Renewable Energy Sources. Sunlight. The ultraviolet B component of sunlight on the skin is an effective source of vitamin D3 (cholecalciferol) from serum cholesterol.
Summary[edit] Sunlight may be recorded using a sunshine recorder, pyranometer, or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth from the surface of the Sun. A photon starting at the centre of the sun and changing direction every time it encounters a charged particle would take between 10 000 and 170 000 years to get to the surface.[2] Solar Company Says Its Tech Can Power 90 Percent of Grid and Cars. Solar-power-plant company Ausra has released a paper claiming that solar-thermal electric technology can provide 90 percent of U.S. grid electricity, with enough left over to power a fleet of plug-in electric vehicles.
The company estimates that such a changeover would eliminate 40 percent of the country’s greenhouse gas emissions with a land footprint of 9,600 square miles, about the size of Vermont (thanks, Kent). The key to the scenario, however, is developing the ability to store energy for 16 hours, thus creating a stable power source through cloudy periods and the night, a feat that has so far eluded engineers. "If we can do storage," Ausra CEO Bob Fishman said, "We can take on coal. " The paper says Ausra expects to commercialize its energy-storage technology within two years.