[HN Gopher] Lightcell: An engine that uses light to make electri...
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Lightcell: An engine that uses light to make electricity
Author : curl-up
Score : 211 points
Date : 2025-01-14 13:36 UTC (4 days ago)
(HTM) web link (www.lightcellenergy.com)
(TXT) w3m dump (www.lightcellenergy.com)
| megaman821 wrote:
| I find the bandgap tuned cell interesting. It reminds me of a TPV
| https://www.nature.com/articles/s41586-022-04473-y which is tuned
| for infrared instead of yellow light.
| ggm wrote:
| less 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 wrote:
| I read their statement of 40% efficiency would be compared to
| the currently available photovoltaics were generally 20%
| efficiency is normal.
| enragedcacti wrote:
| the 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 wrote:
| I 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 wrote:
| I 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 wrote:
| In 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 wrote:
| we'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 wrote:
| I 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 wrote:
| If using compressed natural gas you might not need a fuel
| pump at all.
| DaniFong wrote:
| you 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 wrote:
| Amazing idea. BTW, following Danielle on X, very insightful and
| bright minded person.
| DaniFong wrote:
| thanks!
| Aachen wrote:
| Are you also on Mastodon or something similar?
| jandrese wrote:
| Bottom 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 wrote:
| If 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 wrote:
| The 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 wrote:
| And 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)"
| amluto wrote:
| What 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.)
| ieidkeheb wrote:
| If you electrolyse water with electricity into h2 and o2
| then you have tour first wire.
|
| When you reform the electrons via this engine and the
| photovoltaic cell you have your second wire.
| DaniFong wrote:
| and better than small diesels / turbines / internal
| combustion engines, at closer to 20%
| bobim wrote:
| 500 MW GE turbines claim 64% efficiency, and one can use
| the wasted heat for district heating. If we have to burn
| something then using these turbines seems to be the best
| option, running 2-3 electric cars for the emissions of one.
| And probably 3000 e-bikes. Shouldn't you compete in this
| range of efficiency?
| jillesvangurp wrote:
| There's only so much district heating that is needed. And
| mostly only in the winter. You'd actually need more
| energy for cooling in the summer when nobody wants to
| heat their place. District heating is a nice creative
| solution for waste heat. But there's a limit to how much
| of it you can use and how practical it is to use it.
| Mostly it's still waste heat that's going to be wasted
| (blasted straight into the atmosphere and space).
|
| And we don't have to burn stuff. Which is why coal and
| gas powered electricity generation is a bit under
| pressure in most markets. There are cheaper and better
| ways to get energy now.
| paulsutter wrote:
| This would be a great addition to the website. Also, talk
| about applications, even show a comparison chart vs
| existing solutions
| datadrivenangel wrote:
| The better comparison is Fuel Cells and vehicle based
| electrical generators. So you could put this in a vehicle or
| remote location, run it off hydrogen or natural gas, and get
| better efficiency. Potentially this could be a much better
| option for longer term storage in remote areas as well, where
| excess solar/wind could be used to crack hydrogen which then
| gets stored and later burned in one of these instead of a much
| much larger battery installation.
| jandrese wrote:
| You still need to truck in the sodium additive even if you're
| cracking water on site to store the H2. Dunno if you need a
| couple of mg/kg or if it is like 5% of the fuel to make it
| burn at the right color.
| hgomersall wrote:
| My understanding of fuel cells is they are rather sensitive
| to the purity of the fuel and oxygen. I wonder if this system
| is less sensitive such that, say, piped hydrogen can be used.
| DaniFong wrote:
| we think it will be, it's a good bet
| imglorp wrote:
| The gasoline vs H2 ballpark is a little wider because storage
| is not trivial for H2 -- you need to carry around a cryogenic
| and/or high pressure vessel instead of a plastic box -- which
| will detract from your p/w ratio. It also wants to leak out, so
| H2 is maybe better for fleet vehicle applications where they
| can refill daily. Granted, anything is better than burning more
| hydrocarbons!
| Tade0 wrote:
| Do you mean watts or watt-hours?
| cryptonector wrote:
| It might not be a hard sell compared to home generators. Forget
| hydrogen. Think natgas.
| tomrod wrote:
| Rechargeables/battery packs have inefficiencies due to the grid
| and/or solar cells though, in terms of where to measure
| inefficiency?
| jillesvangurp wrote:
| Battery densities are going towards > 500 wh/kg. There's some
| talk of batteries of several kw/kg long term. And since we're
| talking technology that is very much in the early stages of
| development (see the helpful image in the article), that would
| be an apples to apples comparison. 500wh/kg is basically a done
| deal. Several battery companies have announced products that
| are shipping in the next 2-3 years. From there to 1kw/kg seems
| very feasible. Several companies have hinted at that being a
| goal for them.
| gene-h wrote:
| It's useful for grid storage. Very large amounts of hydrogen
| are already stored in salt domes[0]. Current salt domes have
| volumes in the range of hundreds of cubic kilometers and can
| support pressures around 50-150 bar, translating into storage
| of thousands of tons of hydrogen. Along the texas gulf coast,
| there are hydrogen storage facilities that each store enough
| hydrogen to translate to around 100 GWh chemical energy. Being
| able to convert that chemical energy with 40% end to end
| efficiency means one site could store 40 GWh. In comparison, in
| 2023 the entire world had only around 56-200 GWh of battery
| storage capacity[1] installed.
|
| [0]https://energnet.eu/wp-content/uploads/2021/02/3-Hevin-
| Under... [1]https://www.rethinkx.com/blog/where-is-all-the-
| battery-stora...
| finnh wrote:
| The 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 wrote:
| I 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 wrote:
| I 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 wrote:
| that'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_ wrote:
| *grain of sodium
| tekno45 wrote:
| forbes to prison pipeline?
| bnetd wrote:
| More likely than you think.
| DaniFong wrote:
| come on guys
| josefritzishere wrote:
| The solar panel conversion of sunlight to usable energy to around
| 20%, with a theoretical max of 30%. So it's better than that.
| qayxc wrote:
| That 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
|
| [2] https://publica-
| rest.fraunhofer.de/server/api/core/bitstream...
| sroussey wrote:
| Isn'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 wrote:
| The 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 wrote:
| correct
| selimthegrim wrote:
| So you're recycling the waste heat and reducing the
| operating temperature to normal solar cell levels as
| opposed to thermoelectrics?
| MalbertKerman wrote:
| It's only true for a single junction. https://en.wikipedia.or
| g/wiki/Shockley%E2%80%93Queisser_limi...
|
| Multi-junction cells beat that limit, but they're still
| horribly expensive to manufacture which confines them to
| niche uses like spacecraft.
| DaniFong wrote:
| we're bootstrapping off the multijunction production while
| using just a single junction that matches the sodium D
| light well
| audunw wrote:
| But sunlight is wide spectrum, and a lot of the reasons why the
| efficiency of regular solar panels is low, is that they don't
| absorb all of the spectrum equally well. That's why there's all
| this talk of tandem solar cells with perovskites these days.
| The two solar cells can be tuned to extract energy from
| different wavelengths of light.
|
| Since the light they're making is nearly monochromatic, it's a
| lot easier to get higher efficiency. That's kind of the whole
| point of the invention.
| DaniFong wrote:
| well observed
| selimthegrim wrote:
| Schottky solar cells are also a thing although their
| efficiency isn't great either
| mhb wrote:
| That's not really relevant. They have a light source that runs
| on a fuel and are putting multiple PV cells around it. The
| efficiency they care about is the fuel in to electricity out.
| If you can put more cells around the light, the system
| efficiency goes up.
| jasonjmcghee wrote:
| I'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 wrote:
| It'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 wrote:
| It'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.
| Aachen wrote:
| How do patents work with science actually? I saw upthread
| that they've patented it, so is independent verification
| allowed so long as you don't commercially sell it, or give
| units away at all or so?
| brian-armstrong wrote:
| It probably doesn't help that the website looks like an
| American Science & Surplus catalog
| DaniFong wrote:
| oh god
| olejorgenb wrote:
| I think it looks more than good enough. It loads fast, not
| bloated and mostly to the point. What's lacking in content is
| some links to more details. (patents etc.)
| EA-3167 wrote:
| She seems like someone with an eye for a clever solution to an
| existing problem, an eye for funding (her compressed air
| "LightSail" thing raised over $70 million), and maybe a
| somewhat shaky relationship with practicality.
| DaniFong wrote:
| i'll take it
| EA-3167 wrote:
| For what it's worth, I wish you luck on this.
| DaniFong wrote:
| thanks!
| randomcatuser wrote:
| My 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 wrote:
| To 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 wrote:
| correct
| sesm wrote:
| It'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 wrote:
| From 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 wrote:
| Often 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 wrote:
| Just be careful or you might make a Kugelblitz
| metalman wrote:
| this 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 wrote:
| let me know if you can remember the name or a reference,
| thanks!
| nialv7 wrote:
| Two 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 wrote:
| 1. 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 wrote:
| I 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 wrote:
| maybe 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
| EA-3167 wrote:
| I can see that being a good use, ultra-quiet ISR that can
| stay aloft for extended times and doesn't require the
| complexity of a jet turbine? There has to be enormous
| demand for that.
| amluto wrote:
| Or turn it around a bit. If the entire device could operate
| at high pressure, then one could imagine putting it
| _inside_ a jet or rocket engine. Feed it compressed fuel
| /air mix, burn, extract some energy via
| thermophotovoltaics, and blast the exhaust out a nozzle or
| use it to spin a turbine to drive a bypass fan.
|
| An obvious down side is that most jets have very, very high
| fuel flow and power output, and the area required to
| extract enough electricity to make this whole exercise
| worthwhile may be excessive. Also, a lot of military
| applications are not going to like that sodium illuminant
| lighting up the exhaust gasses, scattering radar, or
| otherwise making the plane more visible.
|
| edit: I see that there's an effort to recirculate the
| sodium. Maybe that's enough.
| nialv7 wrote:
| Wouldn't it generate more heat than is needed to heat the
| fuel mixture?
| Dylan16807 wrote:
| The end goal isn't to preheat the fuel, it's to keep the
| heat from escaping, because you want all the heat to go
| into the sodium.
|
| The heat _is_ being used to generate electricity.
| ordu wrote:
| Fuel is burned to head sodium, if you are getting too much
| heat for your taste you can burn less fuel. It is kinda the
| goal of the exercise.
|
| But in any case, I believe that the more you heat sodium,
| the more light it emits, probably there is a practical
| limit on an incoming heat power after which the thing will
| go boom, but before that it will follow some roughly linear
| law: the more heat energy in, the more light comes out.
| Though I'm not a physicist, so I make be wrong, even if I
| do not see how I can be wrong.
| cryptonector wrote:
| 1. It's hard to capture all the waste heat. If you could run
| this indoors (but vent outdoors if the fuel is anything other
| than H2, naturally) then you could use some of the waste heat
| to heat a building.
|
| 2. There are thermovoltaic generators, but they're limited by
| the need to cool one side of the material. These are typically
| used in deep space probes that use Pu 240 to power them. To my
| knowledge thermovoltaic generation is not scalable or practical
| on Earth at this time.
| PaulHoule wrote:
| People use the thermoelectric effect for various "energy
| harvesting" applications, see
|
| https://www.tegmart.com/wood-stove-thermoelectric-
| generators...
|
| It's an area where you hear about progress from time to time
| because the technology could improve if people find materials
| that have a better ratio of electrical conductivity/thermal
| conductivity.
| DaniFong wrote:
| it can work purely from heat, however our process requires high
| temperature heat for power density.
| idiotsecant wrote:
| This seems like a hydrogen fuel cell with extra steps.
| DaniFong wrote:
| fuel 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 wrote:
| This 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 wrote:
| I 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 wrote:
| indeed 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=US12136.
| ..
| lodovic wrote:
| aha, 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 wrote:
| If 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.
| amluto wrote:
| This 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 wrote:
| oxygen 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 wrote:
| A couple video interviews with the inventor:
|
| https://www.youtube.com/watch?v=aMQYAqIxK1s
|
| https://www.youtube.com/watch?v=1U_KbgF-sAc
| bilbo-b-baggins wrote:
| Reminds me of the TimeCube page...
| DaniFong wrote:
| we'll have to fire the web dev (me)
| palmfacehn wrote:
| 1.6mb, mostly images. A reasonable and to-the-point use of
| resources. Very few "modern" sites achieve this page weight.
| DaniFong wrote:
| hey! 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
| curl-up wrote:
| Hey, 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
| mhb wrote:
| Does 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 wrote:
| we 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%.
| DaniFong wrote:
| our patent is here. https://patents.google.com/patent/US12136
| 898B2/en?oq=18%2f51...
| mhb wrote:
| Thanks
| PaulHoule wrote:
| Why would I use this instead of a fuel cell?
| DaniFong wrote:
| fuel 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
| worik wrote:
| > 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 wrote:
| We detached this subthread from
| https://news.ycombinator.com/item?id=42745018.
| guerrilla wrote:
| Hey Dani, do you have any videos of prototypes in operation?
| george_rsa wrote:
| Did you also consider a thermionic setup before settling for
| thermovoltaics? I assume it would be trickier to design and run.
| ninalanyon wrote:
| How much sodium is used? In what form is the sodium stored?
| Developerx wrote:
| Money laundering continues
| bythreads wrote:
| Isn'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 wrote:
| Their 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=US12136...
| nabla9 wrote:
| Correct 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 EUR2.80-15.65/kgH2." improves with scale.
| 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: ~ EUR0.5/kWh in large scale, EUR2.5/kWh in
| small scale.
|
| Average electricity cost in the EU has been EUR0.289 per kWh.
| amelius wrote:
| Correct me if I'm wrong but I think this is apples and oranges:
| storage can be reused, while electricity is consumed.
| nabla9 wrote:
| That'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.
| diggan wrote:
| > Average electricity cost in the EU has been EUR0.289 per kWh.
|
| I'm curious where you're getting this from, and also what other
| Europeans on HN currently pay?
|
| I'm in Spain with Octopus (via Spock's collective bargaining),
| and my effective price for December ended up being 0.131
| EUR/kWh, while you claim a price that is 3x what I currently
| pay. Just wondering if I'm an outlier with the price Spock
| managed to get us.
|
| Edit:
|
| > The EU average price in the first half of 2024 -- a weighted
| average using the most recent (2022) consumption data for
| electricity by household consumers -- was EUR0.2889 per KWh.
|
| https://ec.europa.eu/eurostat/statistics-explained/index.php...
|
| Guessing that's your source :) Seems that's specific for home
| usage though, while your comment seems to be in a different
| context. Not sure electricity is cheaper/more expensive in
| industrial contexts.
| cameronh90 wrote:
| I'm with Octopus in the UK (so not EU any more), on the Agile
| plan so it changes depending on wholesale prices. My average
| last month was PS0.2061/kWh. Fixed tariffs are closer to
| PS0.25/kWh.
| jacknews wrote:
| This 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 wrote:
| Has this been put into practical use somewhere in
| public/commercial domain?
| dang wrote:
| We detached this comment from
| https://news.ycombinator.com/item?id=42745018.
| nextaccountic wrote:
| Since 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 wrote:
| Making 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 wrote:
| They 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 wrote:
| Sourcing 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__ wrote:
| No contact page?
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