# Energy Summary
APES Energy Unit
Big bang: Hydrogen->fusion -> Helium ->iron stars (red giants)
Giant red giants ->supernova->all elements beyond iron
Hydrogen, Helium and other elements->our sun
Sun: Hydrogen fusion->helium (helios means sun in greek)
Direct solar energy:
Sun is source of photosynthesis
Photosynthesis: light + CO2 + water->sugar (carbon based fuel)
Biomass is using this as renewable fuel (wood, sugarcane->ethanol)
Dead plants and animals (fossil fuels) + oxygen -> energy again
Fossil fuels are slow legacy solar energy, stored from eons ago
Sun is also source of radiant energy:
Solar thermal: capturing radiation, turn to heat, store this thermal energy
Solar photovoltaic: capture radiation, move electrons, create direct current electricity (plus and minus, just like batteries)
Wind energy: from solar radiation heating air, moves across the surface, moves blades, turbine, electricity
Tidal energy: caused by gravity from the sun (and moon) pulling on water, moving it through turbines, electricity
Uranium from those supernova is in the earth core:
Slow nuclear energy: geothermal (actually geo-nuclear-thermal) energy
Fast nuclear energy: dig up Uranium, create heat, make steam, move turbines, create alternating current electricity (like in your house)
Future energy: Use Hydrogen isotopes to create fusion: H + H ->He (like the sun)
issues: 1 million degrees, hard to ignite (pressure and temp like in the sun core)
Renewable Energy:
Direct solar: solar thermal, solar PV
Indirect solar: wind energy, tidal energy
Photosynthesis solar: biomass (wood, sugarcane, ethanol)
Non-renewable energy: (e.g. not from the sun each day)
Fossil fuels: coal, oil, natural gas
Nuclear fuels: uranium, thorium
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