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Assuring environmental sustainable bioenergy production is an international priority nowadays. The objective of this study was to identify the environmental consequences of feedstock selection in biogas production. Two real biogas plants were assessed and compared from a life cycle perspective. Plant A performs the co-digestion of energy crops (78%) and animal waste (22%) while Plant B consumes energy crops (4%), food waste (29%) and animal manure (67%). According to the results, electricity production from biogas implied lower impacts in climate change compared to the existing electric mix. Maize silage (650 Nm3/TVSfed) and food waste (660 Nm3/TVSfed) appeared as an interesting source of bioenergy. However, the cultivation of energy crops was identified as the main hotspot in Plant A. Finally, the use of organic substrates with lower energy potential and high nutrients concentration such as animal manure (450 Nm3/TVSfed) produced higher amounts of digestate, producing impacts in acidification and eutrophication categories. In order to improve the environmental sustainability of bioenergy, specific guideless should be established to achieve harmonised life cycle studies. In addition, environmental policies should promote the use of waste streams and prevent the use of energy crops as well as include goals related with acidification and eutrophication impacts.

International institutions are calling for a transition towards more sustainable systems of production and consumption. In this transition, sustainable innovations are expected to play an ever‐increasing role. In particular, the production of innovative bio‐based products—products wholly or partly derived from biological materials or from innovative production processes and/or innovative biomass such as food waste or forest residuals—will be part of this process. However, the sustainability of such products must be assured along their entire life cycle and across the three dimensions mentioned above. Against this background, our study aimed at identifying a social impact framework tailored to bio‐based products. It employed a two‐step methodological framework encompassing (a) identification of the relevant social impact categories, subcategories, and indicators and (b) validation of these factors, according to participatory stakeholder involvement. The validation exercise enabled us to consider a restricted number of social indicators so as to reduce the amount of data needed for assessing and decreasing related costs The authors are very grateful to the STAR‐ProBio project (Sustainability Transition Assessment and Research of Bio‐based Products) for their financial support. The project is funded by the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement 727740, Work Programme BB‐01‐2016: Sustainability schemes for the bio‐based economy SI

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.

The aim of this study was to compare the environmental performance and sustainability of different management options for livestock waste in Cyprus. The two most common practices in the country, i.e. the use of anaerobic lagoons and conventional biogas plants, were compared with the innovative scheme developed in the LiveWaste project (LIFE12 ENV/CY/000544), which aims not only to produce bioenergy, but also to treat the digestate for nutrient recovery and water reuse. The Life Cycle Assessment (LCA) methodology was combined with the Analytic Hierarchy Process (AHP) to compare the performance of these alternatives. Four relevant indicators were selected for each dimension of sustainability (environmental, social and economic). The results of the evaluations showed that anaerobic lagoons are not an appropriate option for the sustainable management of livestock waste due to environmental (e.g. climate change, acidification and eutrophication) and social impacts (e.g. noise exposure, visual impact and risk perception for human health). The most important strengths and weaknesses of anaerobic treatment with and without digestate treatment were identified. Compared to conventional anaerobic digestion where digestate is directly applied as an organic fertiliser, the technology proposed in the project entails higher technological complexity due to nitrogen removal and phosphorus recovery. The rise in chemical and electricity requirements increased the impacts on some indicators, such as climate change and operational cost (emissions of greenhouse gases and operation costs were around 50% higher), while reduced impacts in others due to proper nutrient management, as acidification and eutrophication impacts (which were 10 and almost two times lower, respectively). For the specific Cypriot conditions, where the overapplication of nutrients leads to pollution of water bodies, the innovative treatment scheme with higher technological development presents an interesting approach. Nevertheless, the treatment of the digestate should be analysed taking into account the specific characteristics of each scenario.

This study aims to evaluate the environmental consequences and energy requirements of a biogas production system and its further conversion into bioenergy by means of the Life Cycle Assessment (LCA) methodology. To do so, an Italian biogas plant operating with pig slurry and two energy crops (maize and triticale silages) as feedstock was assessed in detail in order to identify the environmental hotspots. The environmental profile was estimated through six impact categories: abiotic depletion potential (ADP), acidification potential (AP), eutrophication potential (EP), global warming potential (GWP), ozone layer depletion potential (ODP) and photochemical oxidation potential (POFP). An energy analysis related to the cumulative non-renewable fossil and nuclear energy demand (CED) was also performed, considering this indicator as an additional impact category. According to the results, the biomass production subsystem was identified as the main environmental key issue in terms of ADP, AP, EP, ODP and CED, with contributions ranging from 26% to 61% of the total impact. Regarding ADP, ODP and CED, these results are mainly related with diesel requirements in agricultural machinery, derived combustion emissions and mineral fertilizers production. Concerning AP and EP the production field emissions derived from fertilizers application was observed as the main contributor. Concerning GWP, this step presents an environmental credit due to the uptake of CO2 during crop growth, which contributes to offset the GHG emissions. The bioenergy production plant significantly contributes to the environmental impact in categories such as GWP (43%) and POFP (59%), mostly related with emissions produced in the gas engine and biogas losses. Emissions derived from digestate storage contribute to AP (52%) and EP (41%). The use of the digestate as an organic fertilizer has a beneficial role because this action avoids the production and use of mineral fertilizers. A sensitivity analysis was also conducted to assess the influence of variations in important parameters of biogas systems. The environmental profile of the biogas system turned out to be highly dependent on the selection of system boundaries and the allocation method. To sum up, this study aims to assess the environmental performance of a biogas technology available not only in Italy but also in other European countries. The environmental analysis of the process under study highlights the environmental benefits of the co-digestion processes, which not only produces biofuel but also reduces the disposal of solid wastes and produces digestate, with special value in the fertilization of agricultural soil.

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.

A technical and environmental evaluation of an innovative scheme for the co-treatment of domestic wastewater and domestic organic waste (DOW) was undertaken by coupling an upflow anaerobic sludge blanket (UASB), a sequencing batch reactor (SBR) and a fermentation reactor. Alternative treatment configurations were evaluated with different waste collection practices as well as various schemes for nitrogen and phosphorus removal. All treatment systems fulfilled the required quality of the treated effluent in terms of chemical oxygen demand (COD) and total suspended solids (TSS) concentrations. However, only the configurations performing the short-cut nitrification/denitrification with biological phosphorus removal met the specifications for water reuse. The environmental assessment included the analysis of impacts on climate change (CC), freshwater eutrophication (FE) and marine eutrophication (ME). A functional unit (FU) of 2000 people receiving treatment services was considered. The most relevant sources of environmental impacts were associated to the concentration of dissolved methane in the UASB effluent that is emitted to the atmosphere in the SBR process (accounting for 41% of impacts in CC), electricity consumption, mainly for aeration in the SBR (representing 14% of the impacts produced in CC), and the discharge of the treated effluent in receiving waters (contributing 98% and 57% of impacts in FE and ME, respectively). The scheme of separate waste collection together with biological nitrogen removal and phosphorus uptake via nitrite was identified as the best configuration, with good treated effluent quality and environmental impacts lower than those of the other examined configurations.

The aim of this study was to assess the environmental profile of a bioenergy system based on a co-digestion plant using maize silage and pig slurry as substrates. All the processes involved in the production of bioenergy as well as the avoided processes accrued from the biogas production system were evaluated. The results evidenced the environmental importance of the cultivation step and the environmental credits associated to the avoided processes. In addition, this plant was compared with two different plants that digest both substrates separately. The results revealed the environmental benefits of the utilisation of pig slurry due to the absence of environmental burdens associated with its production as well as credits provided when avoiding its conventional management. The results also presented the environmental drawbacks of the utilisation of maize silage due to the environmental burdens related with its production. Accordingly, the anaerobic mono-digestion of maize silage achieved the worst results. The co-digestion of both substrates was ranked in an intermediate position. Additionally, three possible digestate management options were assessed. The results showed the beneficial effect of digestate application as an organic fertiliser, principally on account of environmental credits due to avoided mineral fertilisation. However, digestate application involves important acidifying and eutrophicating emissions.