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neilzero
2010-Sep-19, 01:50 PM
From the space elevator thread in Space Exploration, Gourdhead typed "motivated by interests in "green" power production, the radiation of power to Earth's surface via microwave transmission and reception has been proposed with no clear conclusion drawn concerning the efficiency of such a process. Although I am highly sceptical about the viability of a space elevator for Earth usage, I am eagerly supportive of a similar device to be used to conduct electrical power from synchronous orbit to the surface as a backup system to microwave radiation in case our technology is not yet up to the task."

Possibly a CNT break though has occurred which will permit construction of a space elevator soon. If the CNT ribbon is twenty or more times stronger than Kevlar (unlikely that good a breakthrough) then perhaps a strand of super conducting material can be in the tether, as our best super conductors have to be cooled with liquid nitrogen or equivelent temperature. There is a slight possibility that an average of one million watts would be delivered (by a single strand) to the anchor ship, which would supplement the energy needs of the anchor ship. The polarity would likely reverse at least occasionally. During the low current transitions a solar power station at the counter weight, could likely supply another megawatt, average. The abandoned climbers at the counterweight have solar panels optimized for the laser frequency, but likely usable working from our sun's light spectrum.
I'm assuming the ribbon is about 100,000 kilometers long or the 92,000 kilometers Dr. Edwards used for calculations.
There is some doubt that the super conductor and cooling system can tolerate being squeezed by the pinch rollers of the climbers, which are yet to be demonstrated, except at low speeds up to one kilometer at contests that have been held several times.
I believe Dr. Edwards optimistically predicted that about 400 watts would be put on the grid, for each square meter of photovoltaic panel = over all efficiency about 30%.
If Solaron meets the contract with the California power company, 100 watts is likely, as thin film PV is presently about 15% efficient, and no other option will likely be available large quantity and space rated by the contract date. It is prohibitively costly to get much heavier high efficiency solar panels into space. The space elevator will not be operational until after the Solaron contract date, but is a possibility for a few years later.
Two conductors in the ribbon is likely impractical except at low voltage which would deliver less than one million watts. Two space elevators = one conductor each, might allow a billion watts, at a million volts, but tangling is likely unless spaced many kilometers apart = likely not a problem which will want to be tackled until there are several space elevators. Please correct if I have some of this wrong and please embellish. Neil