Papers by Author: Yu Liu

Abstract: With the increasing seriousness of climate change problem, carbon footprint has become a very useful method to measure carbon emissions and has been widely accepted. In modern industry, electricity is almost consumed in all industry processes, and electricity is the first "footprint" of most products. As carbon emissions is always measured by theoretical estimation from input inventory but not experimental data, the input inventory of electricity generation becomes very important in carbon footprint analysis. Electricity generation is a very complex process, where all input items inter-dependant on each other and the whole system is an infinite cycle net. But in the traditional calculation model of input inventory, the interaction effect of production system is usually neglected. The major work of this study is to make clear the carbon emissions of provision 1kWh thermal power generation to consumers in China in 2006, since thermal power generation takes the most proportion of Chinese electricity. This study used a matrix-based model which includes interaction effect of the system to calculate the input inventory of electricity generation, and then the carbon emissions of thermal electricity generation in China in 2006 can be calculated. The final result of this paper can be used in carbon footprint, Life Cycle Assessment or some other related fields.

Abstract: The primary problem of eco-materials is how to judge whether a material is environmentally friendly or not, and the method of life cycle assessment is usually used to evaluate it. The depletion of mineral resources is a very important indicator of LCA, but its characterization is still filled with dispute. At present, the most commonly used method is CML, which is put forward by Leiden University, and its core idea is that using the ratio of exploitation amount and reserves of mineral resources as the degree of scarcity. Although being accepted by most of the scholars at work on LCA, CML doesn’t grasp the essence of the depletion of mineral resources. Recently, a new assessment method, injecting new ideas to the conventional life cycle assessment, combines exergy with LCA is arising, which can be used to solve some specific problems of LCA especially the depletion of mineral resources. In this paper, two results of elements’ exergy calculated by Rivero and Szargut respectively are compared, and the exergy of some natural minerals, which can be used in LCA and other minerals-related research, is calculated based on the data of Chinese mineral resources.

Abstract: The major environmental loads of mineral separation process in China iron production (with missing data) are analyzed. And the inner relationship between these loads data is qualified and the missing data are imputed using a statistic method called multiple imputation (MI), aimed to improve the quality of LCA datasets and allow industry to easily conduct a highly reliable LCA. By using computer simulation, MI replaces each missing value with a set of plausible values which represent the uncertainty of the missing data. The multiply imputed datasets are then analyzed by the standard procedures for completing data and combining the results from these analyses. The result proves that MI Method is an effective and reasonable method to solve the problem of missing data and therefore can ensure the validity and reliability of LCA.