Current status of the high enthalpy conventional geothermal fields in Europe and the potential

1. Current status of the high enthalpy conventional geothermal fields in Europe and the potential perspectives for their exploitation in terms of EGS A. Manzella CNR – IGG, Pisa, Italy Hervé Traineau CFG-Services, Orléans, France Olafur Flovenz ISOR, Grensásvegur, Iceland

2. Iceland Portugal (Azores) Italy Russia Turkey (Kamtchatka and Kuril islands) France (Guadeloupe, French West Indies) The electrical energy production from geothermal power plants in Europe comes almost entirely from Iceland, Italy, Russia (Kamtchatka and Kuril islands), France (Guadeloupe, French West Indies), Portugal (Azores) and Turkey.

3. France  Volcanic island (Guadaloupe, French West Indies)  Brines with 60% seawater, 40% meteoric waters  Temperature of 250-260°C intersected by wells at 300-1000 m depth  4MW in Bouillante 1 on 1995-1996, 11MW on 2004, for a total of 15 MW with 2 power plants  Exploration recognized a large extension of the reservoir. Third unit in the pre-fesibility phase  Two other islands (Martinique and La Réunion) in exploration

4. Iceland  Volcanic scenario, active rifting. Large active volcanic zone running SW-NE  Various heat sources (dikes or magma chamber) and fluids: seawater, meteoric water with/without volcanic gases  Water-dominated, > 300°C at 2.5 km depth  Natural recharge and reinjection

5. Iceland  Bjarnarflag on 1969, then Krafla, Nesjavellir and Svartsengi  2 new power plants in 2006 and 2007 for 220 MWe in Hengill area  7 new production field: 3 in N- Iceland, 1 central, 3 in the S 120 MW

6. Iceland In addition there are plans to develop Geothermal Systems. The main idea is to drill deep enough into the intrusion complexes of the volcanic systems to get supercritical fluids and exploit the enormous energy stored in the depth interval within the volcanic systems. The Iceland Project is a part of these plans (see www.iddp.is). Unconventional 3-5 km Min. casing depth Deep Drilling Target depth

7. Italy • 2 exploited areas (Larderello-Travale/Radicondoli and Mt. Amiata) in one region (Latera decommisioned) • A shallow reservoir in carbonatic, a deeper reservoir in metamorphic units • Steam dominated in Larderello-T/R, water dominated in Mt. Amiata (extinct volcano) • 20 MPa and 300-350°C at 3 km

8. Italy • Larderello-T/R in 400 km2, 202 wells, 27 units, 702 MW installed capacity, reinjection • Mt. Amiata 5 units, 88 MW, reinjection • 1° experiment worldwide 1904, 1° production in 1913, increase of production (apart 2nd WW period) • Reinjection and deep exploration in the ’70, when field started to deplate. New rapid increase of production • Increase of 100 MW foreseen in 5 years

9. Portugal • Azores volcanic islands , São Miguel • 2 Power plants, 16 MW • 1 new power plant for 10 MW • Exploratin on-going in Terceira island, project for 12 MW by 2008 (50% energy of island)

10. Russia 1 – suitable for heat pumps; 2 – promising for “direct” utilization; 3 – regions of active volcanism, power generation at binary plants / high capacity GeoPP • Areas of active volcanism, Kamchatka and Kuril Islands • 2 reservoirs, vapour and water dominated fields, 250-310°C

11. Russia • In Kamchatka 3 power plants, 73 MW installed capacity. 106 MW under development • In Kuril Island 6 MW installed capacity, foreseen increase of 14MW

12. Turkey • Kizildere geothermal field, active tectonic setting • Shallow reservoir in limestones and marble (195-205°C at 600- 800 m) and deep reservoir in gneiss (240°C at 1.5 km) • liquid CO2and dry ice production factory

13. Turkey • Discovered in 1968, productive since 1984, 20.4 MW of installed capacity, 12-15 MW running capacity • Reinjection test with positive results. Reinjection wuld solve the decline of production and the pollution due to waste water

14. EUROPE Country Field Drilled area (km2) 1 Geology Type Depth (m) Temperature ºC Wells Wells Running capacity (production) (reinjection) France Guadeloupe Volcanic Water 300 1100 1000 2000 1000 2000 1000 2000 3000 3000 1000 4000 1000 4000 1000 3000 1000 3000 >700 250 3 15 Iceland Krafla 5-6 Volcanic Water 190-210 350 300-320 21 1 60 Nesjavellir 6-8 Volcanic Water 18 90 Svartsengi 6-8 Volcanic Water 240 11 1 46 Reykjanes Hellisheiði Larderello 4 Volcanic Volcanic Metamorphic Seawater Water Steam 290-320 240-280 150-270 350 190-250 350 200-330 14 18 180 0 5 23 (100) (120) 473 6-8 250 Italy Travale Radicondoli Bagnore 50 Metamorphic Steam 22 147 5 Metamorphic Water 7 4 19 Piancastagnaio 25 Metamorphic Water 200-300 19 11 60 Volcanic Volcanic Volcanic Water Water Water/ Steam Water 100-150 200 240-300 5 7 13 11 62 Portugal Russia Pahuzhetka Mutnovsky 12-15 700 2500 17 4 Kizildere Metamorphic 240 17 Turkey

15. EUROPE Country Wells drilled in 2000-2005 Installed capacity [MW] Running capacity [MW] Annual Energy produced [GWh/y] Number of Units % of National Capacity % of National Energy 2005-2000 Increase installed capacity [MW] France 3 15 15 102 2 9% 9% 11 Guadeloupe island 13.7% 1.0% 25% San Miguel island Negligible Negligible Guadeloupe island 16.6% 1.9% Iceland Italy Portugal 23 21 2 202 790 16 202 699 13 1406 5340 90 19 32 5 32 5 Turkey Russia 4 4 20 79 18 79 105 85 1 11 Negligible Negligible 0 56 Installed Capacity (MW) Power Production (GWh/y Installed Capacity (MW) Running Capacity (MW) 800 700 25000 600 20000 500 15000 400 10000 300 5000 200 100 0 0 Actual Ferrara 2010 Ferrara 2020 WGC1995 WGC2000 Italy France Turkey Russia Iceland Portugal

16. EGS techniques and how they could improve high enthalpy geothermal fields Different ways have been tested or are imagined for enhancing and broadening geothermal energy reserves which can Geothermal Resources, i.e. mainly Enhanced Geothermal Systems (EGS) and Supercritical Reservoirs: be classified into Unconventional • stimulating reservoirs in Hot Dry Rock systems, • enlarging the extent of productive geothermal fields by enhancing/stimulating permeability in the vicinity of naturally permeable rocks, • enhancing the viability of current and potential hydrothermal areas by stimulation technology and improving thermodynamic cycles, • defining new targets and new tools for reaching supercritical fluid systems, especially high-temperature downhole tools and instruments, • improving drilling and reservoir assessment technology, • improving exploration methods for deep geothermal resources.

17. Well stimulation methods to improve permeability of poor-producer wells are the most common among the technologies derived from EGS and applied to conventional fields. They were successfully applied in Italy, Guadeloupe and could be profitably applied in other fields, wherever the permeability appears reduced and for broadening the reservoirs. This would correspond to a potential increase of exploitation and hence of power production, and at the same time the sustainability of resources would be guaranteed. Tracer tests are now becoming a tool for detection of reservoir volume and prevent strong interference between wells, in particular during reinjection. They have been applied in Turkey, Iceland and may provide useful information in all the exploited fields. Efficient scale inhibitors to prevent scaling in wells and surface pipes are becoming very important for the maintenance of exploitation. High enthalpy fields are the obvious base for the exploitation of supercritical fluids, which can be found in these fields at drillable depths. High enthalpy steam produced by these fluids would generate a much higher electric power than conventional geothermal wells.

18. Improved geophysical imaging tools to determine the extent of faulted reservoirs as well as integrated reservoir modelling have been developed during the EGS experiments. Their application to conventional system may provide a new insight in geothermal structures that are, by definition, very complex. Time lapse geophysical measurements have proved to be particularly effective in exploring and monitoring the dynamic of EGS, but their application is not common in conventional fields. The improvement of technology and reduction of costs are making them particularly attractive in any kind of geothermal system. The combination of different data through integrated modelling are helping in defining both static and dynamic geothermal features and should be applied in all fields to reduce the mining risks and improve the control of the system.

19. However, the importance of high enthalpy fields is not only restricted to themselves, but to the entire geothermal scenario. These fields should be considered as ideal laboratories geothermal exploitation, since the more accessible depth of interesting temperatures would decrease the cost of the experiment, being the drilling usually the most expensive part of geothermal exploitation. for experimenting new ideas for Moreover, long-exploited fields such as in Italy and Iceland, where a huge amount of data is already available, may serve as demonstration plants for a variety of tests in order to improve the reservoir assessment technology and the exploration methods.