Assessing the carbon footprint of the transport sector in mega cities via streamlined life cycle assessment: a case study of Shenzhen,South China

Purpose

As one of largest energy consumers, the transport sector (TS) has significant impacts on the environment. Shenzhen, a developed megacity in South China, plays a leadership role in promoting the development of energy efficient vehicles in China.

Methods

This paper aims to assess the carbon footprint (CF) of the TS in Shenzhen via a Streamlined Life Cycle Assessment method. Consequently, the current environmental performance of the TS is evaluated and improvement potentials are examined.

Results and discussion

The results show that CF has gained rapid growth over the past decade at an annual rate of 15.3 %, closely corresponding with the growth of the Gross Domestic Product (18.9 %) in Shenzhen. The total CF in 2013 was estimated as 50.7 million tons (ranging from 41.7 to 59.9). Road based freight transport accounts for the largest share of the TS’ emissions. The most significant contributors in this sector are: light duty trucks, urban public transport bus service, and passenger air transport. Meanwhile, this study took new energy vehicles into consideration in order to explore the range of CF mitigation potential in Shenzhen. The potential carbon abatement is not significant in comparison with the impact growth derived from the increasing freight and passenger transport based on the assumption that the transport intensity and its annual growth rate maintain at the current levels.

Conclusions

This study offers a useful approach to evaluate the available options for sustainable transport system planning in Shenzhen. For carbon emissions reductions from the TS, policies and technological innovations are essential to facilitate the transition to a low carbon TS. In addition, the methodology developed in this study could be used for assessing CF in other sectors.

     

A new hybrid method for reducing the gap between WTW and LCA in the carbon footprint assessment of electric vehicles

Purpose

The well-to-wheel (WTW) methodology is widely used for policy support in road transport. It can be seen as a simplified life cycle assessment (LCA) that focuses on the energy consumption and CO₂ emissions only for the fuel being consumed, ignoring other stages of a vehicle’s life cycle. WTW results are therefore different from LCA results. In order to close this gap, the authors propose a hybrid WTW+LCA methodology useful to assess the greenhouse gas (GHG) profiles of road vehicles.

Methods

The proposed method (hybrid WTW+LCA) keeps the main hypotheses of the WTW methodology, but integrates them with LCA data restricted to the global warming potential (GWP) occurring during the manufacturing of the battery pack. WTW data are used for the GHG intensity of the EU electric mix, after a consistency check with the main life cycle impact (LCI) sources available in literature.

Results and discussion

A numerical example is provided, comparing GHG emissions due to the use of a battery electric vehicle (BEV) with emissions from an internal combustion engine vehicle. This comparison is done both according to the WTW approach (namely the JEC WTW version 4) and the proposed hybrid WTW+LCA method. The GHG savings due to the use of BEVs calculated with the WTW-4 range between 44 and 56 %, while according to the hybrid method the savings are lower (31–46 %). This difference is due to the GWP which arises as a result of the manufacturing of the battery pack for the electric vehicles.

Conclusions

The WTW methodology used in policy support to quantify energy content and GHG emissions of fuels and powertrains can produce results closer to the LCA methodology by adopting a hybrid WTW+LCA approach. While evaluating GHG savings due to the use of BEVs, it is important that this method considers the GWP due to the manufacturing of the battery pack.

     

Evaluating the carbon footprint of Chilean organic blueberry production

Purpose

Chile is the second largest blueberry producer and exporter worldwide. At the global level, there is a lack of information by means of field data about greenhouse gas emissions from organic cultivation of this fruit. This study obtains a resource use inventory and assesses the cradle-to-farm gate carbon footprint (CF) of organic blueberry (Vaccinium corymbosum) production in the main cultivation area of Chile in order to identify CF key factors and to provide improvement measures.

Methods

The method used in this study follows the ISO 14040 framework and the main recommendations in the PAS 2050 guide as well as its specification for horticultural products PAS 2050-1. Primary data were collected for three consecutive production seasons from five organic Chilean blueberry orchards and calculations conducted with the GaBi 4 software. Agricultural factors such as fertilizers, pesticides, fossil fuels, electricity, materials, machinery, and direct land use change (LUC) are included. Only three orchards present direct LUC.

Results and discussion

The direct LUC associated with the conversion from annual crops to perennial crops is a key factor in the greenhouse gas removals from the orchards. When accounting for direct LUC, the CF of organic blueberry production in the studied orchards ranges from removals (reported as negative value) of ?0.94 to emissions of 0.61 kg CO₂-e/kg blueberry. CF excluding LUC ranges from 0.27 to 0.69 kg CO₂-e/kg blueberry. The variability in the results of the orchards suggests that the production practices have important effects on the CF. The factors with the greatest contribution to the greenhouse emissions are organic fertilizers followed by energy use causing, on average, 50 and 43 % of total emissions, respectively.

Conclusions

The CF of the organic blueberry orchards under study decreases significantly when taking into account removals related to LUC. The results highlight the importance of reporting separately the greenhouse gas (GHG) emissions from LUC. The CF of blueberry production could be reduced by optimizing fertilizer application, using cover crops and replacing inefficient tractors and large irrigation pumps. The identification of improvement measures would be a useful guide for changing grower practices.

     

Spatial and technological variability in the carbon footprint of durum wheat production in Iran

Purpose

The purpose of this study was to quantify the spatial and technological variability in life cycle greenhouse gas (GHG) emissions, also called the carbon footprint, of durum wheat production in Iran.

Methods

The calculations were based on information gathered from 90 farms, each with an area ranging from 1 to 150 ha (average 16 ha). The carbon footprint of durum wheat was calculated by quantifying the biogenic GHG emissions of carbon loss from soil and biomass, as well as the GHG emissions from fertilizer application and machinery use, irrigation, transportation, and production of inputs (e.g., fertilizers, seeds, and pesticides). We used Spearman’s rank correlation to quantify the relative influence of technological variability (in crop yields, fossil GHG emissions, and N₂O emissions from fertilizer application) and spatial variability (in biogenic GHG emissions) on the variation of the carbon footprint of durum wheat.

Results and discussion

The average carbon footprint of 1 kg of durum wheat produced was 1.6 kg CO₂-equivalents with a minimum of 0.8 kg and a maximum of 3.0 kg CO₂-equivalents. The correlation analysis showed that variation in crop yield and fertilizer application, representing technological variability, accounted for the majority of the variation in the carbon footprint, respectively 76 and 21%. Spatial variation in biogenic GHG emissions, mainly resulting from differences in natural soil carbon stocks, accounted for 3% of the variation in the carbon footprint. We also observed a non-linear relationship between the carbon footprint and the yield of durum wheat that featured a scaling factor of ?2/3. This indicates that the carbon footprint of durum wheat production (in kg CO₂-eq kg^?1) typically decreases by 67% with a 100% increase in yield (in kg ha^?1 year^?1).

Conclusions

Various sources of variability, including variation between locations and technologies, can influence the results of life cycle assessments. We demonstrated that technological variability exerts a relatively large influence on the carbon footprint of durum wheat produced in Iran with respect to spatial variability. To increase the durum wheat yield at farms with relatively large carbon footprints, technologies such as site-specific nutrient application, combined tillage, and mechanized irrigation techniques should be promoted.

     

A flexible parametric model for a balanced account of forest carbon fluxes in LCA

Purpose

Despite a mature debate on the importance of a time-dependent account of carbon fluxes in life cycle assessments (LCA) of forestry products, static accounts of fluxes are still common. Time-explicit inventory of carbon fluxes is not available to LCA practitioners, since the most commonly used life cycle inventory (LCI) databases use a static approach. Existing forest models are typically applied to specific study fields for which the detailed input parameters required are available. This paper presents a simplified parametric model to obtain a time-explicit balanced account of the carbon fluxes in a forest for use in LCA. The model was applied to the case of spruce as an example.

Methods

The model calculated endogenous and exogenous carbon fluxes in tons of carbon per hectare. It was designed to allow users to choose (a) the carbon pools to be included in the analysis (aboveground and belowground carbon pools, only aboveground carbon or only carbon in stem); (b) a linear or sigmoidal dynamic function describing biomass growth; (c) a sigmoidal, negative exponential or linear dynamic function describing independently the decomposition of aboveground and belowground biomass; and (d) the forest management features such as stand type, rotation time, thinning frequency and intensity.

Results and discussion

The parametric model provides a time-dependent LCI of forest carbon fluxes per unit of product, taking into account the typically limited data available to LCA practitioners, while providing consistent and robust outcomes. The results obtained for the case study were validated with the more complex CO2FIX. The model ensures carbon balance within spatial and time delimitation defined by the user by accounting for the annual biomass degradation and production in each carbon pool. The inventory can be used in LCA studies and coupled with classic indicators (e.g. global warming potential) to accurately determine the climate impacts over time. The model is applicable globally and to any forest management practice.

Conclusions

This paper proposes a simplified and flexible forest model, which facilitates the implementation in LCA of time-dependent assessments of bio-based products.

     

Methane oxidation,biogenic carbon,and the IPCC’s emission metrics. Proposal for a consistent greenhouse-gas accounting

Purpose

The fifth assessment report by the IPCC includes methane oxidation as an additional indirect effect in the global warming potential (GWP) and global temperature potential (GTP) values for methane. An analysis of the figures provided by the IPCC reveals they lead to different outcomes measured in CO₂-eq., depending on whether or not biogenic CO₂ emissions are considered neutral. In this article, we discuss this inconsistency and propose a correction.

Methods

We propose a simple framework to account for methane oxidation in GWP and GTP in a way that is independent on the accounting rules for biogenic carbon. An equation with three components is provided to calculate metric values, and its application is tested, together with the original IPCC figures, in a hypothetical example focusing on GWP100.

Results and discussion

The hypothetical example shows that the only set of GWP100 values consistently leading to the same outcome, regardless of how we account for biogenic carbon, is the one proposed in this article. Using the methane GWP100 values from the IPCC report results in conflicting net GHG emissions, thus pointing to an inconsistency.

Conclusions

In order to consistently discriminate between biogenic and fossil methane sources, a difference of 2.75 kg CO₂-eq. is needed, which corresponds to the ratio of the molecular weights of CO₂ and methane (44/16). We propose to correct the GWP and GTP values for methane accordingly.

     

Life cycle inventory practices for major nitrogen,phosphorus and carbon flows in wastewater and sludge management systems

Purpose

Nitrogen, phosphorus and carbon originating from wastewater and sludge can, depending on their partitioning during wastewater treatment, either become available as potential resources or leave as emissions. Several reviews have highlighted the dependence of life cycle assessment (LCA) results on the inventory data. To provide a foundation for future assessments of systems in which resources are utilised from wastewater or sludge, this paper identifies common practice and highlights deficiencies in the selection and quantification of nitrogen, phosphorus and carbon containing flows.

Methods

Inventories of major direct flows containing nitrogen, phosphorus and carbon in 62 studies on wastewater and sludge management operations have been reviewed. A special focus was put on flows of nitrogen, phosphorus and carbon originating from the wastewater and sludge and on how these are either leaving the system as emissions and hereby contributing to environmental impacts, or how potential resource flows of these elements are accounted for, in particular when sludge is used in agriculture.

Results and discussion

The current study shows a large variation between studies regarding what resource and emission flows were included in inventories on wastewater and sludge treatment, the type of data used (primary or secondary data) and, when flows have been modelled rather than measured, how the modelling has been done. Except for nitrogen and phosphorus emissions via the effluent, which were generally quantified using measured data or data modelled to represent the specific situation, direct emissions to air from the water and sludge lines at the wastewater treatment plant were mostly estimated using secondary data, sometimes of poor data quality. In systems where resources were recovered through agricultural application of sludge, studies often credited the system for avoided use of mineral fertiliser, but the considered replacement ratio differed.

Conclusions

The current review identified increased completeness and specificity in the modelling of the evaluated flows as particularly relevant for future studies and highlighted a need for improved transparency of data inventories. The review can be used as a support for LCA analysts in future studies, providing an inventory of common practices and pinpointing deficiencies, and can thereby support more conscious and well-motivated choices as regard which flows to include in assessments and on the quantification of these flows.

     

Life cycle assessment in the furniture industry: the case study of an office cabinet

Purpose

In an effort to reduce the environmental impacts of the furniture sector, this study aimed to diagnose the environmental performance of an office cabinet throughout its life cycle.

Methods

An attributional life cycle assessment (LCA) was used, based on the ISO 14044 Standard and ILCD Handbook. The scope of the study considered the entire supply chain, from cradle to grave, including the steps of pre-manufacturing, manufacturing, use, and post-use of the product. The impact assessment method was the International Reference Life Cycle Data System (ILCD) 2011 midpoint.

Results and discussion

The results identified that the most significant environmental impact of the furniture life cycle was due to the distances covered and production of the main raw material, wood medium-density particleboard (MDP). The evaluation of transport scenarios showed environmental tradeoffs for truck fuel switches and environmental gains for the distribution of MDP from closer suppliers by truck, as well as from current supplier by truck and ship in the major categories. Furthermore, evaluation of the office cabinet post-use options showed that reuse, recycling, or energy recovery from waste cause significant environmental gains in the major categories. Wooden furniture is a potential carbon sink if its life cycle does not emit more greenhouse gases than its materials can store. The impacts of substitution scenarios varied depending on the type of product avoided.

Conclusions

The LCA proved a powerful method to diagnose and manage environmental impacts in complex product systems. The sensitivity analysis showed that it is possible to reduce the environmental impacts and, at the same time, make the furniture industry increase its economic gains and net carbon stock in the anthroposphere.

     

Development of a Climate Choice meal concept for restaurants based on carbon footprinting

Purpose

Significant reductions in greenhouse gas emissions from food production and consumption can be made at the level of individual diet. Together with the food and beverage sector, consumers could play a significant role by making informed choices that benefit the environment and their own health. Communicating information on carbon footprints to consumers is challenging and should be made very simple, yet reliable. This sector is showing interest in using eco-design tools to decrease climate change impacts of their meals.

Methods

A long-term concept for communicating information on carbon footprints associated with meals was developed in Finland. The criteria for a Climate Choice meal were created through stakeholder dialogue, and three restaurant operators piloted the concept in 25 restaurants. In addition to climate change impacts, possibilities to include other sustainability criteria were reviewed. The concept was based on simplified carbon footprinting of raw material production and processing of ingredients for 105 commonly selected lunches. The carbon footprint calculations allowed the development of the Climate Choice meal concept, its criteria, and piloting the concept. Based on experiences from restaurants and consumers from the pilot phase, final criteria were developed.

Results and discussion

The Climate Choice meal concept was created using two alternative climate criteria: one for immediate implementation and another for future implementation, in cases where carbon footprinting is feasible for restaurants. The criteria for immediate implementation include a list of mainly plant-based ingredients with low carbon footprint. Regarding future criteria, it should be made easy enough for restaurants to estimate the carbon footprints of their meals, allowing labeling of meals when their carbon footprints are at least 25 % smaller than for an average meal. In addition to the two climate criteria, Climate Choice meals need to follow Finnish public catering nutritional recommendations, taking into account that fish species on the Red List of WWF’s Finnish seafood guide are prohibited.

Conclusions

To promote climate-friendly eating, a long-term concept rather than a short-term campaign is needed. There is interest among consumers and restaurants for information on food carbon footprints and sustainability. Lunch is regarded as a good opportunity for consumers to learn about climate-friendly eating. The main challenges are to produce sufficiently reliable background data and to raise consumer and the food and beverage sector interest and understanding of carbon footprints associated with food.

     

LCA study of unconsumed food and the influence of consumer behavior

Purpose

In the light of anthropogenic resource depletion and the resulting influences on the greenhouse effect as well as globally occurring famine, food waste has garnered increased public interest in recent years. The aim of this study is to analyze the environmental impacts of food waste and to determine to what extent consumers’ behavior influences the environmental burden of food consumption in households.

Methods

A life cycle assessment (LCA) study of three food products is conducted, following the ISO 14040/44 life cycle assessment guidelines. This study addresses the impact categories climate change (GWP100), eutrophication (EP), and acidification (AP). Primary energy demand (PED) is also calculated. For adequate representation of consumer behavior, scenarios based on various consumer types are generated in the customer stage. The customer stage includes the food-related activities: shopping, storage, preparation, and disposal of food products as well as the disposal of the sales packaging.

Results and discussion

If the consumer acts careless towards the environment, the customer stage appears as the main hotspot in the LCA of food products. The environmental impact of food products can be reduced in the customer stage by an environmentally conscious consumer. Shopping has the highest effect on the evaluated impact categories and the PED. Additionally, consumers can reduce the resulting emissions by decreasing the electric energy demand, particularly concerning food storage or preparation. Moreover, results show that the avoidance of wasting unconsumed food can reduce the environmental impact significantly.

Conclusions

Results of this study show that the influence of consumer behavior on the LCA results is important. The customer stage of food products should not be overlooked in LCA studies. To enable comparison among results of other LCA studies, the LCA community needs to develop a common methodology for modeling consumer behavior.

     

Review: life cycle assessments in Nigeria,Ghana, and Ivory Coast

Purpose

Life cycle assessments (LCAs) are considered common quantitative environmental techniques to analyze the environmental impact of products and/or services throughout their entire life cycle. A few LCA studies have been conducted in West Africa. This study aimed to discuss the availability of LCA (and similar) studies in Nigeria, Ghana, and Ivory Coast.

Methods

An online literature review of reports published between 2000 and 2016 was conducted using the following keywords: “life cycle assessment,” “carbon footprinting,” “water footprinting,” “environmental impact,” “Nigeria,” “Ghana” and “Ivory Coast.”

Results and discussion

A total of 31 LCA and environmental studies in Nigeria, Ghana, and Ivory Coast were found; all but one were conducted after 2008. These were mainly academic and most were publicly available. The industries studied included energy sector, waste management, real estate, food sector, and others such as timber and gold. The minimal number of studies on LCAs and environmental impacts in these West African states could be because companies are failing to promote quantitative environmental studies or studies are kept internally for the use of other assessment techniques. Furthermore, it could be that academic research institutions lack cutting-edge research resources for LCA, environmental impact, carbon, and water footprinting studies.

Conclusions

Further quantitative environmental studies should be conducted in Nigeria, Ghana, and Ivory Coast to increase the understanding of environmental impacts. In these countries, the existence of LCA studies (and by association the localized life cycle inventory (LCI) datasets) is crucial as more companies request this information to feed into background processes.

     

Review: life-cycle assessment,water footprinting,and carbon footprinting in Portugal

Purpose

A review of readily available quantitative environmental data was conducted in order to determine the state of sustainability reporting and identify possible future research areas in Portugal.

Methods

Internet searches of articles written in English and published between 2001 and 2015 were conducted using the keywords “life-cycle assessment,” “LCA,” “water footprint,” “carbon footprint,” and “Portugal.” Additionally, reports from the Global Reporting Initiative (2015 only) were included in the search.

Results and discussion

It was found that 79% of reports found were published in the period 2011–2015. Several reports were found for the forestry, paper and pulp, food and beverage, energy and electricity, waste management, and automotive industries, while no reports were found for the textile, footwear and clothing, and base metal and mineral industries. As such, these are industries on which future studies might focus. No reports found were published by governmental organizations, although it is thought that expanding the search to include Portuguese language results would yields more results. The majority (68%) of companies reporting to the GRI adhered to the relevant guidelines.

Conclusions

A total of 72 reports were found (41 LCAs, water- or carbon footprints, and 31 GRI reports). It is unclear if there are other reports that may be restricted to “hidden” datasets or company specific archives. The aim of this report was to highlight those that were available to a non-specialist or international audiences trying to gain a greater understanding of the LCA space in Portugal.

     

Can social research paradigms justify the diversity of approaches to social life cycle assessment?

Purpose

The present paper aims to offer an explanation for the diversity of methodological approaches proposed up to the present for social life cycle assessment (sLCA), tracking down its roots in the cultural and scientific heritage of social sciences and especially management sciences. A second aim is to shift the current debate on methodologies to an epistemological level, presenting the first results of an ongoing critical review about which underlying paradigms have been applied in sLCA literature.

Methods

This paper moves from the hypothesis that the diversity of positions in philosophy of science and the “multiparadigmatic” character of social sciences have had repercussions on sLCA literature since its beginnings, probably in an unconscious manner. Therefore, a discriminating reflection on the scientific and disciplinary inheritance that can represent the roots of sLCA has been conducted. The philosophy of science and the role of different research paradigms in social sciences have been deepened to provide an overview of the main elements of a paradigm (in terms of ontology, epistemology, and methodology). Finally, a brief but critical review of 133 selected scientific contributions on sLCA has been conducted to highlight which paradigms have been applied in sLCA studies.

Results and discussion

Recognizing that boundaries between paradigms are subtle and that researchers are rarely conscious of which paradigm underpins their works, a distinction between the interpretivist and post-positivist approaches used by the studies has been carried out on the basis of a text analysis conducted by identifying the main “literal” criteria. From an initial population of 209 studies, we excluded those concerning reviews of sLCA literature and those with selected criteria that were insufficient to catch the epistemological viewpoint of the authors. Among the remaining papers (133), 73 % has been ascribed to the group of interpretivism-oriented paradigms and only 24 % could be ascribed to the post-positivist one; the remaining 3 % is represented by studies with both characteristics. This data deserves some attention because, since the beginnings of sLCA methodologies, most sLCA publications explicitly suggest having the same underlying perspectives as environmental life cycle assessment (eLCA).

Conclusions

In light of the reflections carried out, we argue that it is important, before going into methodological questioning issues, to be aware of which paradigm is underlying. Indeed, in this phase of sLCA development, scholars should go beyond the simple methodological debate and recognize the “multilayered” nature of social phenomena and the multiparadigmatic characteristics of social and management sciences.

     

Conceptualising attributional LCA is necessary for resolving methodological issues such as the appropriate form of land use baseline

Purpose

The purposes of this commentary are to further an on-going debate concerning the appropriate form of land use baseline for attributional life cycle assessment (LCA) and to respond to a number of arguments advanced by Soimakallio (Int J Life Cycle Assess 20:1364–1375, 2016). The commentary also seeks to clarify the conceptual nature of attributional LCA.

Methods

The overarching approach for resolving the question of the appropriate form of land use baseline for attributional LCA is to clarify what attributional LCA is seeking to represent, i.e. methodological questions can only be resolved if it is clear what the method is seeking to do. An illustrative example is used to explore the different results produced by ‘natural regeneration’ and ‘natural’ baselines.

Results and discussion

It is proposed that attributional LCA should be conceptualised as an inventory of anthropogenic impacts, conceptually akin to other forms of environmental inventory, such as national GHG inventories. The use of natural regeneration baselines is not consistent with this conceptualisation of attributional LCA, and such baselines necessitate further ad hoc or arbitrary adjustments, such as arbitrary temporal windows or the inconsistent treatment of natural emissions.

Conclusions

The use of natural regeneration baselines may be motivated by the impulse to make attributional LCA both an inventory-type method and an assessment of system-wide change. Pulling attributional LCA in two different directions at once results in a conceptually and methodologically incoherent method. The solution is to recognise attributional LCA as an inventory-type method, which therefore has distinct but complementary uses to consequential LCA, which is an assessment of system-wide change.

     

The EcoSpold 2 format—why a new format?

Purpose

This paper introduces the new EcoSpold data format for life cycle inventory (LCI).

Methods

A short historical retrospect on data formats in the life cycle assessment (LCA) field is given. The guiding principles for the revision and implementation are explained. Some technical basics of the data format are described, and changes to the previous data format are explained.

Results

The EcoSpold 2 data format caters for new requirements that have arisen in the LCA field in recent years.

Conclusions

The new data format is the basis for the Ecoinvent v3 database, but since it is an open data format, it is expected to be adopted by other LCI databases. Several new concepts used in the new EcoSpold 2 data format open the way for new possibilities for the LCA practitioners and to expand the application of the datasets in other fields beyond LCA (e.g., Material Flow Analysis, Energy Balancing).

     

Carbon footprint of pomegranate (<Emphasis Type="Italic">Punica granatum</Emphasis>) cultivation in a hyper-arid region in coastal Peru

Purpose

The cultivation of pomegranate worldwide has increased sharply in the past few years, mainly due to the growing perception that this fruit has numerous medical benefits. Despite the proliferation of studies delving into the properties of pomegranate from a medical and dietary perspective, its analysis from an environmental perspective has yet to be carried out in depth. Hence, the present study aims at understanding the life cycle environmental impacts in terms of greenhouse gas (GHG) emissions derived from the cultivation, processing and distribution abroad of fresh pomegranate grown at an innovative farm in a hyper-arid area in the region of Ica (Peru).

Methods

The international standards for life cycle methodologies were considered in order to obtain the overall carbon footprint (CFP) of fresh pomegranate cultivation, processing and distribution. Data acquisition was performed at the cultivation site and supported by the ecoinvent^® database, whereas GHG emissions were modelled using the IPCC 2007 method. In addition, biogenic carbon sequestration was included in the assessment, using two distinct models, a first one to model the aerial carbon sequestered by the pomegranate trees and a second, using the IPCC Soil Carbon Tool for soil storage.

Results and discussion

Annual results show that on-site GHG emissions can be mitigated to a great extent in the first years of production thanks to biogenic carbon sequestration. However, through time, this tendency is reverted, and in years of maximum pomegranate productivity, GHG emissions are estimated to outweigh those linked to sequestration, despite the relevant minimization of emissions when using innovative irrigation schemes as compared to the conventional flood irrigation in the region.

Conclusions

Despite the threat in terms of water depletion and security, the expansion of Peru’s agricultural frontier in hyper-arid areas appears to be a feasible strategy for carbon fixation, although current agricultural practices, such as the use of machinery or electricity, need to be optimized to make positive the carbon balance.

     

Integrated environmental and economic assessment of current and future fuel cell vehicles

Purpose

Light-duty vehicles contribute considerably to global greenhouse gas emissions. Fuel cell vehicles (FCVs) may play a key role in mitigating these emissions without facing the same limitations in range and refueling time as battery electric vehicles (BEVs). In this study, we assess the environmental impacts and costs of a polymer electrolyte membrane fuel cell system (FCS) for use in light-duty FCVs and integrate these results into a comparative evaluation between FCVs, BEVs, and internal combustion engine vehicles (ICEVs).

Methods

We conduct a detailed life cycle assessment (LCA) and cost assessment for the current state of the technology and two future scenarios for technological development. We compile a detailed and consistent inventory for the FCS by systematically disassembling and integrating information found in cost studies. For the vehicle-level comparison, we use models to ensure that vehicle size, performance, and fuel consumption are unbiased between vehicle types and consistent with the scenarios for technological development.

Results and discussion

Our results show that FCVs can decrease life cycle greenhouse gas emissions by 50 % compared to gasoline ICEVs if hydrogen is produced from renewable electricity, thus exhibiting similar emission levels as BEVs that are charged with the same electricity mix. If hydrogen is produced by natural gas reforming, FCVs are found to offer no greenhouse gas reductions, along with higher impacts in several other environmental impact categories. A major contributor to these impacts is the FCS, in particular the platinum in the catalyst and the carbon fiber in the hydrogen tank. The large amount of carbon fiber used in the tank was also the reason why we found that FCVs may not become fully cost competitive with ICEVs or BEVs, even when substantial technological development and mass production of all components is assumed.

Conclusions

We conclude that FCVs only lead to lower greenhouse gas emissions than ICEVs if their fuel is sourced from renewable energy, as is the case with BEVs. FCVs are an attractive alternative to ICEVs in terms of vehicle performance criteria such as range and refueling time. However, the technological challenges associated with reducing other environmental impacts and costs of FCVs seem to be as large, if not larger, than those associated with the capacity and costs of batteries for BEVs—even when not taking into account the efforts required to build a hydrogen infrastructure network for road transportation.

     

Comparing land use impacts using ecosystem quality,biogenic carbon emissions,and restoration costs in a case study of hydropower plants in Norway

Purpose

Habitat destruction is today the most severe threat to global biodiversity. Despite decades of efforts, there is still no proper methodology on how to assess all aspects of impacts on biodiversity from land use and land use changes (LULUC) in life cycle analysis (LCA). A majority of LCA studies on land extensive activities still do not include LULUC. In this study, we test different approaches for assessing the impact of land use and land use change related to hydropower for use in LCA and introduce restoration cost as a new approach.

Methods

We assessed four hydropower plant projects in planning phase (two upgrading plants with reservoir and two new run-of-river plants) in Southern Norway with comparable geography, biodiversity, and annual energy production capacity. LULUC was calculated for each habitat type, based on mapping of present and future land use, and was further allocated to energy production for each power plant. Three different approaches to assess land use impact were included: ecosystem scarcity/vulnerability, biogenic greenhouse gas (bGHG) emissions, and the cost of restoring affected habitats. Restoration cost represents a novel approach to LCA for measuring impact of LULUC.

Results and discussion

Overall, the three approaches give similar rankings of impacts: larger impact for small and new power plants and less for larger and expanding existing plants. Reservoirs caused a larger total area affected. Permanent infrastructure has a more similar absolute impact for run-of-river and reservoir-based hydropower, and consequently give relatively larger impact for smaller run-of-river hydropower. All approaches reveal impacts on wetland ecosystems as most important relative to other ecosystems. The methods used for all three approaches would benefit from higher resolution data on land use, habitats, and soil types. Total restoration cost is not accurate, due to uncertainty of offset ratios, but relative restoration costs may still be used to rank restoration alternatives and compare them to the costs of biodiversity offsets.

Conclusions

The different approaches assess different aspects of land use impacts, but they all show large variation of impact between the studied hydropower plants, which shows the importance of including LULUC in LCA for hydropower projects. Improved data of total restoration cost (and cost accounting) are needed to implement this approach in future LCA.

     

Bridge processes: a solution for LCI datasets independent of background databases

Introduction

New platforms are emerging that enable more data providers to publish life cycle inventory data.

Background

Providing datasets that are not complete LCA models results in fragments that are difficult for practitioners to integrate and use for LCA modeling. Additionally, when proxies are used to provide a technosphere input to a process that was not originally intended by the process authors, in most LCA software, this requires modifying the original process.

Results

The use of a bridge process, which is a process created to link two existing processes, is proposed as a solution.

Discussion

Benefits to bridge processes include increasing model transparency, facilitating dataset sharing and integration without compromising original dataset integrity and independence, providing a structure with which to make the data quality associated with process linkages explicit, and increasing model flexibility in the case that multiple bridges are provided. A drawback is that they add additional processes to existing LCA models which will increase their size.

Conclusions

Bridge processes can be an enabler in allowing users to integrate new datasets without modifying them to link to background databases or other processes they have available. They may not be the ideal long-term solution but provide a solution that works within the existing LCA data model.