unit 22: alternative energy sources

itp 150 - prof. djassemi - cal poly

renewable energy

energy from a source that isn’t depleted when used (ex: wind, solar)

renewable energy: % used for energy consumption vs. generation

• consumption: 12%

• generation: ~20%

sustainable energy

energy that meets present needs w/o compromising future gens

2 conditions for sustainability

1. produced as fast/faster than consumed

2. doesn’t pollute environment

how energy source is determined as sustainable

1. does it pollute?

2. how fast is it produced?

3. how fast is it consumed?

energy source 1: fossil fuels

• coal, oil, & natural gas formed from ancient plants & animals

• non-renewable, non-sustainable

fossil fuels electricity generation

burn fuel → heat water → steam → turbine → generator → electricity

advantages vs. disadvantages of fossil fuels

• pros:

  • cheap

  • large ⚡️ output

  • easy transport

  • efficient power plants

• cons:

  • CO₂ emissions (greenhouse effect)

  • acid rain from sulfur dioxide

  • oil spills

  • mining damage

energy source 2: nuclear power

• nuclear fission → heat → steam → turbine → generator → electricity

• non-renewable, non-sustainable (w/ current tech)

advantages vs. disadvantages of nuclear energy

• pros:

  • huge energy output

  • no CO₂ emissions

  • reliable

  • small fuel amt needed

• cons:

  • radioactive waste

  • long-term storage risks

energy source 3: solar energy

• photovoltaic (PV) cells converting sunlight into ⚡️

• generation process: photons knock electrons loose → ⚡️ current produced

• renewable, sustainable (limited as sole source)

advantages vs. disadvantages of solar energy

• pros:

  • free energy source

  • no pollution

  • good for remote areas

  • reduces electricity bills

• cons:

  • no ⚡️ at night

  • expensive panels

  • weather-dependent

energy source 4: wind power

• wind spins turbine blades → rotor → generator → electricity

• renewable, sustainable (limited as sole source)

advantages vs. disadvantages of wind energy

• pros:

  • free fuel

  • no emissions

  • small land use

  • good for remote areas

• cons:

  • wind = unpredictable

  • noise pollution

  • visual impact

  • dangerous for airborne birds

yaw mechanism

• system that rotates the wind turbine horizontally so it faces the wind

• keeps turbine aligned w/ wind to maximize power output

turbine blade pitch

• changing angle of turbine blades to control power & rotor speed

• adjusting blade pitch maintains stable power during strong winds/turbulence

energy source 5: hydroelectric power

• water stored in dam → flows thru turbines → generator → electricity

• renewable, sustainable (depends on environmental impact)

advantages & disadvantages of hydroelectric power

• pros:

  • no pollution

  • reliable

  • low operating cost

• cons:

  • expensive dams

  • floods ecosystems

  • environmental impact

energy source 6: biomass energy

• energy from organic waste/plant material

• ⚡️ process: waste → gasification → burn gas → steam → turbine → electricity

• renewable, sustainable (questionable due to pollution)

advantages vs. disadvantages of biomass energy

• pros:

  • uses waste materials

  • cheap fuel

  • renewable supply

• cons:

  • produces greenhouse gases

  • hard to collect enough material

energy source 7: geothermal energy

• hot underground water/steam → turbine → generator → electricity

• renewable, sustainable (depends on site management)

advantages vs. disadvantages of geothermal energy

• pros:

  • no fuel needed

  • low pollution

  • reliable

  • small land use

• cons:

  • difficult drilling

  • some sites run out of steam

residential geothermal heat pumps

• exchanges heat btwn earth & a building for heating/cooling

• advantages:

  • up to 50% energy savings

  • no direct emissions

  • highly efficient

fuel cell tech

• device that generates ⚡️ through a chemical reaction btwn hydrogen & oxygen

• renewability: depends on how hydrogen is produced

how fuel cells work

• hydrogen → anode

• oxygen → canode

• electrolyte moves ions → electrons create electricity → water vapor produced

advantages vs. disadvantages of fuel cells

• pros:

  • very low pollution

  • quiet operation

  • driving range: ~300-400 mi

• cons:

  • hydrogen storage difficult

  • $$$

  • limited fueling stations