• Energy Research

The environmental sustainability is one of the current priorities of the Portuguese pulp and paper industry. Life Cycle Assessment (LCA) was the methodology chosen to evaluate the sustainability of the printing and writing paper production activity. This paper grade represents about 60% of the total production of paper in Portugal and its production is expected to increase in the near future. The main goal of this study was to assess the potential environmental impacts associated with the entire life cycle of the printing and writing paper produced in Portugal from Eucalyptus globulus pulp and consumed in Germany, in order to identify the processes with the largest environmental impacts. Another goal of this study was to evaluate the effect on the potential environmental impacts of changing the market where the Portuguese printing and writing paper is consumed: German market vs. Portuguese market. The main stages considered in this study were: forestry, pulp production, paper production, paper distribution, and paper final disposal. Transports and production of chemicals, fuels and energy in the grid were also included in these stages. Whenever possible and feasible, average or typical data from industry were collected. The remaining data were obtained from the literature and specialised databases. A quantitative impact assessment was performed for five impact categories: global warming over 100 years, acidification, eutrophication, non-renewable resource depletion and photochemical oxidant formation. In the German market scenario, the paper production stage was a remarkable hot spot for air emissions (non-renewable CO2, NOx and SO2) and for non-renewable energy consumption, and, consequently, for the impact categories that consider these parameters: global warming, acidification and non-renewable resource depletion. These important environmental impacts are due to the energy requirements in the printing and writing paper production process, which are fulfilled by on-site fuel oil burning and consumption of electricity from the national grid, which is mostly based on the use of fossil fuels. The pulp production stage was identified as the largest contributor to water emissions (COD and AOX) and to eutrophication. Considering that energy consumed by the pulp production processes comes from renewable fuels, this stage was also the most contributing to renewable energy consumption. The paper distribution stage showed an important contribution to NOx emissions, which, however, did not result in a major contribution to acidification or eutrophication. The final disposal stage was the main contributor to the photochemical oxidant formation potential due to CH4 emissions from wastepaper landfilling. On the other hand, paper consumption in Portugal was environmentally more favourable than in Germany for the parameters/impact categories where the paper distribution stage has a significant contribution (non-renewable CO2, NOx, non-renewable energy consumption, acidification, eutrophication and non-renewable resource depletion) due to shorter distances needed to deliver paper to the consumers. For the remaining parameters/impact categories, the increase observed in the final disposal stage in the Portuguese market was preponderant, and resulted from the existence of significant differences in the final disposal alternatives in the analysed markets (recycling dominates in Germany, whereas landfilling dominates in Portugal). The pulp and paper production stages were found to be of significance for almost all of the inventory parameters as well as for the impact assessment categories. The paper distribution and the final disposal stages were only of importance for some of the inventory parameters and some of the impact categories. The forestry stage played a minor role in the environmental impacts generated during the paper life cycle. The consumption of paper in Portugal led to a decrease in the environmental burdens of the paper distribution stage, but to an increase in the environmental burdens of the final disposal stage, when compared with the consumption of paper in Germany. This study provides useful information that can assist the pulp and paper industry in the planning of future investments leading to an increase in its sustainability. The results of inventory analysis and impact assessment show the processes that play an important role in each impact category, which allow the industry to improve its environmental performance, making changes not only in the production process itself, but also in the treatment of flue gases and liquid effluents. Besides that concern regarding pollution prevention, other issues with relevance to the context of sustainability, such as the energy consumption, can also be dealt with.

Dr. Martín-Gamboa would like to thank the Regional Government of Madrid for financial support (2019-T2/AMB-15713). Ana Cláudia Dias would like to thank FCT/MCTES for the contract CEECIND/02174/2017 and for the financial support to CESAM (UIDB/50017/2020+UIDP/50017/2020) through national funds. A key goal in sustainable supply chain management is the minimisation of risk across supply chains. However, this is jeopardised by underdeveloped aspects such as social risk management, especially in the case of energy systems as they involve complex supply chains. This article constitutes the first time that Social Life Cycle Assessment (S-LCA) is used to lay the foundation for a methodological framework to define, assess and prioritise strategies oriented towards the minimisation of social life-cycle impacts across the supply chain of energy products. This framework combines S-LCA, a novel approach to the definition of alternative supply chain strategies, and multi-criteria decision analysis (MCDA). It was demonstrated through a case study of bioelectricity in Portugal by defining and assessing fifteen strategies on the specific supply chains of oil and fertilisers to check their suitability to enhance the system's social life-cycle performance. The weighted sum method (WSM) and Data Envelopment Analysis (DEA) were used as MCDA tools to further support decision-making by prioritising strategies. According to the results for a set of six social indicators, the strategies proposed on the supply of oil and nitrogen-based fertilisers were deemed suitable trade-off solutions to mitigate the social life-cycle impact of the bioelectricity system.

The European seafood and aquaculture sectors are facing important challenges in terms of environmental threats (climate change, marine debris, resources depletion), social development (worker rights, consumer's awareness) or economic growth (market and nonmarket goods and services, global competitiveness). These issues are forcing all stakeholders, from policy-makers to citizens and industries, to move to more sustainable policies, practices and processes. Consequently, an improvement in collaborations among different parties and beyond borders is required to create more efficient networks along the supply chain of seafood and aquaculture sectors. To achieve this, a â nexus thinkingâ approach (i.e. the analysis of actions in connected systems) combined with a life cycle thinking appears as an excellent opportunity to facilitate the transition to a circular economy.

Wood-fuelled systems are commonly used all over the world for residential heating, and recently wood pellets have been replacing traditional firewood. This article presents an environmental life cycle assessment of five wood-based combustion systems for residential heating: i) a pellet stove using maritime pine pellets; a wood stove using ii) eucalyptus (Eucalyptus globulus Labill.) and iii) maritime pine (Pinus pinaster Ait.) split logs; and a fireplace using iv) eucalyptus and v) maritime pine split logs. The functional unit is 1 MJ of thermal energy for residential heating. System boundaries include four stages: (1) forest management; (2) pellet and wood split log production; (3) distribution; and (4) thermal energy generation. Environmental impacts were calculated for seven impact categories from the ReCiPe 2016 midpoint method, and a sensitivity analysis was performed using the Product Environmental Footprint (PEF) life cycle impact assessment method and modifying the distances travelled. Of the five heating systems analysed, the fireplace presents the worst performance for all the impact categories with the exception of freshwater eutrophication and marine eutrophication, when maritime pine split logs are burned in the fireplace. Comparing the pellet stove with the wood stove, neither system is better for all the impact categories analysed. Regarding sensitivity analysis, the use of an alternative characterisation method leads to similar trends in the results in comparison with those obtained from the ReCiPe method, while changes in transport distances do not affect the total impacts to a large extent.

Recently, wood pellets have become a reliable and clean renewable fuel for residential heating, replacing fossil fuels and reducing greenhouse gas emissions. Wood pellets are normally produced in industrial pellet plants (centralised production), but decentralised small-scale local production also occurs. This study applies Life Cycle Assessment (LCA) to quantify and compare the environmental profile of one centralised and two decentralised alternatives for wood pellet production for residential heating in Portugal: (1) industrial wood pellets production (centralised), (2) wood pellets production at sawmills (decentralised) and (3) wood pellets production at households (decentralised). System boundaries include the stages of forest management, wood pellet production, wood pellet distribution and wood pellet energetic conversion. The impact results show that industrial pellet production ranks as the worst alternative, while pellet production at households has the best environmental profile for all the impact categories under study. However, the environmental impacts of pellet production at the sawmill do not differ greatly from those of the pellet production at households; they are 14 to 16% higher for global warming and fossil resources scarcity and 0.3 to 3% higher for the remaining impact categories. The worst environmental performance of the industrial pellet production alternative is mainly due to high electricity and diesel consumption during wood pellet production and the use of logging residues to generate heat for drying biomass feedstock. A sensitivity analysis was performed to evaluate the influence of changing the distance travelled during the transport of packed pellets to stores and sawdust to households. The results show changes in the environmental performance ranking, highlighting that for short distances, both decentralised alternatives can be more sustainable from an environmental perspective than the centralised alternative, but for larger distances, the pellet production at households should be avoided.

Abstract The Portuguese government's new strategy is based on the predicted increase in the country's installed electricity capacity through the use of biomass residues, including forest biomass residues. However, this strategy implies that the use of forest biomass residues in electricity production will most likely be at the expense of alternative uses, such as heat and biofuel production. Therefore, what is the best use of forest biomass residues available in the country from an environmental perspective? To answer this question, in this study, a consequential life cycle assessment was applied to assess three different scenarios: 1) the production of electricity in dedicated power plants; 2) the cogeneration of electricity and heat in combined heat and power plants; and 3) the production of bioethanol by biochemical conversion. The results showed that the strategy of using forest biomass residues for electricity production would be advantageous in relation to the baseline (i.e. leaving forest residues in forest soil and using fossil fuel sources to produce energy) only in some environmental impact categories. The results showed that the cogeneration of electricity and heat production was the best alternative among the three scenarios. However, regarding the effects related to particulate matter and marine eutrophication, the results showed that this alternative would perform better than baseline if the displaced fuels were coal in electricity production and at least 12% fuel oil (and the rest natural gas) in heat production. The conversion of forest biomass residues to bioethanol was the least beneficial regarding all categories under study.

Moving towards a global bioeconomy can mitigate climate change and the depletion of fossil fuels. Within this context, this work applies a set of multi-criteria decision analysis (MCDA) tools to prioritise the selection of five alternative bioenergy systems for residential heating based on the combination of three commercial technologies (pellet, wood stove and traditional fireplace) and two different feedstocks (eucalypt and maritime pine species). Several combinations of MCDA methods and weighting approaches were compared to assess how much results can differ. Eight indicators were used for a sustainability assessment of the alternatives while four MCDA methods were applied for the prioritisation: Weighted Sum Method (WSM), Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), Elimination and Choice Expressing Reality (ELECTRE), and Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE). Regarding the sustainability performance indicators, the highest environmental impacts were calculated for the fireplace alternatives, and there was not a best environmental option. Also, no clear trend was found for the economic and social dimensions. The application of MCDA tools shows that wood stove alternatives have the best sustainability performance, in particular wood stove with combustion of maritime pine logs (highest scores in the ranking). Regarding the worst alternative, fireplaces with combustion of eucalypt logs ranked last in all MCDA rankings. Finally, a sensitivity analysis for the weighting of the performance indicators confirmed wood stoves with combustion of maritime pine logs as the leading alternative and the key role of the analysts within this type of MCDA studies.