• Energy Research
• 12. Responsible consumption close

The current study makes use of life cycle assessment to evaluate the potential greenhouse gas (GHG) savings in coal electricity generation by 5% co-firing with sorghum pellets. The research models the utilization of 100 thousand hectares of under-utilized marginal land in Flores (Indonesia) for biomass sorghum cultivation. Based on equivalent energy content, 1.12 tons of pellets can substitute one ton of coal. The calculated fossil energy ratio of the pellets was 5.8, indicating that the production of pellets for fuel is energetically feasible. Based on a biomass yield of 48 ton/ha·yr, 4.8 million tons of pellets can be produced annually. In comparison with a coal system, the combustion of only pellets to generate 8,300 GWh of electricity can reduce global warming impacts by 7.9 million tons of CO2-eq, which is equivalent to an 85% reduction in GHG emissions. However, these results changed when reduced biomass yield of 24 ton/ha·yr, biomass loss, field emissions, and incomplete combustion were considered in the model. A sensitivity analysis of the above factors showed that the potential GHG savings could decrease from the initially projected 85% to as low as 70%. Overall, the production of sorghum pellets in Flores and their utilization for electricity generation can significantly reduce the reliance on fossil fuels and contribute to climate change mitigation. Some limitations to these conclusions were also discussed herein. The results of this scenario study can assist the Indonesian government in exploring the potential utilization of marginal land for bioenergy development, both in Indonesia and beyond.

Biofuels are widely seen as substitutes for fossil fuels to offset the imminent decline of oil production and to mitigate the emergent increase in GHG emissions. This view is, however, based on too simple an analysis, focusing on only one piece in the whole mosaic of the complex biofuel techno-system, and such partial approaches may easily lead to ideological bias based on political preference. This study defines the whole biofuel techno-system at three scales, i.e., the foreground production (A), the background industrial network (B, including A), and the supporting Earth biosphere (C, including B). The thermodynamic concepts of energy, exergy and emergy measure various flows at these three scales, viz. primary resources, energy and materials products, and labor and services. Our approach resolves the confusion about scale and metric: direct energy demand and direct exergy demand apply at scale A; cumulative energy demand and cumulative exergy demand apply at scale B; and energy is applied at scale C, where it is named emergy, while exergy also can be applied at scale C. This last option was not examined in the present study. The environmental performance of the system was assessed using a number of sustainability indicators, including resource consumption, input renewability, physical benefit, and system efficiency, using ethanol from corn stover in the US as a technology case. Results were compared with available literature values for typical biofuel alternatives. We also investigated the influence of methodological choices on the outcomes, based on contribution analysis, as well as the sensitivity of the outcomes to emergy intensity. The results indicate that the techno-system is not only supported by commercial energy and materials products, but also substantially by solar radiation and the labor and services invested. The bioethanol techno-system contributes to the overall supply of energy/exergy resources, although in a less efficient way than the process by which the Earth system produces fossil fuels. Our results show that bioethanol cannot be simply regarded as a renewable energy resource. Furthermore, the method chosen for the thermodynamic analysis results in different outcomes in terms of ranking the contributions by various flows. Consequently, energy analysis, exergy analysis, and emergy analysis jointly provide comprehensive indications of the energy-related sustainability of the biofuel techno-system. This thermodynamic analysis can provide theoretical support for decision making on sustainability issues.

Purpose: This study aims to minimize the environmental impacts of thermal seawater desalination by optimizing the required fossil fuel mixture. Life cycle assessment (LCA) is applied to simulate the environmental impacts for each fuel mixture. To prevent mixture designs inherited collinearly from correlating LCA results, fuel mixtures are first sampled prior to conducting LCA and then later optimized using a regression-based methodology to reduce entailed environmental impacts. Method: Setting the functional unit to 1 m 3 of desalinated water induces different reference flows of energy requirements depending on the fuels used. Increasing the level of any fuel type within the fuel mixture scenario will cause a decrease in the level of the other fuel type(s) included. An augmented simplex lattice mixture (ASLM) design is applied to indicate correct experimental conditions and to prevent the correlation due to collinearity inherited from the nature of mixture problems. Regression models are formulated to represent life cycle impact assessment (LCIA) results in a closed form suitable for response surface methodology (RSM) optimization. An overall composite sustainability index (CSI) is a single index calculated by aggregating and normalizing corresponding LCIA responses of different units, ranges, and scales using the geometric mean-based method. Results and discussion: The results indicate that marine sediment ecotoxicity (MSE) is the category most adversely affected by multistage flash distillation (MSF). On a nationwide scale, the LCA optimized results scored a 17% reduction in associated environmental impacts, which corresponds to a 4.2% reduction in the county’s carbon footprint and a 62% reduction in MSE while incurring a minor retrofitting cost to desalination facilities. Conclusions: High MSE results due to excessive fossil fuel consumption/burning in MSF should gain as much attention as paid toward global warming potential. High MSE entails the risk of having heavy metals entering the food chain. On the other hand, the geometric mean approach is found to be an effective model to aggregate the LCIA results into a single index while avoiding the subjectivity of the value judgment used in LCIA weighting. This approach serves as a unit-free rescaling method that is robust to outliers or large values examined across different LCIA impacts.

The increasing trend in the consumption of various materials has also led to a huge increase in the final waste streams especially in the form of municipal solid waste (MSW) and the consequent environmental pollutions in particular greenhouse gas (GHG) emissions. These have made MSW management a significant environmental issue for governments and policy-makers. To address these challenges, developed countries have implemented sustainable material management (SMM) strategies which have been comprehensively reviewed herein. Moreover, waste generation statistics reported for most of the developed and developing countries as well as the existing gaps in MSW management among these countries have been fully discussed. The present paper was also aimed at comprehensively assessing electricity generation potentials from MSW using an integrated solid waste management system (including three different technologies of anaerobic digestion (AD), incineration, and pyrolysis-gasification) while the consequent GHG emission reduction potentials as a result of their implementation were also explored. To facilitate the understanding of the potential impacts of these treatment strategies, Iran's data were used as a case study. More specifically, the theoretical and technical potentials of electricity generation were calculated and the GHG emission reduction potentials were estimated using a life cycle assessment (LCA) approach. Overall, it was found that 5005.4–5545.8 GW h of electricity could be generated from MSW in Iran annually which could lead to approximately 3561–4844 thousand tons of avoided CO2eq. Such GHG reductions would be translated into approximately 0.5% of Iran's annual GHG emissions and would be considered a promising achievement given Iran's international GHGs reduction commitment, i.e., 4% reduction of anthropogenic GHGs emissions by 2030 below the business as usual scenario. Such findings could also be modeled for the other developing countries around the world where efficient MSW management is yet to be implemented.

Sustainability assessments can play an important role in decision making. This role starts with selecting appropriate methods for a given situation. We observed that scientists, consultants, and decision-makers often do not systematically perform a problem analyses that guides the choice of the method, partly related to a lack of systematic, though sufficiently versatile approaches to do so. Therefore, we developed and propose a new step towards method selection on the basis of question articulation: the Sustainability Assessment Identification Key. The identification key was designed to lead its user through all important choices needed for comprehensive question articulation. Subsequently, methods that fit the resulting specific questions are suggested by the key. The key consists of five domains, of which three determine method selection and two the design or use of the method. Each domain consists of four or more criteria that need specification. For example in the domain “system boundaries”, amongst others, the spatial and temporal scales are specified. The key was tested (retrospectively) on a set of thirty case studies. Using the key appeared to contribute to improved: (i) transparency in the link between the question and method selection; (ii) consistency between questions asked and answers provided; and (iii) internal consistency in methodological design. There is latitude to develop the current initial key further, not only for selecting methods pertinent to a problem definition, but also as a principle for associated opportunities such as stakeholder identification.

En réponse à la prise de conscience croissante du changement climatique, les demandes d'établissement de l'empreinte carbone des produits ont augmenté. Les empreintes carbone des produits sont des évaluations du cycle de vie limitées à une seule catégorie d'impact, le réchauffement climatique. Les études d'empreinte carbone des produits génèrent des résultats d'inventaire du cycle de vie, répertoriant les émissions environnementales de gaz à effet de serre du cycle de vie d'un produit, et les caractérisent par leurs potentiels de réchauffement climatique, produisant des empreintes carbone des produits qui sont communément communiquées sous forme de valeurs ponctuelles. Dans la présente recherche, nous montrons que les incertitudes entourant ces valeurs ponctuelles nécessitent des moyens plus sophistiqués de communiquer l'empreinte carbone des produits, en utilisant différentes tailles d'élevages de poissons-chats (Pangasius spp.) au Vietnam comme étude de cas. Comme la plupart des études d'empreinte carbone des produits n'ont qu'une signification comparative, nous avons utilisé un échantillonnage dépendant pour produire des résultats relatifs afin d'augmenter la puissance d'identification de produits supérieurs sur le plan environnemental. Nous soutenons donc que les empreintes carbone des produits, étayées par des estimations quantitatives d'incertitude, devraient être utilisées pour tester des hypothèses, plutôt que pour fournir des estimations de valeur ponctuelle ou des intervalles de confiance simples de la performance environnementale des produits. En respuesta a la creciente conciencia sobre el cambio climático, las solicitudes para establecer huellas de carbono de los productos han ido en aumento. Las huellas de carbono de los productos son evaluaciones del ciclo de vida restringidas a una sola categoría de impacto, el calentamiento global. Los estudios de huella de carbono del producto generan resultados de inventario del ciclo de vida, enumeran las emisiones ambientales de gases de efecto invernadero del ciclo de vida de un producto y las caracterizan por sus potenciales de calentamiento global, produciendo huellas de carbono del producto que comúnmente se comunican como valores puntuales. En la presente investigación mostramos que las incertidumbres que rodean estos valores puntuales requieren formas más sofisticadas de comunicar las huellas de carbono de los productos, utilizando diferentes tamaños de granjas de bagre (Pangasius spp.) en Vietnam como estudio de caso. Como la mayoría de los estudios de huella de carbono de productos solo tienen un significado comparativo, utilizamos el muestreo dependiente para producir resultados relativos con el fin de aumentar el poder para identificar productos ambientalmente superiores. Por lo tanto, argumentamos que las huellas de carbono de los productos, respaldadas por estimaciones cuantitativas de incertidumbre, deberían usarse para probar hipótesis, en lugar de proporcionar estimaciones de valor puntual o intervalos de confianza simples del desempeño ambiental de los productos. In response to growing awareness of climate change, requests to establish product carbon footprints have been increasing. Product carbon footprints are life cycle assessments restricted to just one impact category, global warming. Product carbon footprint studies generate life cycle inventory results, listing the environmental emissions of greenhouse gases from a product's lifecycle, and characterize these by their global warming potentials, producing product carbon footprints that are commonly communicated as point values. In the present research we show that the uncertainties surrounding these point values necessitate more sophisticated ways of communicating product carbon footprints, using different sizes of catfish (Pangasius spp.) farms in Vietnam as a case study. As most product carbon footprint studies only have a comparative meaning, we used dependent sampling to produce relative results in order to increase the power for identifying environmentally superior products. We therefore argue that product carbon footprints, supported by quantitative uncertainty estimates, should be used to test hypotheses, rather than to provide point value estimates or plain confidence intervals of products' environmental performance. واستجابة للوعي المتزايد بتغير المناخ، تتزايد طلبات تحديد آثار الكربون على المنتجات. البصمات الكربونية للمنتج هي تقييمات لدورة الحياة تقتصر على فئة تأثير واحدة فقط، وهي الاحتباس الحراري. تولد دراسات البصمة الكربونية للمنتج نتائج جرد دورة الحياة، وتدرج الانبعاثات البيئية لغازات الدفيئة من دورة حياة المنتج، وتميزها من خلال إمكانات الاحترار العالمي الخاصة بها، وتنتج آثارًا كربونية للمنتج يتم توصيلها عادةً كقيم نقطية. في البحث الحالي، نظهر أن الشكوك المحيطة بقيم النقاط هذه تتطلب طرقًا أكثر تعقيدًا لتوصيل بصمات الكربون للمنتج، باستخدام أحجام مختلفة من مزارع سمك السلور (Pangasius spp.) في فيتنام كدراسة حالة. نظرًا لأن معظم دراسات البصمة الكربونية للمنتج ليس لها سوى معنى مقارن، فقد استخدمنا أخذ العينات المعتمدة لإنتاج نتائج نسبية من أجل زيادة القدرة على تحديد المنتجات المتفوقة بيئيًا. لذلك نجادل بأن آثار الكربون على المنتج، مدعومة بتقديرات عدم اليقين الكمي، يجب استخدامها لاختبار الفرضيات، بدلاً من تقديم تقديرات قيمة النقطة أو فترات الثقة الواضحة للأداء البيئي للمنتجات.

The introduction of environmentally friendly innovations in both transport and energy sectors are included in the list of priorities of the European Union political agenda. This paper investigates the environmental consequences of the introduction of hydrogen and fuel cells technology in the European economic system by applying environmental input-output analysis and life cycle assessment tools. Hydrogen is produced through the reforming of natural gas and it is employed in fuel cells buses that offer transport services to final consumers. We have built three scenarios based on different assumptions on the final demand. We have shown the results for three impact categories: global warming, photochemical oxidation and acidification. The results suggest that the use of hydrogen in fuel cells buses is only environmentally desirable if accompanied either by the employment of renewable sources or by carbon dioxide capture, or both.