Geothermal Energy“Digging Deep to
Discover the Power”Michelle Kennedy & Caitlin Sloan
What is Geothermal Energy?
• Heat produced by molten rock under the Earth’s crust
• Wells are drilled deep into rock to stimulate water flow
• Earthquakes & magma movement break rock covering allowing water to flow
• Hot springs & geysers occur as a result
Where is it Found?• Highest underground temperatures
found in regions with active volcanoes
• The Pacific Rim has many “hot spots”
• Easiest to access in mountainous areas such as western United States
How is it Harnessed?
• A conversion apparatus must be built to convert the heat in steam into electricity
• Most common process “Hydrothermal Convection”
• Another process “Hot Dry Rock”• Proposed plan:– Drill into heated bedrock– Create open reservoir– Pump water into it to be heated
Three Main Designs
• Dry Steam
Three Main Designs
• Flash Steam
Three Main Designs
• Binary Cycle
• Design depends on the resource
• Largest geothermal system in operation is steam-driven plant The Geysers– Located north of San Francisco,
California
– The heat used for energy is all steam, not hot water
Ideal Iceland
• Nearly every building is heated by hot spring water
• 85% of homes are heated by geothermal energy
• Geothermal produces 18% of country’s electricity
• Cost of this energy will continually drop
What is the Cost?
• Conversion apparatus turns heat into electricity at $1,700 per kilowatt
• More than 100 gigawatts could be produced for $1 billion over next 40 years– Equal to:• The cost of just one coal-fired power plant• One third the cost of a new nuclear generator
Fun Facts• Electricity produced annually greater than
solar & wind combined• Amount of heat within 10,000 meters of
Earth’s surface contains 50,000 times more energy than all the oil & gas resources in the world
• Ground source heat pumps
72% more efficient than
electric heating & air
conditioning
Pros of Geothermal Energy
• Renewable resource• The process of extraction produces
low emissions contained underground
• Compatible with many environments• Works 24/7• Minimal cost• Clearly feasible (Iceland)
Cons of Geothermal Energy
• Apparatuses must reach at least 5,000 feet underground
• Geothermal steam naturally contains hydrogen sulfide
• Building power plants can trigger earthquakes
• Type of rock limits location of drilling
The Future of Geothermal Energy• It could succeed anywhere
• Cost of electricity from these systems is declining
• Geothermal development likely to increase
• 2007 MIT study first in 30 years
• Bright future for home & building heating
The End