The Environmental Impact of Geothermal Industry by D. Mendrinos and Dr. C. Karytsas Centre for Renewable Energy Sources February 2006

Geothermal Energy = the heat of the earth Shallow (Geothermal Heat Pumps) Shallow (Geothermal Heat Pumps) Hydrothermal Systems Hydrothermal Systems Low Enthalpy Low Enthalpy High Enthalpy High Enthalpy Enhanced Geothermal Systems Enhanced Geothermal Systems

Geothermal Heat Pumps COP = Heat Delivered / Electricity = COP = Heat Delivered / Electricity = CO 2 emissions reduction: CO 2 emissions reduction: ~ 40% vs Air-Source-Heat Pumps ~ 40% vs Air-Source-Heat Pumps ~ 45% vs Natural Gas ~ 45% vs Natural Gas ~ 50% vs Diesel Oil ~ 50% vs Diesel Oil Adverse Impact: Refrigerant Leaks Adverse Impact: Refrigerant Leaks

Low Enthalpy Hydrothermal Fields emissions reduction: CO 2, CO, C, SO x, NO x emissions reduction: CO 2, CO, C, SO x, NO x CO 2 rich geothermal fluids in Nigrita: CO 2 rich geothermal fluids in Nigrita:  1 / 15 – 1 / 20 CO 2 of fossil fuels  1 / 15 – 1 / 20 CO 2 of fossil fuels Measures: uses in cascade Measures: uses in cascade Fluid Chemistry: Cl -, B, As, NH 4 +, Hg, Metals Fluid Chemistry: Cl -, B, As, NH 4 +, Hg, Metals Solution: reinjection Solution: reinjection Water level drop in shallow aquifers Water level drop in shallow aquifers Solution: reinjection Solution: reinjection

High Enthalpy Hydrothermal Fields Separated brine: as in low enthalpy Separated brine: as in low enthalpy Steam: H 2 S, silica Steam: H 2 S, silica Solution: eliminate steam losses Solution: eliminate steam losses except safety valves … except safety valves … non condensable gasses  cooling tower non condensable gasses  cooling tower Last option: H 2 S treatment plant Last option: H 2 S treatment plant

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 8,30 1,7 % 1,7 % 13,3 % 0,16

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 1,7 %13,3 %0,16 Montetorondo 8,19 8,19 1,6 % 1,6 % 13,2 % 0,16

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 1,7 %13,3 %0,16 Montetorondo 8,19 1,6 %13,2 %0,16 Molinetto17,95 4 % 4 % 17,7 % 0,29

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 1,7 %13,3 %0,16 Montetorondo 8,19 1,6 %13,2 %0,16 Molinetto17,95 4 %17,7 %0,29 Gabbro16,52 12 % 12 % 14,6 % 1,05

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 1,7 %13,3 %0,16 Montetorondo 8,19 1,6 %13,2 %0,16 Molinetto17,95 4 %17,7 %0,29 Gabbro16,52 12 %14,6 %1,05 Radicondou36,89 5 % 5 % 19,0 % 0,34

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 1,7 %13,3 %0,16 Montetorondo 8,19 1,6 %13,2 %0,16 Molinetto17,95 4 %17,7 %0,29 Gabbro16,52 12 %14,6 %1,05 Radicondou36,89 5 %19,0 %0,34 Travale40,75 5 % 5 % 21,0 % 0,31

Steam: CO 2 Plant Net Power MW e CO 2, % w/w Conversionefficiency Kg CO 2 per kWh e Fossil Fuels %0,38-0,90 Lago 8,30 1,7 %13,3 %0,16 Montetorondo 8,19 1,6 %13,2 %0,16 Molinetto17,95 4 %17,7 %0,29 Gabbro16,52 12 %14,6 %1,05 Radicondou36,89 5 %19,0 %0,34 Travale40,75 5 %21,0 %0,31 Milos, Greece - 1,0–1,5 % 19,1 % 0,10

Measures Increase conversion efficiency Increase conversion efficiency 1% efficiency rise  5% CO 2 / kWh less 1% efficiency rise  5% CO 2 / kWh less Geothermal cogeneration of heat & power Geothermal cogeneration of heat & power in cascade  40% CO 2 / kWh less in cascade  40% CO 2 / kWh less waste heat use  80% CO 2 / kWh less waste heat use  80% CO 2 / kWh less

Other Impact Micro-seismic activity Micro-seismic activity action: monitor action: monitor Soil subsidence Soil subsidence action: plant design, monitor topography action: plant design, monitor topography Noise Noise action: plant design, noise barriers action: plant design, noise barriers

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

Enhanced Geothermal Systems 100% CO 2 emissions reduction 100% CO 2 emissions reduction No adverse environmental impact No adverse environmental impact When linked to hydrothermal systems When linked to hydrothermal systems Heat Pollution Heat Pollution Micro-seismic activity Micro-seismic activity