Life Cycle Assessment of Vetiver-Based Biorefinery With Production of Bioethanol and Furfural

Lignocellulosic biomass feedstocks are considered as one of the major alternative for fossil and food based transport fuel and chemicals for the reasons such as fuel/food security, depleting fossil reserves, climate change, mitigate pollution in agriculture and rural socio-economic development. In highly populated and agriculture based countries such as India, the conventional lignocellulosic feedstock such as rice straw and wheat straw are a major source for animal feed and hence non-conventional feedstock that could be cultivated in waste land has to be explored to fulfill the lignocellulosic feedstock supply in the coming years. In this context, this study deals with life cycle assessment of vetiver, a non-conventional lignocellulosic feedstock for bioethanol and biochemical production in India. A prospective LCA was performed to compare the environmental impacts of vetiver based biorefinery system with conventional system. The results reveal that the carbon dioxide and fossil oil consumption could be reduced by 145% and 77% respectively in case of bioethanol production, and 30% and 12% respectively in case of bioethanol and furfural production compared to its reference system. The sensitive analysis indicates that using vetiver biomass a source of energy in biorefinery plant further reduces the carbon dioxide emission and fossil oil consumption significantly by 100% and 60% compared to the coal used for process energy requirement in vetiver biorefinery.

Life Cycle Assessment of Soybean-Based Biodiesel in Argentina for Export

Arnaud Dauriat, Edgard Gnansounou, Luis Alberto Panichelli

Background, aim and scope. Regional specificities are a key factor when analyzing the environmental impact of a biofuel pathway through a life cycle assessment (LCA). Due to different energy mixes, transport distances, agricultural practices and land use changes, results can significantly vary from one country to another. The Republic of Argentina is the first exporter of soybean oil and meal and the third largest soybean producer in the world, and therefore, soybean-based biodiesel production is expected to significantly increase in the near future, mostly for exportation. Moreover, Argentinean biodiesel producers will need to evaluate the environmental performances of their product in order to comply with sustainability criteria being developed. However, because of regional specificities, the environmental performances of this biofuel pathway can be expected to be different from those obtained for other countries and feedstocks previously studied. This work aims at analyzing the environmental impact of soybean-based biodiesel production in Argentina for export. The relevant impact categories account for the primary non-renewable energy consumption (CED), the global warming potential (GWP), the eutrophication potential (EP), the acidification potential (AP), the terrestrial ecotoxicity (TE), the aquatic ecotoxicity (AE), the human toxicity (HT) and land use competition (LU). The paper tackles the feedstock and country specificities in biodiesel production by comparing the results of soybean-based biodiesel in Argentina with other reference cases. Emphasis is put on explaining the factors that contribute most to the final results and the regional specificities that lead to different results for each biodiesel pathway. Materials and methods. The Argentinean (AR) biodiesel pathway was modelled through an LCA and was compared with reference cases available in the ecoinvent® 2.01 database, namely, soybean-based biodiesel production in Brazil (BR) and the United States (US), rapeseed-based biodiesel production in the European Union (EU) and Switzerland (CH) and palm-oil-based biodiesel production in Malaysia (MY). In all cases, the systems were modelled from feedstock production to biodiesel use as B100 in a 28 t truck in CH. Furthermore, biodiesel pathways were compared with fossil low-sulphur diesel produced and used in CH. The LCA was performed according to the ISO standards. The life cycle inventory and the life cycle impact assessment (LCIA) were performed in Excel spreadsheets using the ecoinvent® 2.01 database. The cumulative energy demand (CED) and the GWP were estimated through the CED for fossil and nuclear energy and the IPCC 2001 (climate change) LCIA methods, respectively. Other impact categories were assessed according to CML 2001, as implemented in ecoinvent. As the product is a fuel for transportation (service), the system was defined for one vehicle kilometre (functional unit) and was divided into seven unit processes, namely, agricultural phase, soybean oil extraction and refining, transesterification, transport to port, transport to the destination country border, distribution and utilisation. Results. The Argentinean pathway results in the highest GWP, CED, AE and HT compared with the reference biofuel pathways. Compared with the fossil reference, all impact categories are higher for the AR case, except for the CED. The most significant factor that contributes to the environmental impact in the Argentinean case varies depending on the evaluated category. Land provision through deforestation for soybean cultivation is the most impacting factor of the AR biodiesel pathway for the GWP, the CED and the HT categories. Whilst nitrogen oxide emissions during the fuel use are the main cause of acidification, nitrate leaching during soybean cultivation is the main factor of eutrophication. LU is almost totally affected by arable land occupation for soybean cultivation. Cypermethrin used as pesticide in feedstock production accounts for almost the total impact on TE and AE. Discussion. The sensitivity analysis shows that an increase of 10% in the soybean yield, whilst keeping the same inputs, will reduce the total impact of the system. Avoiding deforestation is the main challenge to improve the environmental performances of soybean-based biodiesel production in AR. If the soybean expansion can be done on marginal and set-aside agricultural land, the negative impact of the system will be significantly reduced. Further implementation of crops’ successions, soybean inoculation, reduced tillage and less toxic pesticides will also improve the environmental performances. Using ethanol as alcohol in the transesterification process could significantly improve the energy balance of the Argentinean pathway. Conclusions. The main explaining factors depend on regional specificities of the system that lead to different results from those obtained in the reference cases. Significantly different results can be obtained depending on the level of detail of the input data, the use of punctual or average data and the assumptions made to build up the LCA inventory. Further improvement of the AR biodiesel pathways should be done in order to comply with international sustainability criteria on biofuel production. Recommendations and perspectives. Due to the influence of land use changes in the final results, more efforts should be made to account for land use changes others than deforestation. More data are needed to determine the part of deforestation attributable to soybean cultivation. More efforts should be done to improve modelling of interaction between variables and previous crops in the agricultural phase, future transesterification technologies and market prices evolution. In order to assess more accurately the environmental impact of soybean-based biodiesel production in Argentina, further considerations should be made to account for indirect land use changes, domestic biodiesel consumption and exportation to other regions, production scale and regional georeferenced differentiation of production systems.

2009

Bioethanol production from oil palm empty fruit bunches

Simone Chiesa

Face to the increasing demand for energy, the declining availability of fossil fuels and the periodical tensions in the geopolitical context of oil-producing countries have raised serious concerns in the governments worldwide as well as in the public opinion. Similarly, awareness has been increasing of the environmental harms caused by burning fossil fuels and of the associated adverse effects on human health. A number of different potential sources of renewable energy have been investigated over the last decades, including wind power, solar energy and biomass, among others. In particular, concerning the use of biomass, the production of ethanol as a transportation fuel has been considered a particularly attractive and feasible option. Production of ethanol from feedstocks containing easily fermentable sugars such as corn or sugar cane has been actually implemented, especially in the US and in Brazil, but it has been harshly debated especially on the ground of the induced competition between energy and food uses. Hence, a so-called second generation production has been envisaged, which makes use of lignocellulosic materials, namely biomass residues from different agricultural and industrial processes, which appear particularly interesting due to their abundance and the lack of possible use for human consumption. Unfortunately, the production of ethanol from cellulosic feedstocks still presents technical challenges to be overcome before production at the industrial scale could become profitable. In a number of tropical countries in Africa, Asia and South America, important amounts of agricultural residues are generated during the process of oil extraction from the fruits of the palm tree Elaeis guineensis. Among these residues, the empty bunches that carry the fruitlets are at present severely underused, despite their high content of cellulose (of roughly 30%) and the presence of other saccharides. In the scientific literature, relatively limited attention has been given to this feedstock, when compared to other residues such as, for instance, corn stover. Moreover, different studies can be difficult to compare because of the many dissimilar factors involved, as the diverse geographical origin of the residues, and different techniques and analytical protocols used. This thesis deals with the comparison of possible alternatives for processing empty fruit bunches to produce ethanol. The attention has been focused on the pretreatment step, the first operation performed on the feedstock, which is crucial because of its cost and impact on downstream processing (enzymatic saccharification and fermentation). Thus, three pretreatment techniques generally accepted as among the most promising have been chosen: dilute acid, dilute alkali and liquid hot water treatment. They have been performed on the same feedstock under controlled laboratory conditions. For each pretreatment, experimental parameters (such as temperature, time, pH, etc.) have been varied according to a statistical experiment design. Pretreated samples have been enzymatically hydrolyzed to assess the degree of conversion of cellulose into fermentable glucose. The influence of the conditions employed during pretreatment have been evaluated using surface response analysis, which also enabled to define optimal conditions with respect to the total amount of glucose liberated upon enzymatic saccharification. Rigorous compositional analyses using wet chemistry protocols have been carried out on the samples before and after pretreatment, allowing their complete characterization. The fate of each type of compound of the biomass could thus be followed during the processing including pretreatment and enzymatic saccharification. Additionally, IR spectroscopy has been used to retrieve precious information about the nature of the solid substrate. The liquids produced during pretreatment have been similarly analyzed to detect the presence of solubilized sugars as well as that of a number of degradation products which could be inhibitors for microorganisms used in a successive fermentation stage. Taken together, all these elements allowed to investigate the mode of action of the pretreatment techniques employed and establishing a meaningful comparison among the options when empty fruit bunches are used as a feedstock. An in-depth discussion is presented concerning the effectiveness of each treatment with respect to the disruption of the recalcitrant lignocellulosic structure, the improvements in glucose conversions which are attainable upon pretreatment, and other significant criteria such as the production of inhibitors and the possible use of the liquid streams. All these factors, in fact, may have a strong impact on a possible extension from the laboratory to the pilot-plant or industrial scale. Treatments using either a dilute sulfuric acid solution or only pure water have proved overall more efficient than the dilute alkali treatment in attacking the lignocellulosic matrix and relevant amounts of sugars could be liberated under optimized conditions. Oppositely, the alkali treatment under the conditions explored shows limitations probably attributable to the feedstock considered, especially given its relevant lignin content. Each pretreatment, however, has characteristic strengths and weaknesses that must be considered carefully before adopting a choice, especially in relation with the possible products of interest: an approach including the production of different chemicals along with ethanol could probably be a realistic option for possible future scale-up. One of the major contributions of this thesis is hence to provide a comparative study of different techniques performed under standardized conditions, and to investigate a feedstock of interest for many countries for which however information about its response to pretreatment techniques is still fragmented.

EPFL2012

LCA of bioethanol and furfural production from vetiver

Edgard Gnansounou, Jegannathan Kenthorai Raman

In this study a prospective life cycle assessment of biorefinery system from vetiver leaves was carried out to know the environmental benefits of this system over conventional systems considering the geographical context of India. The composition of vetiver leaves from the experimental analysis revealed that vetiver is rich in cellulose (32.6%), hemicellulose (31.5%) and lignin (17.3%) that could be used as a feed-stock for biorefinery. The comparative life cycle assessment results show that the carbon dioxide emission and fossil oil depletion could be reduced by 95% and 23% respectively in case of standalone bioethanol system, and 99% and 17% respectively in case of bioethanol and furfural system compared to that of conventional petrol and furfural systems. The sensitivity study indicates that the impact could be further reduced if vetiver biomass is used as a source of energy in biorefinery plant instead to the coal. (C) 2015 Elsevier Ltd. All rights reserved.