Comparative life cycle assessment of first- and second-generation ethanol from sugarcane in Brazil

Abstract

Purpose The use of bagasse and trash from sugarcane fields in ethanol production is supposed to increase the ethanol yield per hectare, to reduce the energy demand, greenhouse gas emissions, and other environmental impacts. In this article, different technological options of ethanol production are investigated and quantified looking at potential environmental impacts. The firstgeneration ethanol from sugarcane is compared to stand-alone second-generation ethanol as well as an integrated first-and second-generation ethanol production. Methods The method applied for this life cycle assessment follows the ISO standards 14040/44. The data used in this life cycle assessment is mainly derived from process simulation, literature, and primary data collection. Background data was taken from databases such as GaBi and ecoinvent. The life cycle impact assessment follows the default methods at midpoint level recommended by the International Reference Life Cycle Data System. The calculations were performed using the GaBi 7 life cycle assessment software. It is assumed that 50% of sugarcane trash is recovered and used for second-generation ethanol production, whereas the other 50% remain in the field to maintain soil fertility and to prevent soil erosion. In the case of first-generation ethanol, the same amount of trash is used for energy generation. Results and discussion The results of the life cycle impact assessment show that, compared to first-generation ethanol, secondgeneration ethanol from sugarcane in Brazil allows significant reductions in all investigated impact categories except resource depletion. Resource depletion, however, is strongly influenced by the demand for ammonium phosphate which is needed for inoculum preparation. Integrated first-and second-generation ethanol production also allows reductions in most of the environmental impacts except for global warming, photochemical ozone depletion, and resource depletion. The yield of ethanol per hectare increases since bagasse and trash are used for the production of second-generation ethanol. Consequently, the results show that agricultural land occupation is reduced for integrated first-and second-generation ethanol by approximately 11%, whereas second-generation ethanol allows reduction of land use by approximately a factor of 30. Conclusions The use of bagasse and trash for ethanol production allows both the reduction of several environmental impacts and land use, in particular, because impacts caused by sugarcane cultivation are avoided. For the integrated first-and secondgeneration ethanol scenario, it is important to further reduce the total energy demand in order to achieve self-sufficiency for the plant energy and to avoid additional emissions from burning fossil fuels.

Human Health Impacts of Aviation Biofuel Production: Exploring the Application of Different Life Cycle Impact Assessment (LCIA) Methods for Biofuel Supply Chains

“…The comparative analysis was conducted for the life cycle impacts of aviation biofuel on human health in the case of Brazil, a key player in global biofuel production. Based on recent literature on aviation biofuel, three feedstocks stand out in respects of techno-economic feasibility [11,42], environmental impacts (mainly GHG emissions reduction) [43], and socioeconomic impacts [44] for the Brazilian context. Therefore, we focused on three aviation biofuel alternatives produced from the feedstocks with corresponding conversion technologies that are suitable for each feedstock: (i) the sugarcane via alcohol to jet (ATJ) pathway, (ii) the eucalyptus via fast pyrolysis (FP) pathway, and (iii) the macauba via hydro-processed esters and fatty acids (HEFA) pathway.…”

“…The practices of feedstock (i.e., sugarcane, eucalyptus, and macauba) cultivation and their related emissions are highly dependent on the locations and technologies available. Thus, data on emissions for feedstocks production were obtained from the most recent context-specific LCA/LCI studies of sugarcane production in Sao Paulo [44], average eucalyptus production (forest production subsystem) in Brazil [45,46], and macauba cultivation in Minas Gerais [47].…”

Improved Performance, Combustion and Emissions of SI Engine Fuelled with Butanol: A Review

“…It is generally known that alternative fuel is often separated into first and second-generation [55][56][57][58]. First-generation biofuels are typically from edible sources such as sugar cane and corn [59,60].…”

Modelling of a Brazilian ethanol plant: impact of the bagasse use and the ethanol dehydration on energy efficiency and sustainability

“…Two commercial plants, Bioflex I in Alagoas and Costa Pinto in São Paulo, are currently operational in Brazil, with nominal capacities of 60 and 40 millions of cubic metres, respectively. However, technical problems with lignin pre-treatment and filtering still hinder the maximum production [15,16]. Therefore, the second-generation ethanol faces still some obstacles related to the current technological development, the large-scale implementation of the pre-treatment of lignocellulose and the costs related to raw material and enzymes for hydrolysis [11].…”

“…Seabra et al [25] investigated through a LCA study the greenhouse gases emissions and energy efficiency of sugar and ethanol produced in Brazil. Maga et al [16] evaluated mainly emissions and land use to produce first-and second-generation ethanol, respectively, or through an integrated process. Even if each production chain can be developed separately, the integration is favourable as the plant shared a unique cogeneration system.…”