Joaquim E.A. Seabra

Comparative LCA of ethanol versus gasoline in Brazil using different LCIA methods

PurposeThe main objective of this study is to expand the discussion about how, and to what extent, the environmental performance is affected by the use of different life cycle impact assessment (LCIA) illustrated by the case study of the comparison between environmental impacts of gasoline and ethanol form sugarcane in Brazil.MethodsThe following LCIA methods have been considered in the evaluation: CML 2001, Impact 2002+, EDIP 2003, Eco-indicator 99, TRACI 2, ReCiPe, and Ecological Scarcity 2006. Energy allocation was used to split the environmental burdens between ethanol and surplus electricity generated at the sugarcane mill. The phases of feedstock and (bio)fuel production, distribution, and use are included in system boundaries.Results and discussionAt the midpoint level, comparison of different LCIA methods showed that ethanol presents lower impacts than gasoline in important categories such as global warming, fossil depletion, and ozone layer depletion. However, ethanol presents higher impacts in acidification, eutrophication, photochemical oxidation, and agricultural land use categories. Regarding to single-score indicators, ethanol presented better performance than gasoline using ReCiPe Endpoint LCIA method. Using IMPACT 2002+, Eco-indicator 99, and Ecological Scarcity 2006, higher scores are verified for ethanol, mainly due to the impacts related to particulate emissions and land use impacts.ConclusionsAlthough there is a relative agreement on the results regarding equivalent environmental impact categories using different LCIA methods at midpoint level, when single-score indicators are considered, use of different LCIA methods lead to different conclusions. Single-score results also limit the interpretability at endpoint level, as a consequence of small contributions of relevant environmental impact categories weighted in a single-score indicator.

Feedstocks for biodiesel production: Brazilian and global perspectives

ABSTRACT Soybean, rapeseed, and palm oil are the main raw materials for biodiesel production worldwide. However, there are other potential feedstocks for biodiesel production. Speculations swirl around the agreements signed at the 21st Conference of the Parties to reduce carbon emissions from the transportation sector and stimulate the biofuel blending. As an increase in the biodiesel demand is expected, Brazil can be an important player in the international market because of the availability of land and the diversity of raw materials. This paper discusses current global oil and biodiesel scenarios and reviews several potential feedstocks focusing on the prospects, limitations, food–fuel nexus, and opportunities to develop added-value products. Despite the variety of potential feedstocks, the biodiesel sector is likely to pursue its development based on large-scale economically competitive alternatives. Animal fat and waste frying oil are options for a short-term scenario. Palm oil is a promising choice for medium term, while algae and second generation routes may contribute to the biodiesel supply in the long term. Development of competitive chains, investment in technologies, processes and logistics, and domestication of species are essential to guarantee the inclusion of such feedstocks in the world biofuel mix.

Biofuel Life-Cycle Analysis

Life-cycle analysis (LCA) is an important tool used to assess the energy and environmental impacts of biofuels. Here, we review biofuel LCA methodology and its application in transportation fuel regulations in the United States, the European Union, and the United Kingdom. We examine the application of LCA to the production of ethanol from corn, sugarcane, corn stover, switchgrass, and miscanthus. A discussion of methodological choices such as co-product handling techniques in biofuel LCA is also provided. Further, we discuss the estimation of greenhouse gas (GHG) emissions of land use changes (LUC) potentially caused by biofuels, which can significantly influence LCA results. Finally, we provide results from LCAs of ethanol from various sources. Regardless of feedstock, bioethanol offers reduced GHG emissions over fossil-derived gasoline, even when LUC GHG emissions are included. This is mainly caused by displacement of fossil carbon in gasoline with biogenic carbon in ethanol. Of the ethanol pathways examined, corn ethanol has the greatest life-cycle GHG emissions and offers 30% reduction in life-cycle GHG emissions as compared to gasoline when LUC GHG emissions are included. Miscanthus ethanol demonstrates the highest life-cycle GHG emissions reductions compared to gasoline, 109%, when LUC GHG emissions are included.

Environmental implications of anaerobic digestion for manure management in dairy farms in Mexico: a life cycle perspective

The environmental profile of milk production in Mexico was analysed for three manure management scenarios: fertilization (F), anaerobic digestion (AD) and enhanced anaerobic digestion (EAD). The study used the life cycle assessment (LCA) technique, considering a ‘cradle-to-gate’ approach. The assessment model was constructed using SimaPro LCA software, and the life cycle impact assessment was performed according to the ReCiPe method. Dairy farms with AD and EAD scenarios were found to exhibit, respectively, 12% and 27% less greenhouse gas emissions, 58% and 31% less terrestrial acidification, and 3% and 18% less freshwater eutrophication than the F scenario. A different trend was observed in the damage to resource availability indicator, as the F scenario presented 6% and 22% less damage than the EAD and AD scenarios, respectively. The magnitude of environmental damage from milk production in the three dairy manure management scenarios, using a general single score indicator, was 0.118, 0.107 and 0.081 Pt/L of milk for the F, AD and EAD scenarios, respectively. These results indicate that manure management systems with anaerobic digestion can improve the environmental profile of each litre of milk produced.

Sustainability of Biomass

The bio-based economy is considered one of the options for mitigating greenhouse gas (GHG) emissions and is pursued by many countries seeking not only emissions reductions but also greater independency and security. In this context, biofuels production has expanded in the first decade of this century, and the same increase can occur with biomaterials in the years to come. However, despite the large appeal of biofuel, various concerns regarding its sustainability have been raised, constraining production and imposing the necessity to attest compliance with some principles and criteria. As a result of interest group advocacy, a diversity of sustainability initiatives has emerged in recent years in the bioenergy context, which may soon be extended to chemicals and biomaterials as well. This chapter presents the main technical regulations and standards for bioenergy currently in place and discusses the social, economic, and environmental issues these address. Guided by the set principles and criteria, there is evidence supporting that, if implemented correctly, the bio-based economy can indeed offer significant contributions toward sustainable development.

Biomass Gasification for Ethanol Production

For a sustainable future, it is essential for mankind to access the largely untapped solar resource by innovative bioenergy routes, an important way to overcome fossil fuel dependence and mitigate related environmental impacts. In this framework, as a good example of the potential to be exploited, among the several biomasses under scrutiny to be used for energy supply, sugarcane appears as one with the most interest and potential, with estimates that about 142 million hectares currently are available for such culture, taking into consideration rain feed areas in tropical countries and without significant impact on food production and the environment (Fischer et al.2008).