. Have you calculated the electricity cost with those efficiency rates when you include the cost of storage? "Overall cost of renewable hydrogen in 2030 varies from €2.80–15.65/kgH2." improves with scale. https://www.sciencedirect.com/science/article/pii/S0360319923032482 https://www.sciencedirect.com/science/article/pii/S036031992... Quick and dirty math, may contain errors: Lightcell target is 0.5 kWh/L. Hydrogen weighs 0.09kg/L. -> storage cost alone: ~ €0.5/kWh in large scale, €2.5/kWh in small scale. Average electricity cost in the EU has been €0.289 per kWh.
- amelius 2y agoCorrect me if I'm wrong but I think this is apples and oranges: storage can be reused, while electricity is consumed.
- nabla9 2y agoThat's the levelized cost over the lifetime. Hydrogen storage is expensive to both build and maintain. The issues include hydrogen embrittlement, constant leakage and safety issues. Containers don't last. H2 is the smallest molecule. It gets into the containers and wears them out and leaks away. Casing and seal damage is constant. Pressure vessel storage loses little below 1% leakage per day.Liquid hydrogen storage is about 1-3% leakage per day. Salt cavern storage much less but they have problem of H2S generation by Micro-organisms.
- amelius 2y ago> That's the levelized cost over the lifetime. I don't see how you can compute that cost if you don't know anything about the amount of energy that goes into and out of the container, and how often that happens.
- nabla9 2y agoThe article I'm quoting gives a range. Larger for small storage, and longer term. Smaller for others.
- jacknews 2y agoThis is a really innovative idea, even more than the previous compressed-air energy storage thing she did, which really seemed like it should have worked. I hope this one does, and I think the inventor has more than enough smarts to find out. Good luck.
- anonymousd3vil 2y agoHas this been put into practical use somewhere in public/commercial domain?
- dang 2y agoWe detached this comment from https://news.ycombinator.com/item?id=42745018 https://news.ycombinator.com/item?id=42745018.
- nextaccountic 2y agoSince you are talking about electrical to electrical, and you compare to lithium batteries in a chart, do you mean that this thing works like a battery? Like, coupled to solar power, can charge during the day (making hydrogen using some cycle) and provide electrical power during the night
- blacklion 2y agoMaking hydrogen is extremely energy-expensive and, as result, money-expensive if it is not by-product of crude oil processing. It is why hydrogen cars & Ko is not viable really if we stop to process crude oil (in additional to the problems with storage and transportation). Hydrogen is greenwashing by big oil companies, only they could provide "cheap" hydrogen, and not some water cracking with electricity from renewable sources.
- TrapLord_Rhodo 2y agoThey use a lithium battery as a base for energy density. The lightcell can use a variety of different fuels to create light in the band they want to capture. They 'lean' towards hydrogen, because it's more 'sustainable', but you can get even higher energy densities if you use petrol.
- ggreer 2y agoSourcing hydrogen from electricity means splitting water and compressing the hydrogen. The electrolysis step is around 50% efficient, and compressing the hydrogen for storage takes some energy as well. If the light cell is 50% efficient at converting hydrogen to electricity, then your "battery" efficiency is around 25%. A typical lithium battery is 80-90% efficient round trip. This setup does have the advantage that the cost of increasing storage capacity is relatively cheap. You only need to increase the size of the hydrogen tank. But power output would be limited by the size of the lightcell. There are other disadvantages besides the poor efficiency. People can't see or smell hydrogen, so you'd also need sensors to detect hydrogen leaks. Depending on how quickly the hydrogen is consumed, you might also have to deal with cold temperatures in some parts of the setup (as ideal gas law means the temperature will decrease as hydrogen flows out of the tank). And hydrogen is a very pernicious molecule. It will leak through metal tanks and pipes. It also tends to make metals brittle. And its flame is almost invisible. Lastly, the lightcell consumes salt, but I'm not sure how much so I don't know how big a reservoir would be or how often it would need to be refilled.
- oliv__ 2y agoNo contact page?
- deleted 2y ago[deleted]
- skaptiq 2y agoI am skeptical. Sounds like this has dubious practicality, perhaps more of a marketing stunt by the inventor than a real product. Maybe more likely he'll be the next Elizabeth Holmes?