Energy production, transformation, transports and end-use generally impacts the environment and ecology even though form RES that has been claimed as green energy. Increasing efficiency along the energy supply chain can reduce the environmental impact of emissions, although increasing efficiency generally requires
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greater operating cost, increasing the environmental burdens associated with these and somewhat offsetting the environmental gains of improved efficiency (Rosen, 2009).
There are several previous works demonstrated the implementation of different environmental/ ecological impacts:
i Rosen (2009) presented the potential usefulness of exergy in addressing environmental impact. Exergy analysis is a thermodynamic technique for assessing and improving systems and processes, which is similar but advantageous to energy analysis, in large part because it is based on the second law of thermodynamics. The exergy of an energy form or a substance is a measure of its usefulness. Relations between environmental impact and exergy in general and chemical exergy of waste emissions in particular are observed to support the use of exergy as such an indicator. The measure of disequilibrium with respect to a reference environment provided by exergy is considered, along with the consequence that the exergy of unrestricted waste emissions has the potential to impact the environment.
ii The Sustainable Process Index (SPI) developed by Narodoslawsky and Krotscheck (1995) is a useful approach to calculate the ecological footprint casused by a process. SPI is based on the assumption that a sustainable economy builds only on solar exergy. Surface area is needed for the conversion of exergy into products and services. Surface area is a limited resource in a sustainable economy because the Earth has a finite surface. Area is the underlying dimension of the SPI. The more area a process needs to fulfil a service the more it costs from the sustainable point of view. SPIonExcel (Sandholzer et al., 2005) calculates the ecological footprint and the SPI of a product or service through the input that characterizes the process given by an eco-inventory (Sandholzer and Narodoslawsky, 2007) . The eco-inventories used for the calculation of the overall footprint contain engineering mass and energy
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flows of processes in terms of input and output flows. Two different classes of inputs, impacts and intermediates, can be defined. An intermediate is a flow derived from and/or going to another process. This includes processes like electricity generation, transportation or waste flows to treatment plants and also products going to final consumption. Intermediates are produced via processes using themselves mass and energy flows. Their ecological pressure can be traced back to these flows, which in themselves can be either impacts or other intermediates. The SPI approached has been used to evaluate environmental performance in (i) integrated bioenergy systems (Krotscheck et al., 2000), and (ii) energy production systems (Narodoslawsky and Krotscheck, 2004)
iii De Benedetto and Klemeš (2009, 2010) proposed a sustainable environmental performance indicator – Environmental Performance Strategy Map. This particular graphical map allows combination of the main environmental indicators (footprints) with the additional dimension of cost. The core of the concept is to calculate some specific sustainability indicators, based on Life Cycle Assessment (LCA). It is suggested to evaluate all options against the following categories:
• Carbon footprint;
• Water footprint;
• Energy footprint (Land, renewables, non-renewables);
• Emission footprint (emissions in air, in water, in soil, waste materials);
• Work environment footprint (work-environment and toxicological impacts).
To represent these relations and to compare options from an environmental and, more generally, business perspective a new graphical representation needs to be introduced: the Environmental Performance Strategy Map (Figure 2.3). The objective of this representation is to build upon the strength of Ecological Footprint and Life Cycle Analyses to provide a single indicator for each option.
The practitioner can make use of this indicator to direct the decision-making
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process towards the best option from a sustainability and environmental perspective.
Figure 2.3 Environmental Performance Strategy Map (De Benedetto and Klemeš, 2009) In this work, Carbon Footprint (CFP) is used to evaluate environmental impacts of biomass process and supply chain. CFP as defined in (POST, 2006) is the total amount of CO2 and other greenhouse gases emitted over the full life cycle of a process or product. CFP has become an important environmental protection indicator as most industrialised countries have committed to reduce their CO2 emissions by an average of 5.2% in the period 2008–2010 in respect to the level of 1990 (Sayigh, 1999).
The CFP of a biomass supply chain is the total CO2 amount emitted throughout the supply chain life cycle (Perry et al., 2008). Energy supplied from biomass cannot be considered truly carbon-neutral even though the direct carbon emissions from combustion had been offset by carbon fixation during feedstock photosynthesis (Anderson and Fergusson, 2006). The net CFP is mainly caused by the indirect carbon emissions generated along the supply chain – especially by processing, transportation and burning which releases emissions. Especially transportation activities could contribute as the major part of the CFP in the supply chain (Forsberg, 2000).
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Another CFP contribution results from the use of fertilisers and land cultivation activities for raising energy crops. The typical locations of biomass sources (farms, forest, etc.), the relatively low energy density, and the distributed nature of the sources require extensive infrastructures and huge transport capacities for implementing the biomass supply networks. For regional biomass supply chains road transport is the usual mode for collection and transportation. This tends to increases the CFP of the biomass based energy.