Geothermal Energy

Hakim SAIBI & SAEED

September 2014

Winner of GRC 2011 photo contest, Reykjanes Geothermal Power Plant, Iceland

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Few Keywords

• Feasibility studies• IEA• Energy• Renewable Energy• Thermal plants• Hybrid systems• Efficiency• Exergy• Reservoir• Geofluid

• Two phase flow• Brine• Well• Drilling • Enthalpy• Entropy• Surface facilities• Utilization• Scaling• Corrosion

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Geothermal Reservoir Fed by Rain Water

Geysers Hot Springs

Fumaroles

Clay Diablo Fumarole (CA) White Island FumaroleNew Zealand

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Earth Temperature Gradient

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Geothermal Regions in the World

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Geothermal Electricity in the World

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Historical Trend of Geothermal Installed Capacity

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Direct Uses of Geothermal Energy

0

25,000

50,000

75,000

100,000

125,000

150,000

175,000

200,000

225,000

1 2 3 4 5 6 7 8 9

Applications

TJ/y

r

1995

2000

2005

2010

1. Geothermal Heat Pumps2. Space Heating3. Greenhouses4. Aquaculture5. Agricultural Drying6. Industrial7. Bathing and Swimming8. Cooling / Air Conditioning9. Others

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Geothermal Reservoir Modeling Workflow

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Numerical model of synthetic enhanced geothermal system with isosurfaces of temperature after 30 years of heat mining by injection of

cold water from the central well and production from two peripheral wells that intersect the stimulated fracture zone.

(GRSJ, 2011)12

Japanese Geothermal Power Plants

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Geothermal Energy in Japan

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How you can get involved?!

• Educational• Professional

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Topics• Borehole geology and alteration mineralogy• Chemistry of thermal fluid• Drilling (depth of interest!)• Energy policy (local and global scale)• Environmental aspects• Geological explorations• Geophysics• Geothermal energy utilization• Geothermal reservoir• Geothermal resources assessment• Hydrology and hydrogeology• Logging• Well testing• Extensive field works

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Education

• UNU-GTP (United Nations University-Geothermal Training Program, Iceland)

– http://www.unugtp.is/

• Geothermal diploma course, University of Auckland, New Zealand

• Smaller contributions from Universities in Japan, USA, Italy, Mexico.

Tem

per

atu

re (

ºC)

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Classification of Geothermal Resources

Japanese Geothermal Resources Classification

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Enthalpy-Entropy diagram for Water

and Steam

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Geothermal Utilization

• High temperature

• Low temperature

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Geothermal Resources

• Hot dry rock

- no water at all, still no commercial utilization• Vapor dominated fields

- deliver steam ready for the turbine• Water dominated fields

- water flows into the wells, and boils partly• Liquid water

- temperature below 100°C (The fluid contains non-condensable gases and dissolved solids)

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The cycles

• Flash (Bjarnarflag (backpressure), Nesjavellir)• Double flash (Krafla, Svartsengi)• ORC (Svartsengi)• Kalina (Husavik)

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Direct use applications• District heating and snow melting• Spas and swimming pools• Greenhouses• Fish farming (aquaculture)• Drying

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District heating in Reykjavík started in 1930. By 1970 nearly all Houses in Reykjavík were receiving hot water for heating and sales began to nearby municipalities. Today Reykjavík Energy serves about 150.000 people or 99.9% of the population of Reykjavík and five neighboring communities.

19901930

REYKJAVÍK Before and after geothermal space heating

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ENVIRONMENTAL IMPACT OF GEOTHERMAL UTILIZATION

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Environmental Concerns

• Surface disturbances• Physical effects - fluid withdrawal• Noise• Thermal pollution• Chemical pollution• Protection• Social and economic effects

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Surface Disturbances

• Excavation• Construction• Roads• Landslides• Scenery• Changes in surface activity• Untidiness

CSmall area of activity, mostly undergroundSource usually exploitednear drillsite

CDrillrigs disappear after Use

CAbandoned or unused boreholes can be hidden

Mitigation

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Sustainable Development

• Sustainable development: Development that meets the needs of the present without compromising the ability of future generations to meet their own needs (World Commission on Environment and Development 1987)

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Sustainable Production of Energy from an Individual Geothermal System

• For each geothermal system, and for each mode of production, there exists a certain level of maximum energy production, E0, below which it will be possible to maintain constant energy production for a very long time (100-300 years). If the production rate is greater than E0 it cannot be maintained for this length of time. Geothermal energy production below or equal to E0 is termed sustainable production, while production greater than E0 is termed excessive production (Axelsson et al. 2001)

Geothermal sustainability

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Cascade Utilization of Geothermal Energy

RefrigerationPlant

Food Processing

Power Plant

ApartmentBuilding

Greenhouse

Fish Farm2000C

1000C

Cascading to maximize useof the geothermal energy

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?

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Winter is coming, stay together!