This article was automatically translated from the original Turkish version.
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Lignite is a type of coal that belongs to the group of fossil fuels and is characterized by carbonization at low temperatures. It typically appears in shades ranging from brown to near black and is a low-calorific fuel (usually 700–3000 kcal/kg) with high moisture content (30–52%) and high ash content. In hard lignites, moisture content is below 20%, while in soft lignites it exceeds 40%. The quality of lignite varies depending on its moisture, ash and sulfur content. The majority of lignite deposits in Türkiye are of low quality and may contain more than 20% ash and over 1% sulfur. Despite its low quality, lignite plays a significant role in energy production due to its domestic origin and transportation advantages. Its energy efficiency can be improved through preprocessing methods such as drying and washing.
Lignite forms from the accumulation of plant debris in oxygen-poor environments and subsequent compression under sedimentary layers. The majority of lignite deposits in Türkiye accumulated during the Tertiary period, particularly the Miocene, following the Alpine orogeny, in freshwater lakes and swamps. Lignite deposits are found within geological units such as Eocene flysch, Oligocene gypsum formations and Miocene freshwater sediments. These depositional environments typically developed in low-pressure subsidence basins, where abundant vegetation provided the necessary biomass for lignite formation. Türkiye, situated within the Alpine belt, offers a geologically favorable setting for such basins due to its tectonically active structure.
Türkiye holds approximately 5.9% of the world’s lignite reserves and ranks 14th globally in terms of reserve volume. Across the country, a total of around 11.5 billion tons of lignite reserves are identified at 116 different locations. Of these reserves, 9.6 billion tons are proven, with the remainder classified as probable and possible. Lignite deposits in Türkiye are predominantly located in Tertiary-aged basins and are operated through public-private sector collaboration. The largest lignite deposits are as follows:
Some of these deposits are extracted by open-pit mining, while others are mined underground. The strategic importance of lignite fields located near planned thermal power plants is particularly high.
The earliest records of lignite presence in Türkiye date back to the Ottoman period. Production began in the 19th century in regions such as Erzurum, Soma and Çeltek. With the establishment of the General Directorate of Mineral Research and Exploration (MTA) in 1935, systematic exploration and reserve development efforts commenced. The “Development of Our Lignite Reserves Project,” initiated in 2005, led to a significant increase in reserve estimates. During the Republican era, state-led initiatives supported lignite production, particularly to ensure energy supply security by directing it as feedstock for thermal power plants. From the 1950s onward, the establishment of briquette factories aimed to enhance the efficient use of lignite.
Lignite is primarily used as a fuel in thermal power plants for electricity generation. Despite its low calorific value, it remains widely used in Türkiye as an alternative to natural gas and imported coal. It is also used for domestic heating in certain regions. The use of low-quality lignite poses environmental risks; therefore, methods such as filtration and briquetting are employed to mitigate environmental impacts. Additionally, lignite can serve as a carbon source in certain chemical processes. Today, clean coal technologies represent important steps toward making lignite use more sustainable.
Lignite reserves are distributed across all regions of Türkiye, but the richest areas are the Mediterranean (Afşin-Elbistan), Central Anatolia (Karapınar), Aegean (Soma, Tunçbilek) and Marmara regions. Reserves in Eastern and Southeastern Anatolia are limited. Regional variations also affect the quality of lignite deposits. For example, while the Afşin-Elbistan deposits are large in volume, they have low calorific value, whereas the Soma and Tunçbilek deposits possess higher heat values. This distinction is a critical parameter for the siting of thermal power plants and fuel efficiency.
The formation of lignite deposits in Türkiye is directly linked to tectonic events following the Alpine orogeny. Lignite is generally found in subsidence basins bounded by faults and within Miocene freshwater environments. Geological deformations have caused some deposits to become fragmented, while others have been divided by faulting. The primary host formations for lignite include Eocene flysch, Oligocene gypsum units and Miocene freshwater sequences. Basin morphology, migration structures and sedimentation rates play a decisive role in determining the distribution and thickness of lignite seams.
Lignite is a strategically important domestic and abundant fossil fuel source for Türkiye’s energy security. Despite its low calorific value and high moisture and ash content, it plays a vital role in energy production, particularly in thermal power plants, due to its extensive nationwide reserves. Lignite deposits, which have been exploited since the Ottoman period, were evaluated more systematically during the Republican era through state policies. Geologically, Türkiye’s position within the Alpine orogenic belt has facilitated the development of subsidence basins favorable for lignite formation. Today, lignite deposits operated by both public and private sectors continue to hold significance in efforts to increase domestic resource utilization. However, given environmental impacts, low efficiency and the transition to clean energy, lignite use must be supported by advanced technologies and managed in accordance with sustainability principles.
Geological Formation
Lignite Reserves and Distribution in Türkiye
Historical Development
Applications
Geographical Distribution
Geological and Tectonic Factors