Environmental life cycle assessment of a commercial office building in Thailand

Background, aim, and scope  To minimize the environmental impacts of construction and simultaneously move closer to sustainable development in the society, the life cycle assessment of buildings is essential. This article provides an environmental life cycle assessment (LCA) of a typical commercial office building in Thailand. Almost all commercial office buildings in Thailand follow a similar structural, envelope pattern as well as usage patterns. Likewise, almost every office building in Thailand operates on electricity, which is obtained from the national grid which limits variability. Therefore, the results of the single case study building are representative of commercial office buildings in Thailand. Target audiences are architects, building construction managers and environmental policy makers who are interested in the environmental impact of buildings. Materials and methods  In this work, a combination of input–output and process analysis was used in assessing the potential environmental impact associated with the system under study according to the ISO14040 methodology. The study covered the whole life cycle including material production, construction, occupation, maintenance, demolition, and disposal. The inventory data was simulated in an LCA model and the environmental impacts for each stage computed. Three environmental impact categories considered relevant to the Thailand context were evaluated, namely, global warming potential, acidification potential, and photo-oxidant formation potential. A 50-year service time was assumed for the building. Results  The results obtained showed that steel and concrete are the most significant materials both in terms of quantities used, and also for their associated environmental impacts at the manufacturing stage. They accounted for 24% and 47% of the global warming potential, respectively. In addition, of the total photo-oxidant formation potential, they accounted for approximately 41% and 30%; and, of the total acidification potential, 37% and 42%, respectively. Analysis also revealed that the life cycle environmental impacts of commercial buildings are dominated by the operation stage, which accounted for approximately 52% of the total global warming potential, about 66% of the total acidification potential, and about 71% of the total photo-oxidant formation potential, respectively. The results indicate that the principal contributor to the impact categories during the operation phase were emissions related to fossil fuel combustion, particularly for electricity production. Discussion  The life cycle environmental impacts of commercial buildings are dominated by the operation stage, especially electricity consumption. Significant reductions in the environmental impacts of buildings at this stage can be achieved through reducing their operating energy. The results obtained show that increasing the indoor set-point temperature of the building by 2°C, as well as the practice of load shedding, reduces the environmental burdens of buildings at the operation stage. On a national scale, the implementation of these simple no-cost energy conservation measures have the potential to achieve estimated reductions of 10.2% global warming potential, 5.3% acidification potential, and 0.21% photo-oxidant formation potential per year, respectively, in emissions from the power generation sector. Overall, the measures could reduce approximately 4% per year from the projected global warming potential of 211.51 Tg for the economy of Thailand. Conclusions  Operation phase has the highest energy and environmental impacts, followed by the manufacturing phase. At the operation phase, significant reductions in the energy consumption and environmental impacts can be achieved through the implementation of simple no-cost energy conservation as well as energy efficiency strategies. No-cost energy conservation policies, which minimize energy consumption in commercial buildings, should be encouraged in combination with already existing energy efficiency measures of the government. Recommendations and perspectives  In the long run, the environmental impacts of buildings will need to be addressed. Incorporation of environmental life cycle assessment into the current building code is proposed. It is difficult to conduct a full and rigorous life cycle assessment of an office building. A building consists of many materials and components. This study made an effort to access reliable data on all the life cycle stages considered. Nevertheless, there were a number of assumptions made in the study due to the unavailability of adequate data. In order for life cycle modeling to fulfill its potential, there is a need for detailed data on specific building systems and components in Thailand. This will enable designers to construct and customize LCAs during the design phase to enable the evaluation of performance and material tradeoffs across life cycles without the excessive burden of compiling an inventory. Further studies with more detailed, reliable, and Thailand-specific inventories for building materials are recommended.     

Assessing future energy and transport systems: the case of fuel cells

Goal, Scope and Background  Assessing future energy and transport systems is of major importance for providing timely information for decision makers. In the discussion of technology options, fuel cells are often portrayed as attractive options for power plants and automotive applications. However, when analysing these systems, the LCA analyst is confronted with methodological problems, particularly with data gaps and the requirement of an anticipation of future developments. This series of two papers aims at providing a methodological framework for assessing future energy and transport systems (Part 1) and applies this to the two major application areas of fuel cells (Part 2). Methods  To allow the LCA of future energy and transport systems forecasting tools like, amongst others, cost estimation methods and process simulation of systems are investigated with respect to the applicability in LCAs of future systems (Part 1). The manufacturing process of an SOFC stack is used as an illustration for the forecasting procedure. In Part 2, detailed LCAs of fuel cell power plants and power trains are carried out including fuel (hydrogen, methanol, gasoline, diesel and natural gas) and energy converter production. To compare it with competing technologies, internal combustion engines (automotive applications) and reciprocating engines, gas turbines and combined cycle plants (stationary applications) are analysed as well. Results and Discussion  Principally, the investigated forecasting methods are suitable for future energy system assessment. The selection of the best method depends on different factors such as required ressources, quality of the results and flexibility. In particular, the time horizon of the investigation determines which forecasting tool may be applied. Environmentally relevant process steps exhibiting a significant time dependency shall always be investigated using different independent forecasting tools to ensure stability of the results. The results of the LCA (Part 2) underline that principally, fuel cells offer advantages in the impact categories which are typically dominated by pollutant emissions, such as acidification and eutrophication, whereas for global warming and primary energy demand, the situation depends on a set of parameters such as driving cycle and fuel economy ratio in mobile applica-tions and thermal/total efficiencies in stationary applications. For the latter impact categories, the choice of the primary en-ergy carrier for fuel production (renewable or fossil) dominates the impact reduction. With increasing efficiency and improving emission performance of the conventional systems, the competition regarding all impact categories in both mobile and stationary applications is getting even stronger. The production of the fuel cell system is of low overall significance in stationary applications, whereas in automotive applications, the production of the fuel cell power train and required materials leads to increased impacts compared to internal combustion engines and thus reduces the achievable environmental impact reduction. Recommendations and Perspectives  The rapid technological and energy economic development will bring further advances for both fuel cells and conventional energy converters. Therefore, LCAs at such an early stage of the market development can only be considered preliminary. It is an essential requirement to accompany the ongoing research and development with iterative LCAs, constantly pointing at environmental hot spots and bottlenecks.     

Life cycle assessment of primary magnesium production using the Pidgeon process in China

Background, aims, and scope  China has been the largest primary magnesium producer in the world since year 2000 and is an important part of the global magnesium supply chain. Almost all of the primary magnesium in China is produced using the Pidgeon process invented in the 1940s in Canada. The environmental problems of the primary magnesium production with the Pidgeon process have already attracted much attention of the local government and enterprises. The main purposes of this research are to investigate the environmental impacts of magnesium production and to determine the accumulative environmental performances of three different scenarios. System boundary included the cradle-to-gate life cycle of magnesium production, including dolomite ore extraction, ferrosilicon production, the Pidgeon process, transportation of materials, and emissions from thermal power plant. The life cycle assessment (LCA) case study was performed on three different fuel use scenarios from coal as the overall fuel to two kinds of gaseous fuels, the producer gas and coke oven gas. The burden use of gaseous fuels was also considered. Methods  The procedures, details, and results obtained are based on the application of the existing international standards of LCA, i.e., the ISO 14040. Depletion of abiotic resources, global warming, acidification, and human toxicity were adopted as the midpoint impact categories developed by the problem-oriented approach of CML to estimate the characterized results of the case study. The local characterization and normalization factors of abiotic resources were used to calculate abiotic depletion potential (ADP). The analytic hierarchy process was used to determine the weight factors. Using the Umberto version 4.0, the emissions of dolomite ore extraction were estimated and the transportation models of the three scenarios were designed. Results and conclusions  The emissions inventory showed that both the Pidgeon process of magnesium production and the Fe–Si production were mainly to blame for the total pollutant emissions in the life cycle of magnesium production. The characterized results indicated that ADP, acidification potential, and human toxicity potential decreased cumulatively from scenarios 1 to 3, with the exception of global warming potential. The final single scores indicated that the accumulative environmental performance of scenario 3 was the best compared with scenarios 1 and 2. The impact of abiotic resources depletion deserves more attention although the types and the amount of mineral resources for Mg production are abundant in China. This study suggested that producer gas was an alternative fuel for magnesium production rather than the coal burned directly in areas where the cost of oven gas-produced coke is high. The utilization of “clean” energy and the reduction of greenhouse gases and acidic gases emission were the main goals of the technological improvements and cleaner production of the magnesium industry in China. Recommendation and perspective  This paper has demonstrated that the theory and method of LCA are actually helpful for the research on the accumulative environmental performance of primary magnesium production. Further studies with “cradle-to-cradle” scheme are recommended. Furthermore, other energy sources used in magnesium production and the cost of energy production could be treated in further research.     

Estimating the Greenhouse Gas Balance of Individual Gas‐Fired and Oil‐Fired Electricity Plants on a Global Scale

Life cycle greenhouse gas (LC‐GHG) emissions from electricity generated by a specific resource, such as gas and oil, are commonly reported on a country‐by‐country basis. Estimation of variability in LC‐GHG emissions of individual power plants can, however, be particularly useful to evaluate or identify appropriate environmental policy measures. Here, we developed a regression model to predict LC‐GHG emissions per kilowatt‐hour (kWh) of electricity produced by individual gas‐ and oil‐fired power plants across the world. The regression model uses power plant characteristics as predictors, including capacity, age, fuel type (fuel oil or natural gas), and technology type (single or combined cycle) of the plant. The predictive power of the model was relatively high (R² = 81% for predictions). Fuel and technology type were identified as the most important predictors. Estimated emission factors ranged from 0.45 to 1.16 kilograms carbon dioxide equivalents per kilowatt‐hour (kg CO₂‐eq/kWh) and were clearly different between natural gas combined cycle (0.45 to 0.57 kg CO₂‐eq/kWh), natural gas single cycle (0.66 to 0.85 kg CO₂‐eq/kWh), oil combined cycle power plants (0.63 to 0.79 kg CO₂‐eq/kWh), and oil single cycle (0.94 to 1.16 kg CO₂‐eq/kWh). Our results thus indicate that emission data averaged by fuel and technology type can be profitably used to estimate the emissions of individual plants.     

Life Cycle Inventories for the Nuclear and Natural Gas Energy Systems,and Examples of Uncertainty Analysis (14 pp)

Goal, Scope and Background The energy systems included in the ecoinvent database v1.1 describe the situation around year 2000 of Swiss and Western European power plants and boilers with the associated energy chains. The addressed nuclear systems concern Light Water Reactors (LWR) with mix of open and closed fuel cycles. The system model ‘Natural Gas’ describes production, distribution, and combustion of natural gas. Methods Comprehensive life cycle inventories of the energy systems were established and cumulative results calculated within the ecoinvent framework. Swiss conditions for the nuclear cycle were extrapolated to major nuclear countries. Long-term radon emissions from uranium mill tailings have been estimated with a simplified model. Average natural gas power plants were analysed for different countries considering specific import/export of the gas, with seven production regions separately assessed. Uncertainties have been estimated quantitatively. Results and Discussion Different radioactive emission species and wastes are produced from different steps of the nuclear cycle. Emissions of greenhouse gases from the nuclear cycle are mostly from the upstream chain, and the total is small and decreasing with increasing share of centrifuge enrichment. The results for natural gas show the importance of transport and low pressure distribution network for the methane emissions, whereas energy is mostly invested for production and long-distance pipeline transportation. Because of significant differences in power plant efficiencies and gas supply, country specific averages differ greatly. Conclusion The inventory describes average worldwide supply of nuclear fuel and average nuclear reactors in Western Europe. Although the model for nuclear waste management was extrapolated from Swiss conditions, the ranges obtained for cumulative results can represent the average in Europe. Emissions per kWh electricity are distributed very differently over the natural gas chain for different species. Modern combined cycle plants show better performance for several burdens like cumulative greenhouse gas emissions compared to average plants. Recommendation and Perspective Comparison of country-specific LWRs or LWR types on the basis of these results is not recommended. Specific issues on different strategies for the nuclear fuel cycle or location-specific characteristics would require extension of analysis. Results of the gas chain should not be directly applied to areas other than those modelled because emission factors and energy requirements may differ significantly. A future update of inventory data should reconsider production and transport from Russia, as it is a major producer and exporter to Europe. The calculated ranges of uncertainty factors in ecoinvent provide useful information but they are more indications of uncertainties rather than strict 95% intervals, and should therefore be applied carefully.     

Assessing future energy and transport systems: the case of fuel cells

Goal, Scope and Background  Assessing future energy and transport systems is of major importance for providing timely information for decision makers. In the discussion of technology options, fuel cells are often portrayed as attractive options for power plants and automotive applications. However, when analysing these systems, the LCA analyst is confronted with methodological problems, particularly with data gaps and the requirement of forecasting and anticipation of future developments. This series of two papers aims at providing a methodological framework for assessing future energy and transport systems (Part 1) and applies this to the two major application areas of fuel cells (Part 2). Methods  To allow the LCA of future energy and transport systems, forecasting tools like, amongst others, cost estimation methods and process simulation of systems are investigated with respect to the applicability in LCAs of future systems (Part 1). The manufacturing process of an SOFC stack is used as an illustration for the forecasting procedure. In Part 2, detailed LCAs of fuel cell power plants and power trains are carried out including fuel (hydrogen, methanol, gasoline, diesel and natural gas) and energy converter production. To compare it with competing technologies, internal combustion engines (automotive applications) and reciprocating engines, gas turbines and combined cycle plants (stationary applications) are also analysed. Results and Discussion  Principally, the investigated forecasting methods are suitable for future energy system assessment. The selection of the best method depends on different factors such as required ressources, quality of the results and flexibility. In particular, the time horizon of the investigation determines which forecasting tool may be applied. Environmentally relevant process steps exhibiting a significant time dependency shall always be investigated using different independent forecasting tools to ensure stability of the results. The results of the LCA underline that, in general, fuel cells offer advantages in the impact categories usually dominated by pol-lutant emissions, such as acidification and eutrophication, whereas for global warming and primary energy demand, the situation depends on a set of parameters such as driving cycle and fuel economy ratio in mobile applications and thermal/total efficiencies in stationary applications. For the latter impact categories, the choice of the primary energy carrier for fuel production (renewable or fossil) dominates the impact reduction. With increasing efficiency and improving emission performance of the conventional systems, the competition in both mobile and stationary applications is getting even stronger. The production of the fuel cell system is of low overall significance in stationary applications, whereas in vehicles, the lower life-time of the vehicle leads to a much higher significance of the power train production. Recommendations and Perspectives  In future, rapid technological and energy economic development will bring further advances for both fuel cells and conventional energy converters. Therefore, LCAs at such an early stage of the market development can only be considered preliminary. It is an essential requirement to accompany the ongoing research and development with iterative LCAs, constantly pointing at environmental hot spots and bottlenecks.     

Life Cycle assessment of bio-ethanol derived from cellulose

Objective, Scope, Background  A comprehensive Life Cycle Assessment was conducted on bio-ethanol produced using a new process that converts cellulosic biomass by enzymatic hydrolysis. Options for sourcing the feedstock either from agricultural and wood waste, or, if the demand for bio-ethanol is sufficient, from cultivation are examined. The main focus of the analysis was to determine its potential for reducing greenhouse gas emissions in a 10% blend of this bio-ethanol with gasoline (E10) as a transportation fuel. Methods  SimaPro 4.0 was used as the analysis tool, which allowed a range of other environmental impacts also to be examined to assess the overall relative performance to gasoline alone. All impacts were assigned to the fuel because of uncertainties in markets for the by-products. This LCA therefore represents a worst case scenario. Results, Conclusion  It is shown that E10 gives an improved environmental performance in some impact categories, including greenhouse gas emissions, but has inferior performances in others. Whether the potential benefits of the bio-ethanol blend to reduce greenhouse gas emissions will be realized is shown to be particularly sensitive to the source of energy used to produce the process steam required to break down the cellulose to produce sugars and to distil the final product. One key area where improvements in environmental performance might be derived is in enzyme production. Recommendations and Outlook  The LCA profile helps to highlight those areas where positive and negative environmental impacts can be expected. Technological innovation can be directed accordingly to preserve the benefits while minimizing the negative impacts as development progresses to commercial scales.     

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)     

Beyond Global Warming Potential: A Comparative Application of Climate Impact Metrics for the Life Cycle Assessment of Coal and Natural Gas Based Electricity

In the ongoing debate about the climate benefits of fuel switching from coal to natural gas for power generation, the metrics used to model climate impacts may be important. In this article, we evaluate the life cycle greenhouse gas emissions of coal and natural gas used in new, advanced power plants using a broad set of available climate metrics in order to test for the robustness of results. Climate metrics included in the article are global warming potential, global temperature change potential, technology warming potential, and cumulative radiative forcing. We also used the Model for the Assessment of Greenhouse‐gas Induced Climate Change (MAGICC) climate‐change model to validate the results. We find that all climate metrics suggest a natural gas combined cycle plant offers life cycle climate benefits over 100 years compared to a pulverized coal plant, even if the life cycle methane leakage rate for natural gas reaches 5%. Over shorter time frames (i.e., 20 years), plants using natural gas with a 4% leakage rate have similar climate impacts as those using coal, but are no worse than coal. If carbon capture and sequestration becomes available for both types of power plants, natural gas still offers climate benefits over coal as long as the life cycle methane leakage rate remains below 2%. These results are consistent across climate metrics and the MAGICC model over a 100‐year time frame. Although it is not clear whether any of these metrics are better than the others, the choice of metric can inform decisions based on different societal values. For example, whereas annual temperature change reported may be a more relevant metric to evaluate the human health effects of increased heat, the cumulative temperature change may be more relevant to evaluate climate impacts, such as sea‐level rise, that will result from the cumulative warming.     

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)     

Comparative life cycle assessment of two landfill technologies for the treatment of municipal solid waste

Goal and Scope  The potential environmental impacts associated with two landfill technologies for the treatment of municipal solid waste (MSW), the engineered landfill and the bioreactor landfill, were assessed using the life cycle assessment (LCA) tool. The system boundaries were expanded to include an external energy production function since the landfill gas collected from the bioreactor landfill can be energetically valorized into either electricity or heat; the functional unit was then defined as the stabilization of 600 000 tonnes of MSW and the production of 2.56x10⁸ MJ of electricity and 7.81x10⁸ MJ of heat. Methods  Only the life cycle stages that presented differences between the two compared options were considered in the study. The four life cycle stages considered in the study cover the landfill cell construction, the daily and closure operations, the leachate and landfill gas associated emissions and the external energy production. The temporal boundary corresponded to the stabilization of the waste and was represented by the time to produce 95% of the calculated landfill gas volume. The potential impacts were evaluated using the EDIP97 method, stopping after the characterization step. Results and Discussion  The inventory phase of the LCA showed that the engineered landfill uses 26% more natural resources and generates 81% more solid wastes throughout its life cycle than the bioreactor landfill. The evaluated impacts, essentially associated with the external energy production and the landfill gas related emissions, are on average 91% higher for the engineered landfill, since for this option 1) no energy is recovered from the landfill gas and 2) more landfill gas is released untreated after the end of the post-closure monitoring period. The valorization of the landfill gas to electricity or heat showed similar environmental profiles (1% more raw materials and 7% more solid waste for the heat option but 13% more impacts for the electricity option). Conclusion and Recommendations  The methodological choices made during this study, e.g. simplification of the systems by the exclusion of the identical life cycle stages, limit the use of the results to the comparison of the two considered options. The validity of this comparison could however be improved if the systems were placed in the larger context of municipal solid waste management and include activities such as recycling, composting and incineration.     

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 Damage Assessment of Carbon Capture and Storage

An end‐point life cycle impact assessment is used to evaluate the damages of electricity generation from fossil fuel‐based power plants with carbon dioxide capture and storage (CCS) technology. Pulverized coal (PC), integrated gasification combined cycle (IGCC), and natural gas combined cycle (NGCC) power plants are assessed for carbon dioxide (CO₂) capture, pipeline transport, and storage in a geological formation. Results show that the CCS systems reduce the climate change‐related damages but increase the damages from toxicity, acidification, eutrophication, and resource consumption. Based on the currently available damage calculation methods, it is concluded that the benefit of reducing damage from climate change is larger than the increases in other damage categories, such as health effects from particulates or toxic chemicals. CCS significantly reduces the overall environmental damage, with a net reduction of 60% to 70% in human health damage and 65% to 75% in ecosystem damage. Most of the damage is due to fuel production and combustion processes. The energy and infrastructure demands of CCS cause increases in the depletion of natural resources by 33% for PC, 19% for IGCC, and 18% for NGCC power plants, mostly due to increased fossil fuel consumption.     

Integrated Economic Equilibrium and Life Cycle Assessment Modeling for Policy‐based Consequential LCA

Consequential life cycle assessment (CLCA) has emerged as a tool for estimating environmental impacts of changes in product systems that go beyond physical relationships accounted for in attributional LCA (ALCA). This study builds on recent efforts to use more complex economic models for policy‐based CLCA. A partial market equilibrium (PME) model, called the U.S. Forest Products Module (USFPM), is combined with LCA to analyze an energy demand scenario in which wood use increases 400 million cubic meters in the United States for ethanol production. Several types of indirect economic and environmental impacts are identified and estimated using USFPM‐LCA. A key finding is that if wood use for biofuels increases to high levels and mill residue is used for biofuels and replaced by natural gas for heat and power in forest products mills, then the increased greenhouse gas emissions from natural gas could offset reductions obtained by substituting biofuels for gasoline. Such high levels of biofuel demand, however, appear to have relatively low environmental impacts across related forest product sectors.     

Environmental performance assessment of hardboard manufacture

Background, aim and scope  The forest-based and related industries comprise one of the most important industry sectors in the European Union, representing some 10% of the EU's manufacturing industries. Their activities are based on renewable raw material resources and efficient recycling. The forest-based industries can be broken down into the following sectors: forestry, woodworking, pulp and paper manufacturing, paper and board converting and printing and furniture. The woodworking sector includes many sub-sectors; one of the most important is that of wood panels accounting for 9% of total industry production. Wood panels are used as intermediate products in a wide variety of applications in the furniture and building industries. There are different kinds of panels: particleboard, fibreboard, veneer, plywood and blockboard. The main goal of this study was to assess the environmental impacts during the life cycle of wet-process fibreboard (hardboard) manufacturing to identify the processes with the largest environmental impacts. Methods  The study covers the life cycle of hardboard production from a cradle-to-gate perspective. A hardboard plant was analysed in detail, dividing the process chain into three subsystems: wood preparation, board forming and board finishing. Ancillary activities such as chemicals, wood chips, thermal energy and electricity production and transport were included within the system boundaries. Inventory data came from interviews and surveys (on-site measurements). When necessary, the data were complemented with bibliographic resources. The life cycle assessment procedure followed the ISO14040 series. The life cycle inventory (LCI) and impact assessment database for this study were constructed using SimaPro Version 7.0 software. Results  Abiotic depletion (AD), global warming (GW), ozone layer depletion (OLD), human toxicity (HT), ecotoxicity, photochemical oxidant formation (PO), acidification (AC) and eutrophication (EP) were the impact categories analysed in this study. The wood preparation subsystem contributed more than 50% to all impact categories, followed by board forming and board finishing, which is mainly due to chemicals consumption in the wood preparation subsystem. In addition, thermal energy requirements (for all subsystems) were fulfilled by on-site wood waste burning and, accordingly, biomass energy converters were considered. Several processes were identified as hot spots in this study: phenol-formaldehyde resin production (with large contribution to HT, fresh water aquatic ecotoxicity and PO), electricity production (main contributor to marine aquatic ecotoxicity), wood chips production (AD and OLD) and finally, biomass burning for heat production (identified as the largest contributor to AC and EP due to NO _X emissions). In addition, uncontrolled formaldehyde emissions from manufacturing processes at the plant such as fibre drying should be controlled due to relevant contributions to terrestrial ecotoxicity and PO. A sensitivity analysis of electricity profile generation (strong geographic dependence) was carried out and several European profiles were analysed. Discussion  Novel binding agents for the wood panel industry as a substitute for the currently used formaldehyde-based binders have been extensively investigated. Reductions of toxic emissions during drying, mat forming and binder production are desirable. The improved method would considerably reduce the contributions to all impact categories. Conclusions  The results obtained in this work allow forecasting the importance of the wood preparation subsystem for the environmental burdens associated with hardboard manufacture. Special attention was paid to the inventory analysis stage for each subsystem. It is possible to improve the environmental performance of the hardboard manufacturing process if some alternatives are implemented regarding the use of chemicals, electricity profile and emission sources in the production processes located inside the plant. Recommendations and perspectives  This study provides useful information for forest-based industries related to panel manufacture with the aim of increasing their sustainability. Our research continues to assess the use phase and final disposal of panels to complete the life cycle assessment. Future work will focus on analysing the environmental aspects associated with plywood, another type of commonly used wood panel.     

Life Cycle Greenhouse Gas Emissions of Electricity Generated from Conventionally Produced Natural Gas

This research provides a systematic review and harmonization of the life cycle assessment (LCA) literature of electricity generated from conventionally produced natural gas. We focus on estimates of greenhouse gases (GHGs) emitted in the life cycle of electricity generation from natural gas‐fired combustion turbine (NGCT) and combined‐cycle (NGCC) systems. The smaller set of LCAs of liquefied natural gas power systems and natural gas plants with carbon capture and storage were also collected, but analyzed to a lesser extent. A meta‐analytical process we term “harmonization” was employed to align several system boundaries and technical performance parameters to better allow for cross‐study comparisons, with the aim of clarifying central tendency and reducing variability in estimates of life cycle GHG emissions. Of over 250 references identified, 42 passed screens for technological relevance and study quality, providing a total of 69 estimates for NGCT and NGCC. Harmonization increased the median estimates in each category as a result of several factors not typically considered in the previous research, including the regular clearing of liquids from a well, and consolidated the interquartile range for NGCC to 420 to 480 grams of carbon dioxide equivalent per kilowatt‐hour (g CO₂‐eq/kWh) and for NGCT to 570 to 750 g CO₂‐eq/kWh, with medians of 450 and 670 CO₂‐eq/kWh, respectively. Harmonization of thermal efficiency had the largest effect in reducing variability; methane leakage rate is likely similarly influential, but was unharmonized in this assessment as a result of the significant current uncertainties in its estimation, an area that is justifiably receiving significant research attention.     

Environmental assessment of urban mobility: Combining life cycle assessment with land-use and transport interaction modelling—Application to Lyon (France)

In France, greenhouse gas (GHG) emissions from transport have grown steadily since 1950 and transport is now the main source of emissions. Despite technological improvements, urban sprawl increases the environmental stress due to car use. This study evaluates urban mobility through assessments of the transport system and travel habits, by applying life cycle assessment methods to the results of mobility simulations that were produced by a Land Use and Transport Interactions (LUTI) model. The environmental impacts of four life cycle phases of urban mobility in the Lyon area (exhausts, fuel processing, infrastructure and vehicle life cycle) were estimated through nine indicators (global warming potential, particulate matter emissions, photochemical oxidant emissions, terrestrial acidification, fossil resource depletion, metal depletion, non-renewable energy use, renewable energy use and land occupancy). GHG emissions were estimated to be 3.02 kg CO₂-eq inhabitant⁻¹ day⁻¹, strongly linked to car use, and indirect impacts represented 21% of GHG emissions, which is consistent with previous studies. Combining life cycle assessment (LCA) with a LUTI model allows changes in the vehicle mix and fuel sources combined with demographic shifts to be assessed, and provides environmental perspectives for transport policy makers and urban planners. It can also provide detailed analysis, by allowing levels of emissions that are generated by different categories of households to be differentiated, according to their revenue and location. Public policies can then focus more accurately on the emitters and be assessed from both an environmental and social point of view.     

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.