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With around two billion cups consumed daily worldwide, the coffee industry faces pressures to improve its sustainability. Focusing on the UK as the fifth largest coffee consumer in Europe, this paper presents for the first time a life cycle environmental and economic sustainability assessment of coffee production at the product and sectoral levels. Both gate-to-gate and cradle-to-gate system boundaries are considered to identify opportunities for improvements in the manufacturing process and along the supply chain. Process design and simulation are combined with life cycle assessment and life cycle costing to evaluate the sustainability of the production of ground and instant coffee roasted to different levels. Based on the functional unit of 1 tonne of coffee produced, instant coffee has higher impacts and costs than ground coffee for both system boundaries because it requires double the amount of green coffee beans and 7-11 times more energy. For gate-to-gate, roasting and packaging are the main contributors to the impacts and costs; for cradle-to-gate, cultivation of coffee beans and packaging are the hotspots. Light roasts generally have lower impacts and costs due to lower material losses and energy requirements. At the sectoral level, the coffee industry emits 863-894 kt CO2 eq. annually, contributing 1.3% to the GHG emissions from the UK food and drinks sector. Key opportunities for improvements include switching to lighter roast and pouch packaging, as well as using air recirculation roasters and silverskin as fuel. These results will be of interest to the coffee industry, policy makers and consumers.

This paper combines process design and modelling with life cycle sustainability assessment to identify opportunities for improving the environmental and economic performance in the cheese industry. Considering both the production and consumption perspectives, the study considers first a range of improvement options in the cheese manufacturing process, followed by an assessment of the rest of the life cycle. For the manufacturing process, the focus is on energy efficiency and valorisation of waste with the following four options considered: Option 1 is a base case that reflects current manufacturing practice and therefore excludes energy recovery and waste utilisation; Option 2 includes heat integration applied to recover waste heat from the process; Option 3 considers the combination of heat integration with treatment of cheese whey via anaerobic digestion to produce biogas; in Option 4, heat integration is combined with treatment of whey via fermentation to produce bioethanol and animal feed. Cheddar cheese has been selected by way of example as one of the most consumed types of cheese in different countries, including the US and the UK. Using life cycle assessment and life cycle costing, the environmental and economic sustainability of cheese have been assessed for these options from farm gate to cheese-plant gate for the production perspective, and from cradle to grave for the consumption perspective. Option 4 is found to be the best alternative across all impacts and costs for both perspectives. For example, compared to the base case, the climate change impact and life cycle costs of cheese are reduced respectively by 148% and 158% for the production perspective, and by 3.4% and 8% for the consumption perspective. These reductions are mainly due to the co-production of bioethanol and animal feed. Production of biogas from whey in Option 3 has higher environmental impacts than the base case, making it the worst alternative. Taking the consumption of cheese at the UK level as an example, improvements in the manufacturing process via Option 4 could reduce the annual climate change impact of the food sector by around 209 kt CO2 eq./yr and primary energy demand by 6.7 PJ/yr, while increasing the value added of cheese by up to 11%. These results will be of interest to cheese producers, food manufacturers, consumers and policy makers.

Negative emissions technologies (NETs) are expected to play a significant role in mitigating climate change. However, there are also concerns that a large scale deployment of NETs may cause various environmental impacts due to the use of land, water and energy resources. A number of studies have assessed the environmental performance of various NETs; however, a comprehensive review comparing a range of different NETs is not available in the literature. To address this research gap, this paper compares life cycle assessment (LCA) studies of the following options for which the data were available in the literature: bioenergy with carbon capture and storage (BECCS), biochar incorporation into soil, afforestation and reforestation, soil carbon sequestration, building with biomass, direct air carbon capture and storage (DACCS), enhanced weathering and mineral carbonation. It is evident from this review that these technologies can have net negative life cycle GHG emissions, ranging from −603 kg CO2 eq./t CO2 removed for building with biomass to −1173 kg CO2 eq./t CO2 removed for biochar incorporation into soil. However, the estimates of GHG removal potentials vary widely among the studies for each technology as well as among the NETs owing to technological differences, methodological choices and differing assumptions. For example, the net global warming potential (GWP) of biochar varies among the reviewed studies between a net positive impact of 1710 to a net negative GWP of 3300 kg CO2 eq./t CO2 removed, depending upon the feedstock, pyrolysis technology and the assumptions for credits for co-products and co-benefits. Overall, biochar used as soil amendment has the lowest GWP per tonne of CO2 removed, followed by soil carbon sequestration, while building with biomass ranks last. The review also reveals that the removal of CO2 by these technologies could lead to a significant increase in other environmental impacts. Especially, the use of energy in non-bio NETs (DACCS, enhanced weathering and mineral carbonation) leads to relatively high fossil depletion, acidification and human toxicity. These impacts can be reduced if the energy demand of NETs is met by renewables instead of fossil fuels. The paper also identifies several methodological issues and challenges in conducting LCA of NETs and provides recommendations to address them.

This study presents a novel combination of microwave irradiation and structured zeolite/SiC foam catalyst to improve the methanol-to-hydrocarbons (MTH) process as well as its environmental sustainability. Accordingly, ZSM-5/SiC foam was studied under microwave irradiation at various reaction temperatures (400–550 °C) and space velocities (8 and 12 h−1) and compared to conventional ZSM-5 pellets. ZSM-5/SiC foam promoted higher selectivity towards C1−C5 hydrocarbons (∼95%) and particularly propylene (∼40% at 400 °C and 8 h−1) compared to ZSM-5 pellets (∼40% and 6–9%, respectively) due to the enhanced mass and heat transfers. The microwave-assisted MTH process with both the structured catalyst and pellets was also assessed on the environmental sustainability via life cycle assessment in comparison with the conventionally-heat process with the structured catalyst. The results showed that the microwave-based process with the structured catalyst could reduce the environmental impacts of propylene production by 22–30% compared to the conventionally-heated process with the same catalyst.

Water scarcity and the consequent increase of freshwater prices are a cause for concern in regions where shale gas is being extracted via hydraulic fracturing. Wastewater treatment methods aimed at reuse/recycle of fracking wastewater can help reduce water stress of the fracking process. Accordingly, this study assessed the catalytic performance and life cycle environmental impacts of cerium-based mixed oxide catalysts for catalytic wet oxidation (CWO) of organic contaminants, in order to investigate their potential as catalysts for fracking wastewater treatment. For these purposes, MnCeO

Information on the scale of food waste, its sources, causes and associated environmental impacts is critical for devising food waste prevention strategies. A number of studies have focused on these issues, but there are still significant knowledge gaps, both in terms of the amount of food waste generated in various parts of the supply chain and the related impacts. In an attempt to address some of these gaps, this study focuses on food waste in the UK to estimate its quantities along the whole supply chains and to assess the resulting life cycle environmental impacts. Furthermore, the contributions of various food groups to food waste and their impacts in different life cycle stages are also quantified. The findings suggest that 13.1 Mt of food waste is generated annually in the UK across all the supply chain, leading to the greenhouse gas emissions of 27 Mt of CO2 eq./yr. The highest volume of waste is generated in the cereals (31%) and vegetables & roots subsectors (28%). However, meat and fish are the major contributors to the total life cycle environmental impacts, even though they account for only 10% of the overall food waste. Although post-consumer waste has the highest contribution, both in terms of waste quantities and environmental impacts, the contribution of other stages (primary production, food processing and distribution) is also significant. These findings emphasise the need to consider environmental impacts of food waste and engage all supply chain actors in formulating food waste reduction strategies.

Wastewater treatment plants can become a source of valuable resources, such as clean water, energy, fuels and nutrients and thus contribute to the sustainable development goals and a transition to a circular economy. This can be achieved by adopting advanced wastewater and sludge treatment techniques. However, these have to be evaluated on their sustainability to avoid any unintentional consequences. Therefore, this paper presents a life cycle sustainability assessment of advanced wastewater and sludge treatment techniques by integrating the environmental, economic and social aspects. The options considered for advanced wastewater treatment are: i) granular activated carbon; ii) nanofiltration; iii) solar photo-Fenton; and iv) ozonation. The technologies for advanced sludge treatment are: i) agricultural application of anaerobically digested sludge; ii) agricultural application of composted sludge; iii) incineration; iv) pyrolysis; and v) wet air oxidation. The results for the advanced wastewater treatment techniques demonstrate that nanofiltration is the most sustainable option if all the sustainability aspects are considered equally important. If, however, a higher preference is given to the economic aspect, ozonation and granular activated carbon would both be comparable to nanofiltration; if the social aspect is considered more important, only activated carbon would be comparable to nanofiltration. Among the sludge treatment methods, agricultural application of sludge is the most sustainable technique for mean-to-high resource recovery. If the recovery rate is lower, this option is comparable with incineration and pyrolysis with high recovery of their respective products. This work helps to identify the most sustainable techniques that could be combined with conventional wastewater treatments for promoting wastewater reuse and resource recovery across a wide range of operating parameters and products outputs. The findings also support the notion that more sustainable wastewater treatment could be achieved by a circular use of water, energy and nutrients contained in urban wastewaters.

Current studies on the food-energy-water nexus do not capture effects on human health. This study presents a new methodology for assessing the environmental sustainability in the food-energy-water-health nexus on a life cycle basis. The environmental impacts, estimated through life cycle assessment, are used to determine a total impact on the nexus by assigning each life cycle impact to one of the four nexus aspects. These are then normalised, weighted and aggregated to rank the options for each aspect and determine an overall nexus impact. The outputs of the assessment are visualised in a "nexus quadrilateral" to enable structured and transparent interpretation of results. The methodology is illustrated by considering resource recovery from household food waste within the context of a circular economy. The impact on the nexus of four treatment options is quantified: anaerobic digestion, in-vessel composting, incineration and landfilling. Anaerobic digestion is environmentally the most sustainable option with the lowest overall impact on the nexus. Incineration is the second best option but has a greater impact on the health aspect than landfilling. Landfilling has the greatest influence on the water aspect and the second highest overall impact on the nexus. In-vessel composting is the worst option overall, despite being favoured over incineration and landfilling in circular-economy waste hierarchies. This demonstrates that "circular" does not necessarily mean "environmentally sustainable." The proposed methodology can be used to guide businesses and policy makers in interpreting a wide range of environmental impacts of products, technologies and human activities within the food-energy-water-health nexus.

The success of deploying energy and water technologies in remote communities in developing countries can be improved by considering their synergistic relationships and their social, economic and environmental implications. This paper first evaluates social implications of current energy and water supply in a prototypical remote community against five future (2030) scenarios for synergistic provision of electricity, heat for cooking and water. This is followed by an integrated assessment of the social, environmental and economic life cycle sustainability through multicriteria decision analysis. The Business-as-usual (BAU) scenario shows high life cycle health impacts but low impacts from local air pollution. The contrary is true for the Independent and Advanced Independent scenarios which assume community self-sufficiency in energy and water supply. Greater access to electricity and water in the Advanced and Advanced Independent scenarios increases the potential for human development and security of supply, but there is an increase in the risk of accidents and decrease in social acceptability of the water supply. Similarly, a transition towards clean cooking fuels away from traditional solid biomass reduces local air pollution but increases reliance on imported fuels (BAU and Advanced scenarios). The Transition scenario is socially the most sustainable option, while Independent and Advanced Independent are the best options environmentally. They also have the lowest total operating costs, but have higher capital requirements than most other scenarios. Overall, unless extreme preferences for either environmental or social aspects are adopted, the Transition and Independent scenarios emerge as the most sustainable options. This suggests that current energy and water supply to remote communities can be transitioned sustainably to a self-sufficient system that does not depend on imported resources. The scenarios developed in this work present a framework for an integrated design and evaluation of energy and water supply in remote communities with the aim of aiding stakeholders in defining sustainable transition pathways.

This paper presents a new framework for evaluating life cycle eco-efficiency of different products and sectors. The framework incorporates life cycle assessment, life cycle costing and multi-criteria decision analysis to enable estimations of the overall eco-efficiency and benchmarking of products and sectors. Overall, 17 eco-efficiency indicators are included in the framework, estimated as a ratio of life cycle environmental impacts and economic value added. The application of the framework is demonstrated by estimating the eco-efficiency in the confectionary and the frozen-desserts sectors in the UK, considering the following four product categories and sub-sectors: biscuits, cakes, chocolates and ice creams. In total, 18 products are evaluated. At the product level, and assuming equal weighting for all indicators, cupcakes are found to be the most eco-efficient and semi-sweet biscuits the least efficient products. By contrast, evaluation at the sub-sectoral level reveals chocolates as the best performing sub-sector, followed by cakes, ice cream and biscuits. The confectionary sector is overall three times more eco-efficient than the frozen-desserts sector. The rankings of the products are strongly dependent on the relative importance of the eco-efficiency indicators. However, the results are less sensitive to the weightings of indicators at the sub-sectoral and sectoral levels. This framework and the results will be of interest to industry for benchmarking and identifying opportunities for eco-efficiency improvements as well as to consumers for identifying more eco-efficient products.

Offshore wind electricity is becoming an important source of renewable energy due to its global warming potential (GWP). However, the GWP can vary significantly, depending on many factors, including the capacity of the installation, distance from the shore, supporting structure andmaintenance requirements. Currently, there is a lack of life cycle assessment (LCA) studies that take these specific conditions into account. As a consequence, developers and policy makers rely on average GWP values which could lead to inaccurate estimates of the GWP and other impacts. To address this gap, this paper presents a new model for estimating the life cycle impacts of offshore wind electricity taking into account specific technical characteristics of individual installations and whole wind farms. Aimed at non-experts, the model provided freely with this paper is developed in Excel and follows the ISO 14040/44 LCA methodology. Supported by the built-in background LCA databases, it requires users to specify only a few key characteristics of an existing or proposedinstallation, thus facilitating quick and yet robust estimations of impacts. Eleven impacts can be considered, including GWP, depletion of resources, human toxicity and eco-toxicities. The application of the model is illustrated by quantifying the LCA impacts of 20 offshore wind farms (OWF) operating in the UK. The results show that the impacts vary considerably with the specific characteristics of OWF, including the age, type and size of wind turbines, their capacity and distance from the shore. For example, the GWP ranges by a factor of three (6.4-19.5 g CO2 eq./kWh) and the other impacts by a factor of 2.2-3.2. The developed model can be used by designers, developers and policy makers to customise the inputs for a specific OWF and estimate the impacts quickly and cost-efficiently, without the need for prior expertise in LCA and extensive data collection. Keywords: Energy planning; Energy modelling; Life cycle assessment; Wind electricity; Sustainable energy

Although electricity supply is still dominated by fossil fuels, it is expected that renewable sources will have a much larger contribution in the future due to the need to mitigate climate change. Therefore, this paper presents a new framework for developing Future Electricity Scenarios (FuturES) with high penetration of renewables. A multi-period linear programming model has been created for power-system expansion planning. This has been coupled with an economic dispatch model, PowerGAMA, to evaluate the technical and economic feasibility of the developed scenarios while matching supply and demand. Application of FuturES is demonstrated through the case of Chile which has ambitious plans to supply electricity using only renewable sources. Four cost-optimal scenarios have been developed for the year 2050 using FuturES: two Business as usual (BAU) and two Renewable electricity (RE) scenarios. The BAU scenarios are unconstrained in terms of the technology type and can include all 11 options considered. The RE scenarios aim to have only renewables in the mix, including storage. The results show that both BAU scenarios have a levelised cost of electricity (LCOE) lower than, or equal to, today’s costs ($72.7–77.3 vs $77.6/MWh) and include 81–90% of renewables. The RE scenarios are slightly more expensive than today’s costs ($81–87/MWh). The cumulative investment for the BAU scenarios is $123-$145 bn, compared to $147-$157 bn for the RE. The annual investment across the scenarios is estimated at $4.0 ± 0.4 bn. Both RE scenarios show sufficient flexibility in matching supply and demand, despite solar photovoltaics and wind power contributing around half of the total supply. Therefore, the FuturES framework is a powerful tool for aiding the design of cost-efficient power systems with high penetration of renewables.

Cakes are a favourite food across the globe and yet little is known about their environmental sustainability. To address this research gap, this paper evaluates the life cycle environmental impacts associated with the production and consumption of industrially-produced cakes. The following main product categories are considered: whole cakes, cake slices, pies, cupcakes and cheesecake. The results reveal that whole cakes have the lowest impacts for 13 out of 18 categories considered. Cheesecake is environmentally the least sustainable option, with all impacts but terrestrial ecotoxicity higher than any other cake type. Raw materials are the major contributors to the majority of impact categories (22%–98%), followed by packaging and manufacturing. Wheat flour, sugar, palm oil and milk-based ingredients are the main hotspots in the life cycle. A range of improvement opportunities is considered across the supply chain. For example, decreasing sugar content in cakes by 30% would lower the impacts by up to 3%–11%, while reducing the amount of packaging and energy used in manufacturing would lower the impacts cumulatively by 9%–23%. Minimising waste would decrease water ecotoxicity by 6%–28%. Based on annual consumption in the UK, the cakes sector contributes 2% to the energy consumption and 1% to the GHG emissions of the whole food sector. The results of this work can assist the industry and government in benchmarking the sector and minimising its environmental impacts. The findings will also be of interest to consumers in identifying environmentally more sustainable cake alternatives.

Various frameworks have been developed to guide organisations in embedding circular economy principles in their strategy and operational practice. However, there is a lack of studies analysing practical implementation of circular economy thinking in the higher education sector. Higher education institutions are strategic agents in supporting sustainable development through teaching, research and social outreach activities. They also represent a source of environmental impacts due to significant resource consumption and waste generation. This paper presents the first comprehensive study showing how higher education institutions can use an action-led step-by-step approach to build a business case and implement circular economy thinking in practice. The University of Manchester is used as an illustrative example of a large higher education institution. First, a background analysis and semi-structured interviews were carried out to determine the scope of the university's current sustainability policies and the ability of the management systems to respond to circular economy challenges. This was followed by stakeholder workshops to identify gaps and opportunities for building a business case for implementation of a circular economy. Finally, a critical assessment of the outcomes was carried out to identify further research needs for implementation of a circular economy in higher education institutions. Although focused on the higher education sector, the proposed action-led approach can be used by any organisation in the service sector looking to build more circular and sustainable business models.

Consumers are the leading producers of food waste (FW) in developed countries and the majority of household FW is still embedded in general waste where it is incinerated or landfilled. There is increasing awareness in the value of collecting FW as a separate waste stream for production of compost or recovery of energy through anaerobic digestion (AD). This study focuses on AD to evaluate the life cycle environmental sustainability of recovering energy and fertilisers from household FW in the UK. The analysis is carried out for two different functional units: i) treatment of 1 tonne of FW, which is compared to incineration and landfilling; and ii) generation of 1 MWh of electricity, which is compared to other electricity generation options. The former results in net negative greenhouse gas (GHG) emissions (−39 kg CO2-eq./t) and primary energy demand (−2 GJ/t) due to the displacement of grid electricity and mineral fertilisers. AD has lower impacts than both incineration and landfilling across 15 of the 19 impacts. However, the application of digestate to land and the release of ammonia and nitrates lead to higher marine eutrophication (ME), terrestrial acidification (TA) and particulate matter formation (PMF). For the second functional unit, AD electricity emits 203 kg CO2-eq./MWh, compared to 357 kg CO2-eq./MWh for the UK grid mix. Compared to renewables, such as wind and solar, AD electricity has lower energy demand, toxicity potentials and metal depletion. However, it has higher global warming potential, ME, TA and PMF. At the UK level, treating 4.9 Mt of kerbside FW collected annually could provide 0.37% of the national electricity demand and save 190,000 t CO2-eq./yr compared to the grid electricity. The digestate produced could displace 1% of industrial nitrogen fertilisers. Although small fractions of the national demands, they represent a valuable return from a largely unutilised waste stream and help towards implementation of a circular economy.

Vegetables are an important constituent of a balanced diet. Nearly 11 million tonnes of vegetables are consumed in the UK annually, 67% of which are purchased as fresh, with the remaining processed into various products. Almost 40% of vegetables are imported, most of them from water-stressed countries. The water and energy demands of different vegetables vary depending on their kind and origin, as well as the type and level of processing. As water and energy are interconnected, it is vital to examine their dependency. Therefore, this work evaluates the environmental impacts of vegetables on the food-energy-water (FEW) nexus. A new methodology has been developed for these purposes, based on a life cycle approach. Eight types of vegetables most consumed in the UK are considered, including fresh and processed products produced domestically and imported. The impacts are considered at both the product and sectoral levels.

This study evaluates the life cycle environmental sustainability of cheddar cheese with energy recovery from cheese whey via anaerobic digestion. Environmental hotspots and improvement opportunities along the supply chain are also identified. The cheddar cheese production process has been simulated by using Aspen Plus. The environmental impacts have been estimated through life cycle assessment (LCA) using the outputs from process simulation. The LCA data for the rest of the life cycle have been sourced from databases and literature. The results reveal that the total primary energy consumed in the whole life cycle of cheddar cheese is 347 MJ, with the carbon footprint equal to 14 kg CO 2 eq. per kg of cheddar. Energy recovered from anaerobic digestion of whey reduces the total life cycle primary energy demand and the carbon footprint by only 2%. Much greater reductions could be achieved by targeting milk production and storage of cheese. However, anaerobic digestion of whey makes the cheese production process energy self-sufficient and reduces the production costs. It also makes the production process carbon negative, reducing its carbon footprint from 0.12 to -0.12 kg CO 2 eq./kg due to the credits for electricity and heat produced from biogas.

This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Reducing food waste and increasing resource efficiency have become worldwide targets as highlighted by the United Nations Sustainable Development Goal 12 - Responsible consumption and production. Food packaging, in particular plastics-based, is a key component of food-related waste: packaging increases the amount of total waste, but also reduces potential food waste by protecting food products and prolonging their shelf life. Therefore, it is important that packaging is designed as to satisfy both technical and environmental criteria. Hence, this paper seeks to develop a decision-support framework and key metrics to aid development and selection of new innovative food packaging within a circular economy context. A set of indicators is proposed, integrating techno-environmental and circular economy criteria to help designers as well as food and packaging manufacturers develop more sustainable products. The methodology is illustrated through a prototype new plastic packaging developed as part of this project, considering its use for two types of product - raspberries and meat - as illustrative examples. UK Research Councils

The poultry industry generates a large quantity of litter, which consists of a mixture of manure, waste bedding and feathers, and can be used for recovery of energy. Recent studies suggest that gasification is a promising technology for an effective conversion of poultry litter to energy. This paper aims to assess the environmental impacts of generating electricity from the gasification of poultry litter in a small-scale integrated gasification combined cycle (IGCC) plant. Gasification of poultry litter has been simulated with ASPEN Plus® software and life cycle assessment has been used to determine the carbon footprint and primary energy demand of the system. The following life cycle stages have been considered: collection and storage of poultry litter, its gasification, syngas cleaning, production of electricity and co-production of ash as a fertiliser. The carbon footprint and primary energy demand of generating 1 kWh of energy by poultry litter gasification plant are estimated at 42 g CO2 eq./kWh and 0.14 MJ/kWh, respectively. Compared to electricity from fossil fuels, this system has 91%-96% smaller carbon footprint and 98%-99% lower primary energy demand. The energy payback period is estimated at 1.5 years. © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)

The consumption of takeaway food is increasing worldwide. Single-use containers used for takeaway food represent a significant source of waste and environmental impacts due to their low recyclability. Consequently, it is important to identify the best available alternatives and improvement opportunities to reduce the environmental impacts of fast-food containers. For these purposes, this study estimates and compares for the first time the life cycle impacts of three most widely-used types of takeaway container: aluminium, polypropylene and extruded polystyrene. These are also compared to reusable polypropylene containers. The findings suggest that single-use polypropylene containers are the worst option for seven out of 12 impacts considered, including global warming potential. They are followed by the aluminium alternative with five highest impacts, including depletion of ozone layer and human toxicity. Overall, extruded polystyrene containers have the lowest impacts due to the lower material and electricity requirements in their manufacture. They are also the best option when compared to reused takeaway polypropylene containers, unless the latter are reused 3–39 times. The number of uses needed for the reusable “Tupperware” polypropylene food savers is even higher, ranging from 16 to 208 times, with terrestrial ecotoxicity being always higher than for extruded polystyrene, regardless of the number of uses. However, extruded polystyrene containers are currently not recycled and cannot be considered a sustainable option. If they were recycled in accordance with the European Union 2025 policy on waste packaging, most of their impacts would be reduced by >18%, while also reducing littering and negative effects on marine organisms. Most of the impacts of the other two types of container would also be reduced (>20%) through increased recycling. Implementing the European Union 2025 policy on recycling of waste packaging would reduce all the impacts by 2%–60%, including a 33% reduction in global warming potential. Based on 2025 million takeaway containers used annually in the European Union, the latter would save 61,700 t CO2 eq./yr, equivalent to the emissions of 55,000 light-duty vehicles. The outcomes of this study will be of interest to packaging manufacturers, food outlets, policy makers and consumers.

Water treated in advanced wastewater treatment plants (WWTP) could be reused as potable water to address water shortages. Furthermore, sludge from WWTPs can be used to recover nutrients, energy and chemicals. Thus, the role of WWTPs could change from traditional pollution control facilities to sources of freshwater and other valuable resources. However, the economic viability of advanced wastewater and sludge treatment methods aimed at production of potable water and recovery of other resources is currently unknown. To address this gap and inform their future development, this paper considers life cycle costs of the following four wastewater treatment methods: granular activated carbon, nanofiltration, solar photo-Fenton and ozonation. For recovery of resources from sludge, the following options are examined: agricultural application of anaerobically-digested and composted sludge, incineration, pyrolysis and wet air oxidation. Ozonation has the lowest life cycle costs, averaging £112 per 1,000 m3 of water treated, followed by nanofiltration at £134. Solar photo-Fenton is the most expensive option with £238/1,000 m3. These costs are significantly lower than water desalination and could be competitive in the future with conventional potable water production. For resource recovery from sludge, anaerobic digestion, pyrolysis and wet air oxidation can operate at a profit with the negative overall life cycle costs (-£65, -£291 and -£26/1,000 kg dry matter, respectively) if all their recovered products are fully utilised. The next best option is composting with the total life cycle costs of £35/1,000 kg dry matter. Incineration is the least preferred alternative with the cost of nearly £54/1,000 kg dry matter. Advanced wastewater and sludge treatment would increase the costs of conventional wastewater treatment by 1.5-2.1 times.

Significance Land degradation due to soil salinization has detrimental impacts on vegetation, crops, and human livelihoods, leading to a need for a methodologically consistent analysis of the variability of different aspects of salt-affected soils. However, previous studies on the soil salinity issue have been primarily spatial and localized, leaving the large-scale spatiotemporal variations of soil salinity widely ignored. To address this gap, we present a globally validated analysis quantifying the long-term variations (40 y) of topsoil salinity at high spatial resolutions using machine-learning techniques. The results have significant implications for agroecological modelling, land assessment, crop growth simulation, and sustainable water management., Knowledge of spatiotemporal distribution and likelihood of (re)occurrence of salt-affected soils is crucial to our understanding of land degradation and for planning effective remediation strategies in face of future climatic uncertainties. However, conventional methods used for tracking the variability of soil salinity/sodicity are extensively localized, making predictions on a global scale difficult. Here, we employ machine-learning techniques and a comprehensive set of climatic, topographic, soil, and remote sensing data to develop models capable of making predictions of soil salinity (expressed as electrical conductivity of saturated soil extract) and sodicity (measured as soil exchangeable sodium percentage) at different longitudes, latitudes, soil depths, and time periods. Using these predictive models, we provide a global-scale quantitative and gridded dataset characterizing different spatiotemporal facets of soil salinity and sodicity variability over the past four decades at a ∼1-km resolution. Analysis of this dataset reveals that a soil area of 11.73 Mkm2 located in nonfrigid zones has been salt-affected with a frequency of reoccurrence in at least three-fourths of the years between 1980 and 2018, with 0.16 Mkm2 of this area being croplands. Although the net changes in soil salinity/sodicity and the total area of salt-affected soils have been geographically highly variable, the continents with the highest salt-affected areas are Asia (particularly China, Kazakhstan, and Iran), Africa, and Australia. The proposed method can also be applied for quantifying the spatiotemporal variability of other dynamic soil properties, such as soil nutrients, organic carbon content, and pH.

A large portion of plastic produced each year is used to make single-use packaging and other short-lived consumer products that are discarded quickly, creating significant amounts of waste. It is important that such waste be managed appropriately in line with circular-economy principles. One option for managing plastic waste is chemical recycling via pyrolysis, which can convert it back into chemical feedstock that can then be used to manufacture virgin-quality polymers. However, given that this is an emerging technology not yet used widely in practice, it is not clear if pyrolysis of waste plastics is sustainable on a life cycle basis and how it compares to other plastics waste management options as well as to the production of virgin plastics. Therefore, this study uses life cycle assessment (LCA) to compare the environmental impacts of chemical recycling of mixed plastic waste (MPW) via pyrolysis with the established waste management alternatives: mechanical recycling and energy recovery. Three LCA studies have been carried out under three perspectives: waste, product and a combination of the two. To ensure robust comparisons, the impacts have been estimated using two impact assessment methods: Environmental footprint and ReCiPe. The results suggest that chemical recycling via pyrolysis has a 50% lower climate change impact and life cycle energy use than the energy recovery option. The climate change impact and energy use of pyrolysis and mechanical recycling of MPW are similar if the quality of the recyclate is taken into account. Furthermore, MPW recycled by pyrolysis has a significantly lower climate change impact (−0.45 vs 1.89 t CO2 eq./t plastic) than the equivalent made from virgin fossil resources. However, pyrolysis has significantly higher other impacts than mechanical recycling, energy recovery and production of virgin plastics. Sensitivity analyses show that some assumptions have notable effects on the results, including the assumed geographical region and its energy mix, carbon conversion efficiency of pyrolysis and recyclate quality. These results will be of interest to the chemical, plastics and waste industries, as well as to policy makers.

Biofuels are being promoted as a low-carbon alternative to fossil fuels as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. However, there are also concerns that their wider deployment could lead to unintended environmental consequences. Numerous life cycle assessment (LCA) studies have considered the climate change and other environmental impacts of biofuels. However, their findings are often conflicting, with a wide variation in the estimates. Thus, the aim of this paper is to review and analyse the latest available evidence to provide a greater clarity and understanding of the environmental impacts of different liquid biofuels. It is evident from the review that the outcomes of LCA studies are highly situational and dependent on many factors, including the type of feedstock, production routes, data variations and methodological choices. Despite this, the existing evidence suggests that, if no land-use change (LUC) is involved, first-generation biofuels can—on average—have lower GHG emissions than fossil fuels, but the reductions for most feedstocks are insufficient to meet the GHG savings required by the EU Renewable Energy Directive (RED). However, second-generation biofuels have, in general, a greater potential to reduce the emissions, provided there is no LUC. Third-generation biofuels do not represent a feasible option at present state of development as their GHG emissions are higher than those from fossil fuels. As also discussed in the paper, several studies show that reductions in GHG emissions from biofuels are achieved at the expense of other impacts, such as acidification, eutrophication, water footprint and biodiversity loss. The paper also investigates the key methodological aspects and sources of uncertainty in the LCA of biofuels and provides recommendations to address these issues.

Access to clean water is one of the targets in the UN Sustainable Development Goals. However, millions of people are still without basic water services, predominantly in rural areas in developing nations. Previous studies have investigated the environmental impacts of water provision, but they mostly focused on large-scale urban systems. This paper considers for the first time the life cycle environmental impacts of different water supply options applicable to remote communities in developing countries. Focusing on the Southeast Asia-Pacific (SEAP) context, a cradle-to-grave approach is followed to estimate the impacts of locally-sourced groundwater, surface water and desalinated seawater as well as externally-sourced bottled water. The results reveal that surface water is environmentally the most sustainable alternative. Locally desalinated water, powered by diesel electricity, has two orders of magnitude higher impacts than surface water. However, externally-sourced water in plastic bottles is the worst option with 4–155 times higher impacts than desalinated water and up to three orders of magnitude higher impacts than surface water. This is largely due to the impacts related to the production of bottles. Doubling their recycling would reduce the impacts by 7–23% but bottled water would still be environmentally the least sustainable option. Although water in single-use bottles currently provides only 3% of the water supply of a representative remote community in the SEAP region considered in this study, it accounts on average for more than 50% of the total impacts from water consumption. By 2030, population increase could lead to greater reliance of remote communities on bottled water and 60–73% higher impacts of water consumption per household. Relying solely on local surface, ground and water desalinated using solar power and avoiding bottled water would reduce the impacts by 33–99% relative to the current situation. This would also improve considerably water availability and security in remote communities. The findings of this study will be of interest to national and local governments developing future policies aimed at increasing access of remote communities to clean water.

Cement production is a highly energy-intensive process, contributing 7% to the global CO2 emissions. Over 80% of the energy used in cement production is consumed by the calcination process. This paper considers a novel solar thermal technology for calcination, to investigate if it could help mitigate the climate change and other environmental impacts from cement production on a life cycle basis. The following three solar options are compared to conventional fossil-fuel calcination via life cycle assessment: a full solar system, which provides all the required thermal energy, and two hybrid systems, where the solar system provides 14% and 33% of the thermal energy, respectively. The results show that all three solar options have lower impacts than conventional calcination in 14 out of 17 categories. The full solar system is the best alternative, with major reductions in climate change (48%), fossil depletion (75%), photochemical ozone formation (92%) and terrestrial ecotoxicity (79%). Based on insolation levels in different parts of the world, the solar systems could be applied to 26% of current global cement production. This would reduce the climate change impact by 15–40%, as well as most other impacts by 14–87%, depending on the fuel mix. However, a limiting factor might be two times greater land occupation than by the conventional process. Furthermore, the solar system has higher human toxicity-cancer (102%) and metals and minerals depletion (6%) due to the construction of solar facilities. Coupling conventional calcination with carbon capture and storage (CCS) is more efficient in reducing the climate change impact (63%) than the solar system (48%) relative to conventional calcination without CCS. However, adding CCS to the solar calciner would still be a better option, decreasing the impact by 81% relative to conventional calcination without CCS. These findings will be of interest to the solar and cement industries as well as other industrial sectors using high-temperature processes.

Access to clean cooking fuels and technologies is essential for achieving the Sustainable Development Goals, particularly in developing countries, to minimise human health and environmental impacts. This paper assesses for the first time the environmental sustainability of household cooking, focusing on remote communities in developing countries in the Southeast Asia-Pacific (SEAP) region and considering both life cycle and local impacts. To guide rural development policies, the impacts of the following cooking fuels are considered: liquefied petroleum gas, kerosene, wood, charcoal, crop residues, biogas and electricity. Both the present situation and three future (2030) scenarios are evaluated on 18 life cycle impacts, as well as on local environmental and health impacts caused by cooking. The results show that electricity is the worst option in 13 out of 18 life cycle categories since it is generated from diesel in off-grid communities. Biogas from manure is the best fuel with 16 lowest life cycle impacts. Biomass fuels can have lower life cycle impacts than fossil fuels but they have high combustion emissions which lead to higher local environmental and health impacts. Future scenarios with higher biomass utilisation have up to 47 times lower life cycle impacts than at present, but 4-23% higher local impacts. Health impacts related to fuel combustion are higher in Vietnam, the Philippines, Cambodia, Laos and Myanmar compared to the other SEAP countries due to regional background pollutant concentrations and health trends. A fuel mix with liquefied petroleum gas, biogas and renewable electricity offers considerable reductions in 13 life cycle impacts compared to the present situation, while also reducing local health impacts by 78-97%. A self-sufficient fuel mix with local biomass and renewable electricity would reduce 17 out of 18 life cycle impacts, but all local impacts, including on health, would be 11-28% higher than at present. The results from this study can be used by policy makers and other stakeholders to develop policies for clean cooking in remote communities and reduce both environmental and human health impacts.

Soil salinity is among the major threats affecting the soil fertility, stability and vegetation. It can also accelerate the desertification processes, especially in arid and semi-arid regions. An accurate estimation of the global extent and distribution of the salt-affected soils and their temporal variations is pivotal to our understanding of the salinity-induced land degradation processes and to design effective remediation strategies. In this study, using legacy soil profiles data and a broad set of climatic, topographic, and remotely sensed soil surface and vegetative data, we trained ensembles of classification and regression trees to map the spatio-temporal variation of the soil salinity and sodicity (exchangeable sodium percentage) at the global scale from 1980 to 2018 at a 1 km resolution. The User’s Accuracies for soil salinity and sodicity classification were 88.05% and 84.65%, respectively. The 2018 map shows that globally ̴ 944 Mha of the lands are saline (with saturated paste electrical conductivity > 4 ds m-1), while ̴ 155 Mha can be classified as sodic soils (with sodium exchange percentage > 15%). Our findings and provided dataset show quantitatively how soil salinization is influenced by a broad array of climatic, anthropogenic and hydrologic parameters. Such information is crucial for effective water and land-use management, which is important for maintaining food security in face of future climatic uncertainties. Moreover, our results combined with the quantitative methodology developed in this study will provide us with an opportunity to delineate the role of anthropogenic activities on soil salinization. This information is useful not only for developing predictive models of primary and secondary soil salinization but also for natural resources management and policy makers.

Improving access to energy and water in remote communities is an important step towards sustainable development. However, integrated sustainability studies at the community or household scale are rare compared to industrial or national studies. Thus, this paper presents an integrated approach to the development and evaluation of energy and water supply systems in remote communities in developing countries. Termed here “synergistic generation” (“synergen”), the approach considers simultaneously electricity, heat for cooking and water supply to determine their environmental and economic sustainability on a life cycle basis. Life cycle assessment and life cycle costing are used for this purpose. Both the current situation and future scenarios to 2030 are considered for a representative remote community. The life cycle costs of the current energy and water supply are estimated at 2944 USD/household per year, most of which (91%) is due to bottled water. The latter is also the main cause of current environmental impacts (62%), followed by cooking fuels (33%) and electricity (5%). If business as usual (BAU) continues to 2030, air pollution and eutrophication could be reduced by >40% but other 14 impacts would increase by 2–63% on the current situation due to higher dependence on diesel for electricity generation and bottled water. For the same reason, BAU also has 82% higher life cycle costs (5364 USD/household∙yr) than at present. Assuming full supply self-sufficiency (Independent scenario) leads to a >12% reduction in all impact categories, except terrestrial ecotoxicity, which increases by 5% – both trends are due to utilisation of waste biomass for cooking. The life cycle costs are reduced by 92% (231 USD/household∙yr), mainly due to the phasing out of bottled water. However, capital costs are 21% higher due to the need for multiple renewable energy installations. Pursuing moderate rather than full independence of supply (Transition scenario) would reduce most impacts and costs below those of the current situation. Overall, the Transition and Independent scenarios have lower impacts than at present in almost all environmental categories as well as lower life cycle costs. These findings demonstrate the environmental and economic feasibility of energy and water independence in remote communities as well as highlighting the likely trade-offs that should be considered during the transition.

© 2020 The Authors. Spent coffee grounds (SCGs) have a potential to be used as a feedstock for higher value-added products, such as biodiesel. However, the environmental implications of the valorisation of SCGs are largely unknown. This study evaluates the life cycle environmental impacts of utilising SCGs for biodiesel production in comparison with the widely used disposal of SCGs as a waste stream: incineration, landfilling, anaerobic digestion, composting and direct application to land. The scope is from cradle to grave and the functional unit is defined as ‘treatment of 1 tonne of SCGs’. The results show that the most environmentally sustainable option is incineration of SCGs, with net-negative impacts (savings) in 14 out of 16 categories, followed by direct application of SCGs to land with 11 net-negative impacts. Biodiesel production is the least sustainable option with the highest impacts in 11 categories, followed by composting. The paper also demonstrates that following various waste hierarchy and resource valorisation guidelines instead of a life cycle approach could lead to a choice of environmentally inferior SCG utilisation options. Therefore, these guidelines should be revised to ensure that they are consistent and underpinned by life cycle thinking, thus aiding sustainable resource management in a circular economy context. UK Engineering and Physical Sciences Research Council (Gr. no. EP/K011820/1) and The University of Manchester through the N8 AgriFood Local Pump Priming Fund

River flow reductions as a result of agricultural withdrawals and climate change are rapidly desiccating endorheic lakes, increasing their salinity and affecting the bio-diversity and human wellbeing in the surrounding areas. Here we present a new framework to guide eco-hydrological restoration of saline lakes and build their resilience to climate change by optimizing agricultural land use and related water withdrawals. The framework involves four steps: 1. selection of global circulation models for the basin under study; 2. establishment of a hydrological balance over the lake’s area to estimate the amount of water required for its restoration; 3. water allocation modeling to determine the water available for restoration and allocation of the remaining water across different users in the lake’s basin; and 4. basin-scale optimization of land use and cropping patterns subject to water availability. We illustrated the general applicability of the framework through the case of the second largest (by volume) hyper-saline lake globally, Lake Urmia, which lost 96% of its volume in only 20 years, primarily as a result of upstream water withdrawals. Through the application of the framework, we estimated the amount of water needed to restore the lake, either fully or partially, and proposed a sustainable land-use strategy, while protect farmers’ income in the basin. Considering future climate change projections under two representative concentration pathways (RCP) 4.5 and 8.5, we found that an average annual surface inflow of 3,648 Mm3 (∼70% increase in RCP 4.5) and 3,692 Mm3 (∼73% increase in RCP 8.5) would be required to restore the lake by 2050, respectively. This would require the respective conversion of 95,600 ha and 133,687 ha of irrigated land to rain-fed cropland or grassland across the basin by 2050. The proposed framework can be used for building resilience to climate change and mitigating human-induced threats to other declining saline lakes.

Sewage sludge handling is becoming a concern in Europe due to its increasing amount and the presence of contaminants, such as heavy metals and pharmaceutical and personal care products (PPCPs). Currently, over 70% of sludge in Europe is treated thermally by incineration or used as fertilizer in agriculture. New thermochemical methods are under development and are expected to be implemented in the near future. This paper considers the life cycle environmental impacts of the following five alternatives for sludge handling, taking into account the presence of heavy metals and PPCPs: i) agricultural application of anaerobically digested sludge; ii) agricultural application of composted sludge; iii) incineration; iv) pyrolysis; and v) wet air oxidation. The results suggest that anaerobic digestion with recovery of nutrients and electricity has the lowest environmental impacts in 11 out of 18 categories considered. For the mean to maximum resource recovery, composting is the worst alternative, followed by pyrolysis with lower recovery rates. Agricultural application of anaerobically digested sludge has the highest freshwater ecotoxicity due to heavy metals, unless their concentration is in the lowest range, as found in some European sewage sludge applied on land. Therefore, stricter control of heavy metals in the sludge is needed for this option to limit freshwater ecotoxicity to the levels comparable with the thermal processes. The results also indicate that PPCPs have a negligible contribution to freshwater ecotoxicity when compared to heavy metals in the anaerobically digested sludge. Since thermal processes are currently drawing attention due to their potential benefits, the findings of this work suggest that their adoption is environmentally beneficial only if high resource recovery rates can be achieved.

International audience; Municipal solid waste (MSW) incinerators require effective flue gas treatment (FGT) to meet stringent environmental regulations. However, this in turn generates additional environmental costs through the impacts of materials and energy used in the treatment – these impacts are currently scarcely known. Therefore, this study uses life cycle assessment to estimate the impacts of different FGT systems typically found in modern MSW incinerators. A total of 12 scenarios are modelled to consider different combinations of the following eight technologies: electrostatic precipitators and fabric filters for removal of particulate matter; dry, semi-dry and wet scrubbers for acid gases; selective non-catalytic and catalytic reduction of nitrogen oxides (NOx); and activated carbon for removal of dioxins and heavy metals. The data are sourced from 90 full-scale incinerators operating in France. The results reveal that a dry system using sodium bicarbonate and selective non-catalytic reduction (SNCR) is the best option for seven out of 18 impacts, including climate change (37.1 kg CO2 eq./t MSW). By contrast, a dry system with calcium hydroxide and selective catalytic reduction (SCR) has the highest impacts in six categories, including climate change (102 kg CO2 eq./t MSW). The wet systems have higher impacts than the dry alternatives, with the semi-dry options being in between. Compared to SNCR, the use of SCR decreases the NOx-related impacts (fine particulate matter formation, terrestrial acidification and photochemical ozone formation) but increases other impacts. For example, the SCR systems have 49–284% greater climate change and 43–150% higher depletion of fossil resources than their SNCR counterparts. Overall, all FGT systems reduce significantly fine particulate matter formation (by 81–88%), photochemical ozone formation (76–90%) and terrestrial acidification (83–90%). However, they also cause 14 other impacts which would not be generated if the flue gas was left untreated, thus creating additional environmental costs. These include climate change, resource depletion and human and ecotoxicities. Therefore, these trade-offs should be considered carefully to minimise the unintended environmental consequences of flue gas treatment from incineration of MSW.