alt Hacker NewsLightcell: An engine that uses light to make electricity
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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?
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?
A couple video interviews with the inventor:
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 €2.80–15.65/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: ~ €0.5/kWh in large scale, €2.5/kWh in small scale.
Average electricity cost in the EU has been €0.289 per kWh.
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?
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
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.
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"
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.
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?
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.
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.
Amazing idea. BTW, following Danielle on X, very insightful and bright minded person.
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.
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
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.
Did you also consider a thermionic setup before settling for thermovoltaics? I assume it would be trickier to design and run.
The solar panel conversion of sunlight to usable energy to around 20%, with a theoretical max of 30%. So it's better than that.
Hey Dani, do you have any videos of prototypes in operation?
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.)
How much sodium is used? In what form is the sodium stored?
I 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?
No contact page?
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.
Has this been put into practical use somewhere in public/commercial domain?
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Money laundering continues
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