The Environmental Impact of Geothermal Industry

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The Environmental Impact of Geothermal Industry

• by
• D. Mendrinos and Dr. C. Karytsas
• Centre for Renewable Energy Sources
• February 2006

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Geothermal Energy the heat of the earth

• Shallow (Geothermal Heat Pumps)
• Hydrothermal Systems
• Low Enthalpy
• High Enthalpy
• Enhanced Geothermal Systems

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Geothermal Heat Pumps

• COP Heat Delivered / Electricity 4 - 6
• CO2 emissions reduction
• 40 vs Air-Source-Heat Pumps
• 45 vs Natural Gas
• 50 vs Diesel Oil
• Adverse Impact Refrigerant Leaks

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Low Enthalpy Hydrothermal Fields

• emissions reduction CO2, CO, C, SOx, NOx
• CO2 rich geothermal fluids in Nigrita
• ? 1/15 1/20 CO2 of fossil fuels
• Measures uses in cascade
• Fluid Chemistry Cl-, B, As, NH4, Hg, Metals
• Solution reinjection
• Water level drop in shallow aquifers
• Solution reinjection

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High Enthalpy Hydrothermal Fields

• Separated brine as in low enthalpy
• Steam H2S, silica
• Solution eliminate steam losses
• except safety valves
• non condensable gasses ? cooling tower
• Last option H2S treatment plant

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Steam CO2
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Steam CO2
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Steam CO2
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Steam CO2
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Steam CO2
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Steam CO2
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Steam CO2
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Measures

• Increase conversion efficiency
• 1 efficiency rise ? 5 CO2 / kWh less
• Geothermal cogeneration of heat power
• in cascade ? 40 CO2 / kWh less
• waste heat use ? 80 CO2 / kWh less

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Other Impact

• Micro-seismic activity
• action monitor
• Soil subsidence
• action plant design, monitor topography
• Noise
• action plant design, noise barriers

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Other Impact

• Damage to local flora
• action no hot brine/steam on plants
• Aesthetics
• action plant design
• Heat Pollution
• action reinjection, waste heat use

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Enhanced Geothermal Systems

• 100 CO2 emissions reduction
• No adverse environmental impact
• When linked to hydrothermal systems
• Heat Pollution
• Micro-seismic activity