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