Most oil-shale fuelled electricity generation is planned to be phased-out by 2030. The industry continues to have a serious impact on the environment producing ordinary and hazardous waste and greenhouse gas emissions, lowering groundwater levels, altering water circulation, and spoiling water quality. Leachates from waste heaps pollute surface and groundwater. Former and current oil shale mines cover about one percent of Estonia's territory. Resource Graptolitic argillite Estonian graptolitic argillite (also known as dictyonema argillite, dictyonema oil shale, dictyonema shale or alum shale) is a marine-type of black shale, belonging to the marinite-type of oil shales. Although the name dictyonema argillite is widely used instead of graptolitic argillite, it is now considered a misnomer as the graptolite fossils in the rock, earlier considered dictyonemids, were reclassified during the 1980s as members of the genus Rhabdinopora. Graptolitic argillite was formed some 480 million years ago during the Early Ordovician under a marine environment. In mainland Estonia, it occurs at the foot of the North Estonian Klint, ranging from the Pakri Peninsula to Narva in an area covering about . When findings in the western Estonian islands are included, its extent increases to about . The thickness of the layer varies from less than to a maximum of in western Estonia, and its depth below the surface varies from . Resources of graptolitic argillite in Estonia have been estimated at 60–70 billion tonnes. Although resources of graptolitic argillite exceed that of kukersite, attempts to use it as an energy source have been unsuccessful due to its low calorific value and high sulfur content. Its organic content ranges from 10 to 20% and its sulfur content from 2 to 4%. Correspondingly, its calorific value is only 5–8 megajoules per kilogram (MJ/kg; 1,200–1,900 kcal/kg) and its Fischer Assay oil yield is 3–5%. However, the graptolitic argillite resource in Estonia contains a potential 2.1 billion tonnes of oil. In addition, it contains 5.67 million tonnes of uranium – making it one of the main potential sources of uranium in Europe – 16.53 million tonnes of zinc, and 12.76 million tonnes of molybdenum. There is as yet no economical and environmentally friendly technology to extract either the metals or the oil. Kukersite Kukersite is a light-brown marine-type Late Ordovician oil shale formed some 460 million years ago. It was named kuckers by the Baltic German geologist Carl Friedrich Schmidt in the mid-19th century, and kukersite by the