Comparative life cycle assessment of commonly used refrigerants in commercial refrigeration systems

Background, Aim and Scope In accordance with the Montreal Protocol and Kyoto Protocols, the refrigeration industry is currently evaluating the environmental performance of using HFCs and the so-called natural refrigerants, such as NH₃ or CO₂, as a long-term substitute for CFCs and HCFCs. The objective of this study is to quantify and compare the environmental impact throughout the life cycle of commercial refrigeration systems using HCFCs, HFCs and natural refrigerants. The function of the system under study is the refrigeration of a standard European supermarket with an average surface area of 2000 m², with a cooling duty of 130 kW over a period of 15 years. Different scenarios have been created involving a combination of the most common refrigerants (HCFCs (R-22), HFCs (R-134a, R-404A, R-407A, R-407C, R-410A, R-507A) and natural ones (R-744 and R-717)), with different commercial refrigeration systems (direct expansion, secondary loop and distributed), for medium and low temperature. For each scenario, an environmental evaluation was carried out, using the Life Cycle Assessment (LCA) methodology, to compare the influence of both the refrigerant and refrigeration system on the overall contribution to impact. Materials and Methods According to ISO 1404X standards, the analysis is performed at the following two levels. 1) Firstly, the emissions accounted for in the inventory stage are sorted into impact categories according to CML to obtain an indicator for each category (mandatory elements). 2) Secondly, the weighting of environmental data to a single unit is applied (optional elements). In compliance with ISO 14042, a sensitivity analysis is performed and three different impact assessment methods (Eco-Indicator’95, Eco-Indicator’99 and EPS’00) are applied in order to analyse their influence on the results. Results The use of natural refrigerants such as R-744 and R-717 in direct expansion and secondary loop systems, respectively, is completely justified from the environmental point of view, taking into account that it offers better results for most impact categories and for all impact assessment methods. The need to promote the use of R-744 has to be stressed, despite the fact that it is presently in an experimental phase, and that its current installation outputs are low, since it has been demonstrated that it will perform better in direct expansion systems from an environmental point of view in a future scenario in which its efficiency equals that of R-404A, in the same way as what occurs with R-717 for secondary loop systems. The need to replace HCFCs by HFCs or natural refrigerants is clearly shown by the contribution to the ozone depletion category. Discussion Energy efficiency of a refrigeration installation is a determinant parameter to assess pollutant emissions to the environment. If we assume a future scenario in which R-744 has an efficiency similar to that of R-404A, then R-744 is seen as the refrigerant which offers a better environmental behaviour in the direct expansion system. Conclusions It can be concluded that this study demonstrates how using the so-called natural refrigerants as a long-term substitute for CFCs and HCFCs, even better than the use of HFCs, is environmentally feasible. Recommendations and Perspectives More investment and research should be carried out with the aim of promoting the use of the so-called natural refrigerants to fulfil the Montreal and Kyoto Protocols. The technology used for R-744 is at a developmental stage, and presently, the efficiency of the installations operating with this refrigerant is lower than those others functioning with HFCs or R-717. In the near future, it will be demonstrated that this natural refrigerant can replace the use of other HFCs. ESS-Submission Editor: Mary Ann Curran (curran.maryann@epa.gov)     

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.     

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.

     

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.

     

Comparative life cycle assessment of three biohydrogen pathways

A life cycle assessment was performed to quantify and compare the energetic and environmental performances of hydrogen from wheat straw (WS-H₂), sweet sorghum stalk (SSS-H₂), and steam potato peels (SPP-H₂). Inventory data were derived from a pilot plant. Impacts were assessed using the impact 2002+ method. When co-product was not considered, the greenhouse gas (GHG) emissions were 5.60 kg CO_2eq kg⁻¹ H₂ for WS-H₂, 5.32 kg CO_2eq kg⁻¹ H₂ for SSS-H₂, and 5.18 kg CO_2eq kg⁻¹ H₂ for SPP-H₂. BioH₂ pathways reduced GHG emissions by 52-56% compared to diesel and by 54-57% compared to steam methane reforming production of H₂. The energy ratios (ER) were also comparable: 1.08 for WS-H₂, 1.14 for SSS-H₂ and 1.17 for SPP-H₂. A shift from SPP-H₂ to WS-H₂ would therefore not affect the ER and GHG emissions of these BioH₂ pathways. When co-product was considered, a shift from SPP-H₂ to WS-H₂ or SSS-H₂ decreased the ER, while increasing the GHG emissions significantly. Co-product yield should be considered when selecting BioH₂ feedstocks.     

Comparative life cycle assessment and social life cycle assessment of used polyethylene terephthalate (PET) bottles in Mauritius

Purpose

Improper disposal of used polyethylene terephthalate (PET) bottles constitute an eyesore to the environmental landscape and is a threat to the flourishing tourism industry in Mauritius. It is therefore imperative to determine a suitable disposal method of used PET bottles which not only has the least environmental load but at the same time has minimum harmful impacts on peoples employed in waste disposal companies. In this respect, the present study investigated and compared the environmental and social impacts of four selected disposal alternatives of used PET bottles.

Methods

Environmental impacts of the four disposal alternatives, namely: 100 % landfilling, 75 % incineration with energy recovery and 25 % landfilling, 40 % flake production (partial recycling) and 60 % landfilling and 75 % flake production and 25 % landfilling, were determined using ISO standardized life cycle assessment (ISO 14040:2006) and with the support of SimaPro 7.1 software. Social life cycle assessments were performed based on the UNEP/SETAC Guidelines for Social Life Cycle Assessment of products. Three stakeholder categories (worker, society and local community) and eight sub-category indicators (child labour, fair salary, forced labour, health and safety, social benefit/social security, discrimination, contribution to economic development and community engagement) were identified to be relevant to the study. A new method for aggregating and analysing the social inventory data is proposed and used to draw conclusions.

Results and discussion

Environmental life cycle assessment results indicated that highest environmental impacts occurred when used PET bottles were disposed by 100 % landfilling while disposal by 75 % flake production and 25 % landfilling gave the least environmental load. Social life cycle assessment results indicated that least social impacts occurred with 75 % flake production and 25 % landfilling. Thus both E-LCA and S-LCA rated 75 % flake production and 25 % landfilling to be the best disposal option.

Conclusions

Two dimensions of sustainability (environmental and social) when investigated using the Life Cycle Management tool, favoured scenario 4 (75 %?% flake production and 25 % landfilling) which is a partial recycling disposal route. One hundred percent landfilling was found out to be the worst scenario. The next step will be to explore the third pillar of sustainability, economic, and devise a method to integrate the three dimensions with a view to determine the sustainable disposal option of used PET bottles in Mauritius.     

Comparative life cycle assessment of rapeseed oil and palm oil

Background, aim and scope  

The environmental effect of globalisation has been debated intensively in the last decades. Only few well-documented analyses of global versus local product alternatives exist, whilst recommendations on buying local are vast. At the same time, the European Environmental Agency’s Third Assessment concludes that the resource use within the EU is stabilising at the expense of increased resource use for import of products to the EU. Taking its point of departure in vegetable oils, this article compares rapeseed oil and palm oil as a local and a global alternative for meeting the increasing demand for these products in the EU. By using detailed life cycle assessment (LCA), this study compares the environmental impacts and identifies alternative ways of producing rapeseed oil and palm oil to the EU market in order to reduce environmental impacts.     

Life cycle assessment of castor-based biorefinery: a well to wheel LCA

Purpose

Diminishing fossil resources and environmental concerns associated with their vast utilization have been in focus by energy policy makers and researchers. Among the different scenarios put forth to commercialize biofuels, various biorefinery concepts have aroused global interests because of their ability in converting biomass into a spectrum of marketable products and bioenergies. This study was aimed at developing different novel castor-based biorefinery scenarios for generating biodiesel and other co-products, i.e., ethanol and biogas. In these scenarios, glycerin, heat, and electricity were also considered as byproducts. Developed scenarios were also compared with a fossil reference system delivering the same amount of energy through the combustion of neat diesel.

Materials and methods

Life cycle assessment (LCA) was used to investigate the environmental consequences of castor biodiesel production and consumption with a biorefinery approach. All the input and output flows from the cultivation stage to the combustion in diesel engines as well as changes in soil organic carbon (SOC) were taken into account. Impact 2002+ method was used to quantify the environmental consequences.

Results and discussion

The LCA results demonstrated that in comparison with the fossil reference system, only one scenario (i.e., Sc-3 with co-production of significant amounts of biodiesel and biomethane) had 16% lower GHG emissions without even considering the improving effect of SOC. Moreover, resource damage category of this scenario was 50% lower than that of neat diesel combustion. The results proved that from a life cycle perspective, energy should be given priority in biorefineries because it is essential for a biorefinery to have a positive energy balance in order to be considered as a sustainable source of energy. Despite a positive effect on energy and GHG balances, these biorefineries had negative environmental impacts on the other damage categories like Human Health and Ecosystem Quality.

Conclusions

Although biorefineries offer unique features as promising solutions for mitigating climate change and reducing dependence on fossil fuels, the selection of biomass processing options and management decisions can affect the final results in terms of environmental evaluations and energy balance. Moreover, if biorefineries are focused on transportation fuel production, a great deal of effort should still be made to have better environmental performance in Human Health and Ecosystem Quality damage categories. This study highly recommends that future studies focus towards biomass processing options and process optimization to guarantee the future of the most sustainable biofuels.

     

Lightweighting in light commercial vehicles: cradle-to-grave life cycle assessment of a safety-relevant component

Purpose

Currently, the reduction of weight in automotive is a very important topic in order to lower the air pollution. In this context, the purpose of the present paper was to analyze a real case study through a comparison of the environmental sustainability between a conventional steel crossbeam for light commercial vehicles and an innovative lightweight aluminum one.

Methods

For both scenarios, a cradle-to-grave life cycle assessment methodology and a sensitivity analysis has been used through the study of the following phases: mineral extraction, component manufacturing, use on vehicle, and end of life. In particular, many primary data and a complete vehicle model simulation with three different European driving cycles have been used in order to reach the highest possible level of accuracy during the analysis.

Results and discussion

Regarding the manufacturing phase, the aluminum component’s production gave the highest impact because of the high energy required in the mineral reduction. Anyway, this stage of the analysis had a low effect on the entire LCA, because the benefit of weight reduction during vehicle use showed a strongly higher contribution. The urban driving cycle had the most relevant impact, as a consequence of the frequent start and stop operations and the longest time with engine at idle speed, while the extra-urban cycle is the less demanding due to its higher average speed and no start and stop.

Conclusions

In conclusion, the present research demonstrated the environmental importance of the lightweight for an actual case study in the commercial vehicles field.

     

Comparative life cycle assessment of uses of rice husk for energy purposes

Purpose  

Recently, the Thai government has been advancing the expanded use of biomass as an alternative source of energy substituting it for the fossil fuels that have been shown to be harmful to the environment. Rice husk, one of the main sources of biomass in Thailand, has already been used as an energy source in many different applications and has been successful in reducing the consumption of fossil fuels. At present (2011), the main use of rice husk in Thailand is as fuel to generate electricity. However, rice husk can potentially be used to produce other forms of energy such as cellulosic ethanol. This paper compares the environmental performance of the current main use of rice husk for energy purposes in the Thai context, i.e., for electricity generation with the prospective use, i.e., for cellulosic ethanol production. The results from this study will identify the more environmentally friendly option for use of rice husk for energy purposes.     

Comparative life cycle assessment of reused versus disposable dental burs

Purpose

Health care infection control has led to increased utilization of disposable medical devices, which has subsequently led to adverse environmental effects attributed to health care and its supply chain. In dental practice, the dental bur is a commonly used instrument that can be either reused or used once and then disposed. To evaluate the disparities in environmental impacts of disposable and reusable dental burs, a comparative life cycle assessment (LCA) was performed.

Methods

The functional unit was defined as one reusable dental bur, where the maximum instances reused was 30 (or in the case of a disposable, the equivalent functional unit would be 30 disposable dental burs). The system boundary included all cradle-to-grave aspects of both single-use and reused burs, including raw material extraction, manufacturing, packaging, distribution, reuse, and disposal. Primary data included the following: operating parameters for ultrasonic cleaning, manual cleaning, and autoclaving of the burs. The secondary data for raw material extraction and production of dental bur and packaging were obtained directly from life cycle inventory databases. Sensitivity analyses were also performed with respect to ultrasonic and autoclave loading.

Results and discussion

Findings from this research showed that when the ultrasonic and autoclave were loaded optimally, reusable burs had 40 % less of an environmental impact than burs used on a disposable basis. When the autoclave and ultrasonic were loaded to approximately two-third capacity, four environmental impact categories favored reusable burs (i.e., ozone depletion, smog, respiratory effects, exotoxicity), and four impact categories environmentally favored disposables (i.e., acidification, eutrophication, carcinogenics, and non-carcinogenics). When the autoclave and ultrasonic were loaded to approximately one-third capacity, reusable dental burs posed more negative environmental impacts in eight of nine environmental impact categories when compared to disposable burs.

Conclusions

Operational efficiency of ultrasonic and autoclave cleaning equipment should be emphasized to enhance the environmental performance of bur reuse. In fact, improper loading of the ultrasonic and autoclave can lead to greater adverse environmental impacts than if the burs were treated as disposables. The environmental and economic impacts associated with bur reuse are expected to be similar with other dental devices that are designated as disposable but are capable of being reused (e.g., scalpels, forceps).     

Comparative life cycle assessment of fired brick production in Thailand

The International Journal of Life Cycle Assessment - Fired bricks are an essential construction material in Thailand where the majority of fired brick kilns use rice husk as feedstock. Given the...     

Comparative life cycle assessment of graphitic carbon nitride synthesis routes

Graphitic carbon nitride (g-C₃N₄) has gained great interest as a visible-light-activated photocatalyst. As an emerging nanomaterial for environmental applications, its competitive performance and environmentally responsible synthesis are critical to its success. A powerful tool for informing material development with reduced environmental impacts is life cycle assessment (LCA). In this study, LCA is used to evaluate the environmental impacts of g-C₃N₄ nanosheet produced via eight existing synthesis routes. The results reveal electricity as the main contributor to the cumulative impacts of all eight g-C₃N₄ syntheses. There are opportunities to reduce energy demand, and consequently the synthesis impacts, by revising synthesis procedures (i.e., removing or reducing time of use of a piece of equipment), optimizing the calcination step (i.e., faster heating rate, lower heating time, lower temperature), and moving to cleaner electricity sources. Further, benchmarking the environmental impacts of g-C₃N₄ nanosheets to a well-established metal-based photocatalyst, titanium dioxide nanoparticles (nano-TiO₂), reveals mixed comparative results. The synthesis method substantially influences the comparative impacts. Considering use-phase benefits of activating g-C₃N₄ with visible wavelength light emitting diodes compared to ultraviolet (UV) wavelengths for nano-TiO₂ results in a 52% energy demand reduction (in kWh). Performance of g-C₃N₄ compared to a high-energy disinfection approach (i.e., conventional UV) reveals an inability to meet drinking water disinfection standards for viral load reduction (4-log reduction) with any mass of g-C₃N₄, given its high embodied resource footprint. This work establishes a foundation to inform and direct g-C₃N₄ nanosheets toward improved sustainable development.     

Integrating life cycle assessment and life cycle cost: a review of environmental-economic studies

The International Journal of Life Cycle Assessment - The purpose of this document is to carry out a critical review of the existing literature by specifically addressing the following: (i) the...     

Comparative life cycle assessment and financial analysis of mixed culture polyhydroxyalkanoate production

A life cycle assessment and financial analysis of mixed culture PHA (PHA(MC)) and biogas production was undertaken based on treating an industrial wastewater. Internal rate of return (IRR) and non-renewable CO(2)eq emissions were used to quantify financial viability and environmental impact. PHA(MC) was preferable to biogas production for treating the specified industrial effluent. PHA(MC) was also financially attractive in comparison to pure culture PHA production. Both PHA production processes had similar environmental impacts that were significantly lower than HDPE production. A large potential for optimisation exists for the PHA(MC) process as financial and environmental costs were primarily due to energy use for downstream processing. Under the conditions used in this work PHA(MC) was shown to be a viable biopolymer production process and an effective industrial wastewater treatment technology. This is the first study of its kind and provides valuable insight into the PHA(MC) process.     

The potential impact of a krill fishery upon pelagic fish in the Prydz Bay area of Antarctica

Summary RMT hauls taken during FIBEX in the Prydz Bay region showed a relatively high incidence of fish compared with most previous reports from the Atlantic sector. Overall, fish comprised 3.8% by number and 8.1% by weight, and these figures rose to 26.8 and 46.1%, respectively in aimed hauls over the continental shelf. Even when only hauls with>50% E. superba are considered, fish accounted for almost 1% by weight of the catch overall, and more in aimed hauls or those taken over the continental shelf. Species composition differed markedly between the continental shelf and deep water zones. Over the shelf the fish catch comprised mainly Pleuragramma antarcticum and channichthyid juveniles, while over deep water it consisted mainly of myctophids and Notolepis coatsi. These data indicate that the potentially large krill fishery in this region could affect the populations of some shelf dwelling demersal species by increasing the mortality among their pelagic juvenile stages.     

Comparative life cycle assessment of first- and second-generation ethanol from sugarcane in Brazil

The International Journal of Life Cycle Assessment - The use of bagasse and trash from sugarcane fields in ethanol production is supposed to increase the ethanol yield per hectare, to reduce the...     

Comparative life cycle assessment of smartphone reuse: repurposing vs. refurbishment

Purpose

Waste management for end-of-life (EoL) smartphones is a growing problem due to their high turnover rate and concentration of toxic chemicals. The versatility of modern smartphones presents an interesting alternative waste management strategy: repurposing. This paper investigates the environmental impact of smartphone repurposing as compared to traditional refurbishing using Life Cycle Assessment (LCA).

Methods

A case study of repurposing was conducted by creating a smartphone “app” that replicates the functionality of an in-car parking meter. The environmental impacts of this prototype were quantified using waste management LCA methodology. Studied systems included three waste management options: traditional refurbishment, repurposing using battery power, and repurposing using a portable solar charger. The functional unit was defined as the EoL management of a used smartphone. Consequential system expansion was employed to account for secondary functions provided; avoided impacts from displaced primary products were included. Impacts were calculated in five impact categories. Break-even displacement rates were calculated and sensitivity to standby power consumption were assessed.

Results and discussion

LCA results showed that refurbishing creates the highest environmental impacts of the three reuse routes in every impact category except ODP. High break-even displacement rates suggest that this finding is robust within a reasonable range of primary cell phone displacement. The repurposed smartphone in-car parking meter had lower impacts than the primary production parking meter. Impacts for battery-powered devices were dominated by use-phase charging electricity, whereas solar-power impacts were concentrated in manufacturing. Repurposed phones using battery power had lower impacts than those using solar power, however, standby power sensitivity analysis revealed that solar power is preferred if the battery charger is left plugged-in more than 20 % of the use period.

Conclusions

Our analysis concludes that repurposing represents an environmentally preferable EoL option to refurbishing for used smartphones. The results suggest two generalizable findings. First, primary product displacement is a major factor affecting whether any EoL strategy is environmentally beneficial. The benefit depends not only on what is displaced, but also on how much displacement occurs; in general, repurposing allows freedom to target reuse opportunities with high “displacement potential.” Second, the notion that solar power is preferable to batteries is not always correct; here, the rank-order is sensitive to assumptions about user behavior.