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Geothermal Energy in Afghanistan:
Prospects and Potential SABA et al 1feb 04
Saba, D. S.1, Najaf, M. E.2, Musazai, A. M.2, and Taraki, S. A.3
1 Consultant, 12201 Mara Lynn Road, #8307, LR, AR 72211, USA. email@example.com
2 Department of Geology and Exploration of Mineral Resources Faculty of Geology and Mines, Kabul Polytechnic Institute, Afghanistan.
3 Faculty of Economics, Herat University, Herat, Afghanistan.
Center on International Cooperation, New York University, New York, USA. &
Afghanistan Center for Policy and Development Studies, Kabul, Afghanistan.
Historically, geothermal energy in Afghanistan has been only used for medical bathing. This application is still one of important utilization of geothermal energy in Afghanistan. Initial exploration efforts for mineral and thermal water resources of Afghanistan began in 1969. However, geological studies, geophysical exploration and drilling programs have not been carried out for characterization of reservoirs and capacity of the country's geothermal prospects. This study is a framework to facilitate such studies.
The structure of Afghanistan is created by the collision of the Indian and Eurasian plates along the Herat-Panjshir E-W striking geosuture, resulting in the uplifting of the Hindu Kush on this axis since the end of the Cretaceous, some 65 million years ago. Neotectonic movements in Afghanistan generated by these collisional events are characterized by seismic and geothermal activities all over the country. Upon this geological condition, many geothermally active areas are currently known with surface manifestations in the form of hot springs, which demonstrate the wide perspective of development and utilization of geothermal prospects in this country.
Further geological, geochemical, and geophysical exploration is required to characterize the reservoirs of numerous geothermal prospects in Afghanistan for possible electric power generation and other technologically advanced uses of this renewable energy resource. Use of geothermal energy in Afghanistan is realistic. However, it is suggested that at this stage, direct use of geothermal energy is the most feasible way to put this abundant renewable energy resource into use. In this framework, there is tremendous potential for applications such as in the food processing, fruit drying, carpet and wool processing, chemical industry, greenhouse industry, fish hatchery and farming, refrigeration, and many other small-scale local industries.
Afghanistan is an energy-deprived country. Anecdotal evidence suggests that per capita energy use in this country is substantially lower by international standards. As the reconstruction process advances further, the demand for energy will increase. As the World Energy Commission puts it, energy affects all aspects of modern life and human development (WEC, 1993). For Afghans to successfully rebuild their country, new initiatives has to be undertaken to satisfy the increasing energy needs of the country. In this circumstance, there is urgent need to deploy sustainable and environmentally clean energy sources, such as geothermal energy, which is abundantly available in Afghanistan.
On a worldwide scale, geothermal energy already makes an important contribution. More than 50% of installed electric power capacity from "new" renewables such as geothermal, wind, tidal, and solar is realized in geothermal power plants. In recent years, significant advances have been achieved with engineered geothermal systems. Innovative power plants permit the production of electricity using low thermal water temperatures of the order of 100 °C. A major advantage of geothermal energy among other renewables is the availability of the resource all day, all year round.
Today, many countries stand out as having made utilization of geothermal resources a national priority. For example, in Tibet, which is very similar in its culture, geography and geological structure to Afghanistan, until 1997, the annual power generation only from Yangbajing power plant was at 110 GWh/yr, which accounts for 41% of total power in the Lhasa in the summers, and up to 52% during the winter times. The development of other potential reservoirs in Tibet is growing at a very fast pace (Du Shaoping, 2000). Approximately 26 percent of electrical power generation in the Philippines, which is another developing country, though very different from Afghanistan, comes from geothermal steam. Afghanistan like many other countries possesses underutilized geothermal resources. The examples of developed geothermal resources in different industrial and developing countries could be replicated, as the World Geothermal Congress declared, if there was the will to do so (WGC, 2000).
As Afghanistan continues the process of reconstruction, the national demand for commercial energy services is expected to grow, especially with respect to the majority of population of the country without access to modern energy services. The current electric power capacity in Afghanistan based on available data could be estimated to be somewhere in the range of 400 MW (megawatt of energy). Hydroelectric dams, most notably at Kajaki, accounts for 260 megawatts, which represents only about 5 percent of the total hydroelectric potential of the country. Thermal plants, fired by oil and coal, provide another 134 megawatts of this capacity (Nyrop and Seekins, 1986). By completion of the Turkmenistan and Iranian transmission lines to western Afghanistan during the 2004, another 80 MW of electrical power would be added to the present capacity. At the same time, anecdotal evidence suggests serious power shortages all over the country. In Kabul, for example, there are frequent blackouts, and in the city's poorer neighborhoods, homes averaged to have only fifteen to twenty hours of power per week. This is at a time that few industries are functioning.
But the status quo is changing. We know that in the United States, a megawatt of electrical power provides 700 typical Americans with their power needs. Of course, this is not a realistic and appropriate level to be adopted as a target for Afghanistan, but, if we assume the level of power consumption by developing countries such as Turkey, Mexico, or Egypt, which is ten times lower than that of the United States (IEA, 1998), as an optimal hypothetical target for Afghanistan, then the country requires at least 3.5 GW (gigawatt of energy) of electrical power, based on the number of the population that has been estimated to be [24,377,530] persons (CSO, 2003). It is obvious that the power capacity and demand gap in Afghanistan is a very wide one. Meeting this growing demand for energy, while at the same time, addressing the adverse environmental effects of using non-renewable fossil fuels, will necessitates an increase in the use of reliable and diversified renewable energy sources, preferably indigenous, be it hydroelectric, geothermal, biomass, solar or wind.
There is a tremendous amount of heat energy locked inside the planet earth in magma, and dry hot rocks, sometimes, as shallow as a mile or two below the surface. In a sense, the earth's interior can be thought of as a natural nuclear power reactor, because, the heat is mainly derived by the decay of radioactive elements. Under normal conditions, the earth's natural heat increases by as much as (10-38º C) with every mile of depth. This heat flow towards the earth's surface is an indication of the colossal amounts of heat energy at the earth's interior. There are times when some of this comes to the surface in the form of lava, steam, or hot water. This is geothermal energy — "geo" meaning earth, and "thermal" meaning heat. Thus, the earth is a reliable source of energy with its potential available at any time.
Presently some sixty countries around the world are either plugging into the earth, tapping its heat, and drawing some of it off in the forms of steam and hot water to run geothermal power plants and produce electricity, or are in the process of developing their geothermal resources. Other countries use this source for residential and district heating systems, heating greenhouses for growing vegetables, fruits, and flowers, or simply use it for balneological applications. It is suggested that wherever geothermal energy is used, in the long run, it turns out to be cheaper than oil or coal, natural gas or nuclear power (Goldin, 1981; WEA, 2000).
For today's energy starved Afghanistan, there is plenty of this renewable energy resource available to be exploited. Geothermal energy is the earth's interior heat made available to man by extracting it from natural hot water or underground rocks by appropriate technology, which is readily accessible. High-temperature geothermal resources suitable for power generation are generally located in areas subjected to volcanic or seismic activity. Afghanistan is located in such an area, where geothermal resources can make a worthwhile contribution to providing a reliable, renewable energy service for the country.
In Afghanistan, active geothermal systems are generally located in the main axis areas of the Hindu Kush, which runs along the Herat fault system, all the way from Herat in the westernmost part of the country, up to the Wakhan corridor in the Afghan Pamirs. This structure marks the compressed boundary of the Eurasian plate and the Gondwanan fragments that have collided onto this boundary in the territory of Afghanistan prior to the final collision of the Indian plate onto Asia. Geothermal systems of Afghanistan are mainly associated with the fault and fracture networks, seismic activity and young magmatism encountered at this boundary and its associated branching fault systems.
Prospects of low to medium temperature geothermal resources are widespread all over Afghanistan. There is tremendous potential for direct-use applications of these resources, such as in the food processing, fruit drying, refrigeration, fish hatchery and farming, carpet and wool processing, recreation and tourism, and many other possible small-scale local industries. Directly using geothermal energy in district heating and commercial operations is much less expensive than using traditional fuels. From the environmental perspectives, geothermal energy is also very clean, producing only a small percentage of the air pollutants emitted by burning fossil fuels.
In the light of such an understanding, geothermal energy is a highly valuable, clean and reliable heat and power source in Afghanistan, still untapped. Through this study, an effort has been made to assess and evaluate the potential of this resource for the development of Afghanistan's energy sector, as well as tourist and food processing industries. Though many indications of geothermal energy in the form of visible heat leakage in Afghanistan are known, but their significance in the energy policy of Afghanistan is never been appreciated, and to date totally ignored. The authors of this study hope to shed light on this forgotten resource of the country and facilitate the development of geothermal resources of Afghanistan.
2. Historical Background
Worldwide, geothermal energy for electricity generation and direct use has been commercially utilized since 1913. Globally, use of geothermal energy amounts to 49 TWh/y (terawatt hour per year of energy) of electricity and 53 TWh/y for direct use. Electricity is produced with geothermal steam in 21 countries. Of these, five countries obtain 10-22% of their electricity from geothermal energy (Fridleifsson, 2000). However, so far, only a small fraction of the global geothermal potential is developed.
The use of geothermal resources in Afghanistan might have begun with the settlement of the first people in the vicinity of the many hot springs in the valleys of Hindu Kush, where these springs, served as a source of warmth, and cleansing, and their mineral water as a source of healing. In this way, probably, long time ago, these people learned to use the healing properties of the hot water that came naturally out of the ground to make their life easier. Through experience, they might have discovered that a good soak in those hot springs cured certain ailments, e.g., stiff muscles and sore backs became limbed, skin diseases cleared up, and wounds healed. For this particular reason, many of these hot springs in Afghanistan are called "chashma-e shafa", meaning the healing spring, a property that deemed them sacred. Thus, the communities all over the country rightfully consider the protection of these springs as their duty (Figure 1).
Figure 1. A satisfied young Afghan enjoys the traditional use of this known "shefa" hot spring that healed his skin condition (Aabe-Garm, Ghorband valley, province of Parwan, Afghanistan).
It is found that traditionally people are knowledgeable that drinking the water which comes from springs with carbonic acid are good for stomach troubles, bathing in sulfur-bearing springs improves their blood circulation, alum springs are helping in healing their skin problems, springs with rare earth elements (REE) contents relieve or even cure certain forms of arthritis, and strong acid springs are good for venereal diseases. During fieldwork in Obe hot springs, the authors met a family from Badghis province, who have traveled hundreds of kilometers along the torturous dirt roads of northwestern Afghanistan to come to this remote valley, just to tap into the healing properties of their known healing hot spring.
Modern use of mineral thermal springs in Afghanistan goes back to 1940s, when few thermal springs in Herat (Obe and Safed Koh), Balkh (Aabe Garm), and Orezgan were developed for therapeutic purposes. However, soon these developments were abandoned. In 1974, the Obe springs in Herat were renovated for bathhouse usage (Akhi, 2001). Probably, at the same times, single bathrooms were built on hot springs along the Kabul-Mazare Sharif highway in Pole-khumri and Hairatan towns. The rest of the hot springs of Afghanistan are left undeveloped to date, but the people continue to use them in their traditional ways (Figure 1).
The potential of modern exploitation of geothermal resources of Afghanistan has not been studied. In 1964, an attempt has been made by Soviet geologists working with the Geological Survey of Afghanistan (GSA) to conduct systematic studies on thermal waters of the country for their potential mineral contents to be used as exploration tools in search of minerals. In this way, the carbonated hot springs in the valleys of Kalu, Ghorband, Shina, Dara-e Soof, and Istalef were explored.
These exploratory studies had culminated with a survey of mineral and thermal waters of Afghanistan during 1969-1970 (Belianin, et al., 1970). However, these works were mainly focused on mineral contents and geological conditions of the mineral water systems. No attempts have been made to characterize the dynamics of geothermal systems of the Hindu Kush, or assess their energy reserves. Thus, the potential of geothermal energy associated with these springs were totally ignored and not been included in the exploration activities of GSA or any other institution. This work is an attempt to kick-start efforts to fill this gap and provide a framework for development of a geothermal databank for Afghanistan.
3. Geothermal Potential in the Structural Domain of the Hindu Kush in Afghanistan
3.1. Geological Structure:
In the earth, a certain amount of heat is generated by friction, as well as by other sources, at the boundaries of the crustal plates. The structure of Afghanistan is the result of accretion of such colliding Gondwanan microplates or fragments onto the margins of Eurasia (Tapponnier, et al., 1981) along the Herat-Panjshir E-W striking geosuture, which is a deep seated strike-slip fault, dipping as deep as up to 700 kilometer into the mantle. This major structural fault and fracture system in Afghanistan facilitates the percolation of water into the superheated zones in the crust to produce geothermal fluids.
Similar structures along the Chaman-Moqor NE-SW striking fault system, the Sarobi-Altimore NE-SW arcuate fault system, and other secondary faults throughout Afghanistan cover most of the regions of this country (Figure 2), where hot springs are the surface indication of geothermal energy resources associated with them.
Neotectonic movements in Afghanistan generated by collisional events since the end of the Cretaceous some 65 million years ago, resulted in the uplifting of the Hindu Kush mountain ranges that extend from the north-easternmost corner of the country in Badakhshan province in a NE-SW-W direction up to the westernmost border of the country in Herat province, dividing the whole structure of Afghanistan into northern and southern structural components (Saba and Avasia, 1995a). Recent tectonic movements are characterized by seismic and geothermal activities all over the country. The dynamic characters of the resulting structures indicate north-south compression and east-west extension. In addition, neotectonic movements show strong vertical uplifting, total rising and differential tilting. Seismic activities in Afghanistan show a decreasing tendency from east to west, with the strongest seismic activity occurring in the northeaster Badakhshan province, where the most active structures of the country are located (Figure 2).
Although the collision processes in the territory of Afghanistan have been ended at the beginning of Palaeogene, approximately some 50 MY ago, based on scenario of the Indian plate's final closure to Eurasia (Beck, et al., 1995), but the geo-structural components of Afghanistan are still under enormous stress from the south, exerted upon them by the ongoing movement of the Indian plate northwards (Saba and Avasia, 1995b). This process produces enormous frictional seismic and heat energy in the crust of this region, particularly along the geosutures, faults and fracture zones.
Figure 2. Surface Indications of Geothermal Prospects of Afghanistan. (Map shows thermal waters with a surface T of more than 20ºC)
Geothermal activities are closely associated with active terrains, and therefore, the activity strength of a given hydrothermal system is directly proportional to the activity strength of its associated active terrain. Due to the collision of many Gondwanan microplates moving northwards onto the southern margin of Eurasian plate, the strongest Neotectonic movements and intensive associated hydrothermal activities are evidenced south of the Hindu Kush main axis or the Herat-Panjshir geosuture. Thus, major geothermal manifestations are located along the Herat-Panjshir geosuture and the Chaman-Moqor fault systems in central Afghanistan active terrain (Figure 3).
Geothermal manifestations in these areas are mostly marked in the fracture systems of active faults, within graben or halfgraben basins and linear faulted valleys or wide valleys of the southern structural component of Afghanistan.
Figure 3. Neotectonic activity in the Hindu Kush resulting in dramatic uplift and displacement of the crust, as viewed in this photo of the Bande-Azhdar, Bamiyan, in central Afghanistan.
3.2. Active Magmatism and Volcanic Terrains:
Almost, all geological formations, i.e., from Precambrian to Quaternary systems are contributing to the geological structure of Afghanistan. Generally, these formations are of marine sediments with carbonaceous and continental characters. Lesser amounts of submarine volcanic formations are also present. Continental volcanism of Palaeogene, Neogene and Quaternary periods are widespread in central, and southwestern Afghanistan (Shareq, et al., 1980), where more than 50 dormant volcanic cones together form a volcanic zone with two distinct belts, occupying a vast surface area in the deserts of these regions.
Geothermal fields of Afghanistan are basically associated with magmatic activity and collisional tectonic structures. A diverse array of magmatic intrusive formations occupy approximately 8 percent of the total surface area of the country (Musazai, 1994), which includes a variety of rocks with wide range of temporal affinities, from the Precambrian era to Quaternary period.
Among these, geothermal indicators are found to be only associated with the Palaeogene-Neogene magmatic formations that resulted from continental collisional processes of Gondwanan fragments and the Eurasian plate margin in the territory of Afghanistan. These are mainly distributed in the form of linear magmatic structures in northeastern, central, southwestern and western Afghanistan. In these geothermal fields, the energy source of geothermal activity is controlled by magma chambers, which are located in shallow and intermediate depths with various intrusion periods, depths and volumes.
An interesting observation in the field reveals that almost all thermal indicators in Afghanistan are located in close contacts with young granitic massifs, which are void of pegmatitic or aplitic vein formations. Thus, we could not find surface manifestation of thermal waters in eastern Afghanistan, despite extensive exposures of magmatic formations in this region. This implies that the permeability in these rocks is controlled by fractures, which are already sealed by pegmatite-aplite bearing mineralisations and the successive hydrothermal alteration minerals, reducing the overall permeability of reservoir rocks.
Laterally continuous permeability forming domes or ridges that is difficult to unequivocally relate to faults has also been reported in a number of geothermal fields that are related to intrusive margins, which are usually very permeable and form large and more easily predicted continuous targets (Bogie and Lawless, 2000). The prospect of geothermal energy is much higher in association with intrusive contacts of such magmatic terrains, which occupy the core of the Hindu Kush mountain system, extending from northeastern extensions of the ranges towards central, southern, and southwestern Afghanistan.
These include magmatic complexes such as the Wakhan with a surface area of 300 km2, Baghe Aareq with a surface area of 2500 km2, and Shiva, with multiple sub-complexes of up to 300 km2 each, in the northeast; the Baraky, with multiple sub-complexes of up to 35 km2 each, the Helmand, which has not been fully exposed on the surface, but exhibit multiple sub-complexes of up to 50 km2, and the Arghandab complex with a surface exposure area of 15000 km2 in central Afghanistan. Without exception, all of these complexes are of Palaeogene-Neogene ages, forming granitoid plutons in multiple temporal phases, exhibiting linear and extended structures with northeast-southwest strikes (Musazai, 1994).
The volcanic-subvolcanic complexes of the Nawor desert to the west of the city of Ghazni have dacite-andesitic compositions, forming volcanic cones with basal diameters of 100-500m, and sometimes up to 1.5 km. The conical subvolcanic carbonatite complex in Khan-Nashin to the left flank of the Helmand River, which is the most recent volcanic activity in Afghanistan (Quaternary), has a diameter of 7 km with a very shallow carbonatitic cover. Similarly, the Malek-Dukan carbonatite conical volcanic complex, located in the Rigestan desert on the foothills of the Chagai-e mountain range in the southwestern corner of Afghanistan, has a basal diameter of 3.6 km, with the carbonatitic cover thickness reaching 500-800m. All volcanic-subvolcanic complexes of Afghanistan, including those in the upstream of the Farahrud in the province of Farah, have young ages that extend from Late Neogene into the Quaternary period (Shareq, et al., 1980).
Some of these geothermal prospect fields may be void of adequate groundwater resources as a heat transport medium, but dry hot rock is also a source of geothermal energy. By definition, dry hot rocks are naturally heated unmelted crustal rocks, which lie beneath the surface in areas where the geothermal gradients are two to three times greater than normal. Dry hot rocks are absolutely certainly present in volcanic and active magmatic regions in shallow depths. The temperature in dry hot rocks hovers around 177ºC in shallower depths, while at a depth of many kilometers, the heat may increase to up to 760ºC (Tester, and Smith (1978/79). Since the rocks are bone dry, there is no medium to transport the heat energy to the surface. The process of artificially making a geothermal reservoir within hot buried rocks is difficult and expensive, but if successful, the potential is enormous. The technology to tap this resource is already in existence in developed countries, but it is yet to be developed into commercially viable means for tapping this resource.
In the view of the authors of this report, considering the recent volcanic activities in south-southwestern structural blocks in Afghanistan, the prospect of these volcanic regions for geothermal energy is very promising. Other prospects associated with the young magmatic complexes of Afghanistan, particularly in the vicinity of fault and fracture systems are as promising and interesting in regards to their potential geothermal energy reserves.
3.3. Geopressured Prospects in Northern Afghanistan:
These very high-pressured geothermal energy prospects are associated with the hydrocarbon-bearing strata of northern Afghanistan. Geopressured thermal zones are deposits of water trapped and buried under thousands of feet of rocks and clay. This kind of water is very old, perhaps a million year or more, which is under abnormally high pressure, and is hot, with temperatures at times as high as 296º C. In these zones, which generally lay some 3-8km below the surface, the heat is trapped and insulated by encircling layers of sand, clay, and shale. The Geopressured zones are a dual source of heat and methane at the same time (Holt, 1977). Indications of this type of prospects are recorded in the oil and gas fields of the Jozjan and Balkh provinces of northern Afghanistan (Kurenoe and Belianin, 1969)
4. Hydrogeochemistry of Thermal Waters in Afghanistan
4.1. Hydrogeochemical Characteristics:
By definition, geothermal reservoirs are naturally occurring hydrothermal convection systems. Natural fluids are usually complex chemical mixtures, thus, hydrothermal waters in Afghanistan, exhibit a wide range of compositions and concentrations of solutes that generally increases with the temperature of the associated geothermal systems.
There are a diversity of thermal water types in Afghanistan, i.e., bicarbonate, chloride, sulphate, and sodium-chloride, all produced by complex geological structures and the development of various metamorphic and metasomatic processes in different geological environments, resulting in a variety of geochemical and hydrogeological conditions. Many categories of thermal waters are distinguished in Afghanistan, such as carbon dioxide rich, which in some instances having viable amounts of REE contents, nitrogen-bearing, hydrogen sulfide-bearing, Fe-Al-bearing, and brine. All these categories of thermal waters are originating from three major hydro-geochemical environments: metamorphic, reducing, and oxidizing (Kurenoe and Belianin, 1969).
In the main geothermal axis of the Hindu Kush, CO2 is the dominant gas phase constituent. Carbon dioxide and CO2-nitrogen-bearing waters are mostly originating from metamorphic environments associated with granitoid complexes. In this case, they are mainly characterized with high surface temperatures (>37ºC), high pH levels (>7.5), and low solid mineral contents in the solution (1-2.5 gm/lit). Such geothermal systems are located in the areas of higher CO2 flux, resulting from their peculiar geological structures that give origin to the geothermal reservoirs of these systems. As a matter of fact, a larger amount