Goal and Scope definition. The very first step of any LCA envisages the definition of the goal of the study, which primarily has to include: i) the intended application of the study; ii) the reason for carrying it out; iii) the intended audience (which affects the technical level of reporting and the interpretation of results); and iv) the commissioner of the study, to highlight potential conflicts of interests. In the case of shale gas, LCA studies can be used i) to compare the environmental performance of shale gas as source of heat or electricity with conventional fossil and alternative sources, ii) to identify the phases of the life cycle that contribute the most to the environmental impacts, thus recommending potential improvements, and also iii) to support governments in the development of new domestic policies, for instance, for tackling climate change. The reasons for carrying out the study can thus be to support decisions (e.g. in developing policies), learning about the environmental impacts of shale gas or about the effect of implemented policies, or to support technical improvements. The intended audience can range from policy-makers (in developing policies) to the general public (e.g. for ex-post policy assessment) to technical people working in the shale gas life cycle (for identification of hot-spots and possible improvements). The definition of the scope of the study has to address two main aspects: It has to provide a quantified description of the function to be satisfied by the product under study, namely the Functional Unit, and a quantified amount of the product necessary to deliver the function, namely the reference flow. It has to specify the boundary of the product system in terms of all the processes that are to be included (see Figure 27). Essentially, there are two alternative approaches to perform LCA (these are also called “modes”), which affect the system boundary as well as the life cycle inventory modelling. The attributional approach analyses a single existing or hypothetical product system, to address the question “what environmental impact can be associated with this product?”. The consequential approach, on the other hand, aims to describe indirect changes outside the immediate product system induced by changes in production rates. The former is appropriate as the basis for environmental product labelling, as well as for aiding decisions that are not deemed to cause structural changes; whilst the latter has been specifically developed to deal w...
