Breaking New Ground with Geothermal Energy Elissa Ledvort, Matthew Wala

Getting to Know Geothermal What is geothermal energy? Geo – Earth Therme – Heat Part of the Earth’s heat that could be recovered and exploited by man

3 Uses of Geothermal Energy Direct Use and District Heating Systems Electrical Generation Geothermal Heat Pumps

I Still Don’t Get It Under Earth's crust, there is a layer of hot, molten rock called magma. Heat is continually produced from the decay of naturally radioactive materials. SO HOTT!! “The amount of heat within 10,000 meters of Earth’s surface contains 50,000 times more energy than all the oil and natural gas resources in the world.” The areas with the highest underground temperatures are in regions with active or geologically young volcanoes, specifically at plate boundaries or at places where the crust is thin enough to let the heat through. Includes the Pacific Rim (Ring of Fire), Alaska, California, Oregon, and Nevada Seismically active. “Earthquakes and magma movement break up the rock covering, allowing water to circulate. As the water rises to the surface, natural hot springs and geysers occur, such as Old Faithful at Yellowstone National Park. The water in these systems can be more than 200°C (430°F).” Geothermal energy is produced when cools water seeps into Earth’s crust, is heated, and forced to the surface. This is then harvested for energy (naturally occuring geothermal energy).

Direct Use and District Heating Systems Well brings hot water to the surface Mechanical system delivers heat to the processes Provides heat for buildings, crop and lumber drying, aquaculture, and horticulture Direct Heating Systems – hot water near Earth’s surface is pumped directly into buildings and industries for heat Not hot enough for electricity

Electricity Generation (Geothermal Power Plants) Commercial use Hydrothermal Systems– “subterranean geothermal reservoir that transfers heat energy upward by vertical circulation of fluids driven by differences in fluid density that correspond to differences in temperature” Deep Geothermal System – extracts heat through created subsurface fracture system where water is injected through injection wells. The water is heated by the contact with the rock and returns to the surface through production wells (similar to hydrothermal) Two types of hydrothermal systems: vapor-dominated and hot water Require high temperatures ( F) that comes from dry steam wells or hot water wells, accessed by drilling wells into Earth and piping steam or hot water from 1-2 miles deep to the surface.

Electricity Generation (Geothermal Power Plants) 3 Types of Power Plants Dry Steam Plant – uses steam piped directly from geothermal resovoirs to turn generator turbines Flash Steam Plant – (most common type) high pressure water from deep inside Earth is converted to steam, which drives generator turbines. The steam cools water and is condensed and injected back into the ground to be used over again Binary Plants - uses subterranean water to vaporize a second fluid for heating 5 Transfers heat from geothermal hot water to another liquid. The heat causes the second liquid to turn to steam, which drives a generator turbine Binary plants will most likely dominate in the future of geothermal energy. 5

Geothermal Power Plants continued Geopressurised Resources – “deeply buried resovoirs of hot brine, under abnormally high pressure, that contain dissolved methane” used along Pacific West Coast Co-produced Geothermal Fluids – “produced water cut” are HOT and often found in waterflood fields by many U.S. oil and gas production areas This is nuissance to oil and gas industry, but “diminishes greenhouse gas emissions and extends the economical use of an oil or gas field”

Geothermal Heat Pumps Temperature in upper 10 ft of Earth’s surface is between degrees Fahrenheit. Geothermal Heat Pumps – transfers heat from ground into buildings during winter, and air conditioning during summer EPA!!!! – most energy efficient, environmentally clean, cost-effective systems for temperature control

Benefits ;) ‏ Economical and environmental Consumes no fuel and creates few emissions. Abundant (proven by Massachusetts Institute of Technology, MIT) 5 Renewable! Virtually no complaints 4

Geothermal Future? Geothermal energy is a respectable method of exploiting renewable energy Geothermal energy is a respectable method of exploiting renewable energy Why don’t we use it more? Why don’t we use it more? Initial Costs 3 Initial Costs 3 Exploratory drilling is a tedious effort and time waster 3 Exploratory drilling is a tedious effort and time waster 3 But……. But…….

Geothermal = Great Long-term Investment Positive impact on environment, consuming no fuel and creating few emissions 4 Positive impact on environment, consuming no fuel and creating few emissions 4 MONEY SAVER when analyzing long term costs MONEY SAVER when analyzing long term costs But currently, it’s underused  But currently, it’s underused 

We Still Have Hope Geothermal energy is gaining popularity in the world. Geothermal energy is gaining popularity in the world. 24 countries currently using a form of geothermal energy countries currently using a form of geothermal energy. 5 The United States uses the most geothermal energy, 2,850 MW of the world’s 8,900 MW. 5 The United States uses the most geothermal energy, 2,850 MW of the world’s 8,900 MW. 5

Current State of World Energy Oil and gas accounted for 63% of world energy usage in 2005 (oil was the most used) 1 Non-hydroelectric renewable resources = <1% of world energy use 1 World uses 84 million barrels of oil a day; 30 billion per year 3 US uses double the energy it produces 3

Oil Production and Prices Oil resources are finite and production has already peaked outside the Middle East There is “substantial range of uncertainty in the world’s future oil markets.” 2

Oil Market Uncertainty Predicted Actual

Geothermal Energy in the United States US is largest user and producer of geothermal energy 3,5 0.36% of US electricity supply is generated with geothermal power 5 The Geysers in California is the largest geothermal plant in the world 5 Geothermal heat pumps power homes and buildings in all 50 states % of potential energy in the United States is geothermal; unfortunately, most of it cannot be used 3

US Geothermal Resources

Geothermal Technology Enhanced (deep geothermal systems) will inject water into rock; will not require reservoir water 3 Co-pressured geothermal fluids: hot water as a byproduct of oil and gas drilling is currently discarded; it could have produced 7585 MW of power in

Geothermal Technology (continued)‏ US geothermal energy development is expected to increase by four times from current levels by Geothermal heat pumps eventually pay for themselves 5

Financial Aspect of Geothermal Energy Most expensive part of geothermal power plant is excavation and construction; initial costs may tempt investors into overusing resources beyond sustainable levels 3 Geothermal plants are cost-effective: “on par with or better than coal plants” 5

Environmental Impact of Geothermal Energy Very minimal environmental impact: “minor, restrainable, or negligible” 4 Dissolved metal and gas in some reservoir water needs to be cleaned out unless using binary plants 5 Most likely problems deal with: water pollution, waste disposal, and high noise levels 4 Injection of water may lead to more frequent small earthquakes 4

Geothermal Energy as Sustainable, Alternative Energy Sustainability: “Meeting the needs of the present generation without compromising the needs of future generations.” 4 Renewable resource: geothermal fields will recover to original state in years 4 after exploitation Alternative energy: Geothermal resources will equal resource of ~3.5 billion barrels of oil by Above: recovery of temperature in a geothermal reservoir

Sources: text “Geothermal – The Energy Under Our Feet”. Bruce Green and Gary Nix, National Renewable Energy Laboratory, “Geothermal energy: sustainability and the environment”. L Rybach, “Heating Up”. Mark Fischetti, October 2007 Scientific American

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