Life Cycle Assessment Of Biofuels Research Articles

Enzymes as an environmental bottleneck in cellulosic ethanol production: Does on-site production solve it?

With the progressive implementation of Low-Carbon Policies based on Life Cycle Assessment (LCA) methodologies to assess climate change mitigation, biofuels’ potential environmental advantages could finally be translated into economic revenues, especially for residue-based production chains. This implies, however, tackling environmental hotspots along the Life Cycle, such as the use of enzymes, an important input in cellulosic ethanol production. While relevant, however, aspects of enzyme manufacturing, crucial to the LCA results, are often oversimplified in databases or even undisclosed, which might render the accounting for this flow unreliable. A potential solution for this is to model enzyme production, disclosing aspects such as carbon source uptakes, energy consumption and purification steps, all of which may carry significant environmental burdens, especially for fossil-reliant procedures. Integrating these steps into the biorefinery process design as an on-site operation, however, would allow access to renewable energy and carbon sources for enzyme production, potentially reducing their burden in the final biofuel LCA profile, when compared with off-site supply. This work, then, aims to evaluate the effect of inserting on-site enzyme production within a stand-alone second-generation (2G) biorefinery, using sugarcane straw as feedstock, to produce ethanol and electricity, as opposed to off-site enzyme supply from manufacturers. The results show that adopting on-site production can reduce the overall environmental impact profile for cellulosic ethanol, in comparison to off-site supply, even though off-site data present significant variability among databases and literature. This trend persisted for varied enzyme dosages in the saccharification process and for different inventories to model off-site supply. The reference inventories for off-site supply lack transparency and details, while also displaying large discrepancies between impact indicators, indicating the need to pursue more consistent, reliable, and complete inventories for its modelling in LCA. Compared to first-generation (1G) sugarcane ethanol, 2G-ethanol (with on-site enzyme production) demonstrated a reduction in the Global Warming Potential category of around 80%. However, relevant trade-offs for 2G ethanol (with off-site enzyme supply) were observed – regarding ecotoxicity, mineral scarcity, eutrophication and even the potential GHG reduction – when different enzyme inventories are used.

CHANGES IN GLOBAL LAND USE AND CO2 EMISSIONS FROM US BIOETHANOL PRODUCTION: WHAT DRIVES DIFFERENCES IN ESTIMATES BETWEEN CORN AND CELLULOSIC ETHANOL?

Land use change (LUC) CO2 emissions associated with bioenergy production depend on the amount of land required to produce bioenergy crops, the carbon stored in such crops (including in the leaves, stalk, roots and soil), and the carbon emitted when another land cover is directly or indirectly displaced as a result. In this study, we use a global integrated assessment model [the Global Change Analysis Model (GCAM)] to explore the differences in estimates of LUC CO2 emissions for two crops (corn and switchgrass) used to produce ethanol in the United States under alternative assumptions about natural lands protection. Varying the latter assumptions for corn ethanol results in net LUC CO2 emissions between 7 and 41 gCO2 per MJ of ethanol, whereas varying the same assumptions for switchgrass ethanol results in net emissions between [Formula: see text]26 and 14 gCO2 per MJ of ethanol. The low-end estimate for each occurs when natural lands are assumed to be fully protected everywhere, which leads to significant cropland intensification. The high-end estimate for each occurs when natural lands are assumed to be unprotected everywhere, leading to greater cropland expansion and associated conversion of unmanaged forest and pasture. Results from this study could be used to inform scenarios of future energy system change or life cycle assessment of biofuels for which LUC emissions would be an input.

Preface

This year, Journal of Environmental Science and Sustainable Development (JESSD) is proud to hold its first international virtual symposium, featuring world-class speakers and editors worldwide. We were incredibly honored to have invited Prof. Shabbir H Gheewala, D. Eng. from King Mongkut’s University of Technology Thonburi, Thailand; Mari E. Mulyani, D.Phil. from University of Oxford, United Kingdom; Dr. Stefanie Steinebach from HAWK-HHG (Hochschule für angewandte Wissenschaft und Kunst-Hildesheim/Holzminden/Göttingen), Germany; Prof. Dr. Ing. Ir. Misri Gozan, M.Tech. from Universitas Indonesia, Indonesia; Assoc. Prof. Dr. Marlia Mohd Hanafiah from Universiti Kebangsaan Malaysia, Malaysia; Ian D. Hollingsworth, Ph.D. from Horizon Environmental Soil Survey and Evaluation Darwin, Australia; Nurdiana Darus from Unilever Indonesia; Dr. Ir. Haruki Agustina, M. Env Eng. Sc. From Director for Contamination Recovery and Emergency Response of Hazardous Waste, KLHK Indonesia; Dr. Yuki M. A. Wardhana from School of Environmental Science UI and Indonesia Infrastructure Guarantee Fund-IIGF/PT Penjaminan Infrastruktur Indonesia-Persero, Indonesia; Prof. Ir. Widjojo Adi Prakoso, M.Sc., Ph.D from Faculty of Engineering, Universitas Indonesia;. Dr Karen Lythgoe from Earth Observatory of Singapore; Walter Mooney Ph.D from U.S. Geological Survey, USA and Dr. Supriyanto Rohadi Center for Research and Development Center, BMKG (Indonesian Agency for Meteorology Climatology and Geophysics), Indoneia.The symposium was held in virtual format due to related restrictions during COVID-19 pandemic. I appreciate everyone’s participation in the first JESSD Symposium: International Symposium of Earth, Energy, Environmental Science, and Sustainable Development, despite the restrictive situation caused by the global COVID-19 pandemic. Instead of being postponed, this symposium was conducted virtually to response to emerging issues mainly related to earth science, energy, environmental science, and sustainability. Moreover, this symposium also facilitates the publications of qualified research on COVID-19 to contribute to the global response towards the pandemic situation.This symposium is slightly different with previous symposium and conference held last year. By making the best use of development in telecommunication platforms, we are able to gather virtually to share our insights and progresses covering numerous subjects ranging from: the broad earth science, energy, and environmental science, to more specific topics on Sustainable Development Goals (SDGs), and the special issues of COVID-19 Research as well as Community Engagement for Better Environment. This symposium utilized Zoom, a widely known cloud-based video conferencing tool, as its telecommunication platform.The symposium was held on 28–30 September 2020. Committees are based in School of Environmental Science, Universitas Indonesia, Jakarta, Indonesia. The symposium consists of plenary sessions and parallel sessions. The plenary sessions include keynote speech from various experts in related fields. The topics of the plenary sessions are considered purposeful in today’s agenda, such as life cycle assessment of biofuels, environmental governance in developing countries, smallholder palm oil and sustainability, collaborative scheme of solid waste management, alternative financing for waste management, plastic recycling, disaster management, and many more. Meanwhile, the parallel sessions facilitate the authors/presenters to discuss about their research in a smaller group based on the topic grouping. Each author/presenter was given up to 9 minutes for presentation and 3 minutes for question and answer. Quick questions were addressed right after each presentation, but longer questions were compiled and discussed at the end of the session. The session was wrapped up by the moderator in his/her closing remarks. The participants (presenters) are coming from 25 different countries all around the world, including: Indonesia, India, Japan, Bulgaria, Russian Federation, Ukraine, Pakistan, Poland, Colombia, Iran, Romania, United Arab Emirates, Malaysia, Finland, Vietnam, Philippines, Nigeria, Sri Lanka, Netherlands, Morocco, Thailand, United Kingdom, Republic of Tajikistan, Brazil, and Ethiopia. Participant (presenter) numbers are 270.We are glad that we received lots of submissions from the symposium and selected a bunch of high-quality papers and compiled them into the proceedings after reviewed them using the double-blind peer review procedure. The symposium is considered successful. Signal loss and some technical issues happened during parallel sessions but had been well and quickly addressed by technical assistants, without causing any significant delay. I express my deep gratitude to the Chairman, all distinguished keynote speakers, committees, reviewers, and all the participants, for their time, hard work, and contribution to support this symposium during this challenging time. I would like to take this opportunity also to express my gratitude for our sponsors, Bank Rakyat Indonesia (BRI), PT Unilever Indonesia Tbk, and PT Larus Birus Utama, for sponsoring the main events, as well as APIKI Indonesia Network (Jaringan Ahli Perubahan Iklim dan Kehutanan Indonesia) and BMKG (Badan Meteorologi, Klimatologi, dan Geofisika) for conducting the joined session. Last but not the least, we send our sincere thanks to the IOP publisher for publishing the proceedings.Depok, 28 September 2020 Editor-in-Chief,Dr. Herdis HerdiansyahList of committees are available in the pdf.

Life Cycle Assessment of Biofuels.

Life cycle assessment (LCA) assesses the environmental burdens or impacts of products from cradle to grave. It is also possible to assess such burdens or impacts for parts of the life cycle. A brief overview is given of LCA methodology. A number of choices have to be made in the goal and scope definition, inventory analysis, and impact assessment stages of life cycle assessments. Such choices can have substantial impacts on LCA outcomes. There are uncertainties in outcomes linked to inventory data and modeling. In the case that future biofuels and production processes are studied, assessment outcomes are characterized by relatively large uncertainties. Choices and uncertainties should be considered in the interpretation stage of life cycle assessments. Methodologies applied to several important environmentally relevant aspects of biofuel life cycles are discussed. These aspects are: emissions of substances impacting climate, depletion of virtually nonrenewable abiotic resources, primary energy demand, and water footprint. LCA can be useful in identifying life cycle stages and processes that are major contributors to environmental burdens, for determining the energetic return on energy invested in biofuels, for the identification of environmental trade-offs, and for comparing the life cycle environmental burdens of products.

Environmental sustainability of biofuels: a review.

Biofuels are being promoted as a low-carbon alternative to fossil fuels as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. However, there are also concerns that their wider deployment could lead to unintended environmental consequences. Numerous life cycle assessment (LCA) studies have considered the climate change and other environmental impacts of biofuels. However, their findings are often conflicting, with a wide variation in the estimates. Thus, the aim of this paper is to review and analyse the latest available evidence to provide a greater clarity and understanding of the environmental impacts of different liquid biofuels. It is evident from the review that the outcomes of LCA studies are highly situational and dependent on many factors, including the type of feedstock, production routes, data variations and methodological choices. Despite this, the existing evidence suggests that, if no land-use change (LUC) is involved, first-generation biofuels can—on average—have lower GHG emissions than fossil fuels, but the reductions for most feedstocks are insufficient to meet the GHG savings required by the EU Renewable Energy Directive (RED). However, second-generation biofuels have, in general, a greater potential to reduce the emissions, provided there is no LUC. Third-generation biofuels do not represent a feasible option at present state of development as their GHG emissions are higher than those from fossil fuels. As also discussed in the paper, several studies show that reductions in GHG emissions from biofuels are achieved at the expense of other impacts, such as acidification, eutrophication, water footprint and biodiversity loss. The paper also investigates the key methodological aspects and sources of uncertainty in the LCA of biofuels and provides recommendations to address these issues.

Life cycle assessment of biofuels in Thailand: Implications of environmental trade-offs for policy decisions

Biofuels have often been considered to have an advantage towards global warming but have caused controversy over competition for the limited availability of natural resources and the adverse impacts on other environmental aspects. This study evaluates the environmental benefits and impacts of biofuels in Thailand by using life cycle assessment with the Thai Eco Scarcity method derived from existing policies in Thailand. The assessment results showed that E85 (85% ethanol from cassava blended with 15% gasoline) and palm biodiesel had 95% and 43% higher impacts than their fossil fuel counterparts. The evaluation of biodiesel and ethanol revealed many trade-offs between environmental impacts; for example between fossil energy resources and other natural resources i.e. freshwater and land, and also between global (greenhouse gas emissions) and local impacts (pesticides). The importance of using the life cycle thinking concept which avoids problem shifting between impacts and between life cycle stages was also revealed. This is a crucial message in policy-making which has largely equated environmental impacts with greenhouse gas emissions leading to unintended consequences on other impacts. As anticipated, both biofuels perform much better than their fossil counterparts when considering greenhouse gas emissions and fossil energy resources. However, including other impact categories, particularly land and freshwater resources, pesticides use and mineral resources completely reverses the comparison, with the fossil counterparts ending up with better environmental profiles. Using a policy-based life cycle impact assessment method reveals comparative results and trade-offs on a single scale which can be easily understood by the policy-makers.

Attributional life cycle assessment of biofuels for shipping: Addressing alternative geographical locations and cultivation systems

The purpose of this study is to evaluate a life cycle assessment of straight vegetable oil (SVO) and biodiesel addressing alternative upstream pathways. The pathways are SVO and biodiesel produced in the United Kingdom (UK) using European rapeseed and also, SVO and biodiesel produced in the UK using soybean grain and soybean oil imported from Argentina. Four environmental impact categories have been assessed using the SimaPro (ReCiPe life-cycle impact assessment) method: this includes global warming potential (GWP); acidification; eutrophication and particulate matter. Rapeseed based biofuel had the lowest emission impact in terms of GHG emissions. Significant greenhouse gas (GHG) emissions can result from land use change due to the expansion and cultivation of soybean in Argentina. When land use change is not considered, the soy based biofuel system has the lowest GHG impact with more than 70% GHG emission reduction. The GHG emission at cultivation stage far outweighs the impacts of the other life-cycle stages irrespective of the feedstock used for the biofuel production systems. The use of fertilizers and associated soil emissions are the main contributors. The environmental impacts of biofuel can be reduced by avoiding land use change, improving soil management practices and yield, and also optimizing transportation routes. Effective implementation of options for biofuels production were explored to improve sustainability in shipping.

An integrated modeling framework for crop and biofuel systems using the DSSAT and GREET models

As global demand for food, energy, and water resources continues to increase, decision-makers in these sectors must find sustainable ways to produce and provide for the growing population. While many models have been created to aid in decision-making in these systems, there is a lack of robust integrated models that enable an understanding of the interconnections of these systems. This study develops a modeling framework that explores the connections of the corn and ethanol systems, two major food and energy resources. A crop modeling tool (DSSAT) and a biofuel life cycle assessment tool (GREET) are connected using a service-oriented architecture programming approach. A Python program is developed to connect these two models and run scenario analyses to assess environmental impacts of the integrated system. This paper explores the impact of decisions such as fertilizer use and plant population on environmental effects of greenhouse gases, energy use, and water in the integrated system.

Harmonized algal biofuel life cycle assessment studies enable direct process train comparison

The conclusions from life cycle assessment of algal biofuels (e.g., biodiesel, renewable diesel) vary significantly due to both modeling and inherent technological uncertainties. The inherent uncertainties of US-based algal biofuels production were investigated by eliminating modeling uncertainty via comprehensive harmonization through a meta-analysis. Following harmonization, the cumulative fossil energy consumption (MJ/MJ), global warming potential (g CO2-eq/MJ) and water consumption (m3/MJ) of different algal biofuel process trains were investigated through a stochastic life cycle model. By focusing on the inherent differences of current technologies, this study identified (1) the differences in impact results between different process trains (i.e., different combinations of technology choices along the fuel production life cycle), (2) high impact hotspots, and (3) possible low impact process trains, all of which are crucial to further improve the sustainability of algal biofuels.The median (range) values of the three indicators for the most common algal biodiesel process train are 3.5 (2.9–4.2) MJ/MJ, 99 (55–151) g CO2-eq/MJ and 0.08 (0.07–0.09) m3/MJ, with corresponding inter-quartile ranges being 63%, 46% and 43% less than the literature values, respectively. The median (range) values of the three indicators for the most common algae renewable diesel process train are 1.7 (1.4–2.2) MJ/MJ, 84 (60–112) g CO2-eq/MJ and 0.04 (0.03–0.05) m3/MJ, with the corresponding reductions in inter-quartile range by 83%, 83% and 84%, respectively. Although neither of the median global warming potential results for algal biofuels met the mandatory thresholds in the Renewable Fuel Standard (45 g CO2-eq/MJ), it is possible to meet the requirement by integrating low impact technology options into the process trains.

Commentary on “carbon balance effects of US biofuel production and use,” by DeCicco et al. (2016)

In their recent publication “Carbon balance effects of U.S. biofuel production and use,” DeCicco et al. present an empirical assessment of net CO2 emission effects over the period 2005–2013 after the US renewable fuel standard (RFS) came into existence and conclude that biofuels have resulted in a net increase in CO2 emissions over the period. The analysis presented by DeCicco et al. relies on three key assertions. First, that if biofuel carbon combustion emissions are not completely offset by additional net ecosystem production (NEP), then the biofuel should not receive full biogenic carbon credit. Second, that changes in agricultural NEP related to biofuel production can be accurately estimated from national-level agricultural production statistics. Third, that agricultural NEP is a pertinent measure of biofuel global warming impacts. We show that following the conventional definition of NEP the combustion of biofuel by definition leads to an exactly equal increase in NEP; therefore, the first assertion is not meaningful. Regarding the second assertion, we show that estimation of biofuel-related NEP changes from agricultural production statistics is not a robust methodology. Finally, we argue that agricultural NEP is an important parameter for estimating land-use change effects, but in isolation is an irrelevant GHG metric for current biofuels. We find that the conclusions above from DeCicco et al. are unfounded and do not invalidate the application of biogenic carbon offsets in life cycle assessments of biofuels currently used in national and international regulations.

Energy Systems and the Knowledge Problem: The Case of Biofuels

This paper examines Life Cycle Assessments of biofuels, and concludes that this literature reaches no conclusion on the energy efficiency of biofuels, and their efficacy for reducing greenhouse gas emissions. The paper analyzes the causes of this inconclusiveness and discusses ways in which better LCA’s can be constructed. While discussions of energy policy presume that the energy mix is a system that can be engineered in order to achieve desired environmental, and economic goals, this paper argues that it is more accurate to understand the energy mix as a spontaneously emergent order that is the product of human action, not human design. The complexity of energy systems, the subjectivist and individualist nature of the human actions determining the outcome of these systems, and the unknowability of technological innovation mean that attempts at designing the energy mix, mandating targets for specific energy sources, or subsidizing specific energy sources can be counter-productive.

A bibliometric overview of Brazilian LCA research

We bibliometrically evaluated the scientific literature outlined around Brazilian life cycle assessment (LCA). Our aim is twofold: (1) Analyze the Brazilian scientific literature on LCA, forming a current view of how the LCA methodology is applied in the country; (2) within this view, trace the evolution of themes, characterize institution collaboration, and indicate major influences in Brazilian LCA community. Data were outlined around academic production and publications, from 1993 to 2015, indexed by the Institute for Scientific Information (ISI- SCIE and SSCI) through a specific group of keywords. Initially, a temporal evolution and projection of papers, PhD and Master Theses, were performed. In sequence, indexed papers were analyzed through performance indicators (i.e., number of authors, impact factor, among others) and content evaluation (for instance, major addressed themes). Finally, a mapping of science was performed, with the aid of Cite Space software application, where coword (and evolution), cocollaboration (and evolution), and cocitation maps were created. The survey identified 429 documents divided among international and national papers, PhD and Master Theses. From those documents, 165 were indexed. In terms of production and performance, the results indicate an undeniable evolution of the Brazilian LCA research, as affirmed by relations solidified through time. The main research field is “LCA application” with 84 % of papers, whereas “LCA methodology” completes the framework. In LCA applications, 25 % of publications are related to Biofuels—divided into bioethanol and biodiesel—which makes it the current dominant LCA research area in Brazil. The collaboration network demonstrates three main institution groups, whereas evolution through the years indicates that this situation may further improve. Influential authors are linked to LCA of biofuels, general LCA guidelines, and methodological LCA developments. Brazilian LCA research has been growing and more complex relations between themes and institutions denote that further developments can be expected. Cocollaboration indicates three main clusters, led by USP, Unicamp, and UFRJ. “Biofuels” is the main research area where sugarcane ethanol and biodiesel from different sources are the domain product systems. Cocitation analysis solidifies this statement, pointing to Isaias Macedo (and other biofuel researchers) as the main author in Brazilian LCA after ISO and Mark Goedkoop.

A Review of Environmental Life Cycle Assessments of Liquid Transportation Biofuels in the Pan American Region.

Life-cycle assessment (LCA) has been applied to many biofuel and bioenergy systems to determine potential environmental impacts, but the conclusions have varied. Different methodologies and processes for conducting LCA of biofuels make the results difficult to compare, in-turn making it difficult to make the best possible and informed decision. Of particular importance are the wide variability in country-specific conditions, modeling assumptions, data quality, chosen impact categories and indicators, scale of production, system boundaries, and co-product allocation. This study has a double purpose: conducting a critical evaluation comparing environmental LCA of biofuels from several conversion pathways and in several countries in the Pan American region using both qualitative and quantitative analyses, and making recommendations for harmonization with respect to biofuel LCA study features, such as study assumptions, inventory data, impact indicators, and reporting practices. The environmental management implications are discussed within the context of different national and international regulatory environments using a case study. The results from this study highlight LCA methodology choices that cause high variability in results and limit comparability among different studies, even among the same biofuel pathway, and recommendations are provided for improvement.

Environmental impacts of bioethanol using the NREL biochemical conversion route: multivariate analysis and single score results

AbstractMandated Environmental Protection Agency biofuel qualifications focused on greenhouse gas (GHG) emissions and fossil fuel use are limited in perspective and have the potential to encourage burden shifting. When a broader host of environmental impacts are examined, environmental trade‐offs often exist when biofuels are compared to gasoline. Multivariate analysis methods examining a wide variety of weighting value systems and methodology assumptions were used to determine process design options with the lowest overall environmental impact. A multivariate environmental analysis was applied to the dilute acid pre‐treatment process followed by enzymatic hydrolysis and the fermentation process for converting loblolly pine, eucalyptus, natural hardwood, switchgrass, and sweet sorghum biomass to ethanol. The influence of co‐product treatment method choices, inclusion of direct land‐use change, and electrical grid assumptions were examined using 16 different weighting methods to create a single score result. Biofuel system rankings based on GHG emissions following the Renewable Fuel Standards 2 (RFS2) methods were very sensitive to the co‐product treatment method, inclusion of land‐use change emissions, and energy grid assumptions. The multivariate analysis ranking was heavily influenced by other environmental impacts resulting from the production of process chemicals used in ethanol conversion. Weighting methods examined had no influence on the environmental preference ranking of the biofuel scenarios. Additionally, the biofuel ranking based on the RFS2 methodology was different than the ranking following the multivariate approach examining additional impacts. These findings demonstrate a robust approach to biofuel life cycle assessment (LCA) scenario analysis and suggest that the limited scope of the RFS2 environmental analysis could result in burden shifting. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Life Cycle Assessment of Switchgrass Cellulosic Ethanol Production in the Wisconsin and Michigan Agricultural Contexts

Spatial variability in yields and greenhouse gas emissions from soils has been identified as a key source of variability in life cycle assessments (LCAs) of agricultural products such as cellulosic ethanol. This study aims to conduct an LCA of cellulosic ethanol production from switchgrass in a way that captures this spatial variability and tests results for sensitivity to using spatially averaged results. The Environment Policy Integrated Climate (EPIC) model was used to calculate switchgrass yields, greenhouse gas (GHG) emissions, and nitrogen and phosphorus emissions from crop production in southern Wisconsin and Michigan at the watershed scale. These data were combined with cellulosic ethanol production data via ammonia fiber expansion and dilute acid pretreatment methods and region-specific electricity production data into an LCA model of eight ethanol production scenarios. Standard deviations from the spatial mean yields and soil emissions were used to test the sensitivity of net energy ratio, global warming potential intensity, and eutrophication and acidification potential metrics to spatial variability. Substantial variation in the eutrophication potential was also observed when nitrogen and phosphorus emissions from soils were varied. This work illustrates the need for spatially explicit agricultural production data in the LCA of biofuels and other agricultural products.

Life Cycle Assessment of Biofuels from Algae Hydrothermal Liquefaction: The Upstream and Downstream Factors Affecting Regulatory Compliance

Life-cycle greenhouse gas (LC-GHG) emissions are a principal metric used by the U.S. Environmental Protection Agency to determine whether a biofuel qualifies under the U.S. EPA’s Renewable Fuel Standard (RFS2). This paper identifies important factors in the quantification of LC-GHG of algae-derived diesel, jet fuel, and gasoline, using hydrothermal liquefaction (HTL) as a case study for algal biofuels. The results indicate that, under certain conditions, algae biofuels produced using HTL offer an over 50% reduction in LC-GHG emissions compared to their petroleum counterparts and would thus qualify as advanced biofuel and biomass-based biodiesel under RSF2. However, the results are sensitive to several upstream and downstream factors, specifically the CO2 supply chains used in feedstock production and the fuels that are produced using these algal feedstocks, respectively. Upstream processes for the production of algae include supplying gas or liquid phase CO2 to maintain culture viability, which is unlike ...

Life cycle assessment of biofuels from an integrated Brazilian algae-sugarcane biorefinery

Sugarcane ethanol biorefineries in Brazil produce carbon dioxide, electricity and heat as byproducts. These are essential inputs for algae biodiesel production. In this paper, we assessed ethanol's life cycle greenhouse gas emissions and fossil energy use produced in an integrated sugarcane and algae biorefinery where biodiesel replaces petroleum diesel for all agricultural operations. Carbon dioxide from cane juice fermentation is used as the carbon source for algae cultivation, and sugarcane bagasse is the sole source of energy for the entire facility. Glycerin produced from the biodiesel plant is consumed by algae during the mixotrophic growth phase. We assessed the uncertainties through a detailed Monte-Carlo analysis. We found that this integrated system can improve both the life cycle greenhouse gas emissions and the fossil energy use of sugarcane ethanol by around 10% and 50%, respectively, compared to a traditional Brazilian sugarcane ethanol distillery.

Life cycle assessment of first-generation biofuels using a nitrogen crop model

This paper presents an alternative approach to assess the impacts of biofuel production using a method integrating the simulated values of a new semi-empirical model at the crop production stage within a life cycle assessment (LCA). This new approach enabled us to capture some of the effects that climatic conditions and crop management have on soil nitrous oxide (N2O) emissions, crop yields and other nitrogen (N) losses. This analysis considered the whole system to produce 1MJ of biofuel (bioethanol from wheat and biodiesel from rapeseed). Non-renewable energy use, global warming potential (GWP), acidification, eutrophication and land competition are considered as potential environmental impacts. Different co-products were handled by system expansion. The aim of this study was (i) to evaluate the variability due to site-specific conditions of climate and fertiliser management of the LCA of two different products: biodiesel from rapeseed and bioethanol from wheat produced in the Basque Country (Northern Spain), and (ii) to improve the estimations of the LCA impacts due to N losses (N2O, NO3, NH3), normally estimated with unspecific emission factors (EFs), that contribute to the impact categories analysed in the LCA of biofuels at local scale. Using biodiesel and bioethanol derived from rapeseed and wheat instead of conventional diesel and gasoline, respectively, would reduce non-renewable energy dependence (−55%) and GWP (−40%), on average, but would increase eutrophication (42 times more potential). An uncertainty analysis for GWP impact showed that the variability associated with the prediction of the major contributor to global warming potential (soil N2O) can significantly affect the results from the LCA. Therefore the use of a model to account for local factors will improve the precision of the assessment and reduce the uncertainty associated with the convenience of the use of biofuels.

Life cycle assessment of biofuels in the European Renewable Energy Directive: a combination of approaches?

The European Renewable Energy Directive (RED) was produced by the European Parliament and the Council of the European Union to promote the uptake of energy from renewable resources by participating member states. It sets greenhouse gas (GHG) saving targets for renewable transport fuels and dictates the method by which this should be calculated. This study examines the life cycle assessment (LCA) methodology set out in the RED and compares it to attributional and consequential assessments. A case study of wheat-based bioethanol is used to illustrate how differences in methodology affect the GHG emission results. The results show that GHG emissions from wheat bioethanol are lowest when calculated under the RED, and highest when substitution credits are applied. The RED has been shown to not only combine attributional LCA and consequential LCA approaches but also to contain rules for specific co-products. For example, cereal residues are not allocated GHG emissions from cultivation, and exported electricity ...

A preliminary life cycle assessment of biofuels produced by the IH2 ™ process

Biofuels are alternatives for vehicular transportation that have the promise of reducing imported petroleum, creating regional agricultural and energy sector employment, and decreasing emission of greenhouse gases. This study analyses greenhouse gas (GHG) emissions associated with the production and delivery of biofuels using the IH2 process. The IH2 process is a new technology for the conversion of a broad range of biomass types into liquid hydrocarbon transportation fuels spanning the range of gasoline and diesel. A cradle‐to‐grave life cycle assessment (LCA) was used to calculate the greenhouse gas emissions associated with producing and using IH2 biofuels from diverse feedstocks. The biomass feedstocks analyzed include algae (microalgae), bagasse from sugar cane (Brazil or southeast US), corn stover from Midwest US locations, and forest feedstocks from northern Wisconsin. Life cycle greenhouse gas emissions savings of 30–96% were calculated for IH2 gasoline and diesel compared to fossil fuels. Different scenarios were investigated to understand the uncertainties in key inputs to the LCA model; in feedstock production, the IH2 biofuel production, and IH2 biofuel transportation. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 322–329, 2014