Lecture: Clean Energy Alternatives

Introduction

• Topic: Clean Energy Alternatives
• Main Focus: Energy efficiency, conservation, and renewable energy sources

Current Energy Usage

• Global and US Context:
  • ~80% of energy comes from fossil fuels
  • 89% from non-renewable sources
  • 11% from renewable sources (geothermal, solar, wind, biomass, hydroelectric)
• Goal: UN aims for 80% reduction in fossil fuel use by 2050

Energy Efficiency and Conservation

• Energy Efficiency: Maximizing output from current technologies
• Energy Conservation: Reducing consumption of oil, gas, and coal
• Benefits: Can save 6 million barrels of oil daily

Efficiency of Light Bulbs

• Incandescent Bulbs: Short lifespan due to filament breaking
• CFL Bulbs: Use 75% less energy, last 10x longer
• LED Bulbs: Most efficient, longest lifespan

Reducing Home Energy Consumption

• Energy Star Products: 10-50% more efficient
• Natural Gas vs. Electricity: Prefer natural gas
• Washing Clothes: Use cold water
• Microwaves vs. Ovens: Microwaves are more efficient
• Electricity Use: Air conditioning (17%), heating (15%), water heating (14%)

Solar Energy

• Solar Energy Basics:
  • Received from the sun (ultraviolet, visible, infrared light)
  • Can deliver ~700 watts/m²
• Flat Plate Collectors:
  • Active Systems: Use pumps
  • Passive Systems: Use gravity/convection
• Photovoltaic Cells (Solar Panels):
  • Convert sunlight directly to electricity
  • Efficiency: 15-20%, newer models ~40%
  • Inverters convert DC to AC
• Solar Power Plants: Large arrays of panels
• Concentrated Solar Power:
  • Methods: Curved reflectors, solar troughs, power towers

Wind Energy

• Overview: Decreasing costs, increasing capacity
• Global Use: China, US, Germany
• Mechanism: Wind blows turbines, generating electricity
• US Potential: 20% of electricity by 2030
• Challenges: Intermittency, visual impact

Hydropower

• Mechanism: Uses water weight to drive generator
• US Usage: 6.6% of electrical power
• Dams: Benefits (flood control, recreation) vs. drawbacks (ecological impact)

Ocean Energy

• Types:
  • Wave Energy: Uses wave motion
  • Tidal Energy: Uses height difference between tides

Biomass Energy

• Overview: Derived from present-day photosynthesis
• Examples: Wood, biogas (methane), biofuels (ethanol, biodiesel)
• Usage:
  • Wood stoves
  • Municipal waste burning
  • Biogas from anaerobic digestion

Hydrogen Energy

• Characteristics:
  • Secondary energy source
  • Byproduct: Water
• Production: Electrolysis (expensive, electricity-dependent)
• Fuel Cells: Convert hydrogen to electricity, more efficient

Cost and Efficiency Comparison

• LCOE: Levelized Cost of Energy
• Expensive:
  • Solar thermal energy
  • Offshore wind
• Cheaper:
  • Geothermal
  • Advanced combined cycle natural gas

Conclusion

• Renewable Energy Future: Increasing use and efficiency
• Call to Action: Review lecture slides, complete online quiz