News 14.12.2021

Optimization of the combustion process of oil shale impacts the number of emissions

The optimization of the combustion process of oil shale has a strong impact on the emissions generated. Research revealed that the amount of secondary emissions that are formed from primary emissions was many times higher than the direct particulate emissions. As the potential of oil shale emissions to produce secondary aerosol in the atmosphere is large, it is very important to take into account gaseous emissions when the emission mitigation systems or emission regulations for oil shale combustion are considered.

Around 30% of the energy is produced in Estonia by oil shale combustion and oil shale will remain as important back-up fuel for energy security for the period 2021–2030. In addition to production of greenhouse gases and harmful gaseous emissions, combustion of oil shale is releasing particles into the atmosphere. Combustion based particles are known to be harmful to human health and they have direct and indirect climate effects.

Finnish Meteorological Institute, together with University of Tampere, Tallinn University of Technology, Estonian Environmental Research Center and University of Helsinki, studied the emissions of oil shale burned in a circulating fluidized bed boiler in the test laboratory of Tallinn University of Technology. A comprehensive set of sophisticated instruments was utilized to investigate the primary and secondary emissions of oil shale combustion.

If the furnace temperature was too high, nitrogen oxides emissions increased, but if the furnace temperature was too low, gaseous organic compound emissions increased. In poor combustion, the amount of particulate pollutants, especially organic compounds, clearly increased.

The gained results are good input for technology selection if carbon capture and storage (CCS) technologies will be considered for enhanced CO2 reduction in oil shale industry.

Further information:

Senior Researcher Minna Aurela, Finnish Meteorological Institute, Aurela, M., Mylläri, F., Konist, A., Saarikoski, S., Olin, M., Simonen, P., Bloss, M., Nešumajev, D., Salo, L., Maasikmets, M., Sipilä, M., Dal Maso, M., Keskinen, J., Timonen, H., and Rönkkö T. Chemical and physical characterization of oil shale combustion emissions in Estonia Atmospheric Environment: X 12, 100139 (2021).

Scientific article is available here.

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