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The objective of the paper is to define CO 2 intensity for Estonian oil shale used for energy generation. Life cycle analysis (LCA) is selected as a modelling tool to reach the objective. The model analysis energy requirements and CO 2 emissions are associated with mining and transportation of shale rocks and production of shale oil. Since the oil shale retorting process works as a 100% self-compensation energy technology (heat and gas derived from retorting of oil shale are reused within the ongoing and next retorting), the paper lays emphasis on analysis of the co-products life cycle in elimination of CO 2 emissions. Preliminary results of the research show that life cycle CO 2 emission factors of oil shale processing mainly depend on the technology used for production of final raw products as shale oil, semi-coke gas and generator gas. Also, boundaries of the researched system must be taken into account due to avoided emissions from co-products production instead of using universal CO 2 emission factors and assumptions. Future work will be focused on 1) material based life cycle analysis to investigate whether the energy produced from oil shale resources can compete with other fuels in terms of life cycle emissions, and 2) LCA impact assessment of the system.

The European Union has set an ambitious goal to transform to a carbon neutral economy. The present paper focuses on thermal treatment of oil shale and biomass blends that could be considered as an important pathway for achieving the carbon neutral goal locally in Estonia. The concept of co-pyrolysis and co-gasification of biomass and oil shale offers various advantages such as higher liquid product yield and higher char conversion than if the oil shale and biomass particles were processed individually. In the paper, an overview of the planned actions for merging oil shale industry carbon neutral economy is given. The selected approaches are justified with information found in scientific literature and initial experimental results. Further, the possible future developments for gasification and pyrolysis in Estonia are also highlighted.

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