Four geological formations

• Hydrothermal reservoirs

  • most common source of geothermal energy production worldwide
  • contains hot water or steam trapped in fractured or porous rock formations by a layer of impermeable rock on top
• Geopressurized

  • are from formations where moderately high temperature brines are trapped in permeable layer of rock under high pressures
  • these brines are found deeper underground than hydrothermal fluids
  • high concentration of salt, minerals and dissolved methane gas
• Hot dry rock

  • are generally hot impermeable rocks at depths shallow enough to be accessible
• Enhanced geothermal system - a rock must be fracture and a fluid circulation system developed
• Hydrothermal fluid - water is then heated by way of conduction as it passes through the fracture in the rock
• Magma

  • molten rock is the largest global geothermal resource and is found in a depth of 3-10 km
  • great depth and high temperature make the resource difficult to access and harness
• Iceland - rely on its abundant source of hot and easily accessible under ground water as an inexpensive source of energy
• United states - have to drill for geothermal energy at a greater cost
• Philippines - is now reducing its dependence on fossil fuels as it taps abundant energy resources such as sun, wind, biomass, geothermal energy, and water
• Indonesia - have abundant geothermal resources
• Geothermal plants - generate about one-fourth of the electricity in the Philippines making the country the second-largest user of geothermal electricity
• Advantage of geothermal energy

  • Eco-friendly
  • High reliability
  • Flexibility
  • Minimum land scape
  • Cost effective
  • Help developing countries grow
• Disadvantages of Geothermal energy

  • Limited Accessibility
  • Financial Constraint
  • Possible pollution