Oil shale is a black or brown fine-grained sedimentary rock containing kerogen. Oil shale consists of organic matter that has not fully degraded (up to 70%) and various minerals. Organic matter usually consists of kerogen, which is formed from the degradation of algae or bacteria. The quantity of oil shale ash generated in a year is 15 times bigger than the quantity of municipal waste. The use of oil shale generates large quantities of waste products – ash and semi-coke. For example, approximately 5 to 7 million tonnes of ash and a million tonnes of semi-coke is generated in Estonia every year at the current pace, and only a very small amount of it is recovered.
The Archimedes Foundation supports the scientific research of the technology required for the treatment of oil shale ashes that environmental company AS Ragn-Sells is currently working on with more than 204,000 euros. The support granted within the scope of the programme Applied Research in Smart Specialisation will be used for the research overseen by Ragn-Sells and carried out by the scientists of TalTech and the University of Tartu, which is aimed at finding the best technological solutions to the valorisation of oil shale ashes.
The total greenhouse gas emissions in Estonia have decreased by 4.5 percent in comparison with the year before and more than twice in comparison with 1990. In 2018, the amount of greenhouse gas emissions in Estonia was equivalent to 20 million tonnes of CO2. The majority of greenhouse gases in the industrial sector – 88% – was generated in the energy sector, 7.2% came from agriculture, 3.1% from industry and 1.6% from waste management.
The oil shale industry has left its mark on the natural environment of Ida-Viru County over the last decades. Ragn-Sells does not promise that the ash hills will disappear overnight, but the solution to be developed by the company would considerably reduce the emergence of ash hills.
The scientists of the Tallinn University of Technology and the University of Tartu and the team of Ragn-Sells AS are developing an industrial technology for the separation and recovery of the elements found in oil shale ash, following the example of similar circular economy projects implemented in Sweden. Releasing a large waste segment into circulation by way of valorisation has two benefits from the viewpoint of environmental sustainability because the quantity of waste is reduced and the primary production of several materials can thereby be reduced as well.
Energy production in Estonia is largely based on oil shale. Although the share of renewable energy is increasing, it still remains at around 30% per year. The remaining electricity is mainly generated from oil shale. The share of electricity generated from renewable energy sources in the total consumption of electricity has increased every year and reached 19.7% in 2018, which is an increase of 5.7% in the last five years.
Swedish environmental company Ragn-Sells entered into a cooperation agreement with Eesti Energia for finding solutions to the valorisation of oil shale ash and its release back into circulation. The new technology currently being tested helps solve one of the challenges of oil shale energy in Estonia – what could be done with the by-product of energy generation, i.e. bottom ash? Approximately 80% of the energy generated in Estonia is produced from oil shale. This creates large quantities of by-products, such as bottom ash, which is currently mostly deposited.