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Drones will fly for days with new photovoltaic engine

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Re: Drones will fly for days with new photovoltaic engine

#61

Post by usrusr »

IanCal wrote: post #20
zaarn wrote: post #4

It reads a bit overhyped, considering they claim to power a house with a generator the size of an envelope; that's a hard no since there is a limit on how much energy hits every square meter and it's not THAT much.

That is talking about heat and power cogeneration, not solar power if that's what you're thinking. The paper they site [0] says the density can 300-400kW/m^2 and so at 300kW, 50% efficiency and a small C5 envelope you're looking at over 5kW. [0] https://scholar.google.com/scholar_lookup?author=M.+Bianchi&...

Solid-state cogen that is simple to include in heating furnaces would be very interesting for old stock high density residential in cold regions. Mire modern heating options than gas furnaces (various variations of heat pumps, usually coupled with solar) don't scale down to individual flats and anything more central (ideally district heating) is effectively impossible to retrofit in a free market economy. But the very high efficiency electricity conversion component of cogen is just too good to skip, so a smallest-scale cogen option would be a welcome addition to the energy mix.

Re: Drones will fly for days with new photovoltaic engine

#63

Post by raducu »

IanCal wrote: post #23

People seem to be misinterpreting this a lot. This is not about solar cells. This is about thermophotovoltalics, and the application here is using a burning fuel source to generate electricity. The "drone" the paper talks about seems to be a reference to another paper on unmanned sea vehicles though. Edit - to be fair the flying drone part is from the corresponding author.

Why couldn't this be used in cars -- 50% seems better than traditional internal combustion engines?

Re: Drones will fly for days with new photovoltaic engine

#64

Post by raducu »

Animats wrote: post #26
wumms wrote: post #9

Earlier quoted context omitted.

Yes, the max. energy from sunlight on earth hitting an envelope should be around 20-30 Watts (at 100% efficiency). Also, the reported 29.1% efficiency have been reached at a temperature of 1,207 °C.

Also, the reported 29.1% efficiency have been reached at a temperature of 1,207 °C. Another 12% and they can compete with a standard steam turbogenerator.

Perhaps for small scale applications this could be cheaper and more reliable? (if they can also get to 50% and if the materials used are cheap enough)

Re: Drones will fly for days with new photovoltaic engine

#65

Post by marcosdumay »

taneq wrote: post #27
Animats wrote: post #26

Earlier quoted context omitted.

Also, the reported 29.1% efficiency have been reached at a temperature of 1,207 °C. Another 12% and they can compete with a standard steam turbogenerator.

Wouldn't you slap this on top of a steam boiler to get the best of both worlds, though?

If you make it harder to cool the turbine by putting those neat the radiator, efficiency will go down; if you make it harder to keep the heater hot, by putting those near the fire, efficiency will go down.

As animats already said, turbine efficiency on power plants is very near the theoretical optimum. The only way left to improve it is by increasing the temperature.

Re: Drones will fly for days with new photovoltaic engine

#66

Post by Intermernet »

mattsears18 wrote: post #62

In 6th grade I connected a 9V battery to my mechanical pencil lead and lit my science folder on fire. Basically the same thing...

Not really, as it didn't use any energy not present in the 9v battery. This is about using solar energy in a more efficient arrangement, through reflection of waste solar energy to heat a medium and create a higher efficiency thermo-voltaic cell based on a photo-voltaic cell (I'm probably very wrong with my terminology in the last sentence, but, either way, it ain't no burning graphite connected to a battery.)

Re: Drones will fly for days with new photovoltaic engine

#67

Post by Tade0 »

dwighttk wrote: post #57

"For the past 15 years, the efficiency of converting heat into electricity with thermovoltaics has been stalled at 23 percent. But a groundbreaking physical insight has allowed researchers to raise this efficiency to 29 percent. Using a novel design, the researchers are now aiming to reach 50 percent efficiency in the near future by applying well-established scientific concepts." ^interesting part, the drone stuff is…

I wonder if this would be enough to create the ultimate flex-fuel vehicle?

Re: Drones will fly for days with new photovoltaic engine

#68

Post by travisporter »

macspoofing wrote: post #49
xsace wrote: post #33

Earlier quoted context omitted.

The idea behind individual solar energy is not consuming it real time but associating it with a storage solution to allow bigger throughput. You're not going to make toasts all day

>You're not going to make toasts all day I bet you're doing something throughout the day. Maybe not making toast, but cooking, ironing, heating, cooling, watching TV etc. I'm not sure you can rely on any excess energy being available for storage if you're not connected to the grid. >The idea behind individual solar energy is not consuming it real time but associating it with a storage solution to allow bigger through…

“Forcing over building of” solar is still cheaper than building a new coal or gas plant in some areas. I am positive there are plenty of people who live off grid and do not always need gas or biofuel backup.

Re: Drones will fly for days with new photovoltaic engine

#69

Post by pjc50 »

acje wrote: post #47

I wonder if it is feasible to make PV panels that concentrate the IR part of the light spectrum and guide it to a TVP unit through fiber optics.

I'm having trouble envisaging how this would work?

What might work though is what I'm going to call Pink Floyd Concentrated Solar: collimate light from the sun over a large area into a beam, then run that beam through a prism. That would allow the use of solar cells with different efficiency bands.

(I doubt this would make overall sense given the cost and size of optics, but it's fun to think about)

Re: Drones will fly for days with new photovoltaic engine

#70

Post by blamestross »

dwighttk wrote: post #57

"For the past 15 years, the efficiency of converting heat into electricity with thermovoltaics has been stalled at 23 percent. But a groundbreaking physical insight has allowed researchers to raise this efficiency to 29 percent. Using a novel design, the researchers are now aiming to reach 50 percent efficiency in the near future by applying well-established scientific concepts." ^interesting part, the drone stuff is…

Does this mean we can make lighter/smaller RTGs?
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