Process-based Life Cycle Assessment Research Articles

Life cycle assessment (LCA) and economic analysis of two-stage anaerobic process of co-digesting palm oil mill effluent (POME) with concentrated latex wastewater (CLW) for biogas production

This study outlines the results of a process-based life cycle assessment (LCA) of the environmental performance of biogas production from co-digestion of palm oil mill effluent (POME) and concentrated latex wastewater (CLW) in the two-stage anaerobic digestion (AD) process. Biogas is utilized global across several sectors, including electricity generation, heating, and transportation. The Open LCA 2.0.2 software was used to evaluate the LCA at the midpoint level by using 18 different impact categories. This study reveals the three main contributions of the AD process, which were global warming (8.65 × 102 kg CO2eq), water consumption (5.32 m3), and land use change (3.39 × 102 m2 a crop eq), this result corresponded with the previous study in Malaysia that examined biogas production from the AD of POME In addition, alternative scenarios, in which a single substrate, have been established to quantify the impacts of potential improvements of biogas production to compare with base scenario of co-digestion. The results show that the environmental impacts of the base scenario released were lower than those of the single POME substrate of alternative scenario 1 in most impact categories. Furthermore, economic analysis is a crucial factor in the practical implementation of the AD process. Linking LCA with economic analysis offers a comprehensive perspective on sustainability, balancing environmental impacts with financial performance to optimize the potential of the AD co-digestion process. This is the first study to apply LCA and economic analysis to this specific co-digestion process in a two-stage AD system. The economic analysis of the two-stage AD of co-digesting POME and CLW was 1200 m3/d production of wastewater (70 % of POME and 30 % of CLW) based on the factories' data. The result indicates net present value, internal rate of return, and payback period of 515,813.94 USD, 9.13 %, and 8.87 years, respectively. This work proposed the potential approach for implementing the two-stage AD co-digestion of POME and CLW while concurrently producing valuable bioenergy carriers.

Pathway decisions for reuse and recycling of retired lithium-ion batteries considering economic and environmental functions

Reuse and recycling of retired electric vehicle (EV) batteries offer a sustainable waste management approach but face decision-making challenges. Based on the process-based life cycle assessment method, we present a strategy to optimize pathways of retired battery treatments economically and environmentally. The strategy is applied to various reuse scenarios with capacity configurations, including energy storage systems, communication base stations, and low-speed vehicles. Hydrometallurgical, pyrometallurgical, and direct recycling considering battery residual values are evaluated at the end-of-life stage. For the optimized pathway, lithium iron phosphate (LFP) batteries improve profits by 58% and reduce emissions by 18% compared to hydrometallurgical recycling without reuse. Lithium nickel manganese cobalt oxide (NMC) batteries boost profit by 19% and reduce emissions by 18%. Despite NMC batteries exhibiting higher immediate recycling returns, LFP batteries provide superior long-term benefits through reuse before recycling. Our strategy features an accessible evaluation framework for pinpointing optimal pathways of retired EV batteries.

Evaluating the carbon emissions of Hong Kong's building sector from the life cycle perspective

The building sector is a typical end-use sector that involves multiple stages associated with carbon emissions (CE). Accurately quantifying the CE of the building sector from the life cycle perspective can establish a foundation for its decarbonisation. This study focuses on Hong Kong to develop a six-stage CE calculation methodology with the process-based life cycle assessment framework. Specifically, the datasets of newly-constructed buildings are analysed to classify the buildings into 11 archetypes. Furthermore, the logarithmic mean Divisia index is used to identify the primary driving factors of the CE. Results show that the CE of Hong Kong's building sector ranged from 34.75 to 40.23 Mt per annum during the ten-year period 2012–2021. Electricity consumption accounted for over 90 % of the operational CE, while the production of major building materials, such as steel, cement, and aluminium, took up over 80 % of the embodied CE. Moreover, energy efficiency and CE efficiency factors were revealed to impose significant impacts on CE decrease by 1.94 and 1.68 Mt cumulatively in 2012–2021, whereas the population factor was found to increase the CE by 1.43 Mt. The findings should inform Hong Kong building sector's decarbonisation plan, and the study provides an innovative approach for tracking the climate change impacts of building sectors in cities.

Comparing life cycle environmental impacts of food access and consumption pre- and during COVID 19 in New York State's Capital Region

The COVID-19 pandemic has significantly influenced household food shopping, food consumption, and food waste generation. However, the dietary environmental impacts for different income groups during COVID-19 remain unknown. To analyze dietary environmental impacts for various income groups, a process-based life cycle assessment (LCA) was conducted based on two electronic food access surveys implemented in the New York State's Capital Region during the COVID-19 pandemic and public and proprietary databases. We found that life cycle global warming potential, cumulative energy demand, acidification potential, and water resource depletion of per capital food consumption in the studied area tended to be lower during COVID-19 than pre-COVID-19. In contrast, life cycle eutrophication during COVID-19 was slightly higher than pre-COVID-19. The environmental impacts occurring at the food production stage were higher than those at the local transportation and waste disposal stages. The lowest income group had the lowest dietary environmental impacts due to their lowest food consumption of all the food categories. The second-highest income group had the highest dietary environmental impacts, since they consumed the most red meat which has a high impact intensity. This is the first study to our knowledge to investigate the differences in dietary environmental impacts among income groups during COVID-19.

Mastering complexity in Life Cycle Assessment for product development: Evaluating the impacts of adaptive façades

Adaptive façades, which can manipulate the physical properties of buildings, represent a promising approach to reducing the environmental impacts of buildings, which are usually assessed using the Life Cycle Assessment (LCA) method. However, the inclusion of additional fields of engineering with their corresponding simulation tools and inclusion of additional adaptive components in building designs leads to an increased number of possible design configurations – in the order of several millions – as well as stronger dependencies between the design and the use phase. This paper proposes a workflow to automatically generating, analysing and evaluating LCA results of all potential configurations within a defined parameter space. It combines and processes data from multiple sources, including process-based LCA models, generic LCA databases, and simulation tools. Various methods for combining and analysing the data are provided in the form of parameter sensitivity and statistical evaluations as well as visualisations. Depending on the area of interest, dynamic benchmarks can be derived and visualised. The results can be structured according to the life cycle phases and exported in common spreadsheet formats. This enables comparison to other LCA results and ensures seamless integration in existing reporting structures. The primary beneficiaries are LCA experts who require ex-ante evaluations for (building) products with a large number of potential configurations and complex interactions between the design and use phases. Identifying hotspots and assessing the sensitivity of parameters at an early stage of product development enables product designers to consider environmental aspects and optimise the product in this respect.

Environmental sustainability of closed-loop regeneration of NaHCO3 in CO2 utilization-driven desulfurization ash: From the perspective of integrated hybrid life cycle assessment

The closed-loop regeneration of NaHCO3 by treating sodium-based desulfurization ash (SDA) using CO2 in flue gas and ammonia by-products demonstrates an attractive perspective of low-cost sodium-based dry desulfurization (SDD) application. To push generation reuse of desulfurization ash into more practices, taking the application in coking plants as a case, this study first compares the environmental and economic performance of four scenarios of flue gas desulfurization (FGD) and desulfurization ash disposal by integrated hybrid life cycle assessment (IHLCA) with life cycle costing. Compared with process-based LCA, IHLCA captures more environmental impacts through the economic input-output (EIO) system, especially 36.40–67.89% of terrestrial ecotoxicity comes from the EIO system. Based on evaluation results of four scenarios, among the ten environmental impact categories (excluding photochemical oxidation), the SDD scenario with NaHCO3 regeneration by CO2 and ammonia (S2) is not only the most environmentally friendly route, but also has the lowest total hourly operating cost. These are mainly due to the offsetting effect of by-products replacing traditional chemicals on the total impact and avoiding landfill and raw material transportation. Furthermore, sensitivity analysis also shows that when technical parameters change, the environmental and economic performance of S2 still remains the best, except for the case when the NaHCO3 regeneration rate is 60%. The findings will be valuable for the selection and optimization of FGD in coking plants, incineration plants, and others.

Environmental and climate impacts of a large-scale deployment of green hydrogen in Europe

Green hydrogen is expected to play a vital role in decarbonizing the energy system in Europe. However, large-scale deployment of green hydrogen has associated potential trade-offs in terms of climate and other environmental impacts. This study aims to shed light on a comprehensive sustainability assessment of this large-scale green hydrogen deployment based on the EMPIRE energy system modeling, compared with other decarbonization paths. Process-based Life Cycle Assessment (LCA) is applied and connected with the output of the energy system model, revealing 45% extra climate impact caused by the dedicated 50% extra renewable infrastructure to deliver green hydrogen for the demand in the sectors of industry and transport in Europe towards 2050. Whereas, the analysis shows that green hydrogen eventually wins on the climate impact within four designed scenarios (with green hydrogen, with blue hydrogen, without green hydrogen, and baseline), mainly compensated by its clean usage and renewable electricity supply. On the other hand, green hydrogen has a lower performance in other environmental impacts including human toxicity, ecotoxicity, mineral use, land use, and water depletion. Furthermore, a monetary valuation of Life Cycle Impact (LCI) is estimated to aggregate 13 categories of environmental impacts between different technologies. Results indicate that the total monetized LCI cost of green hydrogen production is relatively lower than that of blue hydrogen. In overview, a large-scale green hydrogen deployment potentially shifts the environmental pressure from climate and fossil resource use to human health, mineral resource use, and ecosystem damage due to its higher material consumption of the infrastructure.

An integrated life cycle assessment and energy simulation framework for residential building walling systems

Designing building wall systems is a multi-criteria problem characterised by a complex interplay of variables that drive long-term energy and environmental performance. Achieving holistic sustainability outcomes will require the application of life cycle thinking to the design and evaluation of building walling systems. However, the aspiration for minimising operational and embodied energy and mitigating the environmental impacts requires conflicting strategies. Therefore, this study proposes a comprehensive, integrated life cycle and energy simulation (ILES) methodology for analysing different walling systems of residential buildings in India and Australia. This method involves performing a process-based life cycle assessment to compute the environmental impacts of various walling materials, followed by energy modelling to evaluate the performance of these materials in the operational phase of buildings in combination with embodied energy analysis, which accounts for energy consumption during the material manufacturing phases. The results reveal that insulated cavity-clay masonry or concrete walls with extruded polystyrene are favourable Australian walling options, while metal cladding-based walling systems have significant environmental and energy burdens. For India, autoclave aerated block, fly ash bricks, and concrete block-based walling systems are recommended, while reinforced concrete and clay brick walls exhibit significant environmental and energy burdens. This study also advocates the consideration of supply chains in mitigating Scope 3 emissions from building walling systems in residential buildings.

Life cycle assessment of green–grey coastal flood protection infrastructure: a case study from New Orleans

The study compared the life cycle environmental impacts of three coastal flood management strategies: grey infrastructure (levee), green–grey infrastructure (levee and oyster reef), and a do-nothing scenario, considering the flood damage of a single flooding event in the absence of protection infrastructure. A case study was adopted from a New Orleans, Louisiana residential area to facilitate the comparison. Hazus software, design guidelines, reports, existing projects, and literature were utilized as foreground data for modelling materials. A process-based life cycle assessment was used to assess environmental impacts. The life cycle environmental impacts included global warming, ozone depletion, acidification, eutrophication, smog formation, resource depletion, ecotoxicity, and various human health effects. The ecoinvent database was used for the selected life cycle unit processes. The mean results show green–grey infrastructure as the most promising strategy across most impact categories, reducing 47% of the greenhouse gas (GHG) emissions compared to the do-nothing strategy. Compared to grey infrastructure, green–grey infrastructure mitigates 13%–15% of the environmental impacts while providing equivalent flood protection. A flooding event with a 100-year recurrence interval in the study area is estimated at 34 million kg of CO2 equivalent per kilometre of shoreline, while grey and green–grey infrastructure mitigating such flooding is estimated to be 21 and 18 million kg, respectively. This study reinforced that coastal flooding environmental impacts are primarily caused by rebuilding damaged houses, especially concrete and structural timber replacement, accounting for 90% of GHG emissions, with only 10% associated with flood debris waste treatment. The asphalt cover of the levee was identified as the primary contributor to environmental impacts in grey infrastructure, accounting for over 75% of GHG emissions during construction. We found that there is an important interplay between grey and green infrastructure and optimizing their designs can offer solutions to sustainable coastal flood protection.

Quantifying the greenhouse gas emissions of New Zealand households’ food purchases: An analysis by sociodemographic variables

New Zealand has committed to a 50% reduction in greenhouse gas emissions (GHGEs) from 2005 levels by 2030. Dietary changes within New Zealand could simultaneously improve population health and contribute towards the nation’s emissions reduction target, as agricultural emissions are estimated to account for half of New Zealand’s GHGEs(1). This research aimed to quantify the GHGEs associated with household purchases of major food groups in New Zealand and identify the sociodemographic characteristics that are associated with per capita household dietary emissions. Household dietary emissions were estimated using the NielsenIQ Homescan(R) consumer panel — a large sample of households within New Zealand who report purchasing data of take-home food and beverages. The sample is nationally representative in terms of broad geographical regions and selected key demographic characteristics. Carbon emission estimates were assigned to 1,908,485 total food and beverage purchases from 1,775 households over one year (2019) using a process-based life cycle assessment (LCA) dataset initially constructed in the United Kingdom (UK) and adapted for New Zealand(2). This LCA dataset contains estimates of greenhouse gas emissions generated over the life cycle of the production of food products from the following stages: farming and processing, transit packaging, consumer packaging, transport, warehouse and distribution, refrigeration, and overheads. Greenhouse gas emissions are expressed in kg of carbon dioxide equivalents per kg of food product over a 100-year time horizon. Total emissions from purchases of major food groups were then estimated. Multiple linear regression was used to examine the relationships between household variables and per capita dietary emissions. Overall purchases of red and processed meat (35%) and dairy products (19%) were responsible for the greatest proportion of emissions. The age group of the primary household shopper as well as household size were predictors of per capita dietary emissions — households with primary shoppers > 65 years had, on average, 33% (95% CI: 20% to 49%) higher per capita dietary emissions, compared to households with primary shoppers 34 years; and every additional household member was associated with, on average, 11% (95% CI: 9% to 13%) lower per capita dietary emissions. We have shown in this large representative sample of New Zealand households that purchases of just two food groups — red and processed meat, and dairy — were responsible for approximately half of dietary greenhouse gas emissions. Larger households had lower per capita dietary greenhouse gas emissions, and older shoppers had relatively higher greenhouse gas emissions. Whilst similar associations have been reported elsewhere more research is needed to confirm these latter findings. With enhanced understanding of the observed association between age of a household’s primary shopper and per capita dietary emissions, interventions may be devised that encourage shoppers to purchase lower-emitting foods, particularly less meat and dairy.

Evaluating Carbon Emissions during Slurry Shield Tunneling for Sustainable Management Utilizing a Hybrid Life-Cycle Assessment Approach

The construction sector is one of the principal contributors to carbon dioxide emissions (CDEs) and has a vital role to play in responding to the issue of long-term environmental sustainability. This research proposes a process-based hybrid life-cycle assessment (LCA) method depending on a process-based LCA and an input–output LCA. The process-based hybrid LCA model provides a supplementary method to quickly estimate carbon emissions that are not considered in the system boundary due to the limitation of inventory data. The proposed hybrid method was applied to a carbon emissions assessment in a slurry shield tunnel. The results suggest that 93.88% of emissions are from materials. Of the materials contribution, 55.9% comes from steel and 34.55% arises from concrete. It has also been found that emissions during the tunneling stage are negatively correlated with the efficiency of tunnel construction. Recommendations for carbon emissions reductions in tunnel construction are provided for promoting sustainable transportation and management.

Process-based life cycle inventory framework for assessing the carbon footprint of products from complex production paths: Case of dual-phase automotive strip steel

The production paths of industrial products are usually complex, leading to difficulties and a large workload when conducting traditional process-based life cycle assessment (P-LCA). Existing studies on reducing LCA workload have focused mainly on simplifying the process or combining LCA with correlation methods. For complex production paths that cannot be simplified or changed, the methods have weak generality. To fill in these research gaps, a process-based life cycle inventory (P-LCI) framework for complex production paths is proposed. P-LCI contains accurate classification and definition methods for input, output and unit processes, and an interconnection model for calculating process coefficients according to the complexity of the linkages among processes is proposed. Based on the proposed framework, a case study of the dual-phase automotive strip steel (DP) production process is performed. The results show that the production of 1 kg of DP steel consumes 0.679 kg of molten steel from a basic oxygen furnace plant and 0.557 kg from the another. Coke plants produce the largest carbon footprint (CF) per unit of coke, which is 0.889–1.231 kgCO2e/kg-coke. For the cradle-to-gate lifecycle of DP steels, the BFP has the largest CF at 0.614 kgCO2e/kg-DP, accounting for 26.32%. Through the proposed P-LCI framework, unit processes can be clearly defined, and the interconnection model can be used as the basis for environmental impact analysis. When the production path changes, the model can be flexibly adjusted, and the workload of repeated model construction can be reduced.

How environmental impact is considered in economic evaluations of critical care: a scoping review.

Health care is a major contributor to climate change, and critical care is one of the sector's highest carbon emitters. Health economic evaluations form an important component of critical care and may be useful in identifying economically efficient and environmentally sustainable strategies. The purpose of this scoping review was to synthesise available literature on whether and how environmental impact is considered in health economic evaluations of critical care. A robust scoping review methodology was used to identify studies reporting on environmental impact in health economic evaluations of critical care. We searched six academic databases to locate health economic evaluations, costing studies and life cycle assessments of critical care from 1993 to present. Four studies met the review's inclusion criteria. Of the 278 healtheconomic evaluations of critical care identified, none incorporated environmental impact into their assessments. Most included studies (n = 3/4) were life cycle assessments, and the remaining study was a prospective observational study. Life cycle assessments used a combination of process-based data collection and modelling to incorporate environmental impact into their economic assessments. Health economic evaluations of critical care have not yet incorporated environmental impact into their assessments, and few life cycle assessments exist that are specific to critical care therapies and treatments. Guidelines and standardisation regarding environmental data collection and reporting in health care are needed to support further research in the field. In the meantime, those planning health economic evaluations should include a process-based life cycle assessment to establish key environmental impacts specific to critical care.

From quarry to carbon sink: process-based LCA modelling of lime-based construction materials for net-zero and carbon-negative transformation

Materials science, process engineering and environmental science were combined to demonstrate carbon negative scenarios over the life-cycle of a lime-based plaster.

Sustainability assessment of peri-urban organic horticulture — A case study in the United Kingdom

PurposeThere is a growing concern about the resilience and sustainability of horticultural production in the United Kingdom (UK) as a result of high energy costs and insufficient local labour, causing over-reliance on imports. In this study, we present an integrated environmental and economic assessment of organic peri-urban horticulture using primary data from a farm in Sheffield.MethodsThis study includes a farm-to-gate hybrid life cycle assessment (LCA) using the ReCIPE (H) approach for the functional unit of 1-kg tomatoes produced in an unheated polytunnel without supplementary lighting, and 1 kg of field-grown courgettes. All analyses were conducted in SimaPro software using environmental data from the ecoinvent database. Results were compared with those from a systematic literature review of similar studies.ResultsWe found that the production of organic tomatoes and courgettes resulted in a global warming potential (GWP) of 0.61 kg CO2-eq and 0.11 kg CO2-eq respectively using a process-based LCA approach. Using a hybrid LCA approach, however, yielded a GWP of 3.53 kg CO2-eq and 1.70 kg CO2-eq for the production of organic tomatoes and courgettes respectively. An additional scenario included farmgate-to-warehouse transportation for both domestic and imported produce from Spain, but found that the GWP of tomatoes in the case study was 1.87 times higher than those from Spain. Economic analysis showed that the marginal increase in the prices of tomatoes and courgettes from the case study farm was 4.6 and 5.15 times less than the market prices.ConclusionWe conclude that the studied production system is both economically and environmentally sustainable as compared to the existing scenario. Other potential benefits of peri-urban organic horticulture include employment, mental health, community cohesion, which remain to be explored in a future qualitative study. The present study is novel as it appears to be the first application of hybrid LCA to UK horticulture. The findings are highly topical given the recent horticultural supply constraints in the UK.

Life Cycle Assessment (LCA) of Solid Waste Management Systems in African Countries: A Systematic Review

Life cycle assessment (LCA) is a vital tool for evaluating the environmental burden of solid waste. This study investigated the outcomes of selected studies that applied the LCA methodology in assessing the environmental consequences of solid waste management (SWM) systems in Africa. Thirteen process-based LCA studies on SWM were reviewed, drawing from established criteria in databases such as SCOPUS, Elsevier, and Google Scholar. These studies were distributed across various African countries, with three conducted in Mauritius and Nigeria each, two in Zimbabwe and South Africa each, and one in Tanzania, Ghana, and Uganda, respectively. The evaluated parameters included aspects such as goal and scope, functional unit, system boundary, impact assessment categories, and sensitivity analysis. The findings revealed that majority of the studies employed similar waste management scenarios to determine the most environment-friendly, yet they differed considerably in some parameters. Climate change and global warming were the most assessed impact categories. Municipal solid waste (MSW) and plastic waste were the leading waste categories. MSW typically comprises paper, bottles, metal, plastics, glass, organics, and mixed waste proportions. The study also stated that the lack of reliable data on solid waste was a significant challenge faced by African countries in LCA studies. The paper’s findings highlighted that a significant number of the studies, particularly in Nigeria, did not incorporate sensitivity analysis into their assessments, a crucial component for result interpretation. Consequently, the study emphasizes the importance of conducting more LCA research studies in African countries to produce pertinent data on SWM.

Life cycle assessment perspective on waste resource utilization and sustainable development: A case of glyphosate production

The growing demand for pesticide manufacturing and increasing public awareness of sustainable development, have let to urgent requirements for a refined environmental management framework. It is imperative to conduct process-based life cycle assessments (LCAs) to promote clean and environment-friendly technologies. Herein, the cradle-to-gate LCA of glyphosate production was executed as an example to investigate crucial production factors (materials or energy) and multiple environmental impacts during the production processes. Results showed that methanol caused the highest environmental damage in terms of toxicity, with a normalized value of 85.7 × 10−8, followed by coal-fired electricity in 6.00 × 10−8. Furthermore, optimized schemes were proposed, including energy improvement (electricity generated by switching from coal-fired power to solar power) and wastewater targeted conversion. Regarding the normalization results before and after optimization, the latter showed more significant results with the normalized value decreasing by 21.10 × 10−8, while that of the former only decreased by 6.50 × 10−8. This study provides an integrated LCA framework for organophosphorus pesticides (OPs) from upstream control and offers an important supplement to managing the key pollution factors and control links of the OP industry. Moreover, it reveals the positive influence of optimized schemes in facilitating cleaner production technologies, thus ultimately promoting new methodologies for resource recycling.

Lifecycle Assessment of Two Urban Water Treatment Plants of Pakistan

Water treatment technologies are striving to retain their ecological and economic viability despite the rising demand, conventional infrastructure, financial constraints, fluctuating climatic patterns, and highly stringent regulations. This study evaluates the lifecycle environmental impact of urban water treatment systems within the two densely populated South Asian municipalities of Islamabad and Rawalpindi, Pakistan. The scope of this study includes a process-based Life Cycle Assessment (LCA) of the entire water treatment system, particularly the resources and materials consumed during the operation of the treatment plant. The individual and cumulative environmental impact was assessed based on the treatment system data and an in-depth lifecycle inventory analysis. Other than the direct emissions to the environment, the electricity used for service and distribution pumping, coagulant use for floc formation, chlorine gas used for disinfection, and caustic soda used for pH stabilization were the processes identified as the most significant sources of emissions to air and water. The water distribution consumed up to 98% of energy resources. The highest global warming impacts (from 0.3 to 0.6 kg CO2 eq./m3) were assessed as being from the coagulation and distribution processes due to extensive electricity consumption. Direct discharge of the wash and wastewater to the open environment contributed approximately 0.08% of kg-N and 0.002% of kg-P to the eutrophication potential. The outcome of this study resulted in a thorough lifecycle inventory development, including possible alternatives to enhance system sustainability. A definite gap was identified in intermittent sampling at the treatment systems. However, more stringent sampling including the emissions to air can provide a better sustainability score for each unit process.

Quantifying the greenhouse gas emissions of New Zealand households’ food purchases: An analysis by demographic variables

New Zealand has committed to a 50% reduction in greenhouse gas emissions (GHGEs) from 2005 levels by 2030. Dietary changes within New Zealand could simultaneously improve population health and contribute towards the nation's emissions reduction target, as globally, food production is estimated to account for between one quarter and one third of GHGEs. This research aimed to quantify the GHGEs associated with household purchases of major food groups in New Zealand and identify the demographic characteristics that are associated with per capita household dietary emissions. Household dietary emissions were estimated using the Nielsen Homescan(R) consumer panel — a large sample of households within New Zealand (N = 1775) who report purchasing data of take-home food and beverages. The sample is nationally representative in terms of broad geographical regions and selected key demographic characteristics. Carbon emission estimates were assigned to 1,908,485 total purchases in 2019 using a process-based life cycle assessment (LCA) dataset initially constructed in the United Kingdom (UK) and adapted for New Zealand. The emissions from purchases of major food groups were then estimated. Multiple linear regression was used to examine the relationships between household variables and per capita dietary emissions. Purchases of red and processed meat (35%) and dairy products (19%) were responsible for the greatest proportion of emissions using a 100-year time horizon. The age group of the primary household shopper as well as household size were predictors of per capita dietary emissions — households with primary shoppers >65 years had, on average, 33% (95% CI: 19%–49%) higher per capita dietary emissions, compared to households with primary shoppers ≤ 34 years; and every additional household member was associated with, on average, 11% (95% CI: 9%–13%) lower per capita dietary emissions. We have shown in this large representative sample of New Zealand households that purchases of just two food groups — red and processed meat, and dairy — were responsible for 54% of dietary greenhouse gas emissions in 2019. Larger households had lower per capita dietary greenhouse gas emissions, and older shoppers had relatively higher greenhouse gas emissions. Whilst similar associations have been reported elsewhere, more research is needed to confirm these latter findings. With enhanced understanding of the observed association between age of a household's primary shopper and per capita dietary emissions, interventions may be devised that encourage shoppers to purchase lower-emitting foods, particularly less meat and dairy.

Life cycle assessment of energy consumption and carbon emissions of a green maintenance material for asphalt pavement: Warm mix OUFC-5

The warm mix (WM) 4.75 mm nominal maximum aggregate size (NMAS) Open-Graded Ultra-thin Friction Course (WM OUFC-5) represents an innovative green preventive maintenance material boasting commendable road performance. Its potential to address carbon peak and neutrality goals objectives has garnered significant interest. This study aims to quantify the energy-saving and carbon reduction benefits of WM OUFC-5. Three commonly used preventive maintenance materials, including thin overlay (TO), synchronous surface dressing (SSD), and micro-surfacing (MS) in Hubei province, China, were selected as a control group. Employing the process-based life cycle assessment (PLCA), an evaluation framework and computational model was devised to gauge the energy and carbon footprints of each maintenance material. A comparative analysis was then conducted to identify the primary energy and emission contributors of WM OUFC-5 across different life-cycle phases. The results indicate that WM OUFC-5 is a highly sustainable material with low energy consumption and carbon emissions, with its energy consumption being merely 47.2% of TO and 50.7% of MS. And its carbon emissions are 64.3% lower than TO, 26.9% lower than MS, and 49.8% lower than SSD. Throughout the maintenance life cycle, the raw materials production and processing phase and the mixture production phase emerged as the predominant contributors to energy consumption and carbon emissions. The study also provided actionable recommendations to curtail energy and carbon footprints across all phases of the asphalt pavement maintenance life cycle. This study provides support for the low-carbon development of asphalt pavement maintenance in China.