There has been a proposal to produce solar-electricity in North Africa and transmit up to fifty gigawatts of power into Western Europe by 2050. One generation technology involves concentrating the infrared spectrum on to solar tower while advanced photovoltaic technology would convert the combination of the ultra-violet and infrared light to electricity. Advanced lens technology could be developed to isolate the yellow spectrum from the infrared and ultra-violent spectra. The lens technology, the space plane technology and the solar-to-laser evolving technology all have potential for further development. Their convergence could allow natural light to be transmitted around the world for the purpose of illuminating entire cities.
The yellow spectrum of light would be collected in deserts at solar-electric installations. It would then be amplified into laser light using advanced solar-to-laser conversion technology. The yellow laser light would then be aimed at a future satellite technology and be reflected back to earth and illuminate metropolitan areas before sunrise and after sunset. The moon is the earth's biggest satellite with an orbit that is between 223,000-miles and 250,000-miles from the earth. Telecommunications satellites typically orbit the earth at altitudes of 140-miles to 250-miles.
A single reflecting satellite would need to orbit at much higher altitudes (1000-miles to 5000-miles) and be much larger in size than telecommunications satellites. Future optical technology could transmit yellow laser light to a satellite in a low orbit (less than 500-miles) where the laser light may be re-amplified before being beamed to a second satellite. That second satellite may be a reflecting satellite that may occupy a higher orbit. It would receive the yellow laser light and use it to illuminate part of a city after sunset of before sunrise.
Modern laser technology could be developed to transmit highly concentrated beams of yellow laser light to the reflecting surface of reflecting satellites. It may be possible to concentrate the beam of amplified yellow light so as to allow the reflecting satellites (in high orbit) to be built to diameters of under 100-feet. That light could be then reflected back to the earth's surface where it could then illuminate a metropolitan area of several miles in diameter.
Such a satellite could be placed in an orbit over the central USA and receive concentrated yellow light from a solar-electric installation in the Nevada Desert region. That light could be reflected off the satellite to illuminate part of New York City after their sunset during winter. Some of that light could also be reflected off a satellite in orbit between Honolulu and San Diego to provide Honolulu with a few hours of natural light prior to sunrise.
During the northern winter a reflecting satellite traveling in orbit above the North Atlantic Ocean could reflect yellow light from the Western Sahara over New York City for 2 to 3-hours prior to sunrise. Solar technology placed in the deserts on either side of the Red Sea could provide a combination of solar electricity and yellow laser light. Amplified yellow laser light from that region could be aimed at reflecting satellites so as to illuminate some Western European cities prior to their sunrise. That light could then be reflected off other satellites in orbit over Asia so as to illuminate parts of a few cities in China and Southeast Asia after their sunset. It also may be possible to use two satellites in tandem so as to relay laser light to cities in Japan following their sunset.
The reflecting satellite and yellow laser technology could theoretically be used to transmit light in a north-south direction during northern winters. Sunshine is scarce in northern locations during winter. Amplified yellow light collected in the Nevada Desert could be reflected off a satellite that would be in orbit above Seattle. It could used to illuminate Fairbanks in Alaska to extend daylight hours and reduce electric consumption related to lighting. In a similar way yellow laser light from North Africa and the Middle East could provide extra natural illumination to cities in Sweden, Norway, Finland and part of Russia.
A very large part of Australia is a desert with potential to develop solar electric as well as solar-luminescent technology. Concentrated yellow light from Australia could be reflected off a satellite to illuminate cities in India before their sunrise and cities in New Zealand and Hawaii after their sunset. The use of satellites in tandem could allow yellow light to be collected in the desert of Australia were it would be amplified before being transmitted to a relay satellite. The light would be re-amplified at the relay satellite and be transmitted to a reflecting satellite to illuminate metropolitan areas in America after sunset and before sunrise.
Yellow light may be collected and amplified at various installations in the desert regions around the world (Australia, North Africa, Asia, Southern Africa and Chile). That light may be aimed at relay and reflecting satellites to illuminate selected agricultural areas so as to increase crop yields. Extended hours of natural light could eventually become available in many cities around the world courtesy of advances in solar-to-laser technology as well as in satellite technology.
Solar-to-laser technology could be applied to the ultra-violet spectrum of solar light. Amplified ultra-violet (laser) light could be beamed to relay satellites where it would be re-amplified and transmitted to a second satellite. The second satellite could beam the ultra-violet laser light to arrays of photovoltaic panels on earth and allow electric power to be generated after a local sunset or before a local sunrise. It may be cheaper to transmit solar electricity over extended distances via laser than by using long-distance transmission lines. Ultra-violet laser light can also be used to energize solar powered aircraft that carry photovoltaic panels under their wings. Military "targeting" technology could ensure that the u-v laser light that is transmitted from locations on earth remain on target under the airplane wings.