Using Life‐Cycle Assessment in Process Design

Abstract

Summary This article presents the application of life‐cycle assessment in early phases of process design in the context of technology that employs a bio‐based material. The goal is to identify hot spots in the process chains with regard to environmental impacts by performing a dominance analysis. By focusing his activities on the hot spots identified, the designer is given the opportunity to efficiently improve environmental performance. This approach is illustrated for the case of supercritical water gasification, a novel technology for the treatment of organic feedstock with high moisture content. In the reactor under supercritical conditions, organic components are converted into a high‐caloric synthesis gas, with hydrogen, methane, and carbon dioxide as the main products. The data used for the assessment are obtained from laboratory tests and the literature, completed by assumptions for missing data. The scope of assessment ranges from the extraction of raw materials to the product, that is, hydrogen (cradle to gate) with sewage sludge of a municipal wastewater treatment plant used as feedstock. The assessment identifies the main sources of environmental impacts. The predominant process step in terms of global warming potential is the supply of the gasification process with additional heat. The production of a blending agent in the dewatering step is the main source of the impact category of acidification, whereas the wastewater treatment plant is the origin of emissions that lead to eutrophication. The revealed sources are analyzed further and options for reducing the environmental impacts are discussed.

Life cycle assessment (LCA) applied to the process industry: a review

“…Nevertheless this latter option often sees processes as black boxes and constructs LCIs using the literature or industrial data at fixed operating conditions, without taking into account operating parameter variations (Benko and Mizsey 2007;Brentner et al 2011;Gasafi et al 2003;Kenthorai Raman et al 2011;Koroneos et al 2004;Norgate et al 2007;Scipioni et al 2009). This approach is of interest when the aim is to assess the process via an overall approach or to compare different processes in their global nature, but it is limiting when dealing with analysing each process unit as a complex system, and determining what are the best operating conditions.…”

“…DfE is a preventive approach, which involves the incorporation of environmental considerations into the design and optimization of products, processes and management systems at the early stages of conception, in order to minimize environmental impacts (Sroufe et al 2001) and avoid having subsequent reduction measures (Gasafi et al 2003). For example, in the chemical industry, DfE is apparent via development of "green" chemical routes, process intensification and process redesign (Bakshi and Fiksel 2003).…”

“…The methodology was traditionally used to understand three types of problem: assessment of single products to learn about their environmental impacts, comparison of process routes in the production of substitutable products or processes, and comparison of alternative ways for delivering a given function (Berkhout and Howes 1997). More recently, it was similarly argued that LCA is mainly used to compare different products, processes and activities delivering similar functions, but this methodology can also be used as a standalone tool to identify hotspots in a life cycle (Gasafi et al 2003).…”

“…In the field of supercritical water gasification, Gasafi et al (2003) presented one application of LCA in an early phase of process design. They adopted an original approach that consisted of coupling LCA with a hierarchical approach to quantify environmental impact throughout the process chain, and identify the environmental damage "hotspots" which were then focused on for optimization of environmental performance.…”

Environmental optimization of chromium recovery from tannery sludge using a life cycle assessment approach

“…The energy consumption was considered to be 1.4 kWh/ton of dry sludge for stirring the sludge mixture [22] and 52 kWh/ton of dry sludge for filtering it [23]. The inventory data for the oxidative chromium recovery process (presented in Table 3) were based on a laboratory scale process.…”