Sustainability Evaluation Of Cement Enterprise Based On Emergy And Em-LCA

Cement manufacturing is one of the pillar industries in our national economy. Chinese cement production reached 2.49 billion tons in 2014, accounting for about 60% of the total output of cement in the world. However, the rapid development of cement industry has brought serous issues on energy, economy and environment. Huge amount of coal, electricity, diesel and ores are consumed during the production, resulting in the emissions such as CO2 and NOx, and the high running cost. Therefore, it is of great significance to evaluate the sustainability of cement production system and exploit the improvement processes and potentials. Aiming at the characteristics in cement production, this paper constructed the emergy evaluation indicators and an Emergy-Life Cycle Assessment (Em-LCA) method suitable for cement industry based on the traditional emergy analysis theory. Case studies of the cement enterprises and the subsystems of cement production were carried out in this paper.The main contents of this paper are as follows:Firstly, the improved emergy evaluation indicators suitable for cement industry were established. Traditional emergy indicators were modified by taking into account the impact emergy of pollutants on environment and the emergy flow structure with different cement production technologies. By applying the improved emergy indicators, the emergy analysis and comparison were conducted on four cement manufacturing systems:with/without waste heat power generation and with/without cement kiln co-processing industrial solid wastes. The results indicate that the improved emergy evaluation indicators can precisely reflect the sustainability level of the cement enterprises, and both qualitatively and quantitatively analyze the improvement degree of the sustainability level by the waste heat power generation and cement kiln co-processing technologies.Secondly, combining the characteristics of emergy analysis and life cycle assessment, an Emergy-Life Cycle Assessment method suitable for eco-efficiency evaluation on subsystems of cement production was established. By using solar emergy as a unified scale, this method introduced the raw material emergy, reusing resource emergy. non-renewable energy emergy. capital emergy and environmental impact emergy of air pollutants into life cycle frame. The eco-efficiency of cement manufacturing subsystems was evaluated by applying the Em-LCA method. The results indicate that different emergy impact categories vary significantly on different sections of cement production. The cement kiln co-processing industrial solid wastes technology enhances the eco-efficiency of cement production subsystem through changing the emergy flow structure of raw meal preparation system and pulverized coal preparation system. Based on the evaluation results, decision-makers can make targeted technological improvements.