1. Energy in society
Seo
Physics

2. Renewable vs. Nonrenewable
Resource is naturally replenished at a rate greater than it is used
Ex. solar, wind, hydro, biomass, geothermal
Nonrenewable
Resource is used at a greater rate than it renews itself
Ex. Fossil fuels (coal, oil, natural gas) and uranium (debatable)

3. Sustainable
Operationally define as a process that uses natural resources at a rate that does not use up the resource
Energy sources in Tucson sustainability primarily concerns water and economic cost

4. Hydro Impoundment-type Current/tidal type Dams like Hoover Dam
water rushes through a turbine turning an electric generator
GPE  KE
Current/tidal type
River or ocean current turns turbine
similar to wind power

5. Wind Air transfers to the turbine generator turns
KE from air  KE from turbines  EE from generator
Vertical axis on left
Omni directional
Horizontal axis on
right
Directional (pivots)

6. Solar Energy from the sun Source of energy for
Photovoltaic (Light to electricity)
Thermal heating
Wind
Thermal expansion causes high pressure
Hydro
Evaporation part of water cycle
Biomass
photosynthesis

7. Photovoltaic Cells Directly convert solar energy to electrical energy
Photons excite electrons from valence band to conduction band to create an uneven charge distribution that causes a pressure difference (voltage)
Larger cell will collect more power
More voltage or current or both?
More current
How could voltage be increased?
Increase the number of cells on the panel and connect them in series

8. Solar Thermal Use solar energy for heating
Thermal energy can be used to operate a steam turbine or used directly for space/water heating
PS20 plant in Seville, Spain
Produces 20 MW of power

9. Fossil Fuels Coal, Oil and Natural Gas
Hydrocarbons formed under high pressure and heat from organic matter over millions of years
Generate electricity burning fuel to power turbine (generator)
Energy density
Gasoline ~120,000,000 J/gallon
Diesel ~ 136,600,000 J/gallon
LNG ~ 78,300,000 J/gallon
Coal (anthracite) ~ 29,000,000 J/kg

10. Biomass Biomass to electricity Biomass to fuel
Fuel source can be anything organic from trash to vegetation and animal waste to specialized crops
Fuel source is usually burned to heat steam in steam turbines
Biomass to fuel
Biodiesel and ethanol derived from agricultural waste/excess crops like corn, soybean or algae through processes like pyrolysis or fermentation

11. Geothermal
Heat from the core of the earth travels near the surface through the crust and transfers heat to the mantle
Thermal energy comes from
Residual thermal energy from when earth formed
Frictional heating caused by the motion of the dense iron core
Decay of radioactive elements

12. Nuclear
high energy neutron collides with a uranium atom splits it into smaller atoms like strontium, ruthenium, tellurium, and neodymium
E=mc2
The heat is used to power steam turbines to generate electricity
Non-renewable
EX. Lockheed Martin fusion reactor
Fuses deuterium 𝐷 1 2 (hydrogen with one neutron and one proton) and tritrium 𝑇 1 3 (hydrogen with two neutrons and one proton) into helium 𝐻 𝑒 2 4
Difficult to control fusion reactions to generate net electrical energy