Moving Ahead from the Spreadsheet Platform

The integration of emergy analysis with Life Cycle Assessment is not only useful, but, in the opinion of the authors, often essential and overdue. In particular, implementing emergy within one of the commercially-available LCA software packages allows the analyst to make use of the internationally-recognized databases and to produce results in a quicker, more consistent, and more reliable way if compared to the common spreadsheet-based calculations. A preliminary case study is presented for demonstrative purposes. LIFE CYCLE ASSESSMENT Life Cycle Assessment is an internationally-recognized and widely applied tool for the evaluation of the “cradle-to-grave” environmental performance of human-dominated processes. Originally introduced in the early 1960’s with the simple purpose of quantifying the resource requirements and emissions associated to the production of commercial goods, LCA gradually became more and more complex and sophisticated, and was eventually standardized by the Society for Environmental Toxicology and Chemistry (SETAC) in 1993 (Consoli et al., 1993), and later codified by the International Standardization Office (ISO) norms 14040-43 (ISO, 1997a-d). According to the SETAC definition, later modified by LCA-Nordic (Lindfors et al., 1995), Life Cycle Assessment is: “A process to evaluate the environmental burdens associated with a product system, or activity by identifying and quantitatively describing the energy and materials used, and wastes released to the environment, and to assess the impacts of those energy and material uses and releases to the environment. The assessment includes the entire life cycle of the product or activity, encompassing, extracting, and processing raw materials; manufacturing; distribution; use; re-use; maintenance; recycling and final disposal; and all transportation involved. LCA addresses environmental impacts of the system under study in the areas of ecological systems, human health and resource depletion. It does not address economic or social effects.” A complete LCA is comprised of four steps: 1. Goal Definition and Scoping, 2. Life Cycle Inventory (LCI), 3. Life Cycle Impact Assessment (LCIA), and 4. Interpretation. In particular, in step two (LCI), all the input and output flows of the various process steps within the analyzed system are investigated, and the list is extended from the local scale to the life Chapter 3: Nested Emergy Analyses: Moving Ahead... -3.2cycle scale, in order to keep track of all the indirect material and energy requirements and emissions that are associated with each direct system input. The choice of the specific impact assessment method to be employed in step three (LCIA) is left to the discretion of the analyst, and many “upstream” and “downstream” methods have been developed in the scientific literature, ranging from Gross Commercial Energy Requirement to Total Material Requirement, to Global Warming Potential and Acidification Potential, among others. The authors hereby propose that Emergy Analysis could be conveniently and productively implemented as a further, larger-scale, impact assessment method in step three of a conventional LCA, after making some minor and comparatively easy integrations of the LCI (namely the non-commercial natural renewable inputs, such as sun and wind). In fact, many of the necessary requisites of Emergy Analysis are shared by LCA too, such as the completeness and self-consistency of the underlying flow diagram, and the attention to avoid any double-counting. It should be noted that the integration between the two approaches is especially interesting when dealing with industrial or otherwise humandominated systems, for which LCA was introduced in the first place, and for which a wealth of inventory data are available. Spreadsheet-based calculations remain on the other hand a quick and reasonable alternative for all-natural systems, or larger, aggregated nation-wide analyses. COMMERCIALLY-AVAILABLE LCA SOFTWARE Many primary processes have already been analysed from a life cycle perspective by authoritative institutions and the relative LCIs are available as databases (e.g., ETH-ESU and BUWAL250). In particular, comprehensive inventories are available for the raw materials and technological inputs necessary for the mineral industry sector, for the construction sector, for the transport sector, and for the energy sector (fuels and power plants). Typical recycling scenarios are also available for many common materials and can be used as building blocks for a more comprehensive analysis. Several dedicated software packages for Life Cycle Assessment are available on the market (e.g., SimaPro, GaBi, Umberto, TEAM, KCL-ECO, and LCAiT), which allow the user to readily access at least some of the above-mentioned databases from within the programme itself and use the included processes as building blocks for the analysis of more complex products and services (such as a car, house, or specific manufacturing process). Of course, any of the sub-processes can also be edited and modified to better suit the specific case-study being analysed. The obvious pros of using this type of software, when compared to performing lengthy and error-prone spreadsheet-based calculations, are: 1. Availability of the integrated databases, 2. Ease of keeping track of all interconnections and hidden flows within a complex process or system, 3. Suitability for routine analyses, and 4. Availability of company support (updates, upgrades and integrations). The only practical disadvantages are the comparatively steeper learning curve for the novice analyst and the expense of purchasing and updating a user licence. NO NEED TO START FROM SCRATCH! As already implied above, it is the authors’ belief that emergy analysts need not start from scratch when performing their analyses of industrial and human-dominated processes. On the contrary, it would be less time-consuming and often more dependable to rely as much as possible on the authoritative studies that are already available to the wider community of LCA analysts. This is made Chapter 3: Nested Emergy Analyses: Moving Ahead... -3.3especially straightforward by implementing emergy within one of the available software packages for LCA. This has the following advantages. 1. Use can be made of the available LCIs for all the sub-processes included in the integrated databases. 2. Transformities need only be entered once, and only for the primary environmental inputs (i.e. fossil fuels, ground water, mineral ores, etc.). 3. Transformities for all the sub-processes included in the integrated databases are calculated automatically and by the software, based on the (editable) flows diagrams associated with each sub-process, whereby the requirements for all primary environmental inputs are assessed. 4. Further complex processes can be built in a “nested” way, making use of the readily available (or previously analysed) sub-processes, thus always ensuring consistency and completeness. 5. Results can be compared to those of other selected Impact Assessment methods that can be simultaneously applied to the same LCI. In particular, the authors would like to emphasize the importance of this last point (number five), since it is their firm belief (Ulgiati et al., 2006) that in no circumstances can a single method be sufficient to thoroughly describe the environmental performance of a system (emergy being no exception), due to different points of view adopted in each method, different spatial and time scales, and different assumptions. Of course, before starting a new analysis it is still important that the analyst draw a complete systems diagram of the process to be analysed and ensure that no relevant emergy flows are underestimated or left out of the analysis. The self-contained structure of the typical LCA software package is helpful in this exercise by automatically providing consistency checks throughout the procedure. The only issue that remains to be dealt with is that of those uncommon instances where coproduct flows out of a sub-process are then made to re-converge at a later stage of the process. In this case, the software is not capable of recognizing the co-product nature of the flows by itself and the analyst should be careful not to include either co-product in the flow diagram of the software.