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This study evaluates the environmental impacts associated with the conversion of garden organic waste into value-added products, namely compost or biochar, employing various processes. Three distinct scenarios are considered: composting garden organic waste followed by screening of oversized materials (CBP), pyrolysis of oversized screenings of compost into biochar AP(I), and in-situ conversion of garden organics into biochar AP(II). A comprehensive Life Cycle Assessment (LCA) was conducted using OpenLCA software and life cycle impact assessment was conducted using Recipe 2016 midpoint methodology. The environmental ramifications of each scenario were assessed, optimising transport distances in AP(II) to achieve a functional unit of one tonne of biochar produced within a cradle-to-gate system boundary. For the first time, this study offers a holistic exploration of the benefits of soil biochar application, extending its scope to climate change mitigation, incorporating the optimisation of transport distance and its influence when scaling up the technology. The results revealed that global warming was increased from 125 kgCO 2 eq during composting of garden waste to 232 kgCO 2 eq where oversized screenings of compost is converted to biochar at an off-site facility. However, direct conversion of the oversized organic waste to biochar, without composting, showed reduced global warming impact of 56 kgCO 2 eq, and is thus the most favourable scenario to limit climate impacts of this fraction of organic garden waste. However, among 18 environmental impact indicators studied, eight indicators were either not influenced or did not significantly increase by transport distance to an off-site pyrolysis facility, while the magnitude of 10 impact indicators increased with transport distance. The insights and methodologies presented in this study hold global relevance, based on an actual case study in regional Australia, offering valuable recommendations for sustainable waste management practices and establishing biochar as a carbon-neutral or carbon-negative solution. The findings contribute to existing waste management knowledge and provide guidance for accessible carbon dioxide removal and soil carbon sequestration technologies. [Display omitted] • A comprehensive LCA for valorisation of garden organics was conducted. • Direct conversion of garden organics to biochar showed least potential environmental impacts. • Biochar provides opportunities for avoided, reduced, and removed carbon from atmosphere. • Maximum transport distance has been identified for individual impact categories. [ABSTRACT FROM AUTHOR]

Developing non-grain forestry woody fuel industries such as Jatropha curcas L. (JCL) aligns with the national conditions of countries with food shortages and large populations, such as some countries in Africa and Asia, and is an ideal alternative to replace fossil fuels. Determining appropriate planting densities suitable for different regions is one of the most critical practices for agriculture and forestry to achieve high yields and sustainability. This study conducted a life cycle assessment (LCA) of the JCL biodiesel's environmental impact, energy balance, and economic analysis (3E) of two densities and three of the most suitable planting regions in China. Findings reveal that the density of 2500 plants/ha had a better 3E performance than 1600 plants/ha, and Yunnan province outperformed Guizhou province and Sichuan province. JCL biodiesel effectively mitigates the greenhouse effect (1141.14–1936.59 kg CO 2 eq/t) compared to conventional fossil diesel in different cases. Key factors influencing environmental performance include seed yield, urea applied during cultivation, methanol for biodiesel conversion, and electricity for irrigation. The Net Energy Balance (NEB) and Net Energy Ratio (NER) demonstrate the superior energy efficiency of JCL biodiesel over fossil diesel. The cost of producing JCL biodiesel decreased with the maturation of the trees, with water use and labor salary accounting for over 80% due to the necessity of the cultivation stage. Although the Financial Net Present Value (FNPV) was negative when considering only JCL biodiesel, it became positive (12111.64–27342.44 CNY) with the inclusion of by-products (glycerine, press-cake, and shells) in high-density cases. Our findings suggest that JCL biodiesel with appropriate density can serve as a sustainable biofuel alternative, replacing a portion of the fossil diesel currently on the market and significantly contributing to climate change mitigation and nonrenewable energy conservation. [Display omitted] • A comprehensive cradle-to-gate LCA of Jatropha curcas L. biodiesel of two densities × three regions was assessed. • Planting density was an important factor influencing the environmental, energy, and economic performance of Jatropha curcas L. • Jatropha curcas L. biodiesel reduced GHG emissions and saved energy compared to fossil diesel. • Emissions from fertilizers, energy consumption from electricity, and the cost of labor contributed the most to 3E of Jatropha curcas L. biodiesel. [ABSTRACT FROM AUTHOR]

We perform an ex-ante life cycle assessment, integrating cradle-to-gate greenhouse gas emissions into an off-grid energy system model. By applying a multi-objective optimization, minimizing both costs and carbon dioxide equivalent (CO 2 e) emissions, we find the Pareto boundary between these two goals. As a case study, we chose the power supply to an astronomical observatory in Chile, using mostly solar power and energy storage in batteries and hydrogen. We compare the ex-ante study to a prior ex-post life cycle assessment, and furthermore dive into sensitivities of our model regarding component lifetimes and costs. We find (i) low-hanging fruit in lowering emissions with small cost increases, (ii) ex-ante life cycle assessments' possibility to find less CO 2 e intensive power systems compared to ex-post conducted studies, (iii) a pronounced sensitivity of the optimization model on assumed lifetimes of energy storage components. This study shows the importance of including life cycle CO 2 e emissions into the optimization objective of energy system models. This method uncovers the environmental and economic trade-offs associated with high shares of renewable energies in off-grid energy systems. • We integrate life cycle assessment (LCA) into an off-grid energy system optimization. • The applied case study powers a remote astronomical telescope in Chile. • A multi-objective optimization finds Pareto curves at varying costs and lifetimes. • Low-hanging fruit shows low additional system costs to reduce CO 2 e impacts. • In contrast, a separate LCA did not find such trade-offs in costs and CO 2 e emissions. [ABSTRACT FROM AUTHOR]

• A review of the spectrum of emerging Direct Air Capture, DAC technologies. • Several categories are under different levels of development with different working principles. • A widespread data on DAC technical, economic, and environmental performance. • Lack of standardized frameworks for DAC assessment. • Multicriterial assessment frameworks can provide comprehensive guidance for rapid deployment. Direct air capture (DAC) is set to play a crucial role in meeting climate change targets as most recent climate scenarios rely on its large-scale implementation. Nevertheless, despite this widespread consensus, DAC performance and impact have not been sufficiently investigated, which has resulted in hindering its wide-scale deployment for climate change mitigation initiatives. Here, we present a comparative review of different DAC technologies and examine their performance from a holistic perspective by considering different aspects, from technical, commercial, and economic to environmental. We classify DAC technologies into five main categories, namely (i) liquid scrubbing, (ii) solid sorbent, (iii) electrochemical, (iv) cryogenic, and (v) membrane, and within each category, various approaches can be employed. We explore key challenges involved in developing each DAC technology and compare their performance using up-to-date data. We then critically analyze the primary factors contributing to the inconsistencies arising from the economic assessment results and provide valuable guidelines for future studies. Overall, the present review can benefit researchers, engineers, and policymakers in obtaining a holistic understanding of these state-of-the-art technologies in addition to filling key gaps in the DAC field. [ABSTRACT FROM AUTHOR]

• Substitution factors for forest products for the Canadian context were developed. • Substitution factors ranging from 0.51 to 0.91 tC/tC were found. • They will lead to more accurate assessments of the forest GHG mitigation potential. • These factors will help governments to manage forest and fight climate change. Evaluating the climate change mitigation potential of the forest sector requires a holistic approach based on forest carbon (C) sequestration, C storage in harvested wood products (HWP) and substitution on markets. High uncertainty is associated with substitution factors, that express avoided fossil greenhouse gas (GHG) emissions from the use of forest-based products in replacement of GHG-intensive materials and fossil fuels. Few studies have focused on the development of substitution factors in Canada, resulting in the use of unrepresentative generic data. Here, we provide a framework to reduce uncertainties related to substitution factors for primary wood products in a Canadian context. A life cycle assessment framework is used to quantify fossil GHG emissions for a baseline and a wood-intensive scenario. For solid product substitution, we focused on the construction sector and analyzed a range of innovative wood buildings with steel and reinforced concrete as alternative materials. We found non-weighted averages of 0.80 tC/tC for sawnwood and 0.81 tC/tC for panels. For energy substitution, we analyzed cases with different specifications on biomass product, facility type and alternative fossil fuel source in non-residential heat production and biofuel transportation sectors. We found a non-weighted average of 0.80 tC/tC for non-residential heat production and 0.51 tC/tC for biofuel transportation, that can be interpreted as 0.91 tC/tC for heavy fuel oil, 0.69 tC/tC for light fuel oil and 0.68 tC/tC for natural gas substitution. These results provide a benchmark for substitution factors in Canada, to help guide forest management strategies for climate change mitigation. [ABSTRACT FROM AUTHOR]

Crop residue burning is a common practice in many parts of the world that causes air pollution and greenhouse gas (GHG) emissions. Regenerative practices that return residues to the soil offer a 'no burn' pathway for addressing air pollution while building soil organic carbon (SOC). Nevertheless, GHG emissions in rice-based agricultural systems are complex and difficult to anticipate, particularly in production contexts with highly variable hydrologic conditions. Here we predict long-term net GHG fluxes for four rice residue management strategies in the context of rice-wheat cropping systems in Eastern India: burning, soil incorporation, livestock fodder, and biochar. Estimations were based on a combination of Tier 1, 2, and 3 modelling approaches, including 100-year DNDC simulations across three representative soil hydrologic categories (i.e., dry, median, and wet). Overall, residue burning resulted in total direct GHG fluxes of 2.5, 6.1, and 8.7 Mg CO 2 -e in the dry, median, and wet hydrologic categories, respectively. Relative to emissions from burning (positive values indicate an increase) for the same dry to wet hydrologic categories, soil incorporation resulted in a −0.2, 1.8, or 3.1 Mg CO 2 -e change in emissions whereas use of residues for livestock fodder increased emissions by 2.0, 2.1, or 2.3 Mg CO 2 -e. Biochar reduced emissions relative to burning by 2.9 Mg CO 2 -e in all hydrologic categories. This study showed that the production environment has a controlling effect on methane and, therefore, net GHG balance. For example, wetter sites had 2.8–4.0 times greater CH 4 emissions, on average, than dry sites when rice residues were returned to the soil. To effectively mitigate burning without undermining climate change mitigation goals, our results suggest that geographically-target approaches should be used in the rice-based systems of Eastern India to incentivize the adoption of regenerative 'no burn' residue management practices. • Efforts to build SOC for climate change mitigation, while simultaneously avoiding burning, may have unintended consequences. • Tier 1, 2, and 3 modelling approaches were used to compare no-burn rice residue pathways. • Field hydrology had a dominant effect on methane emissions. • Soil incorporation of residues increased emissions relative to open burning, except in comparatively dry fields. • Biochar is estimated to have the lowest GHG emissions of the evaluated 'no burn' alternatives. [ABSTRACT FROM AUTHOR]

Bioenergy with carbon capture and storage (BECCS) is regarded as a crucial negative emission technology (NET) in many prospective climate change mitigation scenarios that limit global warming below 2 °C. However, there is still insufficient understanding of the overall life cycle environmental performance of different BECCS configurations. Despite the fact that BECCS entails many technological combinations, the technology is still regarded as a single "black box" technology in most climate scenarios. This study presents a critical review of life cycle assessment (LCA) on a wide range of BECCS options: biomass direct-fired power generation, biomass gasification power generation, bio-hydrogen production, biomass application in industry sectors and other biomass conversion processes, such as pyrolysis and fermentation. It is evident from the review that the biomass direct-fired and gasification power plant with a 100% biomass firing ratio and the gasification-based bio-hydrogen processes have a strong potential to achieve negative emissions. However, the net negative life cycle emissions range widely among studies for each configuration due to variations in technology, LCA methodology and assumptions. Additionally, there is an insufficient assessment of comprehensive environmental impacts for BECCS systems other than GWP, making it still unclear about the trade-offs between the benefit from climate change mitigation and potential negative impacts. Main recommendations for improving LCA on BECCS include developing a generalized guideline and standardization for BECCS LCA, conducting LCAs with comprehensive impact categories, focusing on BECCS configurations being overlooked, considering the impact of land use change and the global warming potential of biomass, and extending LCA in both temporal and spatial dimension. [Display omitted] • Systematically review of life cycle assessment on BECCS systems. • Detailed review on various biomass conversion technologies. • Net negative life cycle emissions range widely among studies. • Insufficient studies of some biomass conversion pathways. • Insufficient studies on multi-environmental environment impact categories. [ABSTRACT FROM AUTHOR]

With emphasis on constructing low-carbon cities, the renovation of old communities highlights the importance of renewing rainwater management facilities. Rain garden is an exceptional Nature-based Solution for rainwater management. When applying them to renovate old communities, the carbon footprint should be considered. This study focused on renovating facilities in the Greater Bay Area and utilized the Energy Expert platform to calculate rain garden carbon footprint with the Life Cycle Assessment. The carbon reduction benefits during the operation were estimated. This study accounting the life cycle carbon footprint of the 5455 m2 rain garden was 1117.42 tCO 2 e. The carbon footprint contribution, from highest to lowest was the end-of-life phase, materials production phase, construction phase, use and maintenance phase. Regarding carbon emission inventory, waste soil landfill, fertilizer acquisition, and waste soil recycling ranked high. Transportation also accounted for a remarkable carbon emission. The rain garden showed great potential for climate change mitigation, with a total and net carbon reduction of 1927.41 and 809.99 tCO 2 e, respectively. To reduce the carbon footprint of the rain garden, we should focus on waste soil treatment and transportation. Recommendations included increasing waste soil recycling, in situ recycling and green transportation. [ABSTRACT FROM AUTHOR]

As a secondary energy source, hydrogen produced by water electrolysis is a promising way to sustainably use electricity generated from primary renewable resources. Thereby, hydrogen is not only a highly relevant feedstock for producing chemical products, such as fertilizers and platform chemicals, but also a valuable energy carrier that can be readily transported and stored. This study explores how transporting renewable hydrogen via pipeline from regions with high renewable energy potential to large consumer centers can help overcome current challenges in ensuring a climate-friendly renewable energy supply. To this end, this work assesses the environmental impacts of cross-border hydrogen supply chains relative to the attained operating hours of local hydrogen production and the required hydrogen transport distance via pipeline. Environmental hotspots along the hydrogen supply chain and the main parameters affecting the overall environmental impact were identified. Remarkably, an environmental trade-off emerges: the most suitable local conditions for producing renewable hydrogen need to be balanced against the distance of hydrogen transport to consumers. Nonetheless, the relevance of the transport distance decreases with an increasing share of renewable energies in the electricity mix for operating the compressor stations of the pipeline network. Considering the ongoing transition towards renewable power generation technologies, our results indicate that long-distance hydrogen transport via pipeline is environmentally justified provided that the share of renewable energies used to operate the compressor stations increases. • Renewable hydrogen supply chains are associated with environmental impacts. • Critical parameters focus on hotspots along the hydrogen supply chain. • Regions with high renewable energy potential are ideal for hydrogen production. • Benefits increase as the difference in renewable energy potential increases. • Distance becomes less relevant as energy transition progresses. [ABSTRACT FROM AUTHOR]

Plastics account for 4.5% of global greenhouse gas (GHG) emissions, which are hard-to-abate due to the use of fossil fuels as feedstock. Our study develops a cradle-to-gate life cycle assessment of bioethylene production, exploring 33 pathways across Brazil, the EU, and the US. It aims to understand whether substituting fossil-based ethylene with bioethylene contributes to lowering carbon emissions, and in which of the relevant bioenergy-producing regions/countries the valorisation of biofuels as feedstocks would provide a less carbon-intensive bioethylene production. Results indicate that bioethylene production through catalytic dehydration of sugarcane bioethanol in Brazil presents lowest GHG emission. This pathway could deliver up to −2.1 kg CO 2 e/kg ethylene when accounting for biogenic carbon storage in long-lived applications such as infrastructure. In contrast, beef tallow performs the poorest as a raw material, regardless of whether land-use change (LUC) emissions are considered. When biogenic carbon storage is factored out, none of the pathways outperforms conventional fossil-based steam cracking; however, some are within the fossil-based range indicating potential indirect benefits through reduced refinery utilisation. Our study underscores that biomaterials production as a climate mitigation strategy must be on par with circular economy measures and the conservation of native forestry ecosystems. These results are particularly relevant to policymakers and industries seeking to align polymer manufacturing with sustainability objectives. • Bio-ethylene cradle-to-gate GHG emissions were assessed for 33 pathways. • Sugary, starch, lignocellulosic and oily crops are raw materials for bio-ethylene. • Local specificities such as biogenic carbon storage and land-use are critical to LCA GHG emissions. • Sugarcane bioethanol dehydration route yielded 2.1 kgCO 2 e captured per of kg ethylene. • Climate mitigation and circular economy policies must be designed coherently. [ABSTRACT FROM AUTHOR]

Anthropogenic greenhouse gas emissions (GHGE) are behind climate change. In Chile, food system is the second source of GHGE. Changing Chileans dietary patterns is key to reducing such emissions. There is geographic variability in terms of dietary patterns within the country. Here we investigated the dietary GHGE in five different geographical zones, along with the main contributing food groups and socio-demographic variables. Data for 4676 individuals were obtained from the 2010–2011 National Survey of Food Consumption. The carbon footprint value of each food was obtained from studies using life cycle assessment methodology. Median and percentiles of dietary GHGE were calculated, expressed in kilograms of carbon dioxide equivalent per person per day (kgCO 2 eq/person/d) and compared among zones by Kruskal-Wallis and Dunn's tests. Logistic regression models were fitted to analyzed associations among the variables of interest and quartiles of GHGE. Diet-related GHGE ranged from 3.50 (2.34–5.12) in the North-Central Zone to 4.66 (2.89–6.69) kgCO 2 eq/person/d in the South zone. Meat accounted for 53–58% of the GHGE in all the zones, followed by dairy products with 12–13%. Higher GHGE were significantly associated with energy intake (kcal/d) in all of the zones, with high socioeconomic level in the North-Central, South and Metropolitan zones, and with urban residence in the South-Central zone. Tailored policies considering geographic variability are warranted to promote healthy and sustainable diets among the Chilean population. • Differences in dietary greenhouse gas emissions were determined among five Chilean geographical zones. • South and Metropolitan region showed the highest GHGE while North showed the lowest. • Meat and dairy were the most contributing foods in all zones. • GHGE were positively associated with energy intake in all zones & with high socioeconomic level in three zones. • The promotion of sustainable diets in Chile must consider the geographical specificities. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) play a crucial role in driving energy transitions, particularly in electric vehicles (EVs) and energy storage systems. Forecasting LIB prices has received significant attention due to the tightening of raw material markets. Additionally, the implementation of carbon pricing policies has highlighted the need to incorporate the carbon footprint of LIBs in price evaluation. This study presents a comprehensive analysis of the carbon footprint, pricing trajectories, and forthcoming carbon pricing ramifications associated with LIBs. Firstly, the findings derived from the life-cycle carbon footprint assessment indicate that the global production volume-weighted average carbon footprint of EV battery packs spans 49.2–81.1 kgCO 2 eq/kWh, depending on the chosen end-of-life treatment. Strategic end-of-life selections, aligned with battery chemical composition, can diminish the carbon footprint by up to 46% relative to improper disposal methods. Notably, direct cathode recycling of NCA and NMC622 batteries exhibits superior environmental performance. Secondly, techno-economic analysis predicts that the mean price of EV battery packs with diverse chemical compositions will decline to $75.1/kWh by 2030, factoring in the compound annual growth rate of critical raw material prices over the past decade. LFP batteries emerge as the top economic performers. Lastly, the results reveal that monetizing a battery's carbon footprint may offset battery price reductions through learning effects. This underscores the imperative of effective recycling for curtailing the carbon footprint and ensuring the enduring economic and environmental competitiveness of LIBs. • Life-cycle carbon emissions are integrated into future battery price projections. • Direct cathode recycling provides the greatest potential for carbon reduction. • LFP might be the only lithium-ion battery to achieve the $80/kWh price target. • Cost reductions from learning effects can hardly offset rising carbon prices. • Recycling is needed for climate change mitigation and battery economics. [ABSTRACT FROM AUTHOR]

• Building-level hybrid RE systems support net-zero development goals and climate change mitigation. • Energy planning is multi-dimensional, and is affected by uncertainties. • A life cycle thinking based fuzzy decision support model is presented for identifying optimal hybrid building energy mix. • A combinatorial multi-objective optimisation was adopted considering the most viable RE technologies in the local market. • Solar PV and geothermal heating are the optimal residential energy choices for BC, under the selected case study scenario. The increasing concerns about the environmental and economic impacts of conventional centralised energy generation and fossil fuel usage have prompted an interest in renewable-based decentralised energy systems. Implementing such systems at building level can facilitate the development of net-zero energy buildings. Energy system planning is a multi-faceted problem that involves technical, economic, environmental, and social dimensions, and affects multiple stakeholders at different levels. A multi-objective optimisation approach is needed to identify the optimal energy choices at building level, while paying attention to stakeholder priorities and other constraints. The objective of this study is to develop a model to identify the optimal mix of renewable energy (RE) while also accounting for uncertainties, which can be integrated at building level with life cycle thinking. A framework was proposed for planning an optimised hybrid RE system at building level to support the net-zero development goals. The optimisation model was developed considering the objectives of minimising energy system cost, maximising operational cost savings, minimising the life cycle environmental impacts, and maximising the RE fraction. A combinatorial optimisation approach was adopted to reflect the practical engineering aspects of energy planning problems based on technologies available in the market. The developed framework was demonstrated through a case study conducted for an average multi-unit residential buildings (MURB) located in British Columbia, Canada. The results indicated that under the defined stakeholder priorities and constraints, ground source heat pumps and solar photovoltaics (PV) are the optimal energy choices for MURB, and the optimal energy system combination supplied 44% of the building's energy demand through RE. The findings will inform and guide community developers and other stakeholders with an interest in residential buildings, on the most suitable clean energy options for their building project during the pre-project planning stage. [ABSTRACT FROM AUTHOR]

Abstract Strategies for sustainably increasing sugarcane productivity without any negative implications to the environment are challenging. In the present investigation, field trials were conducted to demonstrate the potential of an agro-technique involving foliar applications of Kappaphycus alvarezii seaweed based biostimulant in combination with recommended rate of synthetic fertilizers (RRF) for sustainably enhancing sugarcane production and mitigating environmental impacts. Kappaphycus seaweed extract (KSWE) applied at 5% concentration enhanced cane productivity by 12.5 and 8%, respectively, in plant and ratoon crops. Interestingly, the treatment involving 6.25% KSWE +50% RRF showed yield parity (p < 0.05) with control (water+100% RRF) in ratoon while there was 7.9% reduction over control in plant crop with a concomitant savings of 50% RRF. These results revealed that KSWE application in addition to recommended rate of fertilizer application, can reduce gap between potential and real yield which otherwise requires application of incremental inputs in the form of synthetic fertilizers to obtain similar yields. The findings confirmed our hypothesis that the use of KSWE not only results in hypothetical savings in the incremental application of synthetic fertilizers but also can be used for achieving target yields sustainably. The sugar yield too was enhanced thus increasing the returns on investment. The technique is practically feasibility and scalability. The potential of the KSWE in lowering GHGs is manifested by the way of saving at least 260 kg CO 2 equivalents (Mg cane production)−1 ha−1 when applied at 5% concentration. This would translate in to savings of ca. 9.3 million Mg of CO 2 equivalents if one assumes employing KSWE for at least 10% of the total cane production in India for the year 2015–16. Therefore, the present study advocates a paradigm shift in policy to encourage use of biostimulants in the context of mitigating adverse effects of global climate change and expecting better returns from sugarcane cultivation. Graphical abstract Image 1 Highlights • Kappaphycus seaweed extract (KSWE) at 5% concentration enhanced cane productivity by ca. 10%. • Kappaphycus extract along with 50% RRF showed yield parity with control in ratoon. • Saving of 260 kg per tonne of cane production can be envisaged by use of KSWE. • Kappaphycus seaweed extract can facilitate in mitigating climate change. [ABSTRACT FROM AUTHOR]

Future projections indicate an expansion for both food and energy demands, which can increase pressure on land use, while there is an urgent global need for climate change mitigation. Bioenergy is foreseen as key option to meet future energy demands and reduce greenhouse gas (GHG) emissions, however its sustainability depends on locations and regional characteristics. Simultaneously, agricultural production models that co-produce food, feed, and energy offer sustainability synergies and co-benefits, but site-specific sustainability assessments of their large-scale implementation are missing. This study presents a bottom-up approach to assess spatially explicit sustainability aspects of bioenergy-livestock integrated systems (BLI) in Brazil and shed light on their contribution to future energy demands, to climate change mitigation targets, and their impacts on selected ecosystem services, including bioenergy production, climate change mitigation, reduction of food competition, biodiversity conservation, and avoided deforestation. The proposed integration considers livestock intensification and use of biofuels by-products as animal feed supplement, taking advantage of synergies between these two value chains. The expansion of the BLI system in the Center-South region of Brazil produce up to 89 billion liters of ethanol, enough to meet future domestic ethanol demands from multiple shared socioeconomic pathways and generating surpluses for export. This production takes place on 16 million hectares of pastureland within the Sugarcane Agroecological Zoning, excluding the Amazon and Pantanal biomes, and biodiversity hotspots. BLI expansion mitigate up to 250 million tonnes of CO 2 eq and generate 15 billion dollars of profits. The best locations to maximize the selected ecosystem services are west of São Paulo, east of Mato Grosso do Sul, and the south-central region of the states of Goiás. This study may encourage the formulation of enhanced public policies for the integration of bioenergy and livestock value chains and guide a sustainable large-scale deployment of BLI systems. • Bioenergy and livestock integration (BLI): co-production of food, feed and energy. • BLI systems: 89 billion liters of ethanol and 250 million tonnes of CO 2 eq mitigated. • Enough ethanol to meet future Brazilian demands and surplus to be exported. • Biomass expansion only on pastureland inside Sugarcane Agroecological Zoning. • Without land displacement and deforestation of native vegetation. [ABSTRACT FROM AUTHOR]

This paper provides pathways of the carbon content of electricity extracted from the Intergovernmental Panel on Climate Change’s fifth Assessment Report scenarios database. It demonstrates three policy-relevant aspects of the carbon content of electricity that are implicit in most integrated assessment model results but under-discussed in academia and the policy debate. First, climate stabilization at any level from 1.5 °C to 3 °C requires the carbon content of electricity to decrease quickly and become almost carbon-free before the end of the century. As such, the question for policy makers is not whether to decarbonize electricity but when and how to do so. Second, decarbonization of electricity is still possible and required if some of the key zero-carbon technologies—such as nuclear power or carbon capture and storage—turn out to be unavailable. Third, progressive decarbonization of electricity is part of every country’s cost-effective means of contributing to climate stabilization. The pathways of the carbon content of electricity reported here can be used to benchmark existing decarbonization targets, such as those set by the European Energy Roadmap or inform new policies in other countries. They can also be used to assess the desirable uptake rates of electric and plug-in hybrid vehicles, electric stoves and heat pumps, industrial electric furnaces, or other electrification technologies. [ABSTRACT FROM AUTHOR]

A variety of climate mitigation strategies is available to mitigate climate impacts of buildings. Several studies evaluating the effectiveness of these strategies have been performed at the building stock level, but do not consider the technological change in building material manufacturing. The objective of this study is to evaluate the climate mitigation effects of increasing the use of biobased materials in the construction of new residential dwellings in Sweden under future scenarios related to technological change. A model to estimate the climate impact from Swedish new dwellings has been proposed combining official statistics and life cycle assessment data of seven different dwelling typologies. Eight future scenarios for increased use of harvested wood products are explored under different pathways for changes in the market share of typologies and in energy generation. The results show that an increased use of harvested wood products results in lower climate impacts in all scenarios evaluated, but reductions decrease if the use of low-impact concrete expands more rapidly or under optimistic energy scenarios. Results are highly sensitive to the choice of climate impact metric. The Swedish construction sector can only reach maximum climate change mitigation scenarios if the low-impact building typologies are implemented together and rapidly. [ABSTRACT FROM AUTHOR]

Generation of goods and services are highly dependent on the use of natural resources. Until very recently, there was an implicit belief that the physical expansion of the economic system could be unlimited, as if the planet would have conditions and time enough to recover and continue to supply resources. This belief implies a confidence in an economic system that would provide whatever is necessary for a continuous growing production and consumption. Even believing that technology alone is not enough to solve the current environmental problems, it is certain that it can collaborate to mitigate climate change and to adaptation to changes in the environment. By bringing environmental aspects into discussions, eco-innovations can affect and transform the innovation system in order to create sustainable processes. However, the main challenge towards the transition to a more sustainable, cleaner and more equitable society is to set innovation in a new context, as until very recently it only considered the economic variables. This change means to value the social and environmental dimension of the innovation. In addition to eco-innovation, Life Cycle Assessment (LCA) is spreading in the industrial environment, offering promising perspectives. LCA is considered a valuable methodology in the environmental sustainability of industry. In this context, the present study addresses LCA and its relationship with the generation of eco-innovations. Drawing on contributions from literature on eco-innovation and LCA, the paper analyses available evidence on this relationship in a context of the transition towards sustainable development. To structure the debate, the paper offers a conceptual approach and an illustrative case on international researchers' and practitioners’ perceptions on the potentially positive relationship between eco-innovation and LCA. The study gathers data in the Web of Science (WoS) Core Collection and in Scopus, in order to provide a picture of the distribution of documents retrieved from these databases, dealing with both eco-innovation and LCA topics. The paper concludes that the convergence of the eco-innovation and LCA studies is quite plausible, but at least in its initial phase, the literature that unites both themes is scarcely found in publications in the area of innovation, being more frequent in the area of engineering and management that usually addresses LCA studies. [ABSTRACT FROM AUTHOR]

Post-harvest losses of fruits and vegetables during refrigerated storage, transportation and retail are an important contributor to total environmental impacts of food supply chains in Europe. Ultrasonic humidification can reduce these post-harvest losses, but it is currently unknown whether implementing the technology in practice improves the environmental performance of the supply chains. Here, using life cycle assessment we showed that ultrasonic humidification has the potential to reduce environmental impacts, including climate change impacts, of selected fruits and vegetables in Europe by up to 23% compared to conventional supply chains. The greatest potential is obtained when humidifiers are applied to fruits and vegetables chains with total inherent losses higher than 24% and when humidifiers allow reducing post-harvest losses in each post-harvest stage by 20% or more. Our results suggest that humidification may be an attractive technology for making supply chain management more sustainable. [ABSTRACT FROM AUTHOR]

Wood and other bio-based building materials are often perceived as a good choice from a climate mitigation perspective. This article compares the life cycle assessment of the same multi-residential building from the perspective of 16 countries participating in the international project Annex 72 of the International Energy Agency to determine the effects of different datasets and methods of accounting for biogenic carbon in wood construction. Three assessment methods are herein considered: two recognized in the standards (the so-called 0/0 method and −1/+1 method) and a variation of the latter (−1/+1* method) used in Australia, Canada, France, and New Zealand. The 0/0 method considers neither fixation in the production stage nor releases of biogenic carbon at the end of a wood product's life. In contrast, the −1/+1 method accounts for the fixation of biogenic carbon in the production stage and its release in the end-of-life stage, irrespective of the disposal scenario (recycling, incineration or landfill). The −1/+1 method assumes that landfills offer only a temporary sequestration of carbon. In the −1/+1* variation, landfills and recycling are considered a partly permanent sequestration of biogenic carbon and thus fewer emissions are accounted for in the end-of-life stage. We examine the variability of the calculated life cycle-based greenhouse gas emissions calculated for a case study building by each participating country, within the same assessment method and across the methods. The results vary substantially. The main reasons for deviations are whether or not landfills and recycling are considered a partly permanent sequestration of biogenic carbon and a mismatch in the biogenic carbon balance. Our findings support the need for further research and to develop practical guidelines to harmonize life cycle assessment methods of buildings with bio-based materials. [Display omitted] • Life cycle assessments of the same multi-residential building were carried out by experts from 16 countries. • Effects of methods and datasets of biogenic carbon accounting in wood construction were identified. • Different end-of-life scenarios (incineration, landfill, recycling) cause variations in the results. • Different interpretations of the permanence of storing biogenic carbon in landfills also cause variations in the results. • The input and output flows of biogenic carbon must be balanced to correctly assess its climate change impacts. [ABSTRACT FROM AUTHOR]

With building-related greenhouse gas emissions(GHGE) having more than doubled since 1970, they represent one of the largest and most attractive opportunities for climate change mitigation. However, current focus has mainly been on reducing operational GHGE leaving building embodied GHGE (i.e. the GHG emissions associated with the extraction, manufacture and transportation of materials, and the building construction process itself) largely ignored. These embodied emissions have been estimated to represent between 10% to 97% of a buildings total life cycle GHGE. It is thus critical that decision-making in relation to buildings is based on a life cycle perspective. One of the main barriers to this approach is the uncertainty surrounding the financial implications of life cycle GHGE reduction strategies. Despite project cost being a key driver for decision-making, building developers, designers and owners have insufficient knowledge or appropriate tools to adequately consider these life cycle costs and balance them against GHGE savings. Several methods exist for quantifying the costs of a building, such as life cycle costing (LCC). However, LCC and life cycle GHGE assessments are often used in isolation. This study will address the urgent need to move towards integrating these assessments by developing a framework that can be used to ascertain the important relationships and trade-offs between financial and GHGE performance of various building-related GHGE reduction strategies. This framework can be used as part of the building decision-making process and help create a low carbon, affordable built environment. [ABSTRACT FROM AUTHOR]

This paper asks whether after 20years of development, the new discipline of environmental impact assessment and rating has lost its way. The paper shows examples of problems in building environmental rating systems, and corrupted science in Life Cycle Assessment (LCA), Ecolabelling and Environmental Product Declarations (EPD). Comparisons are drawn with carbon accounting and the problems this will cause for government policies aimed at mitigating climate change internationally. The author speculates on possible causes and provides contrasting examples of initiatives that are trying to produce truly credible, scientifically robust outcomes but struggling to find acceptance. The author concludes with suggestions that might tip environmental impact practice back to legitimacy and relevance. [ABSTRACT FROM AUTHOR]

Among the different cereals, rice plays a relevant role in terms of production and dietary intake. Although the highest rice producers are Asian countries, this crop is also cultivated in Europe and, within Europe, Italy is the most relevant country. There are not studies evaluating in detail the environmental load arising from the application of urban sewage sludge in rice fields that, being flooded, are characterized by anaerobic conditions. The goal of this study was to evaluate the environmental performance of rice cultivation fertilised with urban sewage sludge in the Pavia district. Moreover, three mitigation strategies have been proposed and evaluated: the substitution of urban sewage sludge with compost, the introduction of an additional aeration and the collection of straw. The results suggest that the main contributors to the environmental impact of rice are methane emissions associated with the degradation of the organic matter during the flooding period, nitrogen emissions associated with the application of fertilisers, and diesel used for the field operations. The differences among the proposed alternative scenarios are considerable, suggesting that strategies to improve the environmental performance of rice are possible. In more details, in order to reduce the environmental burdens of rice fertilised with urban sewage sludge, the two most effective possibilities are: the substitution of urban sewage sludge with compost and the implementation of an additional aeration period during the cultivation. The first option determines an improvement in all the categories analysed, and particularly in toxicity-related impact categories, with reductions of 99.6%, 78.8% and 68.7% for human toxicity-cancer effects, human toxicity-non cancer effects and freshwater ecotoxicity, respectively, followed by Climate Change (−25.4%) and Mineral Fossil Resource Depletion (−19.2%). The introduction of an additional aeration is beneficial for the Climate Change and Photochemical Oxidant Formation, with a reduction of 9.7% and 1.6%, respectively. Concerning the results of the Climate Change impact category, the use of standard emission factors for the estimation of methane emission involves uncertainty; the development of country-specific emission factors would be instrumental in overcoming this point of weakness. Finally, despite the focus on the Italian context, this study proposes different mitigation strategies, which can be applied to other rice systems in order to reduce their environmental impact. [ABSTRACT FROM AUTHOR]

Strict energy performance requirements have reduced the building's operational energy use and related environmental impact in the past decades. Consequently, the embodied impacts of buildings gained importance, and hence focussing on the life cycle impacts has become essential to further reduce the environmental impact of buildings. Life cycle assessment (LCA) is an internationally accepted method used for this purpose. Current LCA studies of buildings typically look at their whole life cycle but ignore potential changes in operational energy use due to climate change. However, the latter is expected to influence the operational energy use of buildings to a significant extent. This paper aims to improve the assessment of the operational phase by including variations in the yearly operational energy use caused by climate change and expected changes in the electricity mix as a strategy for climate change mitigation. This adapted dynamic assessment method is used to assess a Belgian office building. The results indicate that a Representative Concentration Pathway (RCP) 8.5 climate change scenario causes a decrease of 18 % for the end use of gas for heating and an increase of 32.4 % for the electricity use for cooling and ventilation. For the case study, the reduction of the environmental impact due to the decrease in gas use compensates the impact increase due to the higher electricity use. An increase in environmental impact in future would however occur if both heating and cooling are provided by electricity. Furthermore, depending on the changes that will occur in the electricity mix, the global warming potential of the office building will change by −13 % for an electricity mix dominated by renewables and by + 10 % for one with mainly production by gas compared to the situation with the current mix. However, the inclusion of a more extended list of environmental indicators shows that the overall environmental impact will only reduce by 4 % or even increase by 7 % compared to the situation with the current mix. [ABSTRACT FROM AUTHOR]

Crop breeding has boosted global agricultural productivity over recent decades, but little is known about its contribution to climate change mitigation. Here we assess greenhouse gas emissions per unit land (GHGL) and greenhouse gas emissions per unit harvest product, i.e. carbon footprint (CFP) of winter wheat (Triticum aestivum) and winter rye (Secale cereale) from official German variety trials in the period 1983 to 2019. We assess the life cycle greenhouse gas (GHG) emissions and analyze the data using mixed effects models. We find that breeding progress led to slightly increased GHGL , amounting to ∼4–10%, but to strongly decreasing CFP, amounting to ∼13–23% in wheat and rye since 1983. With a ∼20% lower GHGL and ∼8% lower CFP in rye compared to wheat, the extension of rye production offers viable climate change mitigation potential. Finally, we find that lower CFP are associated with hybrid breeding, chemical plant protection and larger farms. We conclude that with increasing global food demand and limited cropland, breeding progress contributes considerably to climate change mitigation through reduced CFP. • First evidence on the contribution of breeding progress to climate change mitigation. • 27,652 and 10,523 Genotype x Environment x Management-combinations of wheat and rye. • Rye has lower greenhouse gas emissions (∼20%) and carbon footprint (∼8%) than wheat. • Crop breeding decreased carbon footprint in wheat and rye by ∼13–23% since 1983/1985. [ABSTRACT FROM AUTHOR]

The global methanol industry provides a unique supply chain to a plethora of chemicals and processes while also contributing to high quotas of greenhouse gas (GHG) emissions. Hence, as the world focuses on climate change mitigation, green technologies are emerging, allowing for low carbon operations. However, the timeliness and scalability of these technologies limit the sustainable transition of the current methanol industry. Thus, to promote low carbon operations within business-as-usual methanol production, innovative technologies need to be investigated-boasting high resource and energy efficiencies. Here, we examine the effectiveness of novel gas-heated reforming (GHR) over autothermal (ATR) and steam reforming (SMR)- coupled with carbon capture and storage platforms (CCS), in promoting sustainable methanol operations. Our results highlight the GHR as the most efficient flowsheet- with 11 % overall higher energy efficiency and 17 % increase in resource efficiency over ATR and SMR processes. Furthermore, through coupled CCS and electrification, energy and resource efficiencies were improved with GHR systems- achieving 14–41 % reduced GHG emissions compared to ATR and SMR flowsheets. Lastly, considering process economics, GHR flowsheets outperform- producing minimum selling prices up to 24 % lower than the current market. Ultimately, as the world seeks to promote a sustainable transition through the deployment of low carbon energy sources, GHR systems emerge as the preferred technologies- providing both economic and environmental benefits for future low carbon methanol operations. [Display omitted] • Methanol production through Gas-Heated Reforming (GHR) was investigated. • GHR gives 8 % higher energy efficiency over ATR and SMR systems. • Low-carbon electrification sources reduced GHG emissions by 71 %. • CCS integration further lowers GHG emissions by 44 %. • Overall sustainable operations favours GHR and GHR+CCS systems. [ABSTRACT FROM AUTHOR]

Waste-related methane (CH 4) emissions could account for 31% of total UK CH 4 emissions. Waste management strategies in the UK have recently changed as more waste is diverted from landfills to anaerobic digesters (AD) and composting facilities, which can be significant sources of CH 4. In this study, we combined mobile CH 4 emissions data from waste treatment facilities to perform a life cycle assessment of current biowaste treatment and potential future mitigation, including AD, in-vessel composting, incineration, and landfilling scenarios. We found that diverting biowaste from landfill to AD is an effective strategy, but it is not enough to eliminate emissions. The fugitive CH 4 emissions from anaerobic digesters have a significant impact on the environmental sustainability of waste management strategies, with upgrading the biogas into biomethane being the best option for climate change mitigation, in the case where natural gas is replaced. A change in the biowaste strategy can also reduce CH 4 emissions from the waste sub-sector analysed, from 58.2 to 30.3 kilotonnes per year, an emissions saving of approximately 52%. However, with these technologies, net-zero emissions is challenging unless the absolute minimum emissions from the treatment technologies is consistently achieved. Therefore, we strongly recommend a focus on mitigating CH 4 emissions from AD to achieve the goal of net-zero waste management. [Display omitted] • The UK's biowaste strategies are evaluated using seven different scenarios. • Anaerobic digestion, in-vessel composting, incineration and landfill considered. • The range of methane emissions affect technology's environmental sustainability. • Biomethane generation from anaerobic digestion provides the greatest GWP saving. • Meeting the Net Zero goal in the waste sector is challenging. [ABSTRACT FROM AUTHOR]

With the progressive implementation of Low-Carbon Policies based on Life Cycle Assessment (LCA) methodologies to assess climate change mitigation, biofuels' potential environmental advantages could finally be translated into economic revenues, especially for residue-based production chains. This implies, however, tackling environmental hotspots along the Life Cycle, such as the use of enzymes, an important input in cellulosic ethanol production. While relevant, however, aspects of enzyme manufacturing, crucial to the LCA results, are often oversimplified in databases or even undisclosed, which might render the accounting for this flow unreliable. A potential solution for this is to model enzyme production, disclosing aspects such as carbon source uptakes, energy consumption and purification steps, all of which may carry significant environmental burdens, especially for fossil-reliant procedures. Integrating these steps into the biorefinery process design as an on-site operation, however, would allow access to renewable energy and carbon sources for enzyme production, potentially reducing their burden in the final biofuel LCA profile, when compared with off-site supply. This work, then, aims to evaluate the effect of inserting on-site enzyme production within a stand-alone second-generation (2G) biorefinery, using sugarcane straw as feedstock, to produce ethanol and electricity, as opposed to off-site enzyme supply from manufacturers. The results show that adopting on-site production can reduce the overall environmental impact profile for cellulosic ethanol, in comparison to off-site supply, even though off-site data present significant variability among databases and literature. This trend persisted for varied enzyme dosages in the saccharification process and for different inventories to model off-site supply. The reference inventories for off-site supply lack transparency and details, while also displaying large discrepancies between impact indicators, indicating the need to pursue more consistent, reliable, and complete inventories for its modelling in LCA. Compared to first-generation (1G) sugarcane ethanol, 2G-ethanol (with on-site enzyme production) demonstrated a reduction in the Global Warming Potential category of around 80%. However, relevant trade-offs for 2G ethanol (with off-site enzyme supply) were observed – regarding ecotoxicity, mineral scarcity, eutrophication and even the potential GHG reduction – when different enzyme inventories are used. [Display omitted] • On-site enzyme production leads to lower environmental impact. • Enzyme dosage and off-site inventory choice do not alter this previous conclusion. • With on-site production, enzymes cease to be the major hotspot within the life cycle. • On-site production leads to a 53% GHG emissions reduction, compared to off-site. • There are trade-offs among impact categories for cellulosic ethanol production. [ABSTRACT FROM AUTHOR]

This study aims to quantify the environmentally sustainable and economically feasible potentials of agricultural and agro-industrial residues to generate electricity via direct combustion in centralised power plants in Brazil. Further, the energy savings and greenhouse gas (GHG) reduction potential of replacing natural gas-based electricity by bioenergy have been assessed. To this end, a methodology has been developed based on an integrated evaluation, incorporating statistical and geographical information system (GIS)-based analysis, and a life-cycle-assessment approach. Results reveal that the environmentally sustainable generation potential is nearly 141 TWh/year, mainly concentrated in the South, Southeast, and Midwest regions of the country. Sugarcane, soybean and maize crop residues are the major feedstocks for available bioenergy. On the other hand, the economic potential is far lower, accounting to 39 TWh/year. The total GHG mitigation is nearly 18 million tonne CO 2 e and could reach 64 million tonne CO 2 e yearly, if the technical potential is considered. The gap between technical and economic potentials implies that constraints to bioenergy are not related to a lack of resources, but rather associated to economic, logistical, regulatory and political barriers. [ABSTRACT FROM AUTHOR]

Building sector plays a significant role in China's ambitous climate targets to peak carbon emissions (CEs) by 2030 and to realize carbon neutral by 2060. However, studies in characterizing the CEs of urban residential buildings from life-cycle perspective at regional level are still limited, especially for the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in China. Here, life cycle assessment method and improved building stock turnover model were employed to quantify the annual CEs of urban residential buildings (including materialization CEs of the newly-built urban residential buildings, operational CEs of the existing urban residential buildings, and CEs generated from the demolition of the existing urban residential buildings) in GBA cities from 2000 to 2018. The results show that the total CEs increased dramatically from 44.5 Mt. CO 2 e in 2000 to 75.1 Mt. CO 2 e in 2018 with an annual growth rate by approximately 3%. The CEs from operation stage accounted for around 70%, and recycling building wastes could reduce 7.5% emissions. Compared with other bay areas globally, the operational CEs of urban residential building in GBA became the highest since 2014. Therefore, climate actions in energy saving and emission mitigation are required. Based on scenario analysis, we estimated that Huizhou city can reach the peak target by 2020 if taking some effective measures. These emission findings could provide data references and suggestions for the low-carbon development path for urban residential buildings in GBA and other global cities. [Display omitted] • This study evaluates the life-cycle carbon emissions of urban residential buildings in bay area. • This study provides a reference for the carbon emission of building unit floor area. • Operation stage is the focus of emission reduction in urban residential buildings. • This study explores the path of peak carbon emissions from residential buildings. [ABSTRACT FROM AUTHOR]

Increasing demand for land-based climate mitigation requires more efficient management of agricultural landscapes for competing objectives. Here we develop methods for assessing trade-offs and synergies between intensification and carbon-sequestering conservation measures in annual crop production landscapes using the DayCent ecosystem model and the Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies (GREET) life-cycle assessment (LCA) model. We compiled county-scaled crop yields, fertilizer application rates, and tillage intensity for a corn–soybean farming case study landscape in the US state of Iowa. Using DayCent, we estimated a baseline soil organic carbon (SOC) accrual rate of 0.29 Mg C ha−1 y−1 driven by historical increases in crop productivity and reductions in tillage intensity. We then simulated the effects of management interventions targeted toward intensification (stover removal) and SOC sequestration (tillage intensity reduction and winter cover crop addition) individually and in combination. We propose a new multi-product landscape–LCA approach that analyzes marginal changes in corn grain, corn stover, and soybean production from the landscape in terms of their value for biofuel production (corn ethanol, soy biodiesel, and cellulosic ethanol from stover) and associated net displacement of conventional fossil-derived fuel use. This enables us to evaluate both intensification and sequestration effects in common CO 2 -equivalent mitigation units. We also used DayCent-simulated yields under the different land management scenarios to estimate farm-level costs and revenues. Our results show that intensification via collecting 30% of corn stover for biofuel production would increase the total greenhouse gas (GHG) mitigation potential of this landscape by 0.93 Mg CO 2 e ha−1 y−1 and provide $49 ha−1 y−1 of additional net revenue from biomass sales, but would reduce the baseline SOC accumulation rate by approximately 40%. In contrast, integrated approaches that include co-adoption of winter cover cropping and/or tillage intensity reduction would result in increased rates of SOC accumulation above the baseline, achieving simultaneous improvements in both farm profits and the overall GHG mitigation potential of the landscape. • Our LCA method compares intensification and carbon sequestration in agro-ecosystems. • Fine-scale management data benefits soil carbon modeling in corn–soy landscapes. • Harvesting corn stover increases carbon mitigation in a US Midwest study landscape. • Coadoption of natural solutions with stover harvest optimizes carbon and revenue. • This landscape assessment can inform local landowner and government decision-making. [ABSTRACT FROM AUTHOR]

The ever-increasing anthropogenic greenhouse gas (GHG) emissions worldwide make it quite challenging to meet country-specific Nationally Determined Contributions (NDC) targets. Therefore, it is evident that the existing emissions abatement measures need to be taken a step further. Internationally Transferred Mitigation Outcomes (ITMOs) are allowed in Article 6.2 of the Paris Agreement as a cooperative approach to achieving NDC goals. There is a potential to create ITMOs between Canada and China by replacing coal use in China with British Columbia (BC)'s liquefied natural gas (LNG) supply. Replacing coal with LNG in energy generation applications is a promising approach to mitigate emissions. With global and national pressures to reduce emissions, China has created a market for LNG imports to cater to its rising natural gas (NG) consumption due to the coal-to-gas source switching strategy. However, the terms under Article 6.2 requires generated ITMOs to ensure environmental integrity, support sustainable development goals, and have a robust accounting system. Therefore, the current study aims to quantify the life cycle environmental outcomes of generating ITMOs by exporting LNG from BC to Chinese end-users while integrating uncertainties and to provide policy recommendations in adherence with the requirements of Article 6.2. Different LNG export scenarios were generated in the study and environmental impacts of each scenario were assessed and compared using a life cycle assessment (LCA) framework developed by the authors. Sensitivity and uncertainty analyses were conducted to understand the impacts created by the data uncertainties in the final result. By replacing conventional coal with NG, approximately 40–45% and 26%–32% emissions reductions can be obtainable for Chinese textile and chemical industries, respectively. The highest emissions reduction of approximately 60% was observed when coal is replaced with NG for district heating. The life cycle emissions (LCE) quantification framework provided in the study provides stakeholders with a systematic approach to determine the total GHG emissions and emissions reduction potential of different LNG export scenarios. [ABSTRACT FROM AUTHOR]

Abstract: While issues of land-use have been considered in many direct analyses of biomass systems, little attention has heretofore been paid to land-use in reference fossil systems. Here we address this limitation by comparing forest biomass systems to reference fossil systems with explicit consideration of land-use in both systems. We estimate and compare the time profiles of greenhouse gas (GHG) emission and cumulative radiative forcing (CRF) of woody biomass systems and reference fossil systems. A life cycle perspective is used that includes all significant elements of both systems, including GHG emissions along the full material and energy chains. We consider the growth dynamics of forests under different management regimes, as well as energy and material substitution effects of harvested biomass. We determine the annual net emissions of CO2, N2O and CH4 for each system over a 240-year period, and then calculate time profiles of CRF as a proxy measurement of climate change impact. The results show greatest potential for climate change mitigation when intensive forest management is applied in the woody biomass system. This methodological framework provides a tool to help determine optimal strategies for managing forests so as to minimize climate change impacts. The inclusion of land-use in the reference system improves the accuracy of quantitative projections of climate benefits of biomass-based systems. [Copyright &y& Elsevier]

Highlights: [•] This article develops a life-cycle assessment framework for the vehicle replacement programs. [•] CO2 emissions would only decrease if the participants in the scheme retained their new cars for at least 4.7 years. [•] The emission reduction effect largely differs depending on whether consumers purchase a gasoline car or a hybrid car. [•] The cost–benefit ratio of 0.001–0.04 implies that the scheme is a costly policy for mitigating global warming. [•] The Japanese government failed to determine an optimal target car age for the scrappage scheme. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from energy consumption have become a major focus all over the world. Cities, especially, are playing an important role in responding to the challenges of global climate change. However, there is still a lack of case studies on the whole life stage (including energy import, production, and consumption) at the city level. This is the first study to systematically estimate the whole lifecycle GHG emissions of urban energy consumption in Macau using the life cycle assessment (LCA) method. It identifies the main contributors, draws the balance framework diagram of energy GHG emissions, and proposes the effective reduction measures through a scenario analysis. The results show that the total GHG emissions of energy consumption in Macau increased from 2.10 × 103 kt CO 2 eq. in 2000 to 5.34 × 103 kt CO 2 eq. in 2018. In 2018, the energy-related GHG emissions in the import phase, production phase, and consumption phase were 3.37 × 103, 4.08 × 102 and 5.34 × 103 kt CO 2 eq., respectively. Since the return of Macau from Portugal to China (December 20, 1999), its GHG emissions from energy import have come to depend more on Mainland China, increasing from 71% in 2000 to 98% in 2018. For the consumption phase, indirect GHG emissions are more important, accounting for 75.3% of total GHG emissions in Macau. From the final consumption perspective, the gambling industry results in the largest GHG emissions (38.07% in 2018), followed by the transportation industry; while for the final energy consumption types, electricity consumption has become the predominant source. The scenario analysis shows that under an ideal scenario, the GHG emissions can be slowed down and will peak in 2033. [Display omitted] • It firstly estimates the whole lifecycle GHG emissions from Macau urban energy consumption. • The GHG emission dependence on the mainland China increases from 71% to 98% since 2000. • It draws the balance framework diagram of energy GHG emissions. • Gambling industry results in the largest GHG emissions in Macau. • Under ideal scenario, the GHG emissions will peak in 2033. [ABSTRACT FROM AUTHOR]

Abstract: The increasing demand for environmental information on the global warming impact of products requires a solid methodological framework which guarantees comparability and communicability. The publicly available specification PAS 2050 combines approaches to a variety of greenhouse gas specific assessment issues to deliver a globally applicable product Carbon Footprinting (CF) method, which is expected to be widely accepted. Specifically, this paper aims to demonstrate the implementation of a CF scheme for a common canned mussel product according to PAS 2050 guidelines. A final value of 4.35kg CO2e per triple pack of round cans of mussels was calculated. Furthermore, this CF study led to identify primary packaging (can production) and mussel shell management as the main activities where efforts should focus for climate change mitigation. Throughout this case study, CF opportunities and drawbacks are discussed. The whole text tries to provide a starting point for both mussel processors and policy makers to benefit from the potential advantages of a responsible use of this increasingly popular tool. [ABSTRACT FROM AUTHOR]

The climate mitigation benefits of battery electric vehicles (BEVs) relative to internal combustion engine vehicles (ICEVs) are highly dependent on the carbon intensity of the electricity consumed during their production and use-phase. A consistent and dynamic approach to grid-mix regionalization of BEV life-cycle assessments in Europe is therefore necessary to offer accurate guidance to consumers and policy makers. To this end, we present ReDyFEV, a simple open-source software tool that can be used to calculate attributional, regionalized lifecycle climate impacts of BEVs in Europe for user-defined time periods, including near real-time. We determine the national lifecycle carbon footprints across all EU states for four BEV size segments and compare them to those of fossil-fuelled vehicles of similar sizes. Simplified sensitivity analyses investigate the effect of lifetime assumptions, electricity demand in battery production, and of relocating battery production to Europe on the carbon footprints of BEVs. [ABSTRACT FROM AUTHOR]

In order to achieve current sustainability and circular economy targets, the use of cleaner practices is required. Therefore, for the abatement of emissions in a cost-effective way, the use of waste materials, reduced manufacturing temperatures, and the increased use of bio-based materials should be explored in the asphalt pavement sector. In response to this need, this study carried out a carbon footprint and economic analysis for the three aforementioned strategies. To fully understand the potential of these pathways, the use of reclaimed asphalt (RAP) and crumb rubber (CR) in different quantities, the use of hot-, warm- and half-warm-mix asphalts, and the use of bio-based binders were considered both at the cradle-to-laid and 40-year life cycle level. The results of this study indicate high quantities of RAP and producing mixtures below 100 °C would provide the greatest environmental and cost benefits. At lower amounts of RAP, the use of CR was found to be more viable; especially with a higher durability. Bio-based materials also provide a large GHG saving potential, but would require commercialisation to be viable. The results of this study serve as a primer for researchers, industry and local authorities to better explore and combine climate mitigation and cost-effective strategies. Future work will cover the use of these results for their implementation in a decision-making system, including the novel indicator defined. • Three GHG and cost saving strategies were analysed across their life-cycle. • A novel indicator was defined to clearly interpret its viability. • High reclaimed asphalt at lower manufacturing temperatures was the most viable. • At low reclaimed asphalt quantities, crumb rubber was more viable. • Bio-materials have a large abatement potential when biogenic carbon is considered. [ABSTRACT FROM AUTHOR]

Research on when to use attributional or consequential methods often considers individual applications. However, greenhouse gas (GHG) management frequently comprises a cyclic process, where GHG assessments are used for recurring sub-processes such as reviewing the current situation (making a GHG inventory), setting reduction targets, developing decision support and evaluating progress. This study analysed implications of different method choices for GHG assessment in a cyclic management process for a geographical region. The results show that attributional decision support can lead to unintended increases in global GHG emissions. Further, use of recurring attributional reviews of the current situation can support and reinforce the guidance provided by attributional decision support, but can contradict and thereby weaken the guidance provided by consequential decision support. Consequential reviews of the current situation (GHG inventories), applied here from a production-based and a consumption-based view, endorse consequential decision support. Given the importance of climate change mitigation, use of consequential GHG inventories in GHG management is recommended. • GHG management of regions and companies often involves a cyclic management process. • This process was modelled using attributional and consequential GHG assessments. • Attributional GHG inventories can impede global GHG emissions reductions. • Consequential GHG inventories can facilitate global GHG emissions reductions. • Consequential GHG inventories are recommended in GHG management. [ABSTRACT FROM AUTHOR]

• We modelled prospective life cycle impacts of aluminum production sector up to 2100. • SSP narratives are leveraged to model technology penetration and grid mix evolution. • We forecast global carbon intensities from 8.6 to 18.0 kg CO 2 eq/kg as baseline. • Majority of improvements result from policy in the energy sector. • Absolute sector-wide CO 2 reduction is realistic with aggressive policy efforts. Aluminium is an energy intensive material with an environmental footprint strongly dependent on the electricity mix consumed by the smelting process. This study models prospective environmental impacts of primary aluminium production according to different integrated assessment modeling scenarios building on Shared Socioeconomic Pathways and their climate change mitigation scenarios. Results project a global average carbon intensity ranging between 8.6 and 18.0 kg CO 2 eq/kg in 2100, compared to 18.3 kg CO 2 eq/kg at present, that could be further reduced under mitigation scenarios. Co-benefits with other environmental indicators are observed. Scaling aluminium production impacts to the global demand shows total emission between 1250 and 1590 Gt CO 2 eq for baseline scenarios by 2050 while absolute decoupling is only achievable with stringent climate policy changing drastically the electricity mix. Achieving larger emission reductions will require circular strategies that go beyond primary material production itself and involve other stakeholders along the aluminium value chain. [ABSTRACT FROM AUTHOR]

The ongoing COVID-19 pandemic leads to a surge on consumption of respirators. This study proposes a novel and effective waste respirator processing system for protecting public health and mitigating climate change. Respirator sterilization and pre-processing technologies are included in the system to resist viral infection and facilitate unit processes for respirator pyrolysis, product separation, and downstream processing for greenhouse gas (GHG) emission reduction. We evaluate the system's environmental performance through high-fidelity process simulations and detailed life cycle assessment. Techno-economic analysis results show that the payback time of the waste respirator processing system is seven years with an internal rate of return of 21.5%. The tipping fee and discount rate are the most influential economic factors. Moreover, the unit life cycle GHG emissions from the waste respirator processing system are 12.93 kg CO 2 -eq per thousand waste respirators treated, which reduces GHG emissions by 59.08% compared to incineration-based system so as to mitigate climate change. [ABSTRACT FROM AUTHOR]

Wood and bark chip mulch has been shown to reduce net orchard greenhouse gas (GHG) emissions on an Okanagan Valley (British Columbia, Canada) apple orchard. However, this benefit was shown to be outweighed by the (attributional) life cycle impacts associated with mulch production. The current study expanded the scope of prior investigations to perform a consequential life cycle assessment of the impacts of increasing wood chip/bark mulch use in the production of apples on Okanagan orchards. This assessment included the impacts of the orchard system as well as other current alternative uses of wood chip/bark mulch which included bioenergy production and paper manufacturing. Many environmental impact categories were examined including human toxicity, freshwater aquatic ecotoxicity, depletion of abiotic resources (elements, ultimate reserves), photochemical oxidation, ozone layer depletion, terrestrial ecotoxicity, acidification potential, climate change, eutrophication, land use – land competition, and energy use (including non-renewable: fossil, nuclear, primary forest; and renewable: biomass, geothermal, solar, water and wind). One scenario was modelled to represent the case in which no mulch was used on orchards (only used for alternative products). A second model was created to represent the marginal impacts of adding the amount of mulch to an apple orchard necessary to produce 1 kg of apples (0.575 kg bark and 0.144 kg wood chips). These amounts of bark and wood chips were assumed to be taken away from their current alternative uses (co-generation for bark and paper production for wood chips), thereby decreasing the amount of electricity and heat produced by bark by 0.653 kWh electricity and 0.653 MJ heat, and the amount of paper produced by wood chips by 0.144 kg paper. In turn, these amounts of electricity, heat and paper were assumed to be produced by their marginal production technologies – hydro-electric generation for electricity, natural gas for heat, and recycled paper for paper production. Finally, the scenarios were modelled assuming the marginal market for co-generation from bark was in Washington, USA rather than the Okanagan, as a sensitivity analysis. The results did not show a clear environmental benefit to either using or not using mulch on orchards. In the scenario in which bark mulch was assumed to be used either on apple orchards or for co-generation in British Columbia, impacts in 14 categories (including climate change, eutrophication, acidification, all toxicities, land use and some renewable energy use) were lower when mulch was used on the orchard, and results for 5 categories (including some non-renewable and renewable resources/energy use) were higher. When bark mulch was assumed to be used either on orchards or for co-generation in Washington, terrestrial ecotoxicity, land use, biomass and solar energy use were lower when mulch was used on the orchard, and all others (15 categories) were higher. There was a large amount of uncertainty in the model, coming from data variability, data quality and impact assessment uncertainty. Overall, the orchard system played a significant role in the impact assessment results, and was the main contributor to the overall uncertainty. Based on these results, mulch use on orchards cannot be recommended to reduce environmental impacts, but the marginal impacts of using mulch warrant further investigation. • Wood/bark mulch can reduce direct greenhouse gas emissions on orchards. • Increased use of mulch on orchards would decrease its use in energy and paper production. • Impacts of energy and paper production without mulch are variable. • Overall net impacts of mulch use on orchards depend on displaced alternative uses. [ABSTRACT FROM AUTHOR]

• A retrofit selection strategy employing economic and environmental decision criteria was proposed. • Building energy retrofits were evaluated through a life cycle thinking approach. • Retrofits with operational emissions savings may not be beneficial when considering life cycle impacts. • Energy mix and the heating system of the house greatly impact the effectiveness. • Retrofit selection changes with stakeholder priorities on environment and economics. Improving the energy performance of buildings has been a much-discussed topic over the past few decades. With the current focus on climate change mitigation, emissions reduction has also come to the forefront of this discussion. Retrofitting is an option to improve the energy and emissions performance of buildings. However, in the residential building stock, retrofit planning for existing buildings faces many complexities due to variations in climatic conditions and macro-environment as well as the presence of multiple stakeholder groups. Thus, in identifying solutions, it is necessary to take a holistic perspective that covers these different dimensions. In this paper, commonly used building energy retrofits were evaluated through a life cycle thinking approach. The performance of various retrofit options applicable for single family detached housing were evaluated using the HOT2000 energy simulation software package under the varying climatic conditions and energy supply scenarios across Canada. The retrofits were evaluated in terms of the additional investment, energy use and cost reduction achieved over the life cycle, and life cycle emissions reduction. The findings indicate that the provincial energy mix and the heating system of the house (i.e. electric or natural gas) play a major role in determining the effectiveness of a retrofit, and this "effectiveness" changes at different stakeholder levels. However, not all retrofits that reduce emissions make economic sense and vice versa when life cycle thinking comes into play. The findings will be useful for building owners and occupants as well as for policy developers and other decision makers interested in demand side management. [ABSTRACT FROM AUTHOR]

The building industry is expanding its ability to mitigate the environmental impacts of buildings through the application of life cycle assessment (LCA). Most building LCA studies focus on core and shell (C&S) and rarely assess mechanical, electrical, and plumbing (MEP) and tenant improvements (TI). However, C&S typologies in the commercial sector pose particular challenges to achieving net zero carbon due to the numerous renovations these building undergo through during their service life. MEP and TI are installed multiple times over the lifetime of commercial buildings leading to cumulative environmental impact caused by increasing material quantities and embodied carbon (EC). This study aimed to establish a preliminary range of material quantities and embodied carbon impacts for MEP and TI components, focusing on commercial office buildings in the Pacific Northwest. The first research stage involved quantifying material quantities while a second stage aimed to calculate Embodied Carbon Coefficients (ECC) and LCA impacts using different data sources. The embodied carbon estimates ranged from 40 to 75 kg CO 2 e/m2 for MEP and 45–135 kg CO 2 e/m2 for TI. However, with recurring instalments during a life span of 60 years the impacts become comparable to known impacts of core and shell systems. [ABSTRACT FROM AUTHOR]

The urgent need for climate change mitigation and the potential threat of energy crisis have allowed the popularity of biomass for biofuels to increase. However, the approaches to assess the climate change impacts of biomass utilization are still questionable. To allow a more accurate assessment, we developed a new framework by integrating six impact components including (1) fossil fuel-derived greenhouse gas (GHG) emissions, (2) biogenic CO 2 emissions-loss, (3) biogenic CO 2 emissions-combustion, (4) emissions from land-use practice change, (5) regrowth for compensation, and (6) difference in carbon sequestration. To illustrate the performance of the framework, seven case studies, which covered the first-, second-, and third-generation biofuels, were conducted. The majority of the positive impacts were contributed to by the fossil fuel-derived emissions, biogenic CO 2 emissions, and regrowth for compensation. For the first-generation biofuels, the life cycle GHG emissions were much higher than those of energy-equivalent fossil fuels (144 and 218 kg CO 2 /GJ for Soybean-to-Biodiesel and Corn-to-Ethanol). The second- and third-generation biofuels had less accountable positive GHG emissions (−62 to 53 kg CO 2 /GJ) due to the offset of negative impacts from land-use practice change and difference in carbon sequestration. However, the negative effects are not determinist. High uncertainty from model-simulated carbon sequestration and decomposition is perceivable. High life cycle GHG emissions for the second- and third-generation biofuels are possible. Image 1 • A new framework was developed to estimate the GHG emissions from biomass utilization. • Different biomass feedstock and conversion technologies were studied as illustrations. • The GHG emissions from the first-generation biofuels can be higher than fossil fuels. • The second- and third-generation biofuels could have negative climate change impact. • High uncertainty is perceivable from model simulation for regrowth and decomposition. [ABSTRACT FROM AUTHOR]

Food production contributes substantially to anthropogenic environmental impacts, including 19–29% of greenhouse gas (GHG) emissions. Use of wood and bark chip mulch as a soil cover has previously been found to reduce direct N 2 O emissions and increase soil organic carbon on apple orchards. The current study expanded the scope of this prior investigation to include the "upstream" processes that support production and transportation of the mulch used on orchards using ISO-compliant life cycle assessment. An "attributional" life cycle assessment was conducted to determine the net life cycle environmental impacts of the production of apples on an Okanagan orchard, focusing on the relative contribution of bark and wood chip mulch used as a soil amendment, both compared to other life cycle stages and processes, and to a system producing apples without the use of mulch. This research focused on only the orchard-level GHG reductions benefit associated with mulch use. A variety of environmental impact categories were examined including human toxicity, freshwater aquatic ecotoxicity, depletion of abiotic resources (elements, ultimate reserves), photochemical oxidation, ozone layer depletion, terrestrial ecotoxicity, acidification potential, climate change, eutrophication, land use – land competition, and energy use (including non-renewable: fossil, nuclear, primary forest; and renewable: biomass, geothermal, solar, water and wind). When the entire life cycle was considered, apples produced using mulch had higher life cycle GHG emissions than those without mulch, as well as higher impacts in all of the other impact categories considered. Due to these higher emissions with mulch, the results do not support the recommendation of mulch application on orchards as a GHG mitigation strategy, nor with respect to the other impact categories considered. • Wood/bark mulch can reduce direct greenhouse gas (GHG) emissions on orchards. • Production and application of mulch increases net life cycle GHG emissions. • Mulch use on orchards cannot be recommended as a GHG mitigation strategy. [ABSTRACT FROM AUTHOR]

• The life cycle climate change impact of a solar microgrid in Sweden was estimated. • Average and marginal emission factors were estimated with explicit system boundaries. • Average and marginal emission factors of electricity use in Sweden differ. • Integration of a solar microgrid into the main grid may contribute to climate change. • The environmental performance of a solar microgrid depends strongly on the context. Microgrids are small-scale electricity networks that integrate distributed electricity generation with consumers and, potentially, with storage devices. There is growing interest in these systems, as they can offer solutions for electrification of remote areas, deployment of distributed renewable energy resources, and decarbonization of electricity supply. However, the potential benefits of microgrids in terms of climate change mitigation have not yet been thoroughly assessed. In this study, Life Cycle Assessment was performed to determine the climate change impact of integrating a solar microgrid system in western Sweden into the Swedish electricity grid. To determine whether replacement of grid electricity with electricity from the microgrid can lower greenhouse gas (GHG) emissions, average and marginal GHG emission factors (EFs) for electricity use were estimated with explicit spatial and temporal resolution, using historical data on electricity generation and trade, and life cycle EFs for electricity generation technologies. The assessment, with both marginal and average EFs, showed that integration of the microgrid into the Swedish electricity grid did not provide GHG emissions abatements, as the electricity from the microgrid displaced grid electricity with lower carbon intensity. It was found that a microgrid without batteries would have lower climate change impact, but would still fail to lower overall GHG emissions. Moreover, it was demonstrated that the methodological approach used for estimation of EFs and the definition of spatial boundaries could influence the obtained results. [ABSTRACT FROM AUTHOR]

This article provides a novel designing tool that integrates life cycle and techno-economic analysis in a spatially-explicit optimisation model for the supply chain for biomass-derived synthetic natural gas production from forestry residues, identifying the configurations, including number of plants, locations, sizes, that minimise the environmental and investment associated, necessary for a sustainable transition to a decarbonised gas network. Results show the conversion stage having the highest negative single-score environmental impact with 1725 μPt/MWh, mostly due to the use of rapeseed-oil methyl esters, collection of feedstock with 858 μPt/MWh, then feedstock transport with a maximum of 103 μPt/MWh. The use of rapeseed-oil methyl esters instead of mineral oil, the substitution of biomass-derived synthetic natural gas and co-produced electricity to the natural gas and electricity grids and their end-use provide a net environmental benefit of −1716 μPt/MWh in the conversion stage. However, the benefit is limited to climate change, ionising radiation, ozone depletion and resource depletion, while eutrophication and acidification potentials, photochemical ozone formation and particulate matter categories are damaged. The environmental impact of the supply chain per unit of MWh of biomass-derived synthetic natural gas produced is minimised when increasing the number of the plants and minimising their sizes, reducing the impact of transport. However, when the environmental impact is coupled to its cost, a single plant is the one that presents Pareto optimal solutions. Maps of the configurations that minimise the environmental impact per unit euro expended varying the number of plants are produced, confirming a 67.6 MW single plant as best solution. Image 1 • Bio-SNG production is beneficial for 4 out of 10 of the considered impact categories. • The environmental impact is minimised for small multiple plants. • The single-plant configuration represents the Pareto optimal frontier. • The multiobjective optimisation suggests that large capacities are favoured. • The conversion stage is the source of major impact, because of the use of RME. [ABSTRACT FROM AUTHOR]

In the energy and climate policy commitments of the European Union, the following targets have been foreseen up to 2030: reducing the greenhouse gas emissions of 40%, improving the energy conversion efficiency of 27%, and producing 27% of the energy from renewable energy sources. Nowadays, thanks to the development of reliable and efficient technologies, several possibilities exist to replace fossil fuels with renewable energy sources, such as wind power, solar, hydropower, geothermal, and biomass. In the Alpine region, biomass can play a key role for achieving the objectives foreseen by the EU policy strategy. In the last few years, due to the high available potentials of residues from forestry operations and sawmill processing, the Alpine region witnessed the development of centralized biomass district heating plants. The aim of the present study is to assess the environmental impacts of 18 biomass-based plants located in the Alpine region using a Life Cycle Assessment approach and to analyse the current market destination of the wood residues. The data were collected through face-to-face interviews with the stakeholders of the forest-wood supply chain (managers of biomass-based plant, sawmills, forest owners and enterprises). From the environmental point of view, the results of the Life Cycle Assessment (global climate change impact: 5–90 gCO 2 MJ−1) show that the "critical points" in the forest-wood supply chain are: the transport phase (1–54 gCO 2 MJ−1) and the wood processing phase (6–36 gCO 2 MJ−1). The results provided by Life Cycle Assessment can be used to increase the scientific knowledge of the environmental impacts related to the biomass conversion technology and to underline the weak points of the forest-wood supply chain. Furthermore, these results can support the decision makers in defining climate change mitigation strategies at regional and local level. • LCA is a key tool to highlight the environmental critical points of the bioenergy system. • Feedstock origin and biomass-based plants size affects the environmental impacts. • Short wood supply chain has a key role to reduce environmental impacts. [ABSTRACT FROM AUTHOR]

In this study, field-specific data was collected from a 10-year experiment in central Spain in which vetch (Vicia sp. L.) and barley (Hordeum vulgare L.) were established as cover crops and compared to the traditional fall-winter fallow between two irrigated cash crops, maize (Zea mays L.) and sunflower (Helianthus annuus L.). The global warming potential (GWP) balance included direct and indirect (nitrous oxide (N 2 O) resulting from the deposition of ammonia (NH 3) or from leached nitrate (NO 3 −)) soil greenhouse gas (GHG) emissions, changes in soil organic carbon (SOC) and albedo, and carbon dioxide equivalent (CO 2 eq) emissions from inputs, irrigation and farm operations. Several scenarios involving i) changes in the termination method of the cover crops, ii) consideration of the application of a distinct nitrogen (N) source (urea, slurry or manure instead of ammonium nitrate) or nitrification inhibitors, iii) employing the same N rate for all treatments (i.e., conventional instead of integrated fertilization), iv) modelling SOC accumulation over a 100-year horizon, and v) using default emission factors, were also analysed. Under the conditions of our experiment, cover crops mitigated yield-scaled emissions by 77.4% (barley) and 91.9% (vetch). Synthetic N fertilization (particularly the industrial production of fertilizer) contributed 38% to the balance of the cover cropping treatments, followed by SOC (22.5%), irrigation (14.7%) and albedo (14.5%). All scenarios led to notable mitigation efficacies, ranging from 39% mitigation (in barley when considering default or non-specific emission factors) to a net CO 2 eq sink (i.e., >100% mitigation) in the scenario consisting of the replacement of ammonium nitrate by urea or organic fertilizers although with side effects on NH 3 volatilization and/or yields. Based on these results, the combined use of cover cropping and integrated soil fertility management could lead to the design of C-neutral irrigated cropping systems in semi-arid regions. Image 1 • Vetch and barley as cover crops abated net GWP by 90% and 75%, respectively, in comparison to fallow. • Synthetic N fertilization (particularly the industrial production) contributed 38% to GWP. • Soil organic C, albedo change and irrigation were also important GWP components. • All scenarios led to notable mitigation efficacies, ranging from 39% to a net CO 2 eq sink. • Improving N management enhanced the GWP mitigation potential of cover crops. [ABSTRACT FROM AUTHOR]