Geothermal Energy Overview

Introduction to Geothermal Energy

• Geothermal energy is derived from heat deep beneath the Earth's surface.
• It is a source of clean, renewable electricity.

How Geothermal Works

• Heat from the Earth's crust warms water in underground reservoirs.
• Hot water can break through the Earth's surface in the form of steam or hot water, especially at tectonic plate boundaries.

Types of Geothermal Power Plants

1. Dry Steam Power Plants

   • Most common type.
   • Underground steam flows directly to a turbine, which drives a generator to produce electricity.

2. Flash Steam Power Plants

   • A pump pushes hot fluid into a surface tank.
   • As the fluid cools, it flashes into vapor, which then drives a turbine to generate power.

3. Binary Cycle Power Plants

   • Utilizes two fluids:
     • Hot underground fluid heats a second fluid with a lower boiling point in a heat exchanger.
     • The second fluid vaporizes and spins a turbine to generate electricity.

Environmental Benefits

• Low emissions and small physical footprint.
• Minimal environmental impact; byproducts are often re-injected underground.
• Can assist in recycling wastewater (e.g., Santa Rosa, California).
• Some plants generate solid waste, which can contain sellable minerals, reducing costs.

Potential of Geothermal Energy

• US Geological Survey estimates that untapped geothermal resources could supply 10% of current energy needs, reducing reliance on fossil fuels.
• Approximately 60% of power along the northern California coast is already generated from geothermal energy, contributing to energy independence.