Focus The Sun

Premise -- A Fresnel lens 3 km in diameter would deliver 14 trillion watts of electricity to Earth.

Problem -- What orbit should the Fresnel lens occupy?

Solution 1 -- Two Fresnel lenses in polar orbits around the sun, on mutually perpendicular planes would guarantee at least one line of sight with Earth at all times. Microgravity would allow very large lens structures, and a malfunction would not result in a total loss, with some hope of recovery and repair. However the lens would not be directly between the Sun and Earth, so the optics would have to bend the beam somehow. Is there a reflector based entirely on lossless prismatic effects rather than mirrors?

Solution 2 -- Use a solar sail to place the Fresnel lens in an Earth-synchronous forced-orbit around the Sun. The lens would always have a line-of-sight and the beam would not have to be bent very much. However, the lens would experience gravity, and sag under its own weight. A large lens might not be possible without substantial truss structures supporting it, and if the solar sail malfunctioned, the entire powerplant would plunge straight into the Sun and would be lost forever.

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What other solutions are there? Inclined orbits? Resonant orbits? Retrograde orbits? Lagrange points? What about strange orbits like Asteroid 3753 (1986TO), called "Cruithne", that follows Earth, then reverses direction, in a strange horseshoe pattern? Can that be achieved artificially in a more beneficial manner, maybe by a powerplant inside Mercury's orbit, creating something essentially Earth-synchronous?