Sun is 99.85% of mass of the Solar System Suns magnetic polarity flips regularly with 22-year cycle. Magnetic field is concentrated by 1000x in center of sunspots. Suns luminosity has increased by 30% since its birth --- now grows by 1% every 100 Myr. May cause a runaway Greenhouse on Earth in 500 Myr that will extinguish multicellular life. Nuclear Physics Binding Curve Fission Fusion In its core, the Sun fuses 620 million metric tons of hydrogen each second. Process of nuclear fusion within stars (fusing hydrogen into helium) Solar Flares A full-disk multiwavelength extreme ultraviolet image of the sun taken by Solar Dynamics Observatory on March 30, False colors trace different gas temperatures. Reds are relatively cool (about 60,000 K); blues and greens are hotter (greater than 1 million K). Fig. 6-3, p. 165 Source: LLNL 2008; data are based on DOE/EIA-0384(2006). Credit should be given to LLNL and DOE. 10 ~44% Efficiency U.S. Energy Flow, 2006 (Quads) U.S. Energy Flow, 2006 (Quads) >70% of primary energy for the transportation sector and >60% of primary energy for electricity generation/use is lost Total Rate of World Energy Use = 18 Terawatts 85% is from Fossil Fuels Total Power from the Sun at Earths Surface = 125,000 Terawatts!! ~7000x Total Human Energy Use 1 Hour of Sunlight = 1 Year of Human Energy Use Solar Photovoltaic Commercial Panels: 12% Efficiency Experimental Panels: 22% Efficiency Nanotech Cells: >40% Efficiency Direct electric conversion with several materials Inexpensive organic materials now exceed 6% efficiency For Large-Scale Production, Mirrors Easier/Cheaper Than Panels Example: Kramer Junction solar power plants, Mojave Desert, CA * 150 MW With 10% efficiency: 150 Mw = Solar Farm 2.5 km x 2.5 km (Cost $0.25/kW/hr) Average Solar Power Potential (factoring in atmosphere, clouds & nighttime): 235 W/m 2 Increase in Solar Photovoltaic Power: But issues with toxicity and reliability Second-generation solar power: BIOMASS Second-generation solar power: TRASH Second-generation solar power: BIOFUELS Second-generation solar power: COAL Second-generation solar power: OIL & GAS Second-generation solar power: WIND Second-generation solar power: HYDROELECTIC