Physics Asked by Ben Caesar on June 23, 2021
Internet data is transferred through satellites. Mobile Networks are based on wireless transfer. Why can’t electricity be transferred wirelessly?
In transferring internet data using satellites, electromagnetic (radio) waves are present; this means that electromagnetic signals are sent to the Earth by use of the technology of antennas. And, electromagnetic waves, like light, are made up of photons. Photons are massless so they move at the speed of light, they do not feel the electric/magnetic fields (therefore they can safely travel around the earth), they do not interact with each other (they pass through each other easily). So, all you need is a suitable transmitter to produce (low frequency) radio waves and an appropriate receiver.
Electricity is much different since it is the result of motion of matter (electrons, protons etc) that has a property of electric charge. So, electricity involves massive particles such as electrons. To conduct electrons (for a particular electrical phenomenon), a certain path is required, which must be provided by a medium in which the electrons move. Without the medium, you have to somehow direct the electrons from the satellite to Earth using the laws of physics (Maxwell's laws). Needless to say, this is a very difficult task (the amount of energy required to transfer electrical charge between satellites will be enormously huge!). They cannot pass through each other, so they collide with other charges around the earth. On the other hand, since they have electric charge, the erath's magnetic field easily changes the direction of their movement.
Electromagnetic waves, which easily propagate (radiate) through space, are coherent states of photons. But, in electricity, you cannot have a beam of electrons even in vacuum easily, they repel each other in vacuum, so they are not suitable for transferring information.
Apart from these issues, as mentioned in the comment, electricity in the open air can act like a lightning phenomenon (Imagine constantly seeing lightning from the sky!) Furthermore, it causes a lot of (unwanted) ionization around us, which carries serious risks.
Answered by SG8 on June 23, 2021
You could transfer power via satellite. But it is hard to find a use case where that mechanism is preferred over alternatives.
You could transfer power from one sat to another, but generally it's much easier to put the power generation equipment at the point of use rather than away. The only power generation that is easy to do in space is solar, and just about any other satellite target would be able to do the same. Don't have to deal with targeting another vehicle, simultaneous station keeping, beam focusing, and lots of trouble with the transmission equipment.
That leaves ground to sat or sat to ground as options. Ground to sat could potentially let you leave large solar panels off a space vehicle. But receiving power is difficult without large inductor coils. Any benefit you'd get from leaving the solar panels off would be lost by installing the receiver equipment. And while solar panels can operate on satellites for a minimum of half the orbit (and usually much more), the vehicle would have be in line-of-sight to a transmitter station.
For sat to ground, you do have the nice option that you can harvest solar energy above the clouds and atmosphere, and then beam the energy to the earth in the form of microwaves that won't be attenuated as much by the clouds. And the size of the necessary receiver coils can be accommodated on the ground. But the big problem is making it profitable. The line-of-sight problem still hits, and the beam losses go up fast as you increase the distance. Beaming power from low earth orbit is probably doable, but any vehicle would be in a good position over a ground station for only a few minutes each day. You'd need something like a starlink constellation to get more than a few bursts of power. A high orbit sat could loiter for much longer, but the distance would be so large as to make the energy transfer impractical.
If a Bond villain wanted to do it, physics won't be standing in the way. But I suspect taking the land the receiver would be put on and replacing it with commercial PV panels and a ton of lithium ion batteries for cloudy days would be more reliable, cost much less money, and be ready to provide power in less than a month rather than a few years of R&D plus space launches.
Answered by BowlOfRed on June 23, 2021
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