Application of scenario analysis for assessing the environmental impacts of thermal energy substitution and electrical energy efficiency in clinker production by life cycle approach

Abstract

In this work, a life cycle approach is used to evaluate the potential environmental impacts of thermal energy substitution and electrical energy efficiency applications in clinker production, which is a highly energy-intensive process. Sixteen scenarios are designed in addition to a business-as-usual (BAU) scenario by considering two approaches: (1) eight scenarios that feature different types (dried sludge [DS], refuse-derived fuel [RDF], and residual oil) and substitution rates (15% and 30% of thermal energy) of alternative fuels and (2) eight scenarios that consider the projected electricity consumption and electricity generation mix for 2023 in Turkey. A cradle-to-gate life cycle assessment (LCA) is conducted, including raw material acquisition from nature, transportation of all materials to a cement plant, raw material preparation, raw meal milling, and kiln burning. The life cycle impacts are assessed with the IMPACT 2002+ method, including both the midpoint and endpoint approaches. As the substitution rate of dried sludge and RDF is increased from 15% to 30%, all midpoint impacts are improved except respiratory inorganics because of the additional electricity usage of the pretreatment processes of those waste fuels before incineration in cement kiln. Reducing the specific amount of electricity consumption and the preferred electrical energy produced through renewable sources in clinker production is a more suitable option compared with the thermal energy substitution scenarios. In terms of overall environmental burden, Scenario 6E, which uses RDF with a thermal substitution rate of 30%, is the most environmentally friendly option among the 16 scenarios. On the contrary, Scenario 5, which uses dried sludge with a thermal substitution rate of 30%, is the worst option.