Otávio Cavalett

Integrated versus stand-alone second generation ethanol production from sugarcane bagasse and trash.

Ethanol production from lignocellulosic materials is often conceived considering independent, stand-alone production plants; in the Brazilian scenario, where part of the potential feedstock (sugarcane bagasse) for second generation ethanol production is already available at conventional first generation production plants, an integrated first and second generation production process seems to be the most obvious option. In this study stand-alone second generation ethanol production from surplus sugarcane bagasse and trash is compared with conventional first generation ethanol production from sugarcane and with integrated first and second generation; simulations were developed to represent the different technological scenarios, which provided data for economic and environmental analysis. Results show that the integrated first and second generation ethanol production process from sugarcane leads to better economic results when compared with the stand-alone plant, especially when advanced hydrolysis technologies and pentoses fermentation are included.

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.

Brazilian Soybean Production: Emergy Analysis with an Expanded Scope.

This article offers the results of emergy analysis used to evaluate four different soybean production systems in Brazil that were divided into two main categories: biological models (organic and ecological farms) and industrial models (green-revolution chemical farms and herbicide with no-tillage farms). The biological models show better environmental, economical, and social performance indicators; however, at the national level, discussion of transgenic soybean seed release considers only industrial models without any mention of biological models. Classic emergy analysis shows biological options are the better alternatives but does not explain why decisions taken by farmers and government in Brazil were in opposition to these options. New research is proposed to identify and quantify the external forces that strongly interfere in the definition of public policy for soybean production. New parameters are proposed to enrich emergy methodology: Renewability of each input was considered in emergy calculations and negative externalities were included as additional services.

Technical and economic assessment of trash recovery in the sugarcane bioenergy production system

Mechanized sugarcane (Saccharum spp.) harvest without burning has been increasingly adopted in Brazil, increasing trash availability on the field. This study aims at showing the importance of using an integrated framework tool to assess technical and economic impacts of integral harvesting and baling trash recovery strategies and different recovery rates as well as its implications in the sugarcane production, transport and processing stages. Trash recovery using baling system presents higher costs per unit of mass of recovered trash in comparison to system in which trash is harvested and transported with sugarcane stalks (integral harvesting system). However, the integrated agricultural and industrial assessment showed that recovering trash using baling system presents better economic results (higher internal rate of return and lower ethanol production cost) than the integral harvesting system for trash recovery rates higher than 30 %. Varying trash recovery fraction, stalks productivity and mean transport distance for both integral harvesting and baling systems, sensitivity analyses showed that higher trash recovery fractions associated with higher stalks yields and long transport distances favors baling system, mainly due to the reduction of bulk load density for integral harvesting system under those conditions.

Hybrid Input-Output Life Cycle Assessment of First- and Second-Generation Ethanol Production Technologies in Brazil

A hybrid approach combining life cycle assessment and input‐output analysis was used to demonstrate the economic and environmental benefits of current and future improvements in agricultural and industrial technologies for ethanol production in Brazilian biorefineries. In this article, three main scenarios were evaluated: first‐generation ethanol production with the average current technology; the improved current technology; and the integration of improved first‐ and second‐generation ethanol production. For the improved first‐generation scenario, a US

Life Cycle Assessment of Poly(Lactic Acid) (PLA): Comparison Between Chemical Recycling, Mechanical Recycling and Composting

1 million increase in ethanol demand can give rise to US

Participatory emergy synthesis of integrated food and biofuel production: a case study from Brazil

2.5 million of total economic activity in the Brazilian economy when direct and indirect purchases of inputs are considered. This value is slightly higher than the economic activity (US

Techno-economic analysis and climate change impacts of sugarcane biorefineries considering different time horizons

1.8 million) for an energy equivalent amount of gasoline. The integration of first‐ and second‐generation technologies significantly reduces the total greenhouse gas emissions of ethanol production: 14.6 versus 86.4 grams of carbon dioxide equivalent per megajoule (g CO‐eq/MJ) for gasoline. Moreover, emissions of ethanol can be negative (–10.5 g CO‐eq/MJ) when the system boundary is expanded to account for surplus bioelectricity by displacement of natural gas thermal electricity generation considering electricity produced in first‐generation optimized biorefineries.

Sustainability Assessment Methodologies

This paper presents a life cycle assessment (LCA) comparing three forms of poly(lactic acid) (PLA) disposal: mechanical recycling, chemical recycling and composting. The LCA data was taken from lab scale experiments for composting and hydrolysis steps. Polymerization data in chemical recycling was obtained from computer simulation. Mechanical recycling data from lab scale were combined with the data from a plastics commercial mechanical recycling plant. The analysis considered two different product systems based on the input of the recycled PLA in the product system. Considering the categories: climate change, human toxicity and fossil depletion, the LCA showed that mechanical recycling presented the lowest environmental impact, followed by chemical recycling and composting. Among the forms of recycling, the most important input was the electricity consumption.

Social life cycle assessment of first and second-generation ethanol production technologies in Brazil

Large-scale production of biofuels is increasingly touted in national policies and international trade agreements. This global trend is particularly clear in Brazil. However, the sugarcane monocultures promoted in the country depend on a range of fossil fuel derivates, industrial inputs, chemical fertilizers, agrochemicals, machinery, labor exploitation and various other non-renewable resources, making it a questionable alternative to substitute fossil energy sources. In parallel, an alternative approach has recently emerged in southern Brazil, which promotes integrated food and energy production in small-scale, family managed production units, based on agro-ecological principles and local market orientation. This paper explores the potential of this alternative for more environmentally sustainable and socially fair production of food and biofuels. The scope of the paper is interdisciplinary, in combining environmental and social information from participatory fieldwork and interviews with farmers. Resource flows at farm level are identified and illustrated in diagrams, and interactions between farmers and institutions at local and global levels. The paper also explores opportunities for cross-fertilization between the two approaches applied: emergy synthesis (ES) and participatory learning and action (PLA). Integration was operationalized by drawing emergy diagrams together with local farmers, supported by PLA tools. The result is a systems description that adds information provided by farmers to an understanding based on general systems principles. Apart from accounting for the empirical results from this approach, lessons learned are used for proposing a new framework for participatory emergy synthesis (P-ES), which would facilitate more interdisciplinary and participatory evaluation of agricultural systems.