Life-cycle inventory unit processes

Similarly, Overcash et al. [32] produced an engineering rule-of-practice-based analysis of separate unit processes used in manufacturing. The information is collated in the form of a unit process life cycle inventory, which then helps to evaluate the manufactured products through the quantification of various parameters, including input materials, energy requirements, material losses and machine variables. 

Overcash, M., Twomey, J., and Kalla, D., 2009. Unit process life cycle inventory for product manufacturing operations, ASME International Manufacturing Science and Engineering Conference, West Lafayette, IN, USA. 

Life-Cycle Inventory analysis result (LCI result) provides information about all inputs and outputs in the form of elementary flow to and from the environment from all the unit processes involved in the study. An outcome of a life-cycle inventory analysis result includes the flows crossing the system boundary and provides the starting point for life-cycle impact assessment. 

Life cycle inventory (LCI) is a methodology for estimating the consumption of resources and the quantities of waste flows and emissions caused or otherwise attributable to a product s life cycle [3]. The inventoiy analysis constitutes a detailed compilation of all of the environmental inputs and outputs to each stage of the life cycle [10]. The inventory usually includes raw material and energy consumed, emissions to air and water, and solid waste produced. The processes within the life cycle and the associated material and energy flows as well as other exchanges are modelled to represent the product system and its total inputs and outputs from and to the natural environment, respectively (Fig. 8.2). This results in a product system model and an inventory of environmental exchanges related to the functional unit. 

Life cycle inventory (LCl) analysis is the second step in an LCA. The assessor typically diagrams the steps (or unit processes) in the product or process life cycle as the basis for this analysis. For example. Figure 2.5, which showed the unit operations in the treatment of wastewater, diagrams one portion of the life cycle of 1,4-DCB. 

There are also several points in an LCA that can significantly change the result of a study. These are, among others the functional unit, system boundaries (geographical, natural as well as life cycle), data quality, and allocation. A traditional problem in LCA is how to deal with processes or groups of processes with more than one input and/or output, and how to deal with the use of recycled material in another product than the original. A crucial problem of evaluation and interpretation of the inventory results is that they depend on social and political preferences rather than on technical development. 

The inventory analysis is a technical process of collecting data, in order to quantify the inputs and outputs of the system. Energy and raw materials consumed, emissions to air, water, soil and solid waste produced by the system are calculated for the entire life cycle of the product or service. To make this analysis easier, the system under study is split into several subsystems and unit processes, and the data obtained are grouped in different categories in a LCI table. 

Life cycle assessment of SOFC technology is still uncommon due to the relatively early stage in technical development. However, several studies have been performed since the end of the 1990s. Since there is a lack of standard commercial equipment that could serve as a basis and reference point for analysis, LCA studies mostly refer to hypothetical concepts and/or extrapolate from laboratory and early market prototypes to commercial units. While the first studies had only little access to operation data at aU (for the fuel cell system itself but also for production processes), the main effort was set in the assessment of inventory data using assumptions, simplifications, and correlations [79, 80]. The main outcomes of these studies were the identification of weak points and the setting of benchmarks for further development. With more information about fuel cells available today and a simultaneous advancement in LCA methodology, the studies became more reliable and detailed, regarding system description [81] as well as the assessment of environmental impacts coimected with inputs and outputs [82]. Especially the extensive data of these two studies found their way to commercial databases for LCA [83] and thereby became available to LCA practitioners. In 2005, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)... 

Life cycle assessment is a methodology to assess the environmental impacts of a product, process, or service. ISO 14040 and 14044 are international standards for developing LCA, which has four steps that include definition of goal or scope, inventory of relevant material and energy inputs and relevant environmental outputs, evaluation of environmental impacts per functional unit, and interpretation of results. 

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