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.

     

Environmental impact trade-offs in building envelope retrofit strategies

Purpose

The use of high levels of thermal insulation is a common practice towards reducing the energy consumption of the existing building stock; however, the embodied burdens associated with the additional insulation material are usually not taken into account and questions regarding the risks of over-specifying the insulation levels have been emerging, particularly for mild climate regions. This article addresses the issue presenting an integrated approach that combines life cycle assessment and thermal dynamic simulation to assess alternative retrofit strategies for the roof and exterior walls of two dwellings (from the beginning of the twentieth century), in the historic city center of Coimbra, Portugal. A comprehensive analysis of alternative insulation thicknesses (no insulation, 40, 80, and 120 mm of expanded polystyrene) was made to identify optimal thickness levels minimizing life cycle (LC) environmental impacts for a single-family house and an apartment.

Methods

Embodied and operational impact trade-offs were calculated for six impact categories: climate change, ozone depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, and non-renewable primary energy. The operational energy was calculated using a dynamic thermal modeling software (EnergyPlus). The functional unit selected for this study was 1 m² of living area over a period of 50 years.

Results and discussion

The single-family house embodied impacts account for 26–57 % of total LC impacts. For insulation thicknesses larger than 80 mm, the embodied impacts are greater than operational impacts. For the apartment, embodied impacts account for 25–49 % of total LC impacts. The environmental benefits of additional insulation are very low (<3 %) for thicknesses of more than 80 mm for both roof and exterior walls. For thicknesses above the tipping point (where total LC impacts are minimized), the marginal impacts of additional insulation are higher than the benefits. The results for the apartment show that optimal insulation thicknesses (LC tipping point) range from 30 to 40 mm for the roof and from 60 to 80 mm for the exterior walls. The LC tipping point for the single-family house is achieved by combining 80–100 mm of roof insulation with 60–80 mm of exterior wall insulation.

Conclusions

Extra insulation levels in temperate climates can lead to higher embodied impacts, without significant reduction in operational impacts, which can result in higher total LC impacts. The results show that a tipping point can be identified, and recommendations are provided for the roof and exterior wall retrofits of buildings from the beginning of the twentieth century.

     

A modeling framework to evaluate sustainability of building construction based on LCSA

Purpose

Life cycle sustainability assessment (LCSA) is a method that combines three life cycle techniques, viz. environmental life cycle assessment (LCA), life cycle costing (LCC), and social life cycle assessment (S-LCA). This study is intended to develop a LCSA framework and a case study of LCSA for building construction projects.

Methods

A LCSA framework is proposed to combine the three life cycle techniques. In the modeling phases, three life cycle models are used in the LCSA framework, namely the environmental model of construction (EMoC), cost model of construction (CMoC), and social-impact model of construction (SMoC). A residential building project is applied to the proposed LCSA framework from “cradle to the end of construction” processes to unveil the limitations and future research needs of the LCSA framework.

Results and discussion

It is found that material extraction and manufacturing account for over 90 % to the environmental impacts while they contribute to 61 % to the construction cost. In terms of social impacts, on-site construction performs better than material extraction and manufacturing, and on-site construction has larger contributions to the positive social impacts. The model outcomes are validated through interviews with local experts in Hong Kong. The result indicates that the performance of the models is generally satisfactory.

Conclusions

The case study has confirmed that LCSA is feasible. Being one of the first applications of LCSA on building construction, this study fulfills the current research gap and paves the way for future development of LCSA.

     

Life cycle assessment of ocean energy technologies

Purpose

Oceans offer a vast amount of renewable energy. Tidal and wave energy devices are currently the most advanced conduits of ocean energy. To date, only a few life cycle assessments for ocean energy have been carried out for ocean energy. This study analyses ocean energy devices, including all technologies currently being proposed, in order to gain a better understanding of their environmental impacts and explore how they can contribute to a more sustainable energy supply.

Methods

The study followed the methodology of life cycle assessment including all life cycle steps from cradle to grave. The various types of device were assessed, on the basis of a functional unit of 1 kWh of electricity delivered to the grid. The impact categories investigated were based on the ILCD recommendations. The life cycle models were set up using detailed technical information on the components and structure of around 180 ocean energy devices from an in-house database.

Results and discussion

The design of ocean energy devices still varies considerably, and their weight ranges from 190 to 1270 t, depending on device type. Environmental impacts are closely linked to material inputs and are caused mainly by mooring and foundations and structural components, while impacts from assembly, installation and use are insignificant for all device types. Total greenhouse gas emissions of ocean energy devices range from about 15 to 105 g CO₂-eq. kWh^?1. Average global warming potential for all device types is 53?±?29 g CO₂-eq. kWh^?1. The results of this study are comparable with those of other studies and confirm that the environmental impacts of ocean energy devices are comparable with those of other renewable technologies and can contribute to a more sustainable energy supply.

Conclusions

Ocean energy devices are still at an early stage of development compared with other renewable energy technologies. Their environmental impacts can be further reduced by technology improvements already being pursued by developers (e.g. increased efficiency and reliability). Future life cycle assessment studies should assess whole ocean energy arrays or ocean energy farms.

     

Environmental assessment of the Peruvian industrial hake fishery with LCA

Purpose

The Peruvian hake (Merluccius gayi peruanus) stock has been in a delicate state in the last decades due to overexploitation combined with adverse climatic events. The stock is showing certain signs of recovery since 2012. This work analyses the environmental impacts of current fleet operations and its likely trend.

Methods

The fleet was divided into coherent segments, per holding capacity and engine power. The validity of both segmentations, as well as the presence of an effect of economies of scale driving fuel use intensity (FUI), was tested. Life cycle assessment was used to calculate environmental impacts, per individual sampled vessel and per segment, complemented with indicators of energy efficiency and biotic resource depletion.

Results and discussion

The fleet is highly fuel-efficient (120 kg fuel per tonne fish) when compared with other reported values, despite a large overcapacity that increases the impact of the construction and maintenance phases. Significant inter-annual FUI variations were observed (80.0 kg t^?1 in 2008 to 210.3 kg t^?1 in 2006), but no clear trend. Neither significant differences in FUI among fleet segments nor a clear effect of economies of scale were found (but FUI analysis was based on a small sample of 32 values for nine vessels, two of which had data for a single year). Only the largest vessels, featuring 242 m³ holding capacity and 850 hp engine power, were found to have lower FUI than any of the other vessels, but no statistical test could be applied to validate this difference. Differences in environmental impacts of individual vessels are mostly dominated by their relative FUI. Fuel use and, to a lower extent, maintenance are the main sources of environmental impacts. The most contributing impacts to ReCiPe single score are climate change, human toxicity and fossil depletion. The fishery’s impacts on the biotic natural resource were orders of magnitude higher than many other global hake stocks, due to overexploitation.

Conclusions

The environmental impacts of the national hake fleet are relatively low during the study period, despite an overcapacity of the fleet. With the perspective of expanding its operations and obtaining better yields on the eventuality that the stock fully recovers, these impacts should decrease. More research based on additional FUI data is necessary to effectively compare the performance of these vessels with larger ones (featuring >180 m³ and >500 hp, of which nine existed in 2016) before possibly recommending their preferential use.

     

Life cycle assessment of nickel products

Purpose

To support the data requirements of stakeholders, the Nickel Institute (NI) conducted a global life cycle impact assessment (LCIA) to show, with indicators, the potential environmental impacts of the production of nickel and ferronickel from mine to refinery gate. A metal industry wide agreed approach on by-products and allocation was applied.

Methods

Nine companies, comprising 19 operations, contributed data, representing 52 % of global nickel metal production and 40 % of global ferronickel production. All relevant pyro- and hydrometallurgical production routes were considered, across most major nickel-producing regions. Data from Russia, the biggest nickel-producing nation, was included; the Chinese industry did not participate. 2011 was chosen as reference year for data collection. The LCIA applied allocation of impacts of by-products using both economic and mass allocations. A sensitivity analysis was conducted to further understand the relevance and impact of the different allocation approaches.

Results and discussion

The primary extraction and refining steps are the main contributors to primary energy demand (PED) and global warming potential (GWP), contributing 60 and 70 % to the PED for the production of 1 kg class I nickel and 1 kg nickel in ferronickel, respectively, and over 55 % of the GWP for both nickel products. The PED for 1 kg class 1 nickel was calculated to be 147 MJ, whilst the PED for 1 kg nickel in ferronickel was calculated to be three times higher at 485 MJ. The main factors influencing energy demand in the metallurgical processes are ore grade and ore mineralogy. Sulphidic ore is less energy intensive to process than oxidic ore. Eighty-six percent of the production volume from class 1 nickel producers, in this study, is from sulphidic ore. All ferronickel was produced from oxidic ore. The LCIA results, including a sensitivity analysis of the impact of producers with higher and lower PED, reflect the influence of the production route on energy demand and on environmental impact categories.

Conclusions

Conformant to relevant ISO standards, and backed-up with a technical and critical review, this LCIA quantifies the environmental impacts associated with the production of the main nickel products. With this study, a sound background dataset for downstream users of nickel has been provided. The Nickel Institute aims to update their data in the coming years to reflect upon changes in technology, energy efficiency, and raw material input.

     

A global life cycle assessment for primary zinc production

Purpose

The purpose of this study was to update the average environmental impacts of global primary zinc production using a life cycle assessment (LCA) approach. This study represents the latest contribution from zinc producers, which historically established the first life cycle inventory for primary zinc production in 1998 (Western Europe) and the first global LCA-based cradle-to-gate study for zinc concentrate and special high-grade zinc (SHG; 99.99 %) in 2009. Improvements from the previous studies were realized through expanded geographical scope and range of production technologies.

Methods

The product system under study (SHG zinc) was characterized by collecting primary data for the relevant production processes, including zinc ore mining and concentration, transportation of the zinc concentrate, and zinc concentrate smelting. This data was modeled in GaBi 6 and complemented with background data from the GaBi 2013 databases to create the cradle-to-gate LCA model. Allocation was used to distribute the inputs and outputs among the various co-products produced during the production process, with mass of metal content being the preferred allocation approach, when applicable.

Results and discussion

In total, this global study includes primary data from 24 mines and 18 smelters, which cover 4.7?×?10⁶ MT of zinc concentrate and 3.4?×?10⁶ MT of SHG zinc, representing 36 and 27 % of global production, respectively. While the LCA model generated a full life cycle inventory, selected impact categories and indicators are reported in this article (global warming potential, acidification potential, eutrophication potential, photochemical ozone creation potential, ozone creation potential, and primary energy demand). The results show that SHG zinc has a primary energy demand of 37,500 MJ/t and a climate change impact of 2600 kg CO₂-eq./t. Across all impact categories and indicators reported here, around 65 % of the burden are associated with smelting, 30 % with mining and concentration, and 5 % with transportation of the concentrate. Sensitivity analyses were carried out for the allocation method (total mass versus mass of metal content) and transportation of zinc concentrate.

Conclusions

This study generated updated LCA information for the global production of SHG zinc, in line with the metal industry’s current harmonization efforts. Through the provision of unit process information for zinc concentrate and SHG zinc production, greater transparency is achieved. Technological and temporal representativeness was deemed to be high. Geographical representativeness, however, was found to be moderate to low. Future studies should focus on increasing company participation from underrepresented regions.

     

Life cycle assessment of construction and renovation of sewer systems using a detailed inventory tool

Purpose

The objective was to provide comprehensive life cycle inventories for the construction and renovation of sewers. A detailed inventory was provided with multiple options of pipe materials, diameters and site-specific characteristics, and was embedded into the Excel^®-based tool SewerLCA. The tool allows for life cycle evaluation of different sewers. It was applied to determine the most important phases, processes, and related parameters involved in the construction and renovation of sewers from an environmental and economical perspective.

Methods

Comprehensive life cycle inventories (LCIs) for sewers construction and renovation were obtained by first identifying all processes involved after interviewing construction experts and reviewing sewer construction budgets from a Catalan company; and second transforming the processes into masses of materials and energy usage using construction databases. In order to run the life cycle impact assessment (LCIA) the materials and energy typologies from the inventories were matched to their corresponding equivalents into available LCI databases. Afterwards the potential impacts were calculated through the use of LCIA characterization factors from ReCiPe. Life cycle assessment (LCA) was run several times to assess the construction of a 1-km-long sewer with varying pipe materials, life spans for each material, diameters, transport distances, site-specific characteristics, and pipe deposition options.

Results and discussion

The environmental impacts generated by construction and renovation of a 1 km Polyvinylchloride (PVC) pipe with a diameter of 40 cm are mainly associated with pipe laying and backfilling of the trench. The evaluation of several pipe materials and diameters shows that the exclusion of renovation would underestimate the impacts by 38 to 82 % depending on the pipe materials and diameters. Including end-of-life phase for plastic pipe materials increases climate change (up to an extra 71 %) and human toxicity (up to an extra 147 %) impacts (among all diameters). The preferred pipe materials from an environmental point of view are precast concrete and High-Density Polyethylene (HDPE). Site-specific characteristics (specially the presence of rocky soil and asphalt placement) and material life span have a high influence on the overall environmental profile, whereas changes in transport distances have only a minor impact (<4 %).

Conclusions

Environmental impacts during the construction and renovation of sewers are subject to differences in material type, site-specific characteristics and material life span. Renovation of sewers has a large influence on all potential environmental impacts and costs and, hence, should not be omitted in LCA studies. The treatment and disposal processes of plastic pipes at the end of their life has to be accounted in LCA studies.

     

The environmental impact of activities after life: life cycle assessment of funerals

Purpose

Although the funeral market is propagating new ‘green’ alternatives and exploring innovative techniques like resomation, very little is known about the environmental impact of funerals. This research aimed to develop a benchmark of funerals, by quantifying the environmental impacts of the most common funeral techniques, i.e. burial and cremation, by identifying where the main impacts originate from and by comparing these impacts to impacts of other activities during a person’s life.

Methods

The environmental impacts of funerals were analysed by means of a life cycle assessment (LCA), based on Dutch company information, literature and expert judgements. The results were analysed per impact category but also on an aggregated level by means of shadow prices. Two sensitivity analyses were performed: one examined the high impact of cotton in funeral coffins; the other checked the results by means of another weighting method.

Results and discussion

The results showed no significant difference between the two funeral techniques in five impact categories. Burial has the lowest impact in more than half of the categories, but its impact is many times higher in the two most differing categories than for cremation. The total shadow price of burial is about 30 % higher than the shadow price of cremation, but the main cause for this difference is a highly debated category, namely land use. If the results would be considered without the shadow prices of land impact categories, burial would score 25 % lower than cremation. These results are representing average practise and may deviate on certain aspects for other countries, but as a starting point for further studies, this benchmark is well applicable.

Conclusions and recommendations

This study delivered an environmental benchmark of funerals and insights in the impacts of the individual processes, which can be used in further assessment of ’green’ funeral options. The benchmark results show that the environmental impact of funerals is largely determined by secondary processes and that the total impact can be quite small in comparison to other human activities. Besides these environmental insights, it is important to take into account social, cultural, climatic, local, economical and ethical arguments before changing policies or giving recommendations.

     

Bridge life cycle assessment with data uncertainty

Purpose

Although life cycle assessment (LCA) has been employed to analyze the environmental impacts of bridges, the uncertainties associated to LCA have not been studied, which have a profound effect on the LCA results. This paper is intended to provide a comprehensive environmental impact assessment of bridge with data uncertainty, by assigning probability distributions on the considered parameters, assessing the variability in the acquisition of inventory and identifying the key parameters with significant environmental impacts.

Methods

A life cycle assessment of a bridge in Shanxi Province of China was conducted in a cradle-to-grave manner, by considering the source of the uncertainty of LCA. A statistical method was applied to quantify the uncertainty of measured inventory data and to calculate the probability distribution of the data. The uncertainty propagation was conducted through using a Monte Carlo simulation. Finally, the factor which is of vital importance to the assessment result was identified by sensitivity analysis.

Results and discussion

For the case of bridge, normal distribution can be adopted to fit environmental substances and environmental impact in steel production. The distributions of the weighted value of human health damage, ecological system damage, and resource and energy consumption can be represented by an approximate similar normal distribution function. The coefficient of variance (COV) of each weighted value is about 40, 30 to 40, and about 6 %, respectively. The COV for the total environmental impact is about 10 % in all stages of the bridge’s life cycle, except the operation stage, which is up to 22.67 %. By conducting sensitivity analysis, PM₁₀, NO_x, and oil consumption was found to have a great influence on the result of human health damage, ecological system damage, and resource and energy consumption, respectively.

Conclusions

The COV for the total environmental impact is 22.67 % in the bridge’s operation stage; it is important to establish a reasonable maintenance strategy to decrease the uncertainty of the bridge’s environmental impact. The COVs of the weighted value for human health damage and resource and energy consumption have a quite modest difference among the four stages of the bridge’s life cycle. However, The COV of the weighted value for ecological system damage shows large difference among the four stages of the bridge’s life cycle; construction stage has the greatest uncertainty. In addition, different values of PM₁₀, NO_x, and oil consumption have a profound influence on the result of human health damage, ecological system damage, and resource and energy consumption, respectively.

     

The influence of durability and recycling on life cycle impacts of window frame assemblies

Purpose

A set of comparative life cycle assessment case studies were undertaken to explore key issues relating to the environmental impacts of building materials. The case studies explore modeling practice for long-life components by investigating (1) recycled content and end-of-life recycling scenarios and (2) service life and maintenance scenarios. The study uses a window unit frames as the object of comparison, allowing for exploration of multiple materials and assembly techniques.

Methods

Four window frame types were compared: aluminum, wood, aluminum-clad wood, and unplasticized PVC (PVCu). These used existing product life cycle inventory data which included primary frame material, coatings, weather stripping sealants, but not glazing. The functional unit was a window frame required to produce 1 m² of visible glazing, with similar thermal performance over a building lifespan of 80 years. The frames were compared using both the end-of-life and recycled content methods for end-of-life scenarios. The models were also tested using custom-use scenarios.

Results and discussion

Well-maintained aluminum window frames proved to be the least impactful option across all categories, in large part due to the credits delivered from recycling and expectations of long-life. Wood window frames had the least variability associated with maintenance and durability. The global warming potential (GWP) of a moderately maintained aluminum assembly was found to be 68 % less than PVCu and 50 % less than aluminum-clad wood. Using a long-life scenario, wood windows were found to have a 7 % lower GWP than the long-life scenario for aluminum-clad woods. Moderately and well-maintained aluminum windows require less energy to be produced and maintained over their lifetime than any of the wood scenarios. Expectations of service life proved to be the most important factor in considering environmental impact of frame materials.

Conclusions

The research shows significant gaps in available data—such as average realized life expectancies of common building components—while further underscoring that recycling rates are a driving factor in the environmental impact of aluminum building products. A modeling shift from the recycled content method to the end-of-life recycling method should promote goals of material recovery over pursuit of material with high recycled content. Hybrid methods, such as the use of Module D, may bridge the divide between these two approaches by providing due credit for use of recycled material, while supporting a design for recycling ethos. Further research is needed on how design and construction decisions affect collection and recovery rates in practice.

     

Conventional and exergetic life cycle assessment of organic rankine cycle implementation to municipal waste management: the case study of Mae Hong Son (Thailand)

Purpose

The critical issue of waste management in Thailand has been rapidly increasing in almost all of the cities due to the economic growth and rising population that could double the amount of solid waste in landfill area. The alternative ways of waste treatment that have more efficiency and effectiveness in terms of energy, ecology, and resources become the key issue for each municipality to replace the old fashioned technology and be able to enhance the ability of solid waste problem management. Waste to energy is one of the favorable approaches to diminish the amount of waste to landfill and utilize waste for electricity. The aim of this study is to identify and quantify the life cycle impacts of the municipal solid waste (MSW) of Mae Hong Son municipality (MHSM), and the case study is the selected waste treatment technology of the Refuse-Derived Fuel (RDF) hybrid with 20 kW of Organic Rankine Cycle (ORC).

Methods

The functional unit is defined as 1 t of MSW. The energy, environment, and resource impacts were evaluated by using Life Cycle Assessment (LCA); ReCipe and Net Energy Consumption were referred to calculate the environmental impacts and the benefits of energy recovery of WtE technology. Exergetic LCA was used to analyze the resource consumption, especially land use change.

Results and discussion

The results indicated that the environmental impacts were comparatively high at the operation stage of RDF combustion. On the other hand, the production stage of RDF illustrated the highest energy consumption. The ORC power generation mainly consumed resources from material and energy used. The ORC system demonstrated better results in terms of energy and resource consumption when applied to waste management, especially the land required for landfill. Substitution of electricity production from ORC system was the contributor to the reduction of both energy and resource consumption. Installation of spray dry and fabric filter unit to RDF burner can reduce heavy metals and some pollutants leading to the reduction of most of the impacts such as climate change, human toxicity, and fossil depletion which are much lower than the conventional landfill.

Conclusions

LCA results revealed that the environmental impacts and energy consumption can be reduced by applying the RDF and ORC systems. The exergetic LCA is one of the appropriate tools used to evaluate the resource consumption of MSW. It is obviously proven that landfill contributed to higher impacts than WtE for waste management.

     

Electric car life cycle assessment based on real-world mileage and the electric conversion scenario

Purpose

While almost all life cycle assessment (LCA) studies published so far are based on generic vehicles, type approval energy consumption as well as emission data, and application scenarios related to standardized laboratory-based driving cycles, this projects aims at quantifying the LCA based on a real-world vehicle composition and energy consumption data measured before and after the electric conversion of a mini class car. Furthermore, consequences of a second life of a vehicle’s glider on the environmental impact were investigated.

Methods

After having driven 100,000 km, a Smart was converted from combustion to electric in a laboratory project. The inventory was developed grounded upon materials data from laboratory measurements during the conversion process as well as on real-world energy consumption data prior and after the conversion. Three base models are compared in this life cycle impact assessment: a conventional new Smart (combustion engine), a new electric Smart, and a Smart converted from combustion engine to electric. Together with two sensitivity analyses (four different electricity mixes as well as urban vs. mixed driving conditions) and two EOL treatments, 36 scenarios have been quantified. The inventory is based on Ecoinvent database v 2.2 as a background system and includes raw material extraction.

Results and discussion

In urban use, the modeled battery electric vehicle has a favorable environmental impact compared to the ICEV even when charged with the German electricity mix of the year 2013. The advantage in summed up endpoints of the converted Smart is 23 % vs. the new electric Smart on average for the mixed driving conditions and 26 % for the urban driving conditions, respectively. Over a variety of impact categories, electricity consumption during battery cell production in China as well as impacts due to microelectronic components dominated the life cycle. Results for 18 midpoint categories, endpoints for damages to human health, to resource quality and to ecosystem quality as well as the Single score endpoints are reported.

Conclusions

This investigation points out that real-world treatments in inventory development can more specifically outline the environmental advantages of the electric car. The electric conversion of a used combustion engine vehicle can save an additional 16 % (CO₂-eq) and 19 % (single score endpoints) of the environmental impact over a lifetime, respectively, when compared with the new BEV.

     

Environmental trade-offs across cascading lithium-ion battery life cycles

Purpose

The purpose of this study was to analyze the environmental trade-offs of cascading reuse of electric vehicle (EV) lithium-ion batteries (LIBs) in stationary energy storage at automotive end-of-life.

Methods

Two systems were jointly analyzed to address the consideration of stakeholder groups corresponding to both first (EV) and second life (stationary energy storage) battery applications. The environmental feasibility criterion was defined by an equivalent-functionality lead-acid (PbA) battery. A critical methodological challenge addressed was the allocation of environmental impacts associated with producing LIBs across the EV and stationary use systems. The model also tested sensitivity to parameters such as the fraction of battery cells viable for reuse, service life of refurbished cells, and PbA battery efficiency.

Results and discussion

From the perspective of EV applications, cascading reuse of an LIB in stationary energy storage can reduce net cumulative energy demand and global warming potential by 15 % under conservative estimates and by as much as 70 % in ideal refurbishment and reuse conditions. When post-EV LIB cells were compared directly to a new PbA system for stationary energy storage, the reused cells generally had lower environmental impacts, except in scenarios where very few of the initial battery cells and modules could be reused and where reliability was low (e.g., life span of 1 year or less) in the secondary application.

Conclusions

These findings demonstrate that EV LIB reuse in stationary application has the potential for dual benefit—both from the perspective of offsetting initial manufacturing impacts by extending battery life span as well as avoiding production and use of a less-efficient PbA system. It is concluded that reuse decisions and diversion of EV LIBs toward suitable stationary applications can be based on life cycle centric studies. However, technical feasibility of these systems must still be evaluated, particularly with respect to the ability to rapidly analyze the reliability of EV LIB cells, modules, or packs for refurbishment and reuse in secondary applications.

     

Effect of geographical location and stochastic weather variation on life cycle assessment of biodiesel production from camelina in the northwestern USA

Purpose

The effect of regional factors on life cycle assessment (LCA) of camelina seed production and camelina methyl ester production was assessed in this study. While general conclusions from LCA studies point to lower environmental impacts of biofuels, it has been shown in many studies that the environmental impacts are dependent on location, production practices, and even local weather variations.

Methods

A cradle-to-farm gate and well-to-pump approaches were used to conduct the LCA. To demonstrate the impact of agro-climatic and management factors (weather condition, soil characteristics, and management practices) on the overall emissions for four different regions including Corvallis, OR, Pendleton, OR, Pullman, WA, and Sheridan, WY, field emissions were simulated using the DeNitrification-DeComposition (DNDC) model. openLCA v.1.4.2 software was used to quantify the environmental impacts of camelina seed and camelina methyl ester production.

Results and discussion

The results showed that greenhouse gas (GHG) emissions during camelina production in different regions vary between 49.39 and 472.51 kg CO₂-eq./ha due to differences in agro-climatic and weather variations. The GHG emissions for 1 kg of camelina produced in Corvallis, Pendleton, Pullman, and Sheridan were 0.76 ± 11, 0.55 ± 10, 0.47 ± 18, and 1.26 ± 6 % kg CO₂-eq., respectively. The GHG emissions for 1000 MJ of camelina biodiesel using camelina produced in Corvallis, Pendleton, Pullman, and Sheridan were 53.60 ± 5, 48.87 ± 5, 44.33 ± 7, and 78.88 ± 4 % kg CO₂-eq., respectively. Other impact categories such as acidification and ecotoxicity for 1000 MJ of camelina biodiesel varied across the regions by 43 and 103 %, respectively.

Conclusions

It can be concluded that process-based crop models such as DNDC in conjunction with Monte Carlo analysis are helpful tools to quantitatively estimate the influence of regional factors on field emissions which consequently can provide information about the expected variability in LCA results.

     

Environmental performance of social housing in emerging economies: life cycle assessment of conventional and alternative construction methods in the Philippines

Purpose

The environmental impact of the social building stock is relevant, particularly in emerging economies. Life cycle thinking is not yet established, however. Locally available, alternative building concepts could potentially reduce the environmental impact of the construction segment. This paper examines the environmental performance of “as-built” low-cost housing for an example of the Philippines, and the potential to reduce its environmental impact through use of three alternative building technologies: cement–bamboo frames, soil–cement blocks, and coconut board-based housing.

Methods

Life cycle assessment models are implemented and evaluated with software SimaPro, using the single-impact indicators global warming potential (GWP) and cumulative energy demand (CED) and the multi-impact indicator Impact2002+. According to EN 15978, the life cycle phase product and construction process (A), use stage (B), end-of-life (C) and supplementary information beyond the building life cycle (D) have been assessed. Theoretically calculated inflows from standard construction procedures used in phase A have been verified with 3 years of empirical data from implemented construction projects. For phases B, C and D, attention was given to service life, use-phase, allocation of waste products, biogenic carbon and land-use assumptions. Scenarios reflect the actual situation in the emerging economy. Processes, such as heat recovery from thermal utilization, which are not existing nor near to implementation, were excluded.

Results and discussion

For an assessment of the phases A–B–C–D with GWP, a 35% reduction of environmental impact for soil–cement blocks, 74% for cement–bamboo frame, and 83% for coconut board-based houses is obtained relative to a concrete reference house. In absolute terms, this relates to a reduction of 4.4, 9.3, and 10.3 t CO₂ equivalents over a service life of 25 years. CED showed higher impacts for the biogenic construction methods coconut board and cement–bamboo frames of +8.0 and +4.7%, while the soil–cement technology was evaluated ?7.1% compared to GWP. Sixteen of 17 midpoint categories of Impact2002+ confirmed an overall reduction potential of the alternative building methods, with the midpoint category land occupation being the exception rating the conventional practice over the alternatives.

Conclusions

It is concluded that the alternative construction technologies have substantial potential to reduce the environmental burden caused by the social housing sector. The service life of the alternative technologies plays a vital role for it. LCA for emerging economies needs to incorporate realistic scenarios applicable at their current state or belonging to the most probable alternatives to ensure valuable results. Recommendations for further research are provided.

     

Improved exergetic life cycle assessment through matrix reduction technique

Purpose

The concept of exergy can be used in LCA to quantify the value of natural resources consumed in production processes, as well as to assess the environmental impacts of waste streams. Prior studies noted the complexity of exergy accounting for wastes due to the diversity and complexity of waste streams. We develop an improved method to allow for rigorous exergy accounting of both resources and wastes.

Methods

The exergy content of a mass stream depends on many physical characteristics, including temperature, pressure, and chemical composition. We develop a novel matrix reduction technique to reduce data gathering requirements by multiple orders of magnitude. This method predivides the impact matrix into key rows and processes and “rest of economy” flows. Thermodynamic data can then be gathered for key flows emitted by key processes, and all other flows can be modeled using default values with little loss of accuracy.

Results and discussion

Our method is applied to an example LCA of electricity production via a natural gas combined cycle (NGCC) system. The case study finds that life cycle (economy-wide) exergetic efficiency of NGCC electricity production is ≈43 %, compared to a plant-level (local) exergetic efficiency of ≈54 %. The exergy content of life cycle waste flows is contained primarily in chemical exergy and physical exergy of flue gases, with nearly equal contributions. These waste exergy fluxes represent ≈3 % each of total input exergy.

Conclusions

The matrix reduction technique is found to be robust to assumptions about flows that are not directly modeled. By examining ranges of reasonable assumptions about mass flows not specifically modeled, we show that key rows and processes account for the vast majority of exergy content of interventions.

     

A comparative cradle-to-gate life cycle assessment of three concrete mix designs

Purpose

The concrete industry faces challenges to create concrete mix designs that reduce negative environmental impacts but also maintain high performance. This has led to ‘greener’ cementitious materials being developed which can decrease the use of traditional Portland cement (PC). This study intended to carry out a ‘cradle-to-gate’ life cycle assessment (LCA) on concrete mix designs containing different cementitious blends.

Methods

The aim of this study was to obtain the overall environmental impact, with a particular focus on carbon dioxide (CO₂) emissions of three concrete mix designs: CEM I (100 % PC content), CEM II/B-V (65 % PC content, 35 % Fly Ash (FA) content) and CEM III/B (30 % PC content, 70 % ground granulated blast furnace slag (GGBS) content). Evaluations of the three concrete mixes were performed using ‘SimaPro 8’ LCA software. A comparative cradle-to-gate LCA of these mixes has not currently been explored and could present a new insight into improving the environmental impact of concrete with the use of secondary materials. Recommendations from this work would help the industry make key decisions about concrete mix designs.

Results and discussion

Results show that Mix 2 (CEM II/B-V) and Mix 3 (CEM III/B) could potentially be taken forwards to improve their environmental impacts of concrete production. With respect to optimum mix design, it is strongly recommended that GGBS is selected as the addition of choice for reducing CO₂ emissions. FA does still considerably improve sustainability when compared to PC, but this work proved that inclusion of GGBS environmentally optimises the mix design even further. Advantages of using GGBS include lower CO₂ emissions, a substantial reduction of environmental impacts and an increased scope for sustainability due to the higher PC replacement levels that are permitted for GGBS. Due to mix designs enabling a higher contribution of GGBS additions, it would also indicate an increased positive effect regarding waste scenarios.

Conclusions and recommendations

The main contribution of this work demonstrated that concrete can be produced without loss of performance whilst significantly reducing the negative environmental impacts incurred in its production. The results obtained from this work would help to define the available options for optimising concrete mix design. The only material variations in each mix were the different cementitious blends. So, by determining the best option, a platform to make recommendations can be established based upon cementitious materials.

     

Comparative life cycle assessment of re-use and replacement for video projectors

Purpose

The current focus of environmental legislation for energy-using products is an efficient energy consumption in the use stage. However, the production and waste treatment of electronic products are also related to environmental impacts in terms of declining metal resources and growing waste streams. This paper investigates the environmental impacts of life time extension versus energy efficiency for the product group video projector using life cycle assessment (LCA).

Methods

The product under study was an average video projector based on three LCD projectors. The studied systems included two possibilities after a regular first usage period: reconditioning for a second use or replacement by a primary successor with an energy efficiency increase of 5 and 10%. All impacts addressed were accounted using the ReCiPe 2008 method. The impact contribution of projector components was identified at midpoint and endpoint levels, while life cycle impacts were calculated with a focus on three impact categories. Furthermore, the amortization period of production emissions was quantified.

Results and discussion

LCA results showed that the use stage dominates life cycle impacts of the global warming potential and primary energy demand. For the metal depletion potential, the production stage accounts for most of the total life cycle load. The highest shares in production emissions were identified for electronic components, namely printed wired boards and integrated circuits. Reconditioning and reuse of a secondary projector resulted in minor environmental impacts compared to the replacement and use of a primary projector with an energy efficiency increase of 5%. The saving potential of the primary energy demand is higher only in the case of a 10% more efficient device as compared to the secondary projector.

Conclusions

The study concluded that production emissions and their amortization period are relevant factors offsetting any environmentally beneficial measures applied during the use phase. The study suggests that life time extension of video projectors can provide higher environmental improvement potentials, while energy efficiency increase during usage is less beneficial, given that major improvements in energy efficiency do not occur. Recommendations are valid for this particular case study. The study suggests that the current focus of mandatory product requirements for energy-using products on energy efficiency increase should be extended to measures of life time extension in order to serve the intent of an integrated product policy.

     

On the boundary between economy and environment in life cycle assessment

Purpose

We investigate how the boundary between product systems and their environment has been delineated in life cycle assessment and question the usefulness and ontological relevance of a strict division between the two.

Methods

We consider flows, activities and impacts as general terms applicable to both product systems and their environment and propose that the ontologically relevant boundary is between the flows that are modelled as inputs to other activities (economic or environmental)—and the flows that—in a specific study—are regarded as final impacts, in the sense that no further feedback into the product system is considered before these impacts are applied in decision-making. Using this conceptual model, we contrast the traditional mathematical calculation of the life cycle impacts with a new, simpler computational structure where the life cycle impacts are calculated directly as part of the Leontief inverse, treating product flows and environmental flows in parallel, without the need to consider any boundary between economic and environmental activities.

Results and discussion

Our theoretical outline and the numerical example demonstrate that the distinctions and boundaries between product systems and their environment are unnecessary and in some cases obstructive from the perspective of impact assessment, and can therefore be ignored or chosen freely to reflect meaningful distinctions of specific life cycle assessment (LCA) studies. We show that our proposed computational structure is backwards compatible with the current practice of LCA modelling, while allowing inclusion of feedback loops both from the environment to the economy and internally between different impact categories in the impact assessment.

Conclusions

Our proposed computational structure for LCA facilitates consistent, explicit and transparent modelling of the feedback loops between environment and the economy and between different environmental mechanisms. The explicit and transparent modelling, combining economic and environmental information in a common computational structure, facilitates data exchange and re-use between different academic fields.