Open-air deposition of Estonian oil shale ash: Formation, state of art, problems and prospects for the abatement of environmental impact

Abstract

The growing demand for the world energy supply necessitates the employment of local low-grade fossil fuels like oil shale (OS). The use of such fuels is accompanied by the formation of large amounts of waste ash, which are usually disposed of in open-air deposits and may hence lead to serious environmental problems. The nature of environmental hazards depends on the composition and properties of the deposited ash, which in turn are derived from the composition of the initial fuel, as well as its processing parameters. The exploitation of Estonian OS deposits has a near centurylong history, including over 60 years of industrial production of heat and power, and the respective management of ash deposits. In the current paper, the results of the last decade's studies on the processes taking place in Estonian OS ash fields have been analysed. The complex composition of ash and its transformation reactions under ambient conditions have been considered. It is shown that the hydraulic ash removal and wet depositing system works as a natural CO2 trap. The algorithm for the calculation of the resulting effect has been evaluated. © 2012 Estonian Academy Publishers.