SESSION 5 Local and Globall Geothermal Reserves

APS 4430: Geothermal Energy Mosiori Cliff Orori Technical University of Mombasa DEPARTMENT OF PHYSICS Lecturer: Dr. Mosiori Cliff Orori Date: 30Th May 2022 TOPIC 5 LOCAL AND GLOBAL GEOTHERMAL RESERVES LEARNING OBJECTIVES After the lesson you should be able to, i). Identify the types of geothermal reserves ii). Differentiate different types of geothermal resources iii). Describe the Hot dry rock (HDR) as a geothermal resource iv). Identify both local and global geothermal reserves COURSE CONTENT GENERAL INTRODUCTION  Geothermal reserves are primarily found only where two plates meet, or where the crust is stretched thin through plate tectonics.  The Ideal locations being at the West coast and the Basin and Ranges in the eastern half of the US holds almost no geothermal potential.  Geothermal reserves are often located too far away from cities for efficient energy generation. Types of geothermal Reserves  They include: (i) Hot Dry Rock, (HDR) Reserves  Hot dry rock has the temperature in the excess of 200 0C.  They contain little amount of liquid or geothermal fluid. 1|Page Page 2  Heat is harvested by sending the water under the rock which is rejected and carries the heat from underground.  This method is also called EGS (Enhanced Geothermal System). The Enhanced Geothermal Systems  These systems can be “enhanced” by engineering the reservoirs through hydraulic fracturing.  An injection well is drilled into the hot formation to a depth corresponding to the promising zone.  Cold water is injected under high pressure to open existing fractures or create new ones.  Once the formation reaches a state of sufficient volume and permeability, another well (or wells) is drilled to intercept the newly formed “reservoir.”  A closed loop is created whereby cold water is pumped down the injection well and returned to the surface through the production well after passing through the hot, artificially-fractured formation as illustrated below. Challenges facing hot dry rock reserve (i) It is difficult to control very deep, directional, geothermal wells.. (ii) HDR wells must be precisely aimed to hit the deep target in order to form a closed fluid circuit. 2 Page 3 (iii) Some of the engineered fractures are not connected to the production well, injected fluid may be lost to the formation. This would require continuous makeup water to maintain the power plant in operation. (ii) Geo-pressurized resources o Geo-pressurized resources include sediment-filled reservoirs and hot water confined under pressures up to 600 bars and fluid temperatures in range of 150 180 0C. o In many of these systems the fluid contains methane up to 100,000 ppm. o It is highly corrosive and that is why the fluid is called “geothermal brine”. o Along the western and northern coastline of the Gulf of Mexico, there is a potent energy resource called “geo-pressure.” o Hydrostatic pressure increases with depth in proportion to the weight of water, i.e., at about 0.465 lbf/in2 per ft. o Periodically, subsidence occur causing compaction of the rock layers. o Subsidence result in steeply dipping faults that can isolate elements of the formation. o With the heavy overburden and no way to dissipate the load, the pressure within these lenses of sand grows to levels in excess of hydrostatic. o In the geo-pressured reservoirs of the Gulf Coast, the pressures were sufficiently high to prevent drilling for oil and gas. 3 Page 4 o With improved understanding of these zones and better drilling techniques, these reservoirs can now be safely drilled. o Geo-pressured reservoirs are characterized by three important properties: a. Very high pressure  Allows the use of a hydraulic turbine to extract the mechanical energy stored in the form of high pressure b. High temperature  Allows the use of a heat engine of some kind to extract the thermal energy c. Dissolved methane.  Allows for either the combustion of the gas on site for power generation or for sale to enhance the economics of a development project. Criterion for commercial exploitation of geo-pressured reservoirs o It must be satisfy the following: [1]. A fluid hot enough about 230 0C [2]. A sufficient methane dissolved in the fluid [3]. Sufficiently high-pressure [4]. Sufficiently permeable and thick sand structure [5]. Sufficiently fault-bounded but not too fractured [6]. Guarantee of no subsidence (iii) Magma energy/ Magma or molten rock o Magma or molten rock is under active volcanoes at accessible depths at temperatures in excess of 650 0C. o The magma body should be relatively close to the surface of the Earth so that it is easy to drill a well into the magma, insert an injection pipe, and pump cold water down the well under great pressure. 4 Page 5 o If the water can be made to return to the surface by passing upward through the cracked, extremely hot glassy material, it would reach the surface hot and ready for use in a Rankine-type power plant. Local Geothermal Reserves  In Kenya, the following are the prospective local geothermal resource reserves:  Menengai,  Baringo-Silali,  Suswa,  Mwananyamala,  Homa Hills,  Barrier,  Nyambene Hills  Chyulu hills.  Further to this, Olkaria, Menengai and Baringo-Silali wells have been drilled with fifty-nine (59) geothermal production wells successfully developed in Olkaria geothermal field.  Drilling at Menengai and Baringo-Silali is in progress with a cumulative of fiftyone (51) geothermal wells drilled and approximately 170 MWe equivalent of 5 Page 6 steam already identified for power generation. Global Geothermal Reserves  Indonesia is home to three of the ten biggest geothermal power plant installations in the world, 1) The Geysers Geothermal Complex, California, US – 1.2GW  The Geysers Geothermal Complex located 121km north of San Francisco, California, is comprised of 15 power plants making it the biggest geothermal installation in the world.  The complex has an installed capacity of 1,205MW.  Calpine owns 13 power plants which have a combined net generating capacity of 725MW, while two power plants with a capacity of 240MW each are jointly.  The complex covers an area of 78 km². 6 Page 7  Production from the geothermal field commenced in 1960 and reached its peak in the 1980s. 2) Larderello Geothermal Complex, Italy – 769MW  Larderello Geothermal Complex, comprising 34 plants with a total net capacity of 769MW, is located in Tuscany in central Italy.  The power generated by the complex accounts for approximately 10% of all geothermal energy produced worldwide and caters for 26.5% of regional power needs.  Enel Green Power owns the power plants at the complex serving approximately two million families, 8,700 residential and business customers, and 25ha of greenhouses.  Reservoir depths at the geothermal field range from 700m to 4,000m below the surface.  The first plant at the geothermal field was commissioned over a century ago in 1913, making it the first of its kind in the world.  The first Larderello power plant had a generating capacity of 250kW. 3) Cerro Prieto Geothermal Power Station, Mexico – 720MW  At 720MW, Cerro Prieto Geothermal Power Station in south Mexicali, Baja California in north Mexico.  The power station features four plants, comprising 13 units.  The first plant was commissioned in 1973, while the fourth plant was commissioned in 2000.  The turbines at the complex include: Four 110MW condensing type, four 110MW double-flash type, four single-flash of 37.5MW each, four single-flash of 25MW each, one 30MW single-flash. 4) Makban Geothermal Complex, Philippines – 458MW  Makban Geothermal Power Complex, also known as Makiling-Banahaw Power Plants, is located in the municipalities of Bay and Calauan in the Laguna province and Santo Tomas, in the Batangas province.  The complex consists of six power plants comprising ten units, including a binary plant with five 3MW units and one 0.73MW unit.  The complex, covering an area of 700ha, commenced operations in 1979. 7 Page 8 5) Salak Geothermal Plant, Indonesia – 377MW  The Salak Geothermal power plant located 70km from Jakarta, Indonesia, has an installed capacity of 377MW.  The power plant was originally developed by a group of companies, including Chevron Global Energy and Union Oil Company. 6) CalEnergy Generation’s Salton Sea Geothermal Plants, US – 340MW  CalEnergy Generation’s Salton Sea Geothermal Plants include a cluster of ten generating geothermal plants with a combined generating capacity of 340MW.  Unit one with an output capacity of 10MW was the first to come online in 1982.  It was built by a joint venture of Union Oil Company and Southern California Edison.  The tenth field came online in 2000. 7) Sarulla Geothermal Power Plant, Indonesia – 330MW  The 330MW Sarulla Geothermal power plant is located in the Pahae Julu and Pahae Jae districts of the North Sumatra Province, Indonesia.  Developed with an investment of $1.7bn, the power plant comprises three units of 110MW each.  The first unit commenced operations in March 2017, while the second unit was commissioned in October 2017 and the third unit started operations in May 2018.  The power plant supplies electricity to approximately 2.1 million households. 8) Hellisheidi Geothermal Power Plant, Iceland – 303MW  Hellisheidi geothermal power plant is a flash steam, combined heat and power plant (CHP) located at Mount Hengill, approximately 20km east of the capital city of Reykjavik.  The plant has a production capacity of 303MW of electric energy and 400MW of thermal energy.  The eighth largest geothermal power plant in the world.  The power generated by the plant is supplied primarily to the nearby aluminium refineries.  The plant was commissioned in five phases from 2006 to 2011.  It covers an area of approximately 13,000m². 8 Page 9 9) Tiwi Geothermal Complex, Philippines -289MW  Tiwi Geothermal Complex is located at Tiwi in the province of Albay, roughly 300km south-east of Manila, the Phlippines.  The 289MW (net) complex consists of three power plants featuring two units each.  Drilling works at the geothermal field were commenced in 1972 and the power plant became operational in 1979. 10) Darajat Power Station, Indonesia -271MW  Darajat Power Station is located at Garut in Pasirwangi District, West Java.  It is a 271MW geothermal power station  The power station comprises three plants, which serve the provinces of Java and Bali.  Plants two and three of the power station share common facilities, including the steam gathering system. STUDENT ACTIVITIES End of Topic 6 For more consultations, contact Dr. Cliff Orori Mosiori on email: [email protected] 9