UNU-GTP, KenGen and MEMD-DGSM Short Course on Geothermal Project Management and Development. Entebbe, Nov. 20-22, 2008 GEOTHERMAL POWER PLANTS Benedikt Steingrímsson Sverrir Þórhallson Einar Tjörvi Elíasson Iceland GeoSurvey (ÍSOR), Reykjavík, Iceland
Content Geothermal power generation, history, advantages and concerns Geothermal fields suitible for power generation Overview of power plant designs: World survey of geothermal plants currently in use Prevailing problem types and countermeasures res in operation of power plants. Power plant design parameters
Geothermal Power Plant
Few historical milestones in Geothermal Power Generation (Present installed power is close to 10,000 MW 1904. Geothermalgeneration demonstrated in Larderello, Italy. 1913. 250 kw plant put into service in Larderello 1945 55. 55 Larderello redeveloped after WW2 1958. The Wairakei in NZ commissioned 192 MW 1960. The Geyser field California i starts t at only 14 MW 1971. Námafjall, Iceland 3.2 MW 1980. Tivi, i Phillipinesi 330 MW 1981. Olkaria, Kenya, 45 MWe
Geothermal Power Generation in Iceland Installed power 575 MW in 2008 5.000 4.500 Electricity Generation n (GWh/yea ar) 4000 4.000 3.500 3000 3.000 2.500 2.000 1.500 1.000 Hellisheiði 213 M W Reykjanes 100 M W Húsavík 2 M W Nesjavellir 120 M W 500 0 Bjarnarflag 3,2 M W Krafla 60 M W Svartsengi 76,4 M W 1974 1979 9 1984 1989 9 1994 1999 9 2004 2009 Year
Geothermal Power: Advantages over other renewable energy sources High degree of availability (>98% and 7500 operating hrs/annum common) Low land use Low atmospheric pollution compared to fossil fuelled plants Almost zero liquid id pollution with re injection of effluent liquidid Insignificant dependence on weather conditions Comparatively low visual limpact
Environmental Concerns in Geothermal Roads, drilling platforms, pipelines and power lines Pollution of air and waters Geothermal activity alters or vanishes Rare plants and micro biota are lost Geothermal fields are often in natural conservation areas
High temperature steam dominated dfields T=240 C and P 35 bar Depth: 1 3 km Related to volcanism and plate boundaries Suitable for electricity production o with conventional o turbines The first fields to be developed for power generation, Larderello, Geysers and Kamojang
High temperature liquid dominated fields 200 350 C Depth: 1 3 km Related to volcanism and plate boundaries Suitable for electricity production with conventional turbines The first wet field to be developed for power generation was Wairakei Nesjavellir, Iceland. 300 C fluid used to produce electricity
Medium temperature liquid dominated fields 100 200 C 1 5 km Mostly found din deep sedimentary basins around the world as well as in volcanic areas High flowrates necessary for electricity Binary systems needed for electricity production Húsavík, Iceland. 124 C water used to produce electricity
The three basic turbo generating systems Flashed steam back pressure system; resource temperature range from about 320 C to some 200 C Flashed steam/dry steam condensing system; resource temperature range from about 320 C to some 230 C Binary ayor twin fluid udsyste system (based upon the Organic Rankin or the Kalina cycle); resource temperature range between 100 C to about 200 C
Typical Back Pressure Unit Layout
Typical Condensing Unit Layout Water Steam Steam Turbine / Generator Electricity Sepa rator Conde enser Cooling Tower Water Production Well T > 230 C Reinjection Well
Typical Binary Plant Layout Working Fluid Steam Steam Turbine / Generator Electricity Evapo orator Conde enser Cooling Tower Water Production Well 100 C < T < 200 C Reinjection Well
Hybrid Binary/Back Pressure Layout
The Nesajvellir Plant Electricity and hot water production
Krafla: Single and Twin Pressure Condensing Plant Layout
Typical Binary (Kalina) Plant Layout
Installed capacity of geothermal power plants. Data from Bertani i(2005, 2007 and 2008). COUNTRY Year: 1990 1995 2000 2005 2007 2010 * China 19.2 29 29 28 28 28 Costa Rica 0 55 143 163 163 197 El Salvador 95 105 161 151 204 204 Ethiopia 0 0 7.3 7.3 7.3 7.3 France (Guadeloupe) 4.2 4.2 4.2 15 15 35 Guatemala 0 0 33 33 53 53 Iceland 44.6 50 170 202 421 580 Indonesia 144.8 310 589 797 992 1192 Italy 545 632 785 791 810 910 Japan 215 414 547 535 535 535 Kenya 45 45 45 129 129 164 Mexico 700 753 753 953 953 1178 New Zealand 283 286 437 435 472 590 Nicaragua 35 70 70 77 87 143 Papua New Guinea 0 0 0 6 56 56 Philippines 891 1227 1909 1930 1970 1991 Portugal 3 5 16 16 23 35 Russia 11 11 23 79 79 185 Turkey 20.6 20 20 20 38 83 USA 2774.6 2817 2228 2564 2687 2817 Total: 5832 6833 7972 8933 9732 10993
2005 World review of Geothermal Plant types Plant type Installed capacity (MW e ) Percent Number of units Percent Average size Dry steam 2,545 28 58 12 43.9 Single flash 3,294 37 128 26 25.7 Double flash 2,293 26 67 14 34.2 Binary/combined cycle/hybrid 682 8 208 42 3.3 Back pressure 119 1 29 6 4.1 Total 8,933 100 490 100 Installed/generated geothermal electricity per continent MWe GWh/year 30.000 25.000 20.000 15.000 26794 Installed capacity (Mwe) Electricity generation (GWh/year) 18903 10.000 5.000 0 5745 3941 3290 1124 2791 1088 136 441 Africa America Asia Europe Oceania
Operation of Power Plants Problems and countermeasures The Problems are found in: Power house equipment: Automatic control and communication system: Cooling system: Particulate and/or droplet erosion: Heat exchangers: Gas evacuation systems: Re injection system:
Operation of Power Plants Problems and countermeasures The main problems are related to: 1. Scaling 2. Corrosion 3. Gas emission For countermeasures see the paper
Power Plant Design Parameters Resource Type of resource: Steam dominated or liquid dominated Steam conditions: Optimum turbine inlet steam pressure. Gas (% NCG) in steam. Size (thickness and areal extent), and long term capacity, and natural recharge Temperature and pressure of deep resource fluid Chemical composition (liquid and gas phase) of deep fluid Well productivity/injectivity Two phase zones.
Power Plant Design Parameters Accessibility Topography of resource area Remoteness from population centres Closeness to nature parks and environmentally restricted areas Market Size, type and security of market Proximity of market Accessibility to existing power transmission lines, substations
Power Plant Design Parameters Permits etc. Resource concessions Exploration permits Drilling permits Development permits Environmental Impact Assessment Building and other permits Pre and post investment studies, business plan
Summary Geothermal Power Generation is a well known technology which celebrated its 100anniversary in 2004. There is a wide range in the properties of the geothermal resources that has to be taken into account when designing the Power Plant. Operational problems are several but can be overcome by proper material selection, correct countermeasures and good maintenance. The world wide installed capacity is now about 10.000 MW and annual increase has been about 200 MW/year for the last few years this has grown to about 500 MW/year. There is still a lot of unused geothermal power potential in the world
The Krafla Geothermal Power Plant Emil Thor Thank you