Sustainable Energy Technologies - Chapter on Other Sustainable Energies

Chapter Overview

  • Focus on Other Sustainable Energies including Geothermal, Biomass, Ocean Energy, and Hydrogen Fuel Cells.

Objectives

  • Understand the principles and applications of:
    • Geothermal Energy
    • Biomass Energy
    • Ocean Energy
    • Hydrogen Fuel Cells

Fuel Cell Energy

  • A fuel cell generates electricity via a chemical reaction without combustion.
  • Uses hydrogen's chemical energy to produce:
    • Electricity
    • Water
    • Heat
  • Main components:
    • Electrolyte between 2 electrodes:
    • Anode (negative electrode), fed with hydrogen.
    • Cathode (positive electrode), fed with oxygen (air).
  • Ionization process:
    • Hydrogen is ionized, electrons move to the cathode through an external circuit.
    • Protons migrate through the electrolyte to the cathode.

Advantages of Fuel Cells

  • No need for recharging (operates differently than batteries).
  • No moving parts, resulting in:
    • Minimal maintenance.
    • Reduced noise and no harmful emissions.

Types of Fuel Cells

  • Proton Exchange Membrane Fuel Cell (PEMFC)
  • Solid Oxide Fuel Cell (SOFC)
  • Molten Carbonate Fuel Cell (MCFC)
  • Phosphoric Acid Fuel Cell (PAFC)
  • Direct Methanol Fuel Cell (DMFC)

Applications of Fuel Cells

  • PEMFC: Potential use in buses and cars.
  • Power systems for:
    • Trains
    • Ships
    • Residential and industrial electrical power supply.
  • Stationary power generation: 100KW to 400KW range for commercial use.

Geothermal Energy

  • Utilizes Earth’s internal heat:
    • Heating water for steam to drive turbines.
    • Direct heating applications.
Disadvantages of Geothermal Energy
  1. Water depletion over time.
  2. Risk of inducing earthquakes by injecting water.
  3. Heat depletion in geothermal areas.

Ocean Energy Development

  • Types of devices:
    • Wave power converters.
    • Tidal turbines in coastal areas.
    • In-stream turbines in rivers.
    • Ocean current turbines.
    • Ocean thermal energy converters (OTEC).
Wave Power
  • Generated by:
    • Wind across the sea.
    • Tidal forces and temperature variations.
  • Harnessing method:
    • Focusing waves into a channel to spin turbines.
    • Utilizing a catch basin for water flow to turbines.
Tidal Turbines
  • Tidal barrage operations:
    • Retaining water until low tide, generating electricity on release.
In-stream Turbines
  • Capitalizes on kinetic energy of water flow.
  • Cost-effective renewable source with minimal environmental impact.
Ocean Current Turbines
  • Energy from moving ocean waves, temperature differences, and salinity.
  • Potential of wave power: Estimated yield of 8,000 to 80,000 TWh annually.
Ocean Thermal Energy Conversion (OTEC)
  • Uses temperature differences between warm surface waters and cooler depths.
  • Requirements:
    • Minimum temperature difference of 20° Celsius (36° Fahrenheit).
  • Applications in electricity generation and desalination.

Biomass Energy

  • Derived from living organisms (plants and animals).
  • Energy obtained through:
    • Direct burning for heat.
    • Conversion to electricity.
    • Processing into biofuels.
  • Originates from solar energy captured through photosynthesis:
    • Plants convert CO2 and water into carbohydrates.
Summary of Biomass Applications
  • Provides a method to transform solar energy into usable forms.