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Could Earth's Infrared Emissions Be a New Renewable Energy Source?
Zothecula (1870348) writes "Could it one day be possible to generate electricity from the loss of heat from Earth to outer space? A group of Harvard engineers believe so and have theorized something of a reverse photovoltaic cell to do just this. The key is using the flow of energy away from our planet to generate voltage, rather than using incoming energy as in existing solar technologies."
Just how many watts per square meter are capturable this way? Enough to power a small LED?
A mini Dyson Sphere around the earth?
-- I have a private email server in my basement.
I've got a better way, lets release some greenhouse gases, trap the heat until the oceans boil, reuse old steam engines. WIN!
If programs would be read like poetry, most programmers would be Vogons.
And how is this supposed to be more efficient and financially better than traditional photovoltaic ?
No!
Just get Congress to abolish the Laws of Thermodynamics
No.
This is not a new idea. http://web.mit.edu/newsoffice/...
a reverse photovoltaic cell converts electrical current into light, i.e. a light bulb!
Is this a case of stupid journalism?
Exactly. A bachelor's degree is not sufficient for people working in this kind of sophisticated project.
It'd be amazing if there were a hollywood blockbuster that theorises that doing this will make the Earth run out of rotational energy and fall into the Sun.
For every problem, there is at least one solution that is simple, neat, and wrong.
They are called LEDs.
Higher frequency = higher energy, I suppose this is why infra-red capture beats radio-wave capture for energy harvesting. As TFA states, the primary hold up is getting diodes that can switch fast enough (multiple THz) to rectify the captured signal. It's probably better to stick to visible-light capture via PV, way higher energy density there.
Pesky fedoraed neckbeard earthlings living in their Moon's basement.
If you're capturing the earth's radiant energy...
Wouldn't you already have needed to solve the climate change problem?
Because this seems guaranteed to cause manmade global warming - that thermal radiation never escapes, we're harvesting the energy which creates heat...
Seriously. Capture the heat that is escaping our planet? Wow. Why don't you go to Iceland and learn what geothermal energy is instead of wasting our time. Oh yeah, and the least slashdot can do is fix the thorn in beta!
flip a switch & radio activated poop starts flying everywhere? what a gig...
Ok, even if this is just marginal on earth (because of the low temperature gradient due to the atmosphere), it should be GREAT on the moon.
During the long lunar night when temperatures drop hundreds of degrees, it should be much easier to generate significant power from the still warm lunar soil. Coupled with the solar power from the long lunar day, it should make long term lunar exploration much more feasible (and prevent problems like the shutdown of "Jade Rabbit" due to freezing).
Partly though thermovoltaic cells do exist.
Correct: it's a mostly useless idea.
The problem really is in the laws of thermodynamics.
The total energy radiated is indeed equal to the sunlight energy (although the power density is less by a factor of 4: the Earth absorbs sunlight on an area pi r^2, but radiates heat over an area 4 pi r^2)-- but usable energy is produced not by a heat source, but by the transfer of energy from a heat source to a heat sink-- the Carnot efficiency. The difficulty is that in intercepting the outgoing radiation, you necessarily put a thermal resistor into the circuit. Basically, they end up converting at efficiency characterized by the difference in temperatures of daytime and nighttime. The efficiency is terrible.
http://www.geoffreylandis.com
Or you know, we could just use the basics of passive solar heating. Capture the sun's energy with a large thermal mass and then use the concentrated energy.
I don't know, covering a quarter of an acre of land to heat my place, or some nice statues inside the greenhouse half of my dome with passive piping to a large thermal mass underground. One of them just sounds nicer and less expensive and less of a drain on the planets resources and it extends my growing season and zone.
Don't complain about syntax, grammar, or spelling. There is no.hell like input on android.
Bedouins used to make ice by leaving shallow pans of water open to the desert night air, with a blanket under the pan to keep the heat of the ground from soaking into the water. This idea is essentially using a thermocouple in place of the blanket and exploiting the temperature differential to generate electricity.
Can we dream of suburban rooftops that harvest photoelectric power by day plus whatever small amount of back-seepage of heat into the air can be reclaimed at night?
So, the earth is too hot. It absorbs energy, and then radiates it away. It reaches an equilibrium so it maintains a cyclical average temperature.
So you want to capture the radiating energy and release it on the earth?
Do you see a problem here?
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For all this theoretical work, we could think of putting a huge thermocouple with one end in deep space pulled up by the space elevator. Hey! Let us build the space elevator using two different metals and the rungs using non conducting material. Dual project both space elevator and a space thermocouple! It is totally useless except may be it can sell one more issue of Popular Mechanics with cool graphics.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
My understanding (based on a youtube video I saw once...) is the photovoltaic cells don't capture all the energy of the photons that strike them.
They absorb some energy, converting the visible wavelength photons into infrared wavelength photons.
My question is, does this basically create heat pollution, which is trapped by CO2; while if the same area were covered by white/mirror surface, more energy would exit the atmosphere into space?
How about photocells that convert UV light into energy, and give off visible light (like Florescent materials, that also produce electricity...)?
If this could be applied to my checking account I might be able to pay for my kids education before they graduate!
If it was applied to my weight I would loose the weight of the snack before it hit my stomach!
Hair loss could be a thing of the past?
Um... why not capture more of the Sun's energy on the way *in*, instead of suffering through the lossy process of absorption and re-emission? This sounds like the opposite of "blowing your own sail".
I never get why people are so set on Solar-> Electricity.
Solar -> Heat is a lot more efficient and takes a lot less technology. My father reduced his heating oil bill by 80% by putting thermal collectors on the roof and insulating the old building better. A friend who build a new house with a heat pump that basically in winter pumps heat from the ground into the house, and in summer heat from the house back into the ground.
At least in countries that have hot/cold "seasons" that seems much more efficient way to use that heat difference than trying to generate electricity from the heat difference.
So the idea is to trap infrared for energy. But infrared is effectively heat ( crudely spoken ). So you are trapping heat. Doesn't that add to global warming?
This is why people look down on environmentalists.
Given were all concerned about global warming and that the ultimate form of energy is heat, it seems a little silly to reintroduce "heat" that is escaping from the atmosphere back into the atmosphere.
Whilst clever, I don't think this is a particularly good idea in the big scheme of things.