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A concept paper published in ACS Photonics, describes a photovoltaic cell that works at night.
According Jeremy Munday, one of the paper's authors and a professor in the Department of Electrical and Computer Engineering at UC Davis
a specially designed photovoltaic cell could generate up to 50 watts of power per square meter under ideal conditions at night, about a quarter of what a conventional solar panel can generate in daytime
The described cell is thermoradiative and emits infrared radiation to space, which has a much lower than Earth temperature of 2.73 Kelvin.
"A regular solar cell generates power by absorbing sunlight, which causes a voltage to appear across the device and for current to flow. In these new devices, light is instead emitted and the current and voltage go in the opposite direction, but you still generate power," Munday said. "You have to use different materials, but the physics is the same."
The device would work during the day as well, if you took steps to either block direct sunlight or pointed it away from the sun. Because this new type of solar cell could potentially operate around the clock, it is an intriguing option to balance the power grid over the day-night cycle.
Journal Reference: [Nighttime Photovoltaic Cells: Electrical Power Generation by Optically Coupling with Deep Space, ACS Photonics (DOI: 10.1021/acsphotonics.9b00679)
(Score: 2) by JoeMerchant on Sunday February 02 2020, @05:10PM (7 children)
You don't so much see this case as feel it.
Go to the desert, on a clear and preferably windless night, stand outside and feel the heat leave your body and the landscape into the sky. That is the principle this operates on, and it is a powerful one.
🌻🌻 [google.com]
(Score: 5, Interesting) by pTamok on Sunday February 02 2020, @05:44PM
This is how ancient Egyptians and ancient Persians made ice [fieldstudyoftheworld.com].
p 41, Icehouses, Tim Buxbaum [google.co.uk]
New insight on passive ice making and seasonal storage of the Iranian Yakhchal and their potential for contemporary applications (Hareth Pochee, John Gunstone, Oliver Wilton) [maxfordham.com]
(Score: 2) by Arik on Sunday February 02 2020, @06:40PM (5 children)
If laughter is the best medicine, who are the best doctors?
(Score: 0) by Anonymous Coward on Sunday February 02 2020, @07:16PM (1 child)
Compare going outside on two windless nights, both with air temperatures of 10C. One night with clear skies, one with clouds. The difference is significant.
(Score: 2) by Arik on Sunday February 02 2020, @08:38PM
If laughter is the best medicine, who are the best doctors?
(Score: 2) by JoeMerchant on Sunday February 02 2020, @09:08PM (2 children)
The air temperature falls because of space... it's not as if the ground under your feet sucks up all the heat...
As AC says: the effect is much MUCH reduced with heavy cloud cover - one demonstration of a greenhouse type effect.
The other thing to remember, space is cold, really really cold - 3K cold. So, when your ground temp falls from 40C to -10C, that's only dropping from a 313/3K differential to a 263/3K differential - even at -10C you've got a hell of a long way further you could fall if the Earth didn't rotate you back to face the sun.
🌻🌻 [google.com]
(Score: 2) by Arik on Sunday February 02 2020, @10:15PM (1 child)
Exactly my point.
"even at -10C you've got a hell of a long way further you could fall if the Earth didn't rotate you back to face the sun."
But look, even if we could somehow change the rotation of the Earth to eliminate day and night - to keep the same side facing the sun all year - that would not cause the backside of the Earth to reach 0k. Not ever - not until the Sun itself cools down considerably, at least. The heat absorbed on the side facing the Sun would be passed on around the globe. I suppose the oceans would be eliminated quickly, the atmosphere slowly, and the far side would be quite cold and icy; but not to 0k.
If laughter is the best medicine, who are the best doctors?
(Score: 2) by JoeMerchant on Monday February 03 2020, @02:58AM
Clearly not.
First, space itself has ~3K background temperature, at least in our neighborhood.
Second, the atmosphere would conduct a great deal of heat over from the day side.
Third, something like a grape skin thickness beneath our feet (in relative terms) is magma at roughly 975K.
However, even with all those in mind, also bear in mind that the night side of Mercury is -180C (155K) while the day side cooks at 430C (700K), precisely due to passive radiation of heat to space and the tidal lock that keeps it from rotating. For reference, at our distance from the sun, the moon swings from -173C (100K) to 127C (400K) as it passes through night and day on it's 29 day solar cycle.
So, while we've got stuff on the ground "glowing hot" at 260+K, it's not hard at all to imagine extracting energy from that glow before it heads on to the rather large heat-sink of outer space, particularly in the "color bands" (infra red, I believe) where the atmosphere is most transparent to the glowing energy.
🌻🌻 [google.com]