Life cycle assessment of fuel ethanol from cassava in Thailand

Goal and Scope  A well-to-wheel analysis has been conducted for cassava-based ethanol (CE) in Thailand. The aim of the analysis is to assess the potentials of CE in the form of gasohol E10 for promoting energy security and reducing environmental impacts in comparison with conventional gasoline (CG). Method  In the LCA procedure, three separate but interrelated components: inventory analysis, characterization and interpretation were performed for the complete chain of the fuel life cycle. To compare gasohol E10 and CG, this study addressed their impact potentials per gasoline-equivalent litre, taking into account the performance difference between gasohol and gasoline in an explosion motor. Results and Discussions  The results obtained show that CE in the form of E10, along its whole life cycle, reduces certain environmental loads compared to CG. The percentage reductions relative to CG are 6.1% for fossil energy use, 6.0% for global warming potential, 6.8% for acidification, and 12.2% for nutrient enrichment. Using biomass in place of fossil fuels for process energy in the manufacture of ethanol leads to improved overall life cycle energy and environmental performance of ethanol blends relative to CG. Conclusions and Outlook  The LCA brings to light the key areas in the ethanol production cycle that researchers and technicians need to work on to maximize ethanol’s contribution to energy security and environmental sustainability ESS-Submission Editor: Mark Goedkoop (goedkoop@pre.nl)     

Life cycle assessment of natural gas power plants in Thailand

Background, aim, and scope  The main primary energy for electricity in Thailand is natural gas, accounting for 73% of the grid mix. Electricity generation from natural gas combustion is associated with substantial air emissions. The two technologies currently used in Thailand, thermal and combined cycle power plant, have been evaluated for the potential environmental impacts in a “cradle-to-grid” study according to the life cycle assessment (LCA) method. This study evaluates the environmental impacts of each process of the natural gas power production over the entire life cycle and compares two different power plant technologies currently used in Thailand, namely, combined cycle and thermal. Materials and methods  LCA is used as a tool for the assessment of resource consumption and associated impacts generated from utilization of natural gas in power production. The details follow the methodology outlined in ISO 14040. The scope of this research includes natural gas extraction, natural gas separation, natural gas transmission, and natural gas power production. Most of the inventory data have been collected from Thailand, except for the upstream of fuel oil and fuel transmission, which have been computed from Greenhouse gases, Regulated Emissions, and Energy use in Transportation version 1.7 and Global Emission Model for Integrated Systems version 4.3. The impact categories considered are global warming, acidification, photochemical ozone formation, and nutrient enrichment potential (NEP). Results  The comparison reveals that the combined cycle power plant, which has a higher efficiency, performs better than the thermal power plant for global warming potential (GWP), acidification potential (ACP), and photochemical ozone formation potential (POCP), but not for NEP where the thermal power plant is preferable. Discussion  For the thermal power plant, the most significant environmental impacts are from power production followed by upstream of fuel oil, natural gas extraction, separation, and transportation. For the combined cycle power plant, the most significant environmental impacts are from power production followed by natural gas extraction, separation, and transportation. The significant difference between the two types of power production is mainly from the combustion process and feedstock in power plant. Conclusions  The thermal power plant uses a mix of natural gas (56% by energy content) and fuel oil (44% by energy content); whereas, the combined cycle power plant operates primarily on natural gas. The largest contribution to GWP, ACP, and NEP is from power production for both thermal as well as combined cycle power plants. The POCP for the thermal power plant is also from power production; whereas, for combined cycle power plant, it is mainly from transmission of natural gas. Recommendations and perspectives  In this research, we have examined the environmental impact of electricity generation technology between thermal and combined cycle natural gas power plants. This is the overview of the whole life cycle of natural gas power plant, which will help in decision making. The results of this study will be useful for future power plants as natural gas is the major feedstock being promoted in Thailand for power production. Also, these results will be used in further research for comparison with other feedstocks and power production technologies.     

LEED v4: Where Are We Now? Critical Assessment through the LCA of an Office Building Using a Low Impact Energy Consumption Mix

Various green building rating systems (GBRSs) have been proposed to reduce the environmental impact of buildings. However, these GBRSs, such as Leadership in Energy and Environmental Design (LEED) v4, are primarily oriented toward a building's use stage energy consumption. Their application in contexts involving a high share of renewable energy, and hence a low‐impact electricity mix, can result in undesirable side effects. This paper aims to investigate such effects, based on an existing office building in Quebec (Canada), where more than 95% of the electricity consumption mix is renewable. This paper compares the material impacts from a low‐energy context building to material considerations in LEED v4. In addition to their contributions to the building impacts, material impacts are also defined by their potential to change impacts with different material configurations. Life cycle assessment (LCA) impacts were evaluated using Simapro 8.2, the ecoinvent 3.1 database, and the IMPACT 2002+ method. The building LCA results indicated higher environmental impact contributions from materials (>50%) compared to those from energy consumption. This is in contrast with the LEED v4 rating system, as it did not seem to be as effective in capturing such effects. The conclusions drawn from this work will help stakeholders from the buildings sector to have a better understanding of building environmental profiles, and the limitations of LEED v4 in contexts involving a low‐impact energy mix. In addition, this critical assessment can be used to further improve the LEED certification system.     

Energy requirements and environmental impacts associated with the production of short rotation willow (Salix sp.) chip in Ireland

Willow Salix sp. is currently cultivated as a short rotation forestry crop in Ireland as a source of biomass to contribute to renewable energy goals. The aim of this study is to evaluate the energy requirements and environmental impacts associated with willow (Salix sp.) cultivation, harvest, and transport using life cycle assessment (LCA). In this study, only emissions from the production of the willow chip are included, end‐use emissions from combustion are not considered. In this LCA study, three impact categories are considered; acidification potential, eutrophication potential and global warming potential. In addition, the cumulative energy demand and energy ratio of the system are evaluated. The results identify three key processes in the production chain which contribute most to all impact categories considered; maintenance, harvest and transportation of the crop. Sensitivity analysis on the type of fertilizers used, harvesting technologies and transport distances highlights the effects of these management techniques on overall system performance. Replacement of synthetic fertilizer with biosolids results in a reduction in overall energy demand, but raises acidification potential, eutrophication potential and global warming potential. Rod harvesting compares unfavourably in comparison with direct chip harvesting in each of the impact categories considered due to the additional chipping step required. The results show that dedicated truck transport is preferable to tractor‐trailer transport in terms of energy demand and environmental impacts. Finally, willow chip production compares favourably with coal provision in terms of energy ratio and global warming potential, while achieving a higher energy ratio than peat provision but also a higher global warming potential.     

Life cycle assessment of electrical and thermal energy systems for commercial buildings

Background, Aim and Scope The objective of this life cycle assessment (LCA) study is to develop LCA models for energy systems in order to assess the potential environmental impacts that might result from meeting energy demands in buildings. The scope of the study includes LCA models of the average electricity generation mix in the USA, a natural gas combined cycle (NGCC) power plant, a solid oxide fuel cell (SOFC) cogeneration system; a microturbine (MT) cogeneration system; an internal combustion engine (ICE) cogeneration system; and a gas boiler. Methods LCA is used to model energy systems and obtain the life cycle environmental indicators that might result when these systems are used to generate a unit energy output. The intended use of the LCA analysis is to investigate the operational characteristics of these systems while considering their potential environmental impacts to improve building design using a mixed integer linear programming (MILP) optimization model. Results The environmental impact categories chosen to assess the performance of the energy systems are global warming potential (GWP), acidification potential (AP), tropospheric ozone precursor potential (TOPP), and primary energy consumption (PE). These factors are obtained for the average electricity generation mix, the NGCC, the gas boiler, as well as for the cogeneration systems at different part load operation. The contribution of the major emissions to the emission factors is discussed. Discussion The analysis of the life cycle impact categories indicates that the electrical to thermal energy production ratio has a direct influence on the value of the life cycle PE consumption factors. Energy systems with high electrical to thermal ratios (such as the SOFC cogeneration systems and the NGCC power plant) have low PE consumption factors, whereas those with low electrical to thermal ratios (such as the MT cogeneration system) have high PE consumption factors. In the case of GWP, the values of the life cycle GWP obtained from the energy systems do not only depend on the efficiencies of the systems but also on the origins of emissions contributing to GWP. When evaluating the life cycle AP and TOPP, the types of fuel as well as the combustion characteristics of the energy systems are the main factors that influence the values of AP and TOPP. Conclusions An LCA study is performed to eraluate the life cycle emission factors of energy systems that can be used to meet the energy demand of buildings. Cogeneration systems produce utilizable thermal energy when used to meet a certain electrical demand which can make them an attractive alternative to conventional systems. The life cycle GWP, AP, TOPP and PE consumption factors are obtained for utility systems as well as cogeneration systems at different part load operation levels for the production of one kWh of energy output. Recommendations and Perspectives Although the emission factors vary for the different energy systems, they are not the only factors that influence the selection of the optimal system for building operations. The total efficiencies of the system play a significant part in the selection of the desirable technology. Other factors, such as the demand characteristics of a particular building, influence the selection of energy systems. The emission factors obtained from this LCA study are used as coefficients of decision variables in the formulation of an MILP to optimize the selection of energy systems based on environmental criteria by taking into consideration the system efficiencies, emission characteristics, part load operation, and building energy demands. Therefore, the emission factors should not be regarded as the only criteria for choosing the technology that could result in lower environmental impacts, but rather one of several factors that determine the selection of the optimum energy system. ESS-Submission Editor: Arpad Horvath (horvath@ce.berkeley.edu)     

Life Cycle Assessment of Wood Floor Coverings - A Representative Study for the German Flooring Industry (11 pp)

Goal, Scope and Background The goal of the study is a life cycle assessment according to ISO 14040 –14043 for wood floor coverings (solid parquet, multilayer parquet, solid floor board and wood blocks). The representative study covers approximately 70% of all wood flooring production in Germany. The comparison of the floor coverings among each other was not the aim. Instead the study provides basic data for all wood floor coverings for a possible comparison with other floor coverings later on. The main focus was a hot spot analysis to help the involved industry partners to improve their environmental performance, and to use the results for marketing purposes. - Inventory Analysis. The study covers the whole life cycle from forest management, sawmilling, manufacturing, laying and surface finishing through to refurbishment and end-of-life. The end-of-life scenario is the thermal utilisation of the floor coverings. The energy gained in the end-of-life scenario is accounted for by system expansion (avoided burden approach). - Impact Assessment. In the Impact Assessment the following categories were considered: global warming (GWP), acidification (AP), eutrophication (EP), ozone depletion (ODP) and photo-oxidant formation (POCP) following the CML baseline 2000 method. Furthermore the use of primary energy is presented. The low emissions of greenhouse gases during the life cycle can lead to a negative contribution to the global warming potential if more emissions are avoided through the substitution process than are emitted during the life cycle of the product. Mainly energy consumption and the use of solvents influence the environmental impacts of the systems under analysis. The most relevant unit processes for the issue of energy consumption are 'production' and for photo-oxidant formation 'laying', 'surface finishing' and 'refurbishment'. These are therefore the unit processes with the greatest potential for improvement. - Normalisation and Sensitivity Analysis. The normalisation results show that the photo-oxidant formation potential is most significant in comparison to the other impact categories. Improvement options and the choice of the functional unit have been further explored in a sensitivity analysis. Discussion and Conclusions. The most important opportunities for improvements are located in the unit processes laying, surface finishing and refurbishment. The POCP result can be reduced significantly depending on the choice of glue and varnish at each of these stages. The results of the sensitivity analysis showed a potential for improvement in this category. No data for the production of an oil and wax finish was available. This option would be interesting to consider at in a further study. The time aspect of storing CO2 for a period of time is not considered in this paper, but will be addressed in a forthcoming paper (Nebel and Cowell 2003).     

A life cycle comparison of disposal and beneficial use of coal combustion products in Florida

Background, aim, and scope  Beneficial use of coal combustion products (CCPs) in industrial or construction operations has the potential to minimize environmental and human health impacts that would otherwise be associated with disposal of CCPs in the life cycle of coal used for electricity generation. To assess opportunities for reducing impacts associated with four CCP materials considered in this study, fly ash, bottom ash, boiler slag, and flue gas desulfurization (FGD) material, this paper reports results of expanding a life cycle inventory of raw material and emissions (part 1 of this series of papers) by performing life cycle impact assessment on five scenarios of CCP management. Materials and methods  SimaPro 5.1 software (PRé Consultants) was used to calculate comparative environmental impacts of all scenarios using CML2001 and Environmental Design of Industrial Products 1997 midpoint impact assessment methods and Heirarchist and Individualist levels of the Eco-indicator 99 end point method. Trends were compared for global and local environmental and human health impact categories of global warming, acidification, smog formation, human toxicity, and ecotoxicity. Results  In each impact category, beneficial use of fly ash, bottom ash, and FGD material resulted in a reduced impact compared to disposal of these materials. The extent to which beneficial use reduced impacts depended on several factors, including the impact category in consideration, the magnitude of potentially avoided impacts associated with producing raw materials that CCPs replace, and the potential impact of CCP disposal methods. Global warming impacts were reduced by the substitution of fly ash for Portland cement in concrete production, as production of Portland cement generates large quantities of CO₂. However, for categories of global warming, smog formation, and acidification, impact reductions from CCP beneficial use are small, less than 6%, as these impacts were attributable, in greater part, to upstream processes of coal mining, transportation, and combustion. Human toxicity and ecotoxicity categories showed larger but more varied reductions, from 0% to 50%, caused by diverting CCPs from landfills and surface impoundments. Discussion  When comparing beneficial use scenarios, the four impact assessment methods used showed similar trends in categories of global warming, acidification, and smog formation. However, results diverged for human toxicity and ecotoxicity categories due to the lack of consensus among methods in classification and characterization of impacts from heavy metal release. Similarly, when assessing sensitivity of these results to changes in assumptions or system boundaries, human toxicity and ecotoxicity categories were most susceptible to change, while other impact categories had more robust results. Conclusions  Impact assessment results showed that beneficial use of CCPs presented opportunities for reduced environmental impacts in the life cycle of coal combusted for electricity generation, as compared to the baseline scenario of 100% CCP disposal, although the impact reductions varied depending on the CCPs used, the ultimate beneficial use, and the impact category in consideration. Recommendations and perspectives  As regulators and electric utilities increasingly consider viability and economics of the use of CCPs in various applications, this study provides a first-basis study of selected beneficial use alternatives. With these initial results, future studies should be directed towards beneficial uses that promise significant economic and environmental savings, such as use of fly ash in concrete, to quantify the currently unknown risk of these applications.     

Integrating triple bottom line input–output analysis into life cycle sustainability assessment framework: the case for US buildings

Purpose

With the increasing concerns related to integration of social and economic dimensions of the sustainability into life cycle assessment (LCA), traditional LCA approach has been transformed into a new concept, which is called as life cycle sustainability assessment (LCSA). This study aims to contribute the existing LCSA framework by integrating several social and economic indicators to demonstrate the usefulness of input–output modeling on quantifying sustainability impacts. Additionally, inclusion of all indirect supply chain-related impacts provides an economy-wide analysis and a macro-level LCSA. Current research also aims to identify and outline economic, social, and environmental impacts, termed as triple bottom line (TBL), of the US residential and commercial buildings encompassing building construction, operation, and disposal phases.

Methods

To achieve this goal, TBL economic input–output based hybrid LCA model is utilized for assessing building sustainability of the US residential and commercial buildings. Residential buildings include single and multi-family structures, while medical buildings, hospitals, special care buildings, office buildings, including financial buildings, multi-merchandise shopping, beverage and food establishments, warehouses, and other commercial structures are classified as commercial buildings according to the US Department of Commerce. In this analysis, 16 macro-level sustainability assessment indicators were chosen and divided into three main categories, namely environmental, social, and economic indicators.

Results and discussion

Analysis results revealed that construction phase, electricity use, and commuting played a crucial role in much of the sustainability impact categories. The electricity use was the most dominant component of the environmental impacts with more than 50 % of greenhouse gas emissions and energy consumption through all life cycle stages of the US buildings. In addition, construction phase has the largest share in income category with 60 % of the total income generated through residential building’s life cycle. Residential buildings have higher shares in all of the sustainability impact categories due to their relatively higher economic activity and different supply chain characteristics.

Conclusions

This paper is an important attempt toward integrating the TBL perspective into LCSA framework. Policymakers can benefit from such approach and quantify macro-level environmental, economic, and social impacts of their policy implications simultaneously. Another important outcome of this study is that focusing only environmental impacts may misguide decision-makers and compromise social and economic benefits while trying to reduce environmental impacts. Hence, instead of focusing on environmental impacts only, this study filled the gap about analyzing sustainability impacts of buildings from a holistic perspective.     

东北有机及常规大豆对环境影响的生命周期评价

选择我国主要有机出口农产品之一——大豆作为研究对象,采用生命周期评价、DNDC模型、实地调研等方法建立大豆生命周期资源消耗和环境排放清单,分析比较了出口型有机大豆、国内消费型有机大豆以及国内消费型常规大豆的生命周期环境影响.结果表明:3种不同生产消费型大豆生命周期中资源消耗、酸化以及全球变暖对综合环境影响贡献最明显,基本上占到综合环境影响评价的30％左右,而富营养化和生态毒性的贡献率较低,小于10％.从生命周期的不同阶段分析,3种消费模式的大豆其运输阶段对于各分类环境影响的贡献率最大,都在50％以上,对资源消耗的贡献率更是在80％以上.从2种不同的生产模式看无论是全球变暖、酸化、资源消耗还是生态毒性都是有机大豆的环境影响综合指数小于常规大豆,对环境产生的负面影响较小.综合比较3种不同生产消费型大豆,国内消费的有机大豆生命周期综合环境影响最小,其环境影响综合指数比常规大豆的减少31％.但是出口有机大豆由于出口使运输距离延长,其生命周期综合环境影响最大.因此,环境管理关键是提倡有机产品本地消费以缩短运输距离,或者采用环保型能源以减少环境排放.     

Comparative life cycle assessment and life cycle costing of lodging in the Himalaya

Purpose

The main aim of the study is to assess the environmental and economic impacts of the lodging sector located in the Himalayan region of Nepal, from a life cycle perspective. The assessment should support decision making in technology and material selection for minimal environmental and economic burden in future construction projects.

Methods

The study consists of the life cycle assessment and life cycle costing of lodging in three building types: traditional, semi-modern and modern. The life cycle stages under analysis include raw material acquisition, manufacturing, construction, use, maintenance and material replacement. The study includes a sensitivity analysis focusing on the lifespan of buildings, occupancy rate and discount and inflation rates. The functional unit was formulated as the ‘Lodging of one additional guest per night’, and the time horizon is 50 years of building lifespan. Both primary and secondary data were used in the life cycle inventory.

Results and discussion

The modern building has the highest global warming potential (kg CO_2-eq) as well as higher costs over 50 years of building lifespan. The results show that the use stage is responsible for the largest share of environmental impacts and costs, which are related to energy use for different household activities. The use of commercial materials in the modern building, which have to be transported mostly from the capital in the buildings, makes the higher GWP in the construction and replacement stages. Furthermore, a breakdown of the building components shows that the roof and wall of the building are the largest contributors to the production-related environmental impact.

Conclusions

The findings suggest that the main improvement opportunities in the lodging sector lie in the reduction of impacts on the use stage and in the choice of materials for wall and roof.

     

Steel‐versus‐Concrete Debate Revisited: Global Warming Potential and Embodied Energy Analyses based on Attributional and Consequential Life Cycle Perspectives

In the study of sustainable building materials, the comparison of the life cycle environmental performance of steel and reinforced concrete has been a popular and important topic. Based in Singapore, this is one of the first studies in the literature that applies both attributional and consequential life cycle approaches to compare the global warming potential and embodied energies of these two materials, which are widely used for the structural parts of buildings. It was found that 1 kilogram (kg) of steel can be replaced by 1 or 4.25 kg of reinforced concrete. Two consequential scenarios for each of three combinations of primary and secondary steel were assessed. It was found that reinforced concrete produces less carbon dioxide emissions and incurs less embodied energy in most of these cases, but when different sustainable primary steel‐making technologies were incorporated, these results may be reversed. We applied consequential life cycle assessment and scenario analysis to describe how changes in the demand for structural steel and reinforced concrete in Singapore's building industry give rise to different environmental impacts. Specifically, the consequential life cycle approach revealed that, over the short term, the impact of substituting steel with reinforced concrete depends on the difference in impacts resulting from the transportation of these two materials within Singapore. Based on these lessons, integrated technology policies to improve the overall sustainability of using steel for construction were proposed.     

Utilization of woody biomass in Singapore: technological options for carbonization and economic comparison with incineration

Background, aim and scope  The interest in the use of biomass as a renewable energy resource has rapidly grown over the past few years. In Singapore, biomass resources are mostly from waste wood. This article presents a few technological options, namely carbonization, for the conversion of woody biomass into a solid fuel, charcoal. Materials and methods  In the first stage, a life cycle assessment (LCA) ‘gate-to-gate’ system was developed for a conventional carbonizer system, a modern carbonizer from Japan, and a proposed four-stage partial furnace carbonizer from Tunisia. The potential environmental impacts were generated for global warming potential, acidification, human toxicity and photochemical oxidant potential. Based on the first set of results, the second LCA investigation was carried out comparing the selected carbonizer from Japan and an existing incinerator in Singapore. The second LCA adopted a unique approach combining social costs of pollution with the economic factors of the two biomass conversion technologies. Results  The carbonizer from Japan resulted in approximately 85% less greenhouse gases than the conventional carbonization system and 54% less than the proposed four-stage carbonizer from Tunisia. In terms of acidification and human toxicity, the carbonizers from Japan and Tunisia display nearly similar results—both were considerably lower than the conventional carbonizer. For photochemical oxidant potential, very minimal emissions are generated from the four-stage carbonizer and nearly zero impact is realized for the carbonization technology from Japan. Discussion  From the first set of LCA results, the Japanese carbonizer is favored in terms of its environmental results. The highest environmental impacts from the conventional carbonizer were due to large and uncontrolled emissions of acidic gases, greenhouse gases (particularly CO₂ and CH₄), particulates, and non-methane volatile organic compounds from both fugitive sources and energy requirements. The second LCA addressed the performance of the carbonizer from Japan against an existing incinerator in terms of environmental as well as cost performances. This unique approach translated pollution emissions into monetary costs to highlight the impacts of social health. Conclusions  For the first LCA, the accumulated impacts from the Japanese carbonizer proved to display significantly lower environmental impacts, especially for global warming potential. The overall environmental performance of the four-stage carbonizer from Tunisia ranked slightly lower than the one from Japan and much higher than the conventional carbonizer. The second LCA results displayed a noteworthy improvement of 90% for human health from the modern Japanese carbonizer technology—when compared against conventional incinerators. Without considering health issues or social costs, the total value per ton of wood treated is nearly similar for both incinerator and carbonizer. Recommendations and perspectives  The interest in biomass as raw material for producing energy has emerged rapidly in many countries. However, careful analysis and comparison of technologies are necessary to ensure favorable environmental outcomes. A full life cycle study, along with costs and the impact of pollution on society, should be performed before any large-scale biomass conversion technology is implemented. LCA can be applied to quantify and verify the overall environmental performance of a particular technology of interest as well as further explore the proposed technology in terms of costs and social implications.     

Life cycle assessment of bread produced on different scales

A case study of white bread has been carried out with the purpose of comparing different scales of production and their potential environmental effects. The scales compared are: home baking, a local bakery and two industrial bakeries with distribution areas of different sizes. Data from the three bakeries and their suppliers have been collected. The systems investigated include agricultural production, milling, baking, packaging, transportation, consumption and waste management. Energy use and emissions have been quantified and the potential contributions to global warming, acidification, eutrophication and photo-oxidant formation have been assessed. The large industrial bakery uses more primary energy and contributes more to global warming, acidification and eutrophication than the other three systems. The home baking system shows a relatively high energy requirement; otherwise, the differences between home baking, the local bakery and the small industrial bakery are too small to be significant.     

Cradle to gate: life cycle impact of primary aluminium production

Purpose

The International Aluminium Institute’s (IAI) aim was to publish life cycle inventory (LCI) data for use by life cycle assessment (LCA) practitioners through professional databases. The need to provide robust data stems from the increasing application of LCA as a tool for making material and design choices and the importance for representative, up-to-date information to underpin such studies. In addition to this, the institute aimed to evaluate the significance of potential environmental impacts, based on the LCI results, against a defined set of impact categories which can be tracked over time.

Methods

Key environmental data collected as part of the IAI’s long-running industry surveys provided the foundation for the life cycle inventory. In order to evaluate the environmental impact, direct input and output data for primary aluminium production were supplemented with background data for indirect processes available in GaBi version 6 (PE International, 2013b). A cradle-to-gate model was constructed with two distinct datasets, global (GLO) and global minus China (rest of world (RoW)). A partial life cycle impact assessment (LCIA) was completed using the models, and the following six CML (2001–Nov 2010) midpoint environmental impact categories were reported: acidification potential, depletion of fossil energy resources, eutrophication potential, global warming potential, ozone depletion potential and photo-oxidant creation potential. Water scarcity footprint of primary aluminium (Buxmann et al. in this issue) was also included.

Results and discussion

The results indicated that the largest greenhouse gas contributions were attributed to the alumina refining and electrolysis unit processes in both datasets, with electricity and thermal energy, being the major contributing factors to these higher values. The energy intensive nature of primary aluminium production means energy supply can significantly influence the overall environmental impact. Electricity production was found to contribute between 25 % and 80 % to all impact category indicator results, with higher values in the global dataset, a result of the inclusion of Chinese energy data and the increased share of coal-based electricity consumption that it represents.

Conclusions

The global aluminium industry remains dedicated to transparent reporting of its environmental impacts and ensuring that up-to-date, representative LCI data is available. Development of suitable methodologies for new indicators will be required to ensure that the industry continues to report accurately all its relevant impacts. Additionally, with the increased importance of Chinese aluminium production, inclusion of foreground data from Chinese production would further enhance the dataset from which the global impacts of aluminium production are assessed from cradle to gate.

     

Environmental assessment of energy production from municipal solid waste incineration

Background, Aims and Scope During the combustion of municipal solid waste (MSW), energy is produced which can be utilized to generate electricity. However, electricity production from incineration has to be evaluated from the point view of the environmental performance. In this study, environmental impacts of electricity production from waste incineration plant in Thailand are compared with those from Thai conventional power plants. Methods The evaluation is based on a life cycle perspective using life cycle assessment (LCA) as the evaluation tool. Since MSW incineration provides two services, viz., waste management and electricity production, the conventional power production system is expanded to include landfilling without energy recovery, which is the most commonly used waste management system in Thailand, to provide the equivalent function of waste management. Results The study shows that the incineration performs better than conventional power plants vis-à-vis global warming and photochemical ozone formation, but not for acidification and nutrient enrichment. Discussion There are some aspects which may influence this result. If landfilling with gas collection and flaring systems is included in the analysis along with conventional power production instead of landfilling without energy recovery, the expanded system could become more favorable than the incineration in the global warming point of view. In addition, if the installation of deNO_x process is employed in the MSW incineration process, nitrogen dioxide can be reduced with a consequent reduction of acidification and nutrient enrichment potentials. However, the conventional power plants still have lower acidification and nutrient enrichment potentials. Conclusions The study shows that incineration could not play the major role for electricity production, but in addition to being a waste management option, could be considered as a complement to conventional power production. To promote incineration as a benign waste management option, appropriate deNO_x and dioxin removal processes should be provided. Separation of high moisture content waste fractions from the waste to be incinerated and improvement of the operation efficiency of the incineration plant must be considered to improve the environmental performance of MSW incineration. Recommendations This study provides an overall picture and impacts, and hence, can support a decision-making process for implementation of MSW incineration. The results obtained in this study could provide valuable information to implement incineration. But it should be noted that the results show the characteristics only from some viewpoints. Outlook Further analysis is required to evaluate the electricity production of the incineration plant from other environmental aspects such as toxicity and land-use.     

Environmental burdens of producing bread wheat,oilseed rape and potatoes in England and Wales using simulation and system modelling

Background, aims and scope  

Food production is essential to life. Modern farming uses considerable resources to produce arable crops. Analysing the environmental burdens of alternative crop production methods is a vital tool for policymakers. The paper describes the production burdens (calculated by life cycle analysis) of three key arable crops: bread wheat, oilseed rape and potatoes as grown in England and Wales using organic and non-organic (contemporary conventional) systems. Resource use (e.g. abiotic and energy) and burdens from emissions are included (e.g. global warming potential on a 100-year basis, global warming potential (GWP), and eutrophication and acidification potentials).     

Environmental impact of thin-film GaInP/GaAs and multicrystalline silicon solar modules produced with solar electricity

Background, aim, and scope  The environmental burden of photovoltaic (PV) solar modules is currently largely determined by the cumulative input of fossil energy used for module production. However, with an increased focus on limiting the emission of CO₂ coming from fossil fuels, it is expected that renewable resources, including photovoltaics, may well become more important in producing electricity. A comparison of the environmental impacts of PV modules in case their life cycle is based on the use of PV electricity in contrast to conventional electricity can elucidate potential environmental drawbacks in an early stage of development of a solar-based economy. The goal of this paper is to show for ten impact categories the environmental consequences of replacing fossil electricity with solar electricity into the life cycle of two types of PV modules. Materials and methods  Using life cycle assessment (LCA), we evaluated the environmental impacts of two types of PV modules: a thin-film GaInP/GaAs tandem module and a multicrystalline silicon (multi-Si) module. For each of the modules, the total amount of fossil electricity required in the life cycle of the module was substituted with electricity that is generated by a corresponding PV module. The environmental impacts of the modules on the midpoint level were compared with those of the same modules in case their life cycle is based on the use of conventional electricity. The environmental impacts were assessed for Western European circumstances with an annual solar irradiation of 1000 kWh/m². For the GaInP/GaAs module, the environmental impacts of individual production steps were also analysed. Results  Environmental burdens decreased when PV electricity was applied in the life cycle of the two PV modules. The impact score reductions of the GaInP/GaAs module were up to a factor of 4.9 (global warming). The impact score reductions found for the multi-Si module were up to a factor of 2.5 (abiotic depletion and global warming). Reductions of the toxicity scores of both module types were smaller or negligible. This is caused by a decreased use of fossil fuels, on the one hand, and an increased consumption of materials for the production of the additional solar modules used for generating the required PV electricity on the other. Overall, the impact scores of the GaInP/GaAs module were reduced more than the corresponding scores of the multi-Si module. The contribution analysis of the GaInP/GaAs module production steps indicated that for global warming, the cell growth process is dominant for supply with conventional electricity, while for the solar scenario, the frame becomes dominant. Regarding freshwater aquatic ecotoxicity scores associated with the life cycle of the GaInP/GaAs module, the cell growth process is dominant for supply with conventional electricity, while the reactor system for the cell growth with the associated gas scrubbing system is dominant for the solar scenario. Discussion  There are uncertainties regarding the calculated environmental impact scores. This paper describes uncertainties associated with the used economic allocation method, and uncertainties because of missing life cycle inventory data. For the GaInP/GaAs module, it was found that the global warming impact scores range from −66% to +41%, and the freshwater aquatic ecotoxicity scores (for an infinite time horizon) range from −40% to +300% compared to the default estimates. For both impact categories, the choices associated with the allocation of gallium, with the electricity mix, with the conversion efficiency of the commercially produced GaInP/GaAs cells, and with the yield of the cell growth process are most influential. For freshwater aquatic ecotoxicity, the uncertainty concerning the lifetime of the reactor system for the GaInP/GaAs cell growth process and the gas scrubbing system is particularly relevant. Conclusions  Use of PV electricity instead of fossil electricity significantly reduces the environmental burdens of the GaInP/GaAs and the multi-Si module. The reductions of the toxicity scores, however, are smaller or negligible. Toxicity impacts of the GaInP/GaAs cells can be reduced by improvement of the yield of the cell growth process, a reduced energy demand in the cell growth process, reduction of the amount of stainless steel in the cell growth reactor system and the gas scrubbing system, and a longer lifetime of these systems. Recommendations and perspectives  Because the greenhouse gas emissions associated with the production of fossil-fuel-based electricity have an important share in global warming on a world-wide scale, switching to a more extensive use of solar power is helpful to comply with the present international legislation on the area of global warming reduction. As reductions in toxicity impact scores are smaller or negligible when fossil electricity is replaced by PV electricity, it is desirable to give specific attention to the processes which dominantly contribute to these impact categories. Furthermore, in this study, a shift in ranking of several environmental impacts of the modules has been found when PV electricity is used instead of fossil electricity. The results of a comparative LCA can thus be dependent of the electricity mix used in the life cycles of the assessed products. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Life Cycle Assessment of Offshore Wind Farm Siting: Effects of Locational Factors,Lake Depth,and Distance from Shore

According to previous studies, the life cycle energy intensity of an offshore wind farm (OWF) varies between 0.03 and 0.13 megawatt‐hours (MWh) of primary energy for each MWh of electricity generated. The variation in these life cycle energy intensity studies, after normalizing for capacity factor and life span, is significantly affected by OWF location because of geographical properties, namely, wind speed and water depth. To improve OWF siting, this study investigates how an OWF's distance from shore and geographical location impacts its environmental benefit. A process‐based life cycle assessment is conducted to compare 20 OWF siting scenarios in Michigan's Great Lakes for their cumulative fossil energy demand, global warming potential, and acidification potential. Each scenario (four lake locations at five offshore distances) has unique foundation, transmission, installation, and operational requirements based on site characteristics. The results demonstrate that the cumulative environmental burden from an OWF is most significantly affected by (1) water depth, (2) distance from shore, and (3) distance to power grid, in descending order of importance, if all other site‐relevant variables are held constant. The results also show that when OWFs are sited further offshore, the benefit of increased wind energy generation does not necessarily outweigh the increase in negative environmental impacts. This suggests that siting OWF nearer to shore may result in a better life cycle environmental performance. Finally, we demonstrate how much an OWF's environmental burdens can be reduced if the OWF system is either recycled, transported a shorter distance, or manufactured in a region with a high degree of renewable energy on the grid.