Environmental Science (Chapter 16)

these are just notes

Reasons for renewable energy

• Reduce air pollution and greenhouse gas emissions.

• Diversify energy mix.

• Create green-collar jobs.

Solar Energy

• Passive: Building design to absorb sunlight.

• Active: Devices like flat-plate solar collectors.

• Photovoltaic (PV): Converts sunlight → electricity.

• Thin-film solar cells: Cheap, flexible, less efficient.

• Net metering: Excess power subtracts from bill.

• Pros:

  • Inexhaustible, clean, low maintenance.

  Cons:

  • High up-front cost, not sunny everywhere, intermittent.

Wind Power

• Turbines convert wind → electricity.

• Turbines can yaw to face wind.

• Often built in wind farms, especially in Great Plains and mountains.

Pros:

• High EROI (energy return on investment).

• Reduces emissions.

• Scalable.

Cons:

• Intermittent.

• Needs transmission networks.

• Can harm birds/bats.

Geothermal Energy

• Comes from Earth’s interior heat.

• Ground-source heat pumps use steady underground temps.

Pros:

• Renewable, efficient heating/cooling.

Cons:

• Can deplete if overused.

• May cause earthquakes with enhanced systems.

Ocean Energy

• Tidal energy: Uses height difference in tides.

• OTEC: Ocean thermal energy conversion—experimental.

• Uses warm surface water to evaporate chemicals like ammonia.

Hydropower

• Uses river flow to spin turbines.

Types:

• Storage: Dam + reservoir.

• Run-of-river: No big reservoir.

• Pumped storage: Moves water uphill/downhill based on demand.

Pros:

• Clean, renewable, high EROI.

Cons:

• Ecosystem damage (fish, sediment, flooding issues).

Bioenergy

• Derived from biomass (plants, waste, etc.).

• Biopower: Biomass → electricity.

• Biofuels: Ethanol (from corn), biodiesel, cellulosic ethanol.

Pros:

• Renewable.

• Reduces waste.

• Some fuels (e.g., algae-based) are promising.

Cons:

• Deforestation.

• Not carbon-neutral if fossil fuels used in production.

Energy Storage

• Needed due to intermittency of renewables.

• Batteries, pumped storage, research ongoing to improve.

Hydrogen and Fuel Cells

• Electrolysis: Splits water to produce hydrogen.
  
  

• Fuel cells: Combine hydrogen & oxygen → electricity.
  
  

Pros:

• Zero emissions.
  
  

• High efficiency.
  
  

• Abundant fuel (H₂).
  
  

Cons:

• Expensive infrastructure.
  
  

Hydrogen leakage risks.