Tallinn University of Technology

What is oil shale?


Estonian oil shale, or kukersite (the name comes from the village of Kukruze in Ida-Virumaa, where the oil shale was found), – one from solid fossil fuels. Oil shale was formed about 450 million years ago in the shallow warm salt sea. In favourable years, layers of algae settled on the bottom, mixing with clay and lime minerals.

Oil shale consists of not fully decomposed organic matter (50-70%) and non-combustible mineral part. The organic or combustible part of the oil shale is formed by carbon and hydrogen, as well as oxygen and nitrogen, to lesser extent phosphorus and chlorine. When burning oil shale remains almost 55% of the ash.

In Estonia, oil shale is used to produce electricity and shale oil. The calorific value of oil shale produced in Estonia is 5–20 МJ/kg. Estonia is the most non-volatile country in the European Union, mainly due to the energy obtained from the oil shale. Shale enterprises produced 9.6 TWh of electricity in 2017, which is 90% of all electricity produced in Estonia. Products of the oil shale industry are shale oil, bitumen, coke, fine chemistry products, alkylresorcinols, phenols and resins. In 2017, Estonia produced more than a million ton of shale oil for the first time, almost 90% of which was exported. The wastes of oil shale industry are a barren rock, semi-coke and ash.

The enterprises of the shale industry are Eesti Energia AS, Viru Keemia Grupp AS, Kiviõli Keemiatööstuse OÜ (Alexela Group AS) and Kunda Nordic Tsement AS. In 2017, the revenue of the Estonian shale industry from sales amounted to 663 million euro, 7387 people were employed at the enterprises, total 15.6 million ton of oil shale were mined, and the contribution of enterprises to the state Treasury was more than 103 million euro.

In the world, oil shale is found in 33 countries in more than 600 fields. The largest deposits of shale are in the USA, Canada, China, Russia, Israel, Jordan and Brazil. According to the World Energy Council, the world's entire supply of oil shale contains almost 6 050 billion barrels of shale oil. This potential oil content overcomes four times more than all the world's petroleum reserves. In Estonia, oil shale is located in the fields of Estonia and Tapa in the north-western part of the country. There are two types of oil shale in Estonia: kukersite and mudstone. Estonian oil shale deposits are evaluated at 16 million barrels (amount of shale oil, contained in the oil shale), Estonia ranks tenth in the world in terms of oil shale reserves.


  1.     Estonian oil shale industry yearbook 2017 (2018). TalTech Virumaa college Oil Shale Competence Center.
  2.     Kukersite and mudstone. The story of our energy (2014). Eesti Energia AS, Motor.