Conceptualizing waste biorefinery for recovery of value added products. Display omitted
•Resource recovery of bioenergy and platform chemicals from waste.•Biorefinery as a sustainable approach for ...waste mining.•Exploitation of waste would enhance biorefinery competitiveness & social acceptance.
Increased urbanization worldwide has resulted in a substantial increase in energy and material consumption as well as anthropogenic waste generation. The main source for our current needs is petroleum refinery, which have grave impact over energy-environment nexus. Therefore, production of bioenergy and biomaterials have significant potential to contribute and need to meet the ever increasing demand. In this perspective, a biorefinery concept visualizes negative-valued waste as a potential renewable feedstock. This review illustrates different bioprocess based technological models that will pave sustainable avenues for the development of biobased society. The proposed models hypothesize closed loop approach wherein waste is valorised through a cascade of various biotechnological processes addressing circular economy. Biorefinery offers a sustainable green option to utilize waste and to produce a gamut of marketable bioproducts and bioenergy on par to petro-chemical refinery.
•Overview of life cycle assessments concerning CO2-based chemical production.•Detailed review of methodological choices and technological differences.•Methodological choices are functional unit, ...allocation method, and system boundary.•Meta-LCA provides harmonized environmental impacts of CCU pathways.•Formic acid produced via hydrogenation is a promising CCU pathway.
Carbon capture and utilization (CCU) is perceived as a technology to mitigate climate change and conserve non-renewable resources, especially in the chemical industry. Numerous life cycle assessments (LCA) of individual CCU systems have been carried out. The goal of this review is to understand the environmental effects of CO2-based chemical production comprehensively. In order to achieve this goal, a systematic literature review and a meta-analysis were conducted. 52 peer-reviewed articles were found that deal with LCA and CO2-based chemical production. Amongst the case studies found, the methodological choices and technological parameters differ. The meta-analysis reveals that there is no CO2-based chemical production technology that performs better in all analyzed impact categories (IC) compared to conventional production. Nevertheless, looking at the results from the meta-analysis, it has been found that the CO2-based production of formic acid (FA) via H2 is a promising CCU pathway. FA produced via hydrogenation performs better in 11 out of 15 ICs using the German grid mix as the electricity supplier and better in 14 out of 15 ICs using wind power as the electricity supplier compared to the conventional production. The global warming impact of FA production can be reduced by 95.01% when produced via CO2 hydrogenation. The meta-analysis also unveils CCU technologies that are not favorable from an environmental perspective because CO2-based kerosene and dimethyl carbonate (DMC) production lead to higher impacts in all ICs compared to conventional production. This study can inform decision-makers about the differences in published LCA studies on CCU and the harmonized environmental impacts of CO2based chemical production.
The assessment of ecosystem services (ES) is covered in a fragmented manner by environmental decision support tools that provide information about the potential environmental impacts of supply chains ...and their products, such as the well-known Life Cycle Assessment (LCA) methodology. Within the flagship project of the Life Cycle Initiative (hosted by UN Environment), aiming at global guidance for life cycle impact assessment (LCIA) indicators, a dedicated subtask force was constituted to consolidate the evaluation of ES in LCA. As one of the outcomes of this subtask force, this paper describes the progress towards consensus building in the LCA domain concerning the assessment of anthropogenic impacts on ecosystems and their associated services for human well-being. To this end, the traditional LCIA structure, which represents the cause-effect chain from stressor to impacts and damages, is re-casted and expanded using the lens of the ES ‘cascade model’. This links changes in ecosystem structure and function to changes in human well-being, while LCIA links the effect of changes on ecosystems due to human impacts (e.g. land use change, eutrophication, freshwater depletion) to the increase or decrease in the quality and/or quantity of supplied ES. The proposed cascade modelling framework complements traditional LCIA with information about the externalities associated with the supply and demand of ES, for which the overall cost-benefit result might be either negative (i.e. detrimental impact on the ES provision) or positive (i.e. increase of ES provision). In so doing, the framework introduces into traditional LCIA the notion of “benefit” (in the form of ES supply flows and ecosystems' capacity to generate services) which balances the quantified environmental intervention flows and related impacts (in the form of ES demands) that are typically considered in LCA. Recommendations are eventually provided to further address current gaps in the analysis of ES within the LCA methodology.
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•Ecosystem services (ES) are not fully encompassed in Life Cycle Assessments (LCAs).•The ES cascade model is investigated and proposed as one solution to address this gap.•This framework addresses externalities associated with the supply and demand of ES.•Through a cascade model, LCA can account for both environmental costs and benefits.
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•Social Network Analysis and Text Mining to analyze 8024 abstracts on LCA and Building.•The semantic brand score measures the semantic importance of seven issues related to Building ...and Sustainability.•Limited publications assessing the social impact of LCA in buildings.•Materials are the most central issue in the literature on sustainable buildings.
Research on Life Cycle Assessment (LCA) is being conducted in various sectors, from analyzing building materials and components to comprehensive evaluations of entire structures. However, reviews of the existing literature have been unable to provide a comprehensive overview of research in this field, leaving scholars without a definitive guideline for future investigations. This paper aims to fill this gap, mapping more than twenty years of research. Using an innovative methodology that combines social network analysis and text mining, the paper examined 8024 scientific abstracts. The authors identified seven key thematic groups, building and sustainability clusters (BSCs). To assess their significance in the broader discourse on building and sustainability, the semantic brand score (SBS) indicator was applied. Additionally, t building and sustainability trends were tracked, focusing on the LCA concept. The major research topics mainly relate to building materials and energy efficiency. In addition to presenting an innovative approach to reviewing extensive literature domains, the article also provides insights into emerging and underdeveloped themes, outlining crucial future research directions.
Digital tools based on Building Information Modelling (BIM) provide the potential to facilitate environmental performance assessments of buildings. Various tools that use a BIM model for automatic ...quantity take-off as basis for Life Cycle Assessment (LCA) have been developed recently. This paper describes the first application of such a BIM-LCA tool to evaluate the embodied global warming potential (GWP) throughout the whole design process of a real building. 34 states of the BIM model are analysed weekly. The results show that the embodied GWP during the design phase is twice as high as for the final building. These changes can be mainly attributed to the designers' approach of using placeholder materials that are refined later, besides other reasons. As such, the embodied GWP is highly overestimated and a BIM-based environmental assessment during the design process could be misleading and counterproductive. Finally, three alternatives to the established automatic quantity take-off are discussed for future developments.
•First application of a BIM-LCA approach throughout the design process of a real building•Tracking of design decisions using 34 fixed states of the continuously evolving BIM model•Identification of limitations of the current BIM-LCA approach•Proposals for future effective environmental performance improvement during the design phase
•We perform Life Cycle Assessment (LCA) of current and future passenger vehicles.•We include gasoline, diesel and natural gas as well as battery and fuel cell cars.•An integrated vehicle simulation ...framework guarantees consistency.•Only electric cars with “clean” electricity and H2 allow for pollution mitigation.•Complete LCA is mandatory for environmental evaluation of vehicle technologies.
This paper contains an evaluation of the environmental performance of a comprehensive set of current and future mid-size passenger vehicles. We present a comparative Life Cycle Assessment (LCA) based on a novel integrated vehicle simulation framework, which allows for consistency in vehicle parameter settings and consideration of future technological progress. Conventional and hybrid gasoline, diesel and natural gas cars as well as battery and fuel cell electric vehicles (BEV and FCV) are analyzed, taking into account electricity and hydrogen production chains from fossil, nuclear and renewable energy resources.
Our results show that a substantial mitigation of climate change can be obtained with electric passenger vehicles, provided that non-fossil energy resources are used for electricity and hydrogen production. However, in terms of other environmental burdens such as acidification, particulate matter formation, and toxicity, BEV may in some cases and FCV are likely to perform worse than modern fossil fueled cars as a consequence of emissions along vehicle and fuel production chains. Therefore, the electrification of road transportation should be accompanied by an integration of life cycle management in vehicle manufacturing chains as well as energy and transport policies in order to counter potential environmental drawbacks.
The European transport sector was responsible for more than 25% of the EU total greenhouse gas (GHG) emissions in 2017. 53% of these emissions came from the passenger cars and light-commercial ...vehicles segments. Biofuels are seen as one of the options to limit these emissions in Europe. To understand the recent evolution of biofuels and their future, this review gives an overview on the production, use, legislation, and environmental impacts of biofuels in Europe for light-duty vehicles. In 2017, biofuels made up 4.5% of the energy consumption in the road transport and non-road mobile machinery. Biodiesel in 2018 accounted for 62% of the biofuels consumed in the EU, followed by bioethanol (17.5%), HVO (16.6%), upgraded biogas (1.7%) and bio-ETBE (1.1%). A review of 86 LCA studies published between 2013 and 2020 indicated that the climate change impact of biofuels is generally lower than diesel and petrol, with average emission savings depending on the type of biofuel: 70% for biohydrogen, 63% for upgraded biogas, 41% for pure biodiesel, between 54% and 7% for bioethanol (depending on the blend percentage, between 100% and 10%). An important issue identified is the limited consideration of the land use change effects, which are rarely assessed and are of paramount importance, as the values found in this review were as high as 231 g CO2eq/MJ in some cases and thus non-negligible. Biofuels perform generally similarly or worse than fossil fuels for most of the non-GHG-related impact categories, except for ozone, fossil resource and abiotic depletion. Currently, it is highly recommended to move towards non-edible feedstocks, waste and by-products which guarantee a lower risk of land use change. The European legislation, through the Directive 2018/2001 and the regulation 2019/807, is pushing in that direction.
•The EU is encouraging advanced feedstock for biofuels.•The range of types of promising advanced biofuels is very broad and evolving.•Regarding the climate change, biofuels have generally a better conduct than diesel and petrol.•The land use change effects are rarely included in life cycle assessments.
Conventional wastewater treatment plants (WWTPs) clean wastewater and minimize water pollution; but, while doing so, they also contribute to air pollution and need energy/material input with ...associated emissions. However, energy recovery (e.g. anaerobic digestion) and resource recovery (e.g. water reuse) allow us to offset the adverse environmental impacts of wastewater treatment. Life cycle assessments (LCA) have been used more and more to evaluate the environmental impacts of WWTPs and to suggest improvement options. There is a need to search for resource recovery applications that genuinely realize a net-zero impact on the total environment of WWTPs. In this work, a scheme with highly efficient energy and resource recovery (especially for thermal energy) is proposed and evaluated. The environmental impact of a conventional WWTP in comparison with the scheme proposed here, with energy/resource recovery included, was calculated, and discussed with reference to LCA methodology. In the process of using LCA, it was necessary to choose a regional situation to focus on. In this case, a Chinese situation was focused as a reference, but the qualitative information gained is of worldwide relevance. The results clearly revealed that conventional WWTP does not benefit the total environment as a whole while the new scheme benefited the total environment via resource/energy recovery-based processes. Among others, thermal energy recovery played a significant role towards a net-zero LCA analysis (contributing around 40%) which suggests that more attention and research should be focused on it.
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•Impacts of resource recovery on the environment was assessed by an improved LCA.•Resource recovery can help WWTPs in their goal of a zero net environmental impact.•Effluent reuse alone is not sufficient to attain a zero net environmental impact.•Thermal energy recovery would contribute the most to improving the impact of WWTPs.
Purpose
Good background data are an important requirement in LCA. Practitioners generally make use of LCI databases for such data, and the ecoinvent database is the largest transparent unit-process ...LCI database worldwide. Since its first release in 2003, it has been continuously updated, and version 3 was published in 2013. The release of version 3 introduced several significant methodological and technological improvements, besides a large number of new and updated datasets. The aim was to expand the content of the database, set the foundation for a truly global database, support regionalized LCIA, offer multiple system models, allow for easier integration of data from different regions, and reduce maintenance efforts. This article describes the methodological developments.
Methods
Modeling choices and raw data were separated in version 3, which enables the application of different sets of modeling choices, or system models, to the same raw data with little effort. This includes one system model for Consequential LCA. Flow properties were added to all exchanges in the database, giving more information on the inventory and allowing a fast calculation of mass and other balances. With version 3.1, the database is generally water-balanced, and water use and consumption can be determined. Consumption mixes called market datasets were consistently added to the database, and global background data was added, often as an extrapolation from regional data.
Results and discussion
In combination with hundreds of new unit processes from regions outside Europe, these changes lead to an improved modeling of global supply chains, and a more realistic distribution of impacts in regionalized LCIA. The new mixes also facilitate further regionalization due to the availability of background data for all regions.
Conclusions
With version 3, the ecoinvent database substantially expands the goals and scopes of LCA studies it can support. The new system models allow new, different studies to be performed. Global supply chains and market datasets significantly increase the relevance of the database outside of Europe, and regionalized LCA is supported by the data. Datasets are more transparent, include more information, and support, e.g., water balances. The developments also support easier collaboration with other database initiatives, as demonstrated by a first successful collaboration with a data project in Québec. Version 3 has set the foundation for expanding ecoinvent from a mostly regional into a truly global database and offers many new insights beyond the thousands of new and updated datasets it also introduced.
The boost of the greenhouse gases (GHGs, largely carbon dioxide – CO2) emissions owing to anthropogenic activity is one of the biggest global threats. Bio-CO2 emission reduction has received more and ...more attention as an environmentally sustainable approach. Microalgae are very popular in this regard because of excellent speed of growth, low costs of production, and resistance to extreme environments. Besides, most microalgae can undergo photosynthesis, where the CO2 and solar energy can be converted into sugar, and subsequently become biomass, providing a renewable and promising biofuel strategy with a few outstanding benefits. This review focuses on presenting CO2 sequestration by microalgae towards wastewater treatment and biodiesel production. First, the CO2 fixation mechanism by microalgae viz., sequestration and assimilation of CO2 in green microalgae as well as cyanobacteria were introduced. Besides, factors affecting CO2 sequestration in microalgae, containing microalgae species and cultivation conditions, such as light condition, photobioreactor, configuration, pH, CO2 concentration, temperature, and medium composition, were then comprehensively discussed. Special attention was given to the production of biodiesel as third-generation biofuel from various wastewater (CO2 biofixation), including processing steps of biodiesel production by microalgae, biodiesel production from wastewater, and improved methods. Furthermore, current life cycle assessment (LCA) and techno-economic analysis (TEA) used in biodiesel production were discussed. Finally, the research challenges and specific prospects were considered. Taken together, this review provides useful and updated information to facilitate the development of microalgal “green chemistry” and “environmental sustainability”.
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•Both wastewater repair and carbon dioxide fixation are achieved with microalgae.•The information on CO2 fixation mechanism inside the algal cells is limited.•Wastewater as a nourishment source for microalgae growth can yield biodiesel.•Nutrient starvation is the most typical method to enhance lipid production.•Integration of LCA and TEA enables systematic analysis and provides more info.
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