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US startup begins producing 40%-efficient thermophotovoltaic cells

pv-magazine.com

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Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#111

Post by regularfry »

throwaway20304 wrote: post #44
spoiler wrote: post #41

Earlier quoted context omitted.

A bettery, from the viewpoint of a circuit, is just another source. So we could call them chemical electricity generators, if we're brave enough to indulge the confusion

I still don't quite understand it. Where does the battery get the energy? I understand that there's no difference in a circuit, but why is this comparison relevant? Many power sources are way less efficient that using a battery, but we need to charge the battery.

Alkaline batteries are never charged, per se. The energy comes from the one-way chemical breakdown of cathode and the anode.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#112

Post by fnordpiglet »

15457345234 wrote: post #46
londons_explore wrote: post #37

> emitter temperature of 2,400 C GE's combined cycle turbines can get system level efficiency of around 63% from these sorts of temperatures. (For those not familiar with them: They're basically aircraft jet engines followed by steam turbines using the hot exhaust. They are in widespread use to generate electricity from gas, but they can also run off any other liquid fuel, or simply off anything that gets very hot.)

There are a looooot of moving parts in a CCGT generating station, multiple oil loops, multiple coolant loops, many consumables, a complex control flow. Being able to replace the combined turbine/alternator assembly with a 'when it gets hot, voltage comes out' unit would give you significant reliability gains and lower operating costs.

Yeah came here to say this. A complex turbine setup is large and complex. A panel setup with liquid cooling and a heat exchanger isn’t.

I feel like these sorts of things should be useful in situations where there’s a lot of excess heat in some other process that’s typically wasted. Smelters, incinerators, high temperature chemical reactions, etc. Because they are presumably not large you can clad and enclose the high temperature area in these sorts of panels and capture 40% of the wasted energy and divert it back into the process. That would have compounding effects.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#113

Post by fnordpiglet »

pbmonster wrote: post #49
15457345234 wrote: post #46

Earlier quoted context omitted.

There are a looooot of moving parts in a CCGT generating station, multiple oil loops, multiple coolant loops, many consumables, a complex control flow. Being able to replace the combined turbine/alternator assembly with a 'when it gets hot, voltage comes out' unit would give you significant reliability gains and lower operating costs.

Well, you still have to cool those cells. It's still a heat engine, after all. And you can't just let radiation do the job for you, no way the semiconductor likes getting anywhere close to this hot.

Liquid cooling with a heat exchanger can be pretty low profile.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#114

Post by benj111 »

nine_k wrote: post #90
benj111 wrote: post #74

So what are the trade offs between these and peltier devices? They're much more efficient, I assume much more expensive?

Expense is usually a function of scale. Everything new and custom is expensive. Electronic chips with incredibly complex structure of some rare materials inside them are priced in cents.

What I was getting at is I think I might be missing a gotcha.

There's a fair amount of niche applications where peltiers are currently used even though they aren't very good.

But no one's mentioning them as an alternative to peltiers.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#115

Post by AtlasBarfed »

londons_explore wrote: post #84
labcomputer wrote: post #79

Earlier quoted context omitted.

You have to do some “energy accounting” sleight of hand to get 63%, though. That number assumes that some of the low-grade waste heat can be used for, e.g., district heating. It’s also a peak steady-state number, only achievable under optimal load conditions.

I believe that figure is electric efficiency only. For combined heat and power plants, the efficiency routinely goes over 80%, and for heat-only plants, 95+% is common. However, there is still sleight of hand. The efficiency quoted is when the equipment is new and clean. Fouling and wear both take single digit percentages off. Also, they use the lower-heating-value for the gas energy supply. That, in my view, is dish…

And of course carbon removal from burning the natural gas is totally out of the equation.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#116

Post by fnordpiglet »

pjc50 wrote: post #76
leereeves wrote: post #63

Earlier quoted context omitted.

Wouldn't this process also contribute to climate change by trapping energy on Earth that would have been reflected back into space? Edit: Apparently, yes, current PV solar may also do this: > We found temperatures over a PV plant were regularly 3–4 °C warmer than wildlands at night https://www.nature.com/articles/srep35070 But I suspect/conjecture that turning sunlight directly into heat, then turning some of that he…

There is an "albedo effect", yes, but it's not cumulative while CO2 in the atmosphere is. Arguably there should be a "white roof" campaign for urban areas, it would be a cheap way of reducing the urban heat island effect.

Many major cities already have such regulations even outside desert areas.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#117

Post by kgabis »

awestroke wrote: post #51
kgabis wrote: post #50

Earlier quoted context omitted.

We also have this thing called night, as well as weather and seasons.

And we also have this looming thing called climate emergency, which should conceivably motivate us to forge ahead with renewables and adjust our energy usage patterns to match production peaks, lest we doom humanity to extinction

Renewables alone won't let us decarbonise, they are too expensive and intermittent. We need lots of nuclear if we want to stand a chance.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#118

Post by benj111 »

londons_explore wrote: post #85
benj111 wrote: post #72

Earlier quoted context omitted.

Afterburner? That wouldn't impact blade temp.

terrible for efficiency.

Is the jet used to superheat water, or directly drive a turbine generator?

If the latter, it would be a waste of time, if the former then you just want heat, and the fan is there to provide enough oxygen to burn the fuel so why would it impact efficiency?

Edit: I was thinking literal jet engines that have indeed been used as generators, not combined cycle generators.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#119

Post by kgabis »

ChrisRR wrote: post #77
kgabis wrote: post #50

Earlier quoted context omitted.

We also have this thing called night, as well as weather and seasons.

I don't know why people always comment this on posts about renewables as if it's some kind of gotcha. When there's no sun, then other countries probably have sun. When there's no sun, there's hydro. When there's no hydro there's wind. When there's no wind, there's tidal. When there's no tidal there's geothermal. And when there's none of those, there's stored energy in batteries. And if for some reason all of those co…

Those things don't add up - there's often no wind, no sun, no hydro. Energy storage is also orders of magnitude too small to store reasonable amounts of energy. I would argue we should start with the cleanest source of energy (which is nuclear, of course) and fill the gaps with renewables.

Re: US startup begins producing 40%-efficient thermophotovoltaic cells

#120

Post by lazide »

ChrisRR wrote: post #77
kgabis wrote: post #50

Earlier quoted context omitted.

We also have this thing called night, as well as weather and seasons.

I don't know why people always comment this on posts about renewables as if it's some kind of gotcha. When there's no sun, then other countries probably have sun. When there's no sun, there's hydro. When there's no hydro there's wind. When there's no wind, there's tidal. When there's no tidal there's geothermal. And when there's none of those, there's stored energy in batteries. And if for some reason all of those co…

Many of the plans for the future currently involve drastically undersized battery storage and decommissioning nuclear. That’s why.
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