Renewable sources of energy

• Geothermal: energy obtained by tapping the heat of the earth below its surface. Hot underground water or steam is used to produce electricity.
  
  
• Biogas: produced from wastes of paper and sugar industries, animal and so on. CH₄ is the product.
  
  
• Bio fuel: Biodiesel, ethanol etc. are derived from plants.
  
  
• Solid Biomass: Wood fuel, biogenic portion of municipal waste, certain plants. Biomass may be used in a number of ways to produce energy. The common methods are gasification, combustion, fermentation and anaerobic digestion. India is very rich in biomass
  
  
• Hydro-thermal: Energy in water in the form of KE, temperature difference
  
  
• Solar Energy: Energy collected from sunlight. It can be used in many ways:
  • Generate electricity using photovoltaic cells.
  • Generate electricity using concentrating solar power.
  • Photovoltaic cells have a low efficiency factor.