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Among the different alternatives to conventional fossil fuels, the production of renewable energy from biomass (i.e. bioenergy) is regarded as an interesting option since it involves the valorisation of waste streams, residues and non-food crop biomass. Although a standardised framework regulates the Life Cycle Assessment (LCA) methodology, its application in practice poses some methodological difficulties. This chapter reviews the main methodological issues that a LCA practitioner has to face when it comes to the environmental assessment of bioenergy systems. Despite its complexity, consequential LCA is considered an interesting approach for informing policy-makers and decision-makers about the indirect effect of a specific strategy. In this sense, indirect environmental burdens such as indirect land use change should be included in the study. Moreover, the selection of the system function and system boundaries are other methodological issues that directly affect the results obtained and, therefore, the comparability of LCA studies, intensified in particular in the case of bioenergy systems due to their complexity. In more detail, some bioenergy systems co-produce multiple products, increasing the variability of the functions provided by the system, as well as of the system boundaries chosen to overcome multifunctionality (subdivision, system expansion or allocation). The selection of the appropriate methodology and impact categories, as well as the gaps in characterisation factors, is other methodological drawbacks.

In recent times, society has been confronted with problems related to food safety and environmental protection. As a result, consumers are increasingly demanding an evolution towards the consumption of healthy products, produced within a framework of protection of natural resources and the environment. As a primary source of protein and micronutrients, meat products are considered essential elements of the human diet. In the search for products that meet the criteria of excellence of natural products produced in a sustainable way, the Community of Natural Parks of Galicia (Northwest Spain) is a territory recognized and protected as a region of magnificent landscapes and natural ecosystems. In this context, a framework for action has been planned to define environmental sustainability criteria for the award of a specific eco-label for products produced in these ecosystems. In particular, the sustainable use and economic development of the territory through livestock farming is proposed. To this aim, an environmental analysis has been carried out to identify and compare livestock systems based on extensive practices for beef production in the framework of the Galician Natural Parks. To this end, several environmental indicators were selected, although special attention was paid to two of them because of their particular relevance in assessing the environmental profile of livestock products: Carbon Footprint (CF) and Water Footprint (WF). The principles of the Life Cycle Assessment (LCA) were applied by the former, while the Water Footprint Network (WFN) guidelines were followed in the latter case. According to the results obtained for the different indicators, feed production (including grass, cereals and concentrated feed) contributed significantly to the overall impacts of the supply chain (up to the farm gate), regardless the environmental indicator evaluated. Considering the key role played by the production of the various ingredients for the formulation of feeds and their associated transport, the need to promote more sustainable production methods, as well as the exploitation of agricultural land adjacent to the farms, should be stressed, so that the environmental impacts are even lower than those estimated in this study. In addition, diffuse emissions also had a significant impact on most LCA-based categories, mainly due to the emission of nitrogen compounds to air from manure storage and their application to agricultural soils. Similarly, water demand from both irrigation steps in cultivation practices and on-farm activities had a critical role in WF results. From these outcomes, it would be desirable for waste management (especially livestock manure) to be carried out in accordance with principles of minimum impact, valuing the different streams to obtain reclaimed water for irrigation and bio-fertilizers that can replace those of chemical synthesis. Finally, the main results were compared with published works (in terms of CF and WF ratios) focusing on beef products and lower environmental impacts were registered. On this basis, common criteria for eco-labelling in beef production systems were defined in the framework of the Galician natural areas.

The search for alternatives to fossil fuel resources relies on the use of renewable bioenergy. The objective of this research is to define the most relevant sustainability criteria in the exploitation of feedstocks for bioenergy production from a life cycle perspective. Three types of biofuels were evaluated: biogas, bioethanol and biodiesel. In addition, conventional and innovative biomass sources for bioenergy will be analysed and compared. A comprehensive literature review was conducted to identify the most suitable feedstocks for each type of biofuel in terms of environmental impacts and energy-related indicators. Many studies have identified inconsistent results (from very positive to negative environmental consequences), leading to great uncertainty on this issue. Cereal crops (wheat, maize and triticale) and animal waste are examples of feedstocks for biogas production. Sugarcane, sugar beet and their by-products (molasses and bagasse) are recognised as technologically validated biomass sources for bioethanol production. As for biodiesel, oilseeds (soybean, palm, sunflower, etc.) and cooking oil residues are possible feedstocks. The number of environmental studies related to emerging biofuel feedstocks, such as algae and jatropha for biodiesel; poplar, beech, black locust for bioethanol and macroalgae for biogas, is steadily increasing. Therefore, the processes involved in feedstock production should be properly calculated for an accurate assessment, as they play an important role in the substitution of fossil fuels. The outputs from the life cycle assessment (LCA) methodology will help to support decision-making in the analysis of alternatives and avoid misleading conclusions. The Energy Return on Investment (EROI) methodology was found to be suitable for comparing conventional and innovative biomass sources for bioenergy. The results vary considerably from one feedstock to another, due to differences in geographical distribution, agricultural practices and energy efficiency index. In many cases, it was found that the use of by-products (e.g. maize stover for bioethanol) or waste (pig slurry for biogas) as a biomass source for biofuels could have better EROI values than first-generation feedstocks due to the allocation of environmental burdens.

This study aims to analyse the potential environmental benefits and impacts associated to the anaerobic mono-digestion of two different substrates (pig slurry and maize silage). The Life Cycle Assessment methodology was applied in two full-scale Italian biogas plants (Plant A - pig slurry and Plant B - maize silage) in order to calculate the environmental profile of both systems with the aim of identifying the most suitable alternative from an environmental point of view. The study also includes credits due to avoided processes such as electricity production from the grid and mineral fertilisation as well as the conventional management of pig slurry regarding Plant A. The main outcomes show the importance of the feedstock composition on the environmental performance of these systems. While the assessment of Plant A ended up in environmental benefits in all impact categories as a consequence of credits related to replaced processes, its capacity for bioenergy production was limited. On the contrary, the use of maize silage as substrate provided a larger production capacity but it was also associated to negative environmental impacts. In this system, the cultivation of maize showed up as the largest responsible of the environmental impacts, specifically due to diesel fuel consumption in agricultural activities as well as on-site emissions linked to the application of fertilisers. A sensitivity analysis proved that the environmental profile of these bioenergy systems could be improved through surplus heat use as well as technological improvements such as the replacement of the traditional dehumidification unit by a chiller.

This study assesses from an environmental perspective two different configurations for the combined treatment of wastewater and domestic organic waste (DOW) in a small and decentralised community having a population of 2000. The applied schemes consist of an upflow anaerobic blanket (UASB) as core treatment process. Scheme A integrates membranes with the anaerobic treatment; while in Scheme B biological removal of nutrients in a sequencing batch reactor (SBR) is applied as a post treatment to UASB effluent. In energy-related categories, the main contributor is electricity consumption (producing 18–50% of the impacts); whereas in terms of eutrophication-related categories, the discharge of the treated effluent arises as a major hotspot (with 57–99% of the impacts). Scheme B consumes 25% more electricity and produces 40% extra sludge than Scheme A, resulting in worse environmental results for those energy categories. However, the environmental impact due to the discharge of the treated effluent is 75% lower in eutrophication categories due to the removal of nutrients. In addition, the quality of the final effluent in Scheme B would allow its use for irrigation (9.6 mg N/L and 2 mg P/L) if proper tertiary treatment and disinfection are provided, expanding its potential adoption at a wider scale. Direct emissions due to the dissolved methane in the UASB effluent have a significant environmental impact in climate change (23–26%). Additionally, the study shows the environmental feasibility of the use of food waste disposers for DOW collection in different integration rates.

The aim of this study was to analyse the eco-efficiency of 15 agricultural biogas plants located in Northern Italy. For this, the combination of life cycle assessment (LCA) and data envelopment analysis (DEA) methodologies was considered with the purpose of identifying efficient operational plants and proposing improvement measures for the inefficient ones. The environmental profile of both the original and the virtual plants (obtained after the improvement measures) were compared in order to identify the net environmental gains linked with the inputs reduction. As a result of improvement measures, the production of electricity from biogas in all plants would imply environmental benefits compared with the average electricity production in the Italian grid. In light of the results obtained, special attention should be paid to the feedstock selection since it has a key role in the overall eco-efficiency of the plant, due to their different origin and composition.

Conventional foams derived from petroleum are extensively used for insulating uses. Research into alternative sources to petroleum based chemicals is attracting a great deal of attention. Softwood bark and in special, maritime pine bark from European forests is an abundant co-product from forest industries. In this study, the production of formaldehyde-free tannin based biofoams to be used as building insulation materials was environmentally assessed using the Life Cycle Assessment methodology (cradle-to-grave approach) as well as their valorisation into bioenergy (electricity and thermal energy) at end of their life cycle by means of their gasification into tar-free syngas and its further combustion in a CHP unit. The production chain was divided into four subsystems: forest activities (SS1), sawmill (SS2), biofoams production (SS3) and bioenergy production (SS4). Wherever possible, primary data from pilot plants were managed. Since two main co-products are obtained, three different approaches were considered and discussed: total allocation of environmental burdens to the electricity (main product), exergy based allocation and system expansion. According to the results, SS3 was identified as the environmental hotspot regardless the impact category considered for assessment. The large requirements of electricity in the tannin extraction unit as well as the production of chemicals required for the biofoam formulation were the responsible factors of these notable contributions. Special attention should also be paid to the uncontrolled pentane emissions associated to the biofoam formulation, specifically in terms of photochemicals oxidant formation. Remarkable environmental benefits were obtained in terms of climate change, fossil fuels depletion as well as in some toxicity related impact categories in comparison with the petroleum based foams, mainly based on the use of an abundant renewable source as raw material to produce the foams. Improvement actions should look at the reduction (or even recovery) of chemicals used, the control of diffuse emissions (e.g. pentane from evaporation unit and CHP unit) as well as the installation of a cogeneration unit to produce the electricity requirements to reduce dependence on fossil fuels.