As mentioned in the goal and scope definition, the goal of this study was to support public decision-makers of the CWDM to identify the most favourable lignocellulosic bioenergy system. In the original study (Von Doderer 2012), the lignocellulosic bioenergy systems were assessed not only from an environmental perspective, but also from a financial — and socio-economic perspective. The gen­erated performance data was further applied in a multi-criteria decision-making analysis using the analytical hierarchy process, to determine the most sustainable alternative. The study concludes that lignocellulosic bioenergy system 26 is most favourable, showing a strong financial-economic viability, a high socio-economic potential and a relatively low environmental impact.

Generally, the main driver for each criterion, whether it be of an environmental, financial-economic or socio-economic nature, is the overall conversion efficiency (OCE) of the biomass upgrading and bioenergy conversion system. The greater the OCE, the less biomass is required, resulting in fewer upstream activities and less land required for biomass production. In terms of the environmental impact of the LBSs, a greater OCE is desired, resulting in lower total emissions and, therefore, in lower impacts for each life-cycle impact category. Similarly, for the financial — economic viability of the LBSs, a greater OCE results in lower costs, both in terms of capital and operating expenditure, as well as in higher internal rates of return on the capital invested.

Another important driver is the efficiency of the harvesting system, which has an effect similar to the OCE. The greater the degree of mechanisation and automation, the lower the environmental impact and the higher the cost-effectiveness and profitability.

11.4 Conclusions

As shown in this Chapter, the life-cycle assessment (LCA) approach, originally developed as an environmental assessment tool, is a very useful tool to provide environmental performance information in a structured and comprehensive way. It can be understood intuitively as a tool to capture the environmental impacts along the entire life-cycle of a product or a service (from its ‘cradle’ to its ‘grave’). The LCA method is structured in four phases, namely (1) goal and scope definition, (2) life-cycle inventory (LCI) analysis, (3) life-cycle impact assessment (LCIA), and (4) interpretation of the results.

The first phase sets the foundation of an LCA, by defining goal and scope and by specifying functional unit and the different dimensions of the system boundaries. All relevant inputs and outputs of the considered system are brought together during the second phase, the life-cycle inventory. In the third phase, all potential environmental impacts associated with the inputs and outputs are evaluated, by translating the environmental loads into impacts, which makes the results more environmentally relevant, comprehensible and easier to communicate. Several LCIA methods exist, and there is not always an obvious choice between them. Common areas of protection covered by LCAs are human health, natural environment, natural resources, and to some extent, the man-made environment. However, other environmental concerns, such as impact on biodiversity, water balance or land-use change, which are more difficult to specify, are not included in the LCA method.

Due to its systematic and transparent approach, LCA is well suited to being extended to measure a product’s financial and social aspects along with its life­cycle. There is broad agreement in the scientific community that LCA is one of the most effective methods for evaluating the environmental burdens associated with biofuel and bioenergy production. This was confirmed in the second section of this chapter, which entails some of the results of a recent study aimed at determining the most sustainable lignocellulosic bioenergy system. Along the lines of the LCA framework, important aspects for assessing the environmental impacts of bioenergy systems are discussed. Furthermore, the from translating the environmental loads of 37 lignocellulosic bioenergy systems results in terms of their respective global warming potential were presented.

When comparing various bioenergy pathways, it can be further concluded that the overall conversion efficiency (OCE) of the biomass upgrading and bioenergy conversion system is one of the main drivers affecting the environmental perfor­mance of the assessed systems. The greater the OCE, the less biomass is required, resulting in fewer upstream activities and less land required for biomass production. In terms of the environmental impact of the LBSs, a greater OCE is desired, resulting in lower total emissions and, therefore, in lower impacts for each life-cycle impact category.

The efficiency of the harvesting system has an effect similar to the OCE. The results of this study show, that the greater the degree of mechanisation and automation, the lower the environmental impact.

[1]

[2]Code for additive estimation of biomass components for the freely available statistical language

R (R Core Team 2012) and a set of example data can be downloaded from http://www. springer. com/life+sciences/forestry/book/978- 94- 007-7447-6