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 micro plates or fragments onto the margins of Eurasia (Tapponnier, et al., 1981) along the Herat-Panjshir E-W striking geo suture, 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 HinduKush 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 major geothermal manifestations are located along the Herat-Panjshir geo suture and the Chaman-Moqor fault systems in central Afghanistan active terrain Geothermal manifestations in these areas are mostly marked in the fracture systems of active faults, within graben or half graben basins and linear faulted valleys or wide valleys of the southern structural component of Afghanistan.
Geothermal Energy For Electricity Production:
Geothermal energy reserves in Afghanistan could provide part of the electricity needs required to satisfy the demand. Electrical power production is the most profitable use of geothermal energy, and worldwide has grown the most, comparing to other geothermal applications. Electricity is produced with geothermal steam in 21 countries, with the USA being the top producer in 1999, producing 2228 MWe. In the Philippines, about 22% of the electricity is generated with geothermal steam. Other countries presently generating 10-20% of their electricity with geothermal energy are Costa Rica, El Salvador, Iceland and Nicaragua (Huttrer, 2001). Currently many developing countries such as Turkey, Kenya, Taiwan, Chile, and Tibet in China are also developing their geothermal fields.
To generate electricity from geothermal hot water, two prerequisites are required to be fulfilled: adequate technology, and an abundant high-temperature water or steam. At present, efficient and durable technology is readily available to Afghanistan to produce low-cost electricity from its geothermal resources. At the meantime, the tectonic structure of Afghanistan suggests the presence of vast hot water circulation systems underground. But only under certain conditions of depth, temperature, and chemistry does it pay to drill into these systems, conditions that require further explorations to be undertaken.
Geothermal Energy for Direct Uses:
Direct-use geothermal technologies use naturally hot geothermal water for commercial applications. Afghans know the medicinal and healing properties of hot water springs, especially its therapeutic power for skin conditions and rheumatic arthritis. Medicinal bathing or balneology is an important sector to be considered for modern developments of some of the well-know healing hot springs of the country. This has the potential to contribute to the improvement of life standard and the overall well being of the people of Afghanistan, while creating hundreds of new and permanent jobs.