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• Biogas upgrading is environmentally and energetically favourable over combustion. • Storage or utilisation of the captured CO 2 has larger savings than biogas upgrading. • Upgrading, CO 2 storage or utilisation perform well in all impact categories. • The energy system has a substantial impact on the environmental performance. • Methanation provides large climate change savings only in renewable energy systems. Biogas from anaerobic digestion is an important renewable energy source. Combining its utilisation with carbon capture and storage (CCS) or carbon capture and utilisation (CCU) may improve climate change performance. This study uses life cycle assessment to evaluate the environmental impacts of 17 biogas management technology configurations (TCs). The technologies include biogas combustion, upgrading to natural gas quality, CCS, direct utilisation of CO 2 and methanation. The focus is mainly on energy balances and climate change impacts, and the results are subjected to sensitivity-, uncertainty-, and energy system analysis. The TCs with CCS and CCU provide the largest climate change savings (-1400 to - 2100 kg CO 2 -eq/1000 Nm3 biogas). Specifically, the methanation TCs provide the highest savings, but they also depend strongly on the energy sources. When combustion and upgrading TCs are amended with CCS, the resulting climate change savings are robust across the energy systems. The biogas upgrading TCs exhibit substantial climate change savings, mainly due to the natural gas substitution. Combustion TCs without CCS have the lowest climate change savings and the highest quantified uncertainties. The biogas upgrading TCs with storage or direct utilisation of CO 2 provide a good compromise between climate change savings and energy recovery. In the remaining impact categories, the CCU TCs generally perform best, followed by the upgrading TCs and finally, the combustion TCs. The CCS TCs consistently perform worse than their counterparts without CCS, opposite to the climate change results. Overall, amending biogas utilisation with CCS or CCU can contribute to climate change mitigation. [ABSTRACT FROM AUTHOR]

This research aims to explore the current evidence on the sustainability of Bioenergy with Carbon Capture and Storage under a life cycle approach and to understand how research on this topic has evolved in the last decade. A systematic literature review was performed, and the main focus was identifying methodological shortcomings and analysing Global Warming Potential results. Forty-seven studies were selected for in-depth revision. Results show that the number of Life Cycle Assessment (LCA) studies on BECCS has increased in the last couple of years and that most of these studies report near-carbon neutral or carbon-negative results for electricity, biofuel energy, and other products. However, in many cases, some aspects have been omitted from the discussion, such as proper accounting of land use impacts, impact allocation procedure, accounting of leakage from storage sites, and impacts related to carbon utilisation. Despite this methodological variability, Global Warming Potential results are mostly carbon-negative and carbon-neutral for both power BECCS and industrial BECCS systems. Consequently, current scientific evidence suggests climate change mitigation benefits from BECCS despite methodological variability. However, it is still insufficient to reach a consensus on the sustainability of this technology as a solution for a global energy transition. It is recommended that further LCA research deals carefully with methodological and product systems variability, which may affect environmental impact results. Moreover, carbon capture approaches with high potential benefits should be further analysed, and the most optimal BECCS typologies should be identified. Finally, additional life cycle impact categories should be reported, along with the assessment of the economic and social dimensions of BECCS. [Display omitted] • Life Cycle Assessment (LCA) of Bioenergy with Carbon Capture and Storage (BECCS) was reviewed. • LCA methodology choices were discussed. • Global Warming Potential ranges between −3.873 and 0.366 kg CO 2 eq per MJ. • Current evidence is insufficient to confirm that BECCS is a sustainable solution for climate change mitigation. [ABSTRACT FROM AUTHOR]

Existing assessments of climate mitigation technologies, like carbon capture utilisation and storage (CCUS), often rely on life cycle assessments (LCA), which are helpful for quantification but may not always be the most complete tools for decision-making. The novel contribution of this study is to provide the first application of a consequential carbon accounting approach, presented as a time-series analysis, to measure the system-wide change in emissions from CCUS linked to CO 2 -enhanced oil recovery. This method includes emissions from marginal oil production, a variable typically excluded in other LCA methods. The method was applied to a hypothetical CCUS project in Mexico to understand critical factors determining whether such an intervention can effectively contribute to emissions reduction in alignment with net-zero goals. Four intervention scenarios were assessed, comparing two distinct CO 2 injection strategies in oil reservoirs (water alternating gas and continuous gas injection) and two energy policy scenarios (current and sustainability). The findings suggest that the energy grid's role in overall emissions is relatively minor, with only a ∼2% difference between the compared scenarios, in contrast, the injection strategy has a significant impact on emissions. Scenarios 1 and 3 report a total change in emissions of −28.39 and −29.87MtCO 2 e, and scenarios 2 and 4 account for −19.63 and −21.22MtCO 2 e, respectively. The results highlight the importance of conducting system-wide analysis and comparing different scenarios to identify the critical components that drive changes in emissions and, therefore, support decision-making and project planning. • Consequential carbon accounting quantifies the system-wide change caused by CCUS. • A time-series provides decision-relevant information on climate change mitigation. • Market-mediated effects are highly relevant for CCUS projects. • CCUS is not consistent with net zero due to as remaining emissions. [ABSTRACT FROM AUTHOR]

Sustainable fuels and technologies are expected to significantly contribute towards climate change mitigation considering that the transportation sector provides a 23% share out of the total CO 2 emissions. Biodiesel is a green fuel produced by transesterification of triglycerides with an alcohol in the presence of a catalyst. The current study entails modelling and simulation of biodiesel production, through an acid transesterification process, using both classic and intensified methods, coupled with an environmental impact analysis performed following the Life Cycle Assessment methodology. The traditional biodiesel production consists in the synthesis and separation sections, while the intensified method is based on reactive distillation. ChemCAD software was used to simulate and evaluate the processes from a technical point of view. Methanol is generated using CO 2 and H 2 , this method being considered as a new approach for CO 2 utilization. Water electrolysis is employed for H 2 generation, with either biomass or natural gas as power source. A cradle-to-gate environmental analysis is performed within the current research by means of GaBi software, considering the following system boundaries: i) upstream processes: catalyst supply chain, sunflower oil supply chain, natural gas supply chain, limestone extraction and decomposition, ii) main-processes: methanol and biodiesel production, iii) downstream processes: disposal of wastes. ReCiPe method was chosen as the impact assessment method. High purities for the main product and by-product are obtained (i.e., purities higher than 99%). The outcome of the process simulation points to the conclusion that the intensified path gives better performances from technical point of view. The environmental results show that the classic approach performs better when CO 2 and H 2 are used as raw materials, while reactive distillation displays a higher efficiency when natural gas is used as feedstock. [Display omitted] [ABSTRACT FROM AUTHOR]

The renewal of old bridges is sometimes restricted to avoid the high carbon emissions caused by materials and construction, which however might not be conductive to climate change mitigation due to their insufficient functions. In order to facilitate the optimization of renewal timing and strategy from the perspective of reducing the comprehensive global warming impacts, we put forward the low-carbon bridge renewal decision method referring to the ideas of consequential life cycle assessment (LCA) and dynamic LCA. In the proposed method, a comparative system boundary matching the bridge renewal characteristics is constructed, where the carbon emission reduction owing to the traffic efficiency improvement by functional updating is incorporated as the low-carbon benefits of renewal, and three types of time-dependent factors, i.e., time-dependent characterization factor, trend factors and changes of traffic demands, are introduced to characterize the influence of renewal timing. The proposed method provided guidance for the renewal of Maogang Bridge, the first long-span cable-stayed bridge in Shanghai. Results illustrate that the global warming impacts of renewal construction activities and the low-carbon benefits from functional updating decrease with the renewal timing. For Maogang Bridge, the rapidly increasing traffic demands inevitably advocated renewal in advance, and the reduction of global warming impacts from emission reduction or carbon uptake could be manifested for renewal in advance. Adopting material recycling in the disposal of old bridge helped reconstructing a new bridge while deconstructing the old one in 2019 becoming the finally selected low-carbon renewal strategy, which is expected to reduce 15.04 kt CO 2 e-2019 compared to the essential renewal in 2050 with the landfill disposal method. The robustness of the strategy choice has been justified, given the variations of analytical time horizon, expected emission trends and repair emissions. In this way, the low-carbon renewal decision method could build a quantitative basis for judging the urgency of functional updating and verifying the low-carbon benefits of immediate concrete recycling in up-coming urban renewals. • Low-carbon bridge renewal decision optimizes renewal timing and strategy. • System boundary is expanded for quantifying benefits from functional updating. • Emission trends and time-dependent characterization factors are explored. [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]

Temporary carbon storage and substitution benefits of harvested wood products (HWPs) aid in mitigating global warming. However, the extent of this effect remains unclear. Current studies typically rely on a simple summation of the annual carbon sink. This method overlooks the fact that, due to radiative forcing delay, each ton of carbon sequestered has an impact on global warming, which dynamically changes year by year. Such an oversight could lead to an underestimation of HWPs' contribution to global warming mitigation. This study focused on a forestry resource-based city in Northeast China and utilized the Carbon Budget Model for the Canadian Forest Sector (CBM-CFS3) and dynamic life cycle assessment (DLCA) to quantify the dynamic global warming impact (DGWI) of forestry biogenic carbon. The results indicate that: 1) From 2020 to 2120, the maximum DGWI could reach −42.70 Mt CO 2 e. Enhancing the collection and utilization of harvesting residues and promoting products with longer lifespans and higher substitution potential can further increase these benefits. 2) The DLCA method, integrating substitution effects, offers a more precise evaluation of forestry's climate mitigation benefits. Across all scenarios and periods in this study, HWPs' contribution to mitigating global warming, as calculated by the DLCA method, exceeds that estimated by the simple carbon sink summation method by 7.70 %–560.72 %. These findings help to delve deeper into the role of forests in emission reduction and carbon sequestration, providing important references for achieving sustainable forestry management. • Developing and strategically using HWPs positively impacts global warming mitigation. • Method of simply summing up carbon sinks undervalues HWPs' cumulative climate impact. • DLCA method helps assess dynamic global warming impact of forestry biogenic carbon. • Forest management should balance wood production and climate mitigation. [ABSTRACT FROM AUTHOR]

• Solar thermal systems for buildings: environmental life-cycle assessment and policy. • Materials with considerable impacts on human health/ecosystems have been identified. • By involving recycling, appreciable reduction in these impacts can be achieved. • During the phase of usage, solar thermal systems offer considerable avoided impacts. • The avoided impacts based on the electricity mixes of Spain and Italy are presented. Solar thermal systems play a pivotal role in the building sector. However, for the development of sustainable energy systems, different parameters should be taken into account. The present article sets out to present a multidimensional approach. To this end, the first part of the article discusses energy policies, placing emphasis on solar thermal applications. The second part of the article is based on Life Cycle Assessment (LCA) and evaluates the environmental performances of a thermal-energy-storage device and other components appropriate for solar thermal systems for buildings. The analysis has been based on global warming potential, cumulative energy demand, ReCiPe and USEtox. The results show that steel and copper are the materials which are responsible for the major part of the storage-device impact. Based on ReCiPe endpoint/with characterisation, steel and copper present 2.2E-03 DALY (damage to human health) and 5.9E-06 (species.yr) (damage to ecosystems). The results show that the metallic components have the highest environmental impacts. By involving recycling, a remarkable reduction in these impacts can be achieved. Issues related to building-integrated solar systems and future prospects are also discussed. Moreover, the avoided impacts due to the use of a solar thermal system instead of using a conventional electric heater for hot water production have been evaluated, considering multiple environmental indicators. The results based on the Spanish electricity mix have been compared with those based on the Italian electricity mix. In both cases, the findings verify that solar thermal systems offer considerable avoided environmental impacts. [ABSTRACT FROM AUTHOR]

In the quest for carbon neutrality, the cement industry employs various CO 2 mitigation strategies, including material efficiency, cement plant technologies, and clinker-to-cement ratio reductions. This study reviews the past decade's Life Cycle Assessment (LCA) literature on cement production to assess the feasibility of modeling these strategies. Heating energy is the predominant factor in energy consumption, benefiting from energy efficiency measures. Allocation consistently favors cement in evaluations of secondary fuel-related impacts, leading to significant reductions in energy consumption and Greenhouse Gas (GHG) emissions. However, transparency improvements are necessary to clarify the origin and calculation of combustion-related emissions. Challenges arise from limited data availability when assessing grinding energy, especially for high-quality cement aligned with a material efficiency strategy. In our examination of Ground Granulated Blast Furnace Slag (GGBS) as Supplementary Cementitious Materials (SCMs), we have observed that production process variations and allocation assumptions significantly influence LCA models, while highlighting the absence of waste availability consideration in current substitution-focused LCA methods for both secondary fuels and SCMs. • Cement functionalities are generally not described and should be based on strength. • Existing models overlook impacts of increased cement quality due to grinding energy. • Allocation method choice affects climate change impacts of slag-blended cement. • Excluding allocation methods, slag recovery shows climate change impacts variability. • Substantial variability is also found for heating energy for clinkerization. [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]

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]

Recently, electric fuels (E-fuel), which are the chemicals produced from the conversion of renewable-based hydrogen (H 2), are actively being developed as a sustainable energy carrier. Renewable methane is particularly a promising alternative to fossil-based natural gas, which can be produced from CO 2 or syngas methanation. In this work, techno-economic assessment (TEA) and life-cycle assessment (LCA) for renewable methane production are performed through syngas methanation, where CO 2 is collected using direct air capture (DAC) and syngas is produced by solid oxide electrolysis (SOE) with renewable-based electricity. This research considers the different technical, economic, and environmental performances of the systems for renewable methane production. A favorable reduction in a maximum of 23.3% of CH 4 production cost is observed by the scale-up effects of SOE system from 1 MW to 10 MW. TEA draws the conclusion that economic infeasibility is proved at the current level, but additional research and improvement of SOE system and a plunge in renewable electricity prices can lead to the economic equivalent of conventional natural gas. Furthermore, given that certain energy resources with low energy intensity (0.0394 kg CO 2 -eq MJ−1) are integrated with SOE system for methane production, the LCA results that renewable methane production at a large scale has a potential to access negative CO 2 emissions and accelerate climate change mitigation. Consequently, it is concluded that syngas methanation with renewable-based energy systems and DAC can make a considerable opportunity for climate change mitigation under the assumption that SOE system and renewable energy are significantly improved. [Display omitted] • Feasibility of renewable methane production from syngas methanation is investigated • Solid oxide electrolysis for syngas production with renewable energy is covered • Direct air capture as CO 2 capture technology is considered for renewable methane • Possibility of negative CO 2 emission is confirmed by utilizing direct air capture • Mitigating climate change is proved by renewable methane with direct air capture [ABSTRACT FROM AUTHOR]

The Intergovernmental panel on climate change raised awareness on the urgent need for action to limit climate change. Answers include bioenergy with carbon capture and storage (BECCS), which could theoretically generate negative emissions. The life cycle assessment (LCA) method needs to be applied to BECCS systems to assess their negative emission potential and prevent transfers from one environmental impact category to another. To allow for informed decision-making, the quality of LCA results should be evaluated. The quality of results is related to the quality of the data used. The purpose of this article is thus to review the life cycle inventory data that are used for BECCS LCA. To this end, 35 recent BECCS LCA were selected and the inventory data they used was collected. Synthesis inventory tables were then compiled, including the observed range of variability for each data item. These tables cover biomass harvesting, pre-treatment, combustion, gasification, and carbon dioxide capture with a monoethanolamine (MEA) based solvent. Data quality is also reviewed, through the representativeness, reproducibility and completeness of the life cycle inventories highlighted in the selected articles. Only a third of the articles (13/35) provide life cycle inventory tables. Only half of the articles assess the impact on climate change leading to inventory cut-offs. BECCS systems including combustion followed by MEA-based capture have been most referenced (12/35 articles). More transparency on data quality is recommended. Certain promising BECCS systems should also be further studied. This applies, for instance, to BECCS systems that involve second-generation solvents. • A review of the data quality used in life cycle assessment (LCA) of BECCS is assessed. • Only a third of the studied articles provide their life cycle inventory tables. • Inventory data currently used in LCA of BECCS is compiled into synthesis tables. • BECCS systems including MEA-based capture are most frequently referenced. • BECCS systems that should be further assessed with LCA are identified. [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]

Bioeconomy addresses the triple balancing challenge posed by the Paris Agreement: inducing additional GHG mitigation alongside biophysical carbon dioxide removals, while keeping fossil carbon in the ground. The use of woody plants as construction materials could simultaneously address this challenge: CO 2 is absorbed through photosynthesis, while wood-based products provide mitigation by replacing either petrochemical materials such as plastic boards or energy-intensive materials like bricks. This study combines, at the scale of France, static and dynamic life cycle assessment with soil carbon simulations to investigate the long-term environmental performance of using, as input for the building sector, black locust (Robinia pseudoacacia L.) planted on "carbon vulnerable lands". These are areas specifically selected for their low soil organic carbon (SOC) levels and low potential to interfere with food security. After the consecutive cultivation of three rotations, black locust was shown to stock an additional 92000 kg ha−1 of carbon in soils as SOC. The mitigation effect from the plastic board replacement is the major contributor to the assessed environmental impacts, including climate change, leading the black locust system to generally perform better than the reference system where the carbon vulnerable areas are left as they are with their initial vegetation. Considering that cultivation starts in 2022, the dynamic evaluation of the global mean temperature change (GMTC) shows that the black locust system results in net negative emissions in the near- and mid-term, but with a GMTC overshot in the second half of the century. Even if a considerable carbon stock is created through time (e.g., 81% and 39% of the carbon captured by photosynthesis, in 2050 and 2100 respectively), the GHG emissions stemming from manufacturing and end-of-life processes were shown to offset the benefit of carbon capture. [Display omitted] • Black locust plantation and utilization in buildings induce negative emissions. • Black locust system yields greater climate benefits than the initial vegetation. • Plastic board replacement explains the superior performance for 13/16 impacts. • By 2136, the largest temperature reduction of 3.9E-09 K per ha is simulated. • 15% of the carbon captured by 3 rotations is still stocked after 260 years. [ABSTRACT FROM AUTHOR]

Agent-based models (ABMs) are particularly suitable to simulate human-natural systems since they allow modelers to consider the behavioral aspects of individuals. Life Cycle Assessment (LCA) has also been widely used in research, industry, and policy to assess systems' environmental sustainability. In this paper, we introduce a coupled ABM-LCA model to simulate mixed crop-livestock farming activities in the Grand Duchy of Luxembourg. The simulator considers a wide range of aspects related to typical farming business activities and allows the calculation of the environmental and economic impacts of the decisions taken by agents as well. The paper simulates different scenarios. Scenario A is the baseline scenario. Scenario B considers reducing the stocking rate from 1.6 to 1.3 livestock units per ha (LSU/ha). Scenario C aims to reduce the soybean ratio in animals' feed rations to the minimum possible level that is feasible for each farm. Scenario D simulates an increase in soybean autonomy: the farmer chooses to adopt local soybean (instead of imported one) into the crop rotation if its green consciousness exceeds a pre-fixed threshold. As expected, in scenario B, all impact categories show improvement with respect to the baseline scenario, the highest ones being an almost 25% reduction in freshwater eutrophication, 21% in climate change - human health, and 19% in freshwater ecotoxicity. For natural land transformation, the most significant improvements are obtained in scenarios C (11% reduction) and D (13% reduction). On the other hand, in scenario C, the change in feed composition, combined with an expected decrease in stocking rates, also has a positive effect (about 16% reduction compared to the baseline) on agricultural land occupation, due to the utilization of pasture and locally produced crops. An analysis of the systemic uncertainty calculated at the endpoint indicators level showed low coefficients of variation (CV) for all the scenarios, with scenario A always having the lowest values of CV in every impact category, scenario C having the highest CV in the ecosystem quality and the human health categories and scenario B having the highest CV in the resources category. The consideration of subsidy schemes in the Grand Duchy of Luxembourg allows the modelers to better interpret the resulting revenue and cost structures of different scenarios. The results show that the farm profitability stays on the same level when the stocking rate is reduced, and the subsidy granted for reducing nitrogen emissions is in place at the same time. Moreover, the soybean autarky in Luxembourg can be increased to 17% if the farmers are willing to incorporate soybean into their rotation scheme, thus reducing the impacts due to the transportation and production of soybean in South American countries. • The first ABM-LCA simulator that models animals and fields as main units of farms. • Economic sustainability is possible via subsidies if stocking rate is reduced 18%. • 20% drop in climate change impact is possible with 15% more subsidy in 10 years. • 18% reduction in stocking rate brings 20% mitigation in climate change impacts. • Local soya production allows 17% autarky with 20% climate change impact reduction. [ABSTRACT FROM AUTHOR]

• Crop residue-derived biochar production reduces global warming potential. • The feedstock composition and pyrolysis temperature strongly regulate biochar yields. • Slow pyrolysis and microwave-assisted pyrolysis suitable for biochar production. • Physical and chemical properties of biochar are critically discussed. • The concept of biochar, bio-oil, and gas nexus is important for sustainability. Worldwide surge in crop residue generation has necessitated developing strategies for their sustainable disposal. Pyrolysis has been widely adopted to convert crop residue into biochar with bio-oil and gas being two co-products. The review adopts a whole system philosophy and systematically summarises up-to-date knowledge of crop residue pyrolysis processes, influential factors, and biochar applications. Essential process design tools for biochar production e.g., cost-benefit analysis, life cycle assessment, and machine learning methods are also reviewed, which has often been overlooked in prior reviews. Important aspects include (a) correlating techno-economics of biochar production with crop residue compositions, (b) process operating conditions and management strategies, (c) biochar applications including soil amendment, fuel displacement, catalytic usage, etc., (d) data-driven modelling techniques, (e) properties of biochar, and (f) climate change mitigation. Overall, the review will support the development of application-oriented process pipelines for crop residue-based biochar. [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]

[Display omitted] • Midpoint and endpoint environmental profiles for bio-based isobutene are performed. • Pre-treatment represents the largest environmental burden due to steam demand. • From a system approach, co-produce lignin increases the impacts of the biorefinery. • In a product point view, the isobutene profile benefits sharing impacts with lignin. • Allocation method is a relevant decision to declare an environmental profile product. Moving toward a bioeconomy system is fundamental to climate change mitigation, nevertheless, the biotechnological routes should guarantee an environmental sustainability. Isobutene, a precursor in several industrial applications, is one of those chemicals that the environmental effects of its bio-based production have been scarcely explored. This study aims to assess the environmental performance of two biorefinery systems: the first one focuses only on the production of isobutene (I) and the second one on the co-production with lignin (I + L), both from the valorisation of wheat straw. The Life Cycle Assessment methodology is used to determine the environmental impacts considering mid-point and end-point categories. Biorefineries report 0.65 and 1.32 kg CO 2 -eq per kg of biomass processed for I and I + L system, respectively. The most affected endpoint damage category corresponds to Human Health, regardless of the scenarios. Moreover, the pre-treatment stage constitutes the main hotspot of both systems considering midpoint and endpoint perspectives. [ABSTRACT FROM AUTHOR]

• Circular pathway through use of FCS aggregate and fly ash in concrete was explored. • An eco-efficient mix design method based on PPOT was adopted. • Ten types of concrete mixes were prepared using PPOT and conventional mix design. • The techno-environmental performance of all mixes were studied. • FCSAC with 30% fly ash designed by PPOT was ranked as the most sustainable mix. Climate change mitigation and resource efficiency have emerged as crucial challenges for long-term sustainability of concrete. Implementing circular approach through waste valorisation in concrete production with eco-efficient mix design is an efficient mitigation pathway to combat natural resources depletion and environmental issues. This paper investigates techno-environmental sustainability of concrete utilizing 100% ferrochrome slag as alternate coarse aggregate and fly ash as partial cement substitute (0–40%) adopting particle packing optimization technique (PPOT) as a sustainable mix design method. Total of ten types of concrete mixtures were prepared using the alternate materials and mix design methods (PPOT and IS:10262(2009)). Natural aggregate concrete prepared by IS:10262(2009) mix design was considered as the reference mixture. Technical assessment of concrete was performed experimentally in terms of compressive strength and tensile strength. Environmental performance was investigated through life cycle assessment (LCA) as per ISO 14040-44 guidelines using cradle-to-gate system boundary and two functional units: 1 m3 concrete and 1 MPa compressive strength. Results revealed that ferrochrome slag aggregate concrete (FCSAC) containing fly ash up to 30% prepared by PPOT has enhanced strength than reference concrete. Regardless of the functional units used, FCSAC with 30% fly ash designed by PPOT was ranked as the most sustainable mix with significant environmental savings (around 50–70%) without compromising desired requirements. Sensitivity analysis was performed by varying transportation distance, mode of transport and energy mix. Results showed that FCSAC with 30% fly ash is not sensitive to the scenarios investigated. The outcomes will be helpful for decision-makers to develop policy directives and frameworks on synergistic use of ferrochrome slag and fly ash towards concrete sustainability. [ABSTRACT FROM AUTHOR]

One of the main initiatives in the context of global warming brought by the COP26 is global transition to green energy. Bioenergetic utilization of unharnessed renewable resources, such as native rangeland frequently subjected to fires, is a promising alternative to displace fossil fuels. Spartina argentinensis is a native perennial grass that develops in a depressed area of 33,000 km2 in Santa Fe province (Argentine) named "Los Bajos Submeridionales". A life cycle assessment (LCA) was performed analyzing the bioenergetic utilization of S. argentinensis. Two alternative scenarios (AS) were assessed and compared to their business as usual (BAU) counterparts: pellets for i) gasification to deliver electricity to the grid (ASp), contrasted to the Argentinean energy mix (BAUp) and ii) residential heating (ASh) contrasted to natural gas heating (BAUh). Carbon Balance of both AS were negative noticeably lower than BAU and the energy balance was promising considering that the produced energy was higher than that required along the complete system assessed. This is the first LCA of bioenergy from S. argentinensis and according to the results, this biomass resource could collaborate remarkably in climate change mitigation, which is auspicious considering the vast region occupied by this grass and others with similar characteristics. [Display omitted] • Spartina argentinensis can be pelletized without need of an additive. • Pellets can produce syngas for CHP or can be burnt for residential heat. • Renewable energies assessed produce significant lower GHG than fossil counterparts. • Renewable scenarios present high Energy Return on Investment. [ABSTRACT FROM AUTHOR]

The decarbonization of industrial heat, especially utilization process heat over 100 °C, is important for the transition to a sustainable society, including climate change mitigation and the transition to a circular economy. This study focused on a mobile thermal energy storage system for industrial use using a zeolite water vapor adsorption and desorption cycle that can utilize waste heat not only in space but also over time, and a prospective life cycle assessment (LCA) to design the system and provide feedback for further development. A numerical model was developed to predict the performance of the system using a moving bed indirect heat exchange system as the heat-discharging system and a moving bed countercurrent contact system as the heat-charging system, coupled with mass, energy, and momentum conservation equations for obtaining the foreground data for the prospective LCA. A prospective LCA was conducted to calculate greenhouse gas emissions (GHG) and resource consumption. The results showed that the m-TES reduces lifecycle GHG, and there are conditions for zeolite flow rates that minimize GHG emissions. It was also found that the resource consumption of m-TES increases as the system size increases, but is less than that of batteries. The hot spots are the fuel-saving effect at the heat-discharging side, auxiliary power at the heat-charging side, and the zeolite manufacturing stage. • A mobile thermal energy storage using zeolite was designed by numerical analysis. • A prospective LCA provides feedbacks to further development required. • There are conditions for zeolite flow rates that minimize lifecycle greenhouse gas. • Abiotic resource consumption is lower than other energy storage. [ABSTRACT FROM AUTHOR]

The shipping sector is seeking options to reduce its emissions of greenhouse gases (GHGs) and achieve ambitious climate change mitigation goals. Unlike short-sea shipping that can rely on electrification of coastal vessels, drop-in biofuels are among the most promising options for deep-sea shipping decarbonization. However, environmental sustainability analyses of marine biofuels are limited, and usually do not include the influence of future changes in the background energy system nor the climatic effects of near-term climate forcers (NTCFs). In our study, we assess the climate change mitigation potential of various marine biofuels produced from forest residues in Norway (a country with ambitious plans for emission reduction from shipping) using a prospective life-cycle assessment (LCA) where the projected trends in the energy and transport sectors are integrated with improvements in the biofuel value chain for the next decades (2030–2050). Relative to fossil-based alternatives, climate mitigation potentials of biofuels range from 65% to 85% with short-term (GWP20) and to 78%–87% with long-term (GTP100) climate impacts. The inclusion of NTCFs reduces the mitigation benefits of biofuels in the short term, while it slightly increases them in the long term. The explicit modeling of technology and socio-economic changes under future policy scenarios indicates a reduction in the climate impacts of biofuels by up to 54% in 2050 when compared to the current situation. The amount of residues potentially available in Norway is sufficient to meet the present demand for liquid fuels in deep-sea shipping, thus providing yearly climate mitigation of 0.9–1.1 million tons of CO 2-eq (equal to 6–7% of today's climate impacts from the entire transport sector in the country). Our analysis shows the large climate change mitigation potential of drop-in biofuels, and it provides new quantitative estimates that can help guiding a sustainability shift in the deep-sea shipping sector. [Display omitted] • Climate mitigation from biofuels can range from 65% to 87% relative to fossil fuels. • Future inventory databases can cut up to 54% of marine biofuel's climate impacts. • NO x and SO x lower the climate impacts of biofuels in the short and medium terms. • Marine biofuels can mitigate 6–7% of the Norwegian transport sector's emissions. [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]

Prospective Life Cycle Assessment (pLCA) is useful to evaluate the environmental performance of current and emerging technologies in the future. Yet, as energy systems and industries are rapidly shifting towards cleaner means of production, pLCA requires an inventory database that encapsulates the expected changes in technologies and the environment at a given point in time, following specific socio-techno-economic pathways. To this end, this study introduces premise , a tool to streamline the generation of prospective inventory databases for pLCA by integrating scenarios generated by Integrated Assessment Models (IAM). More precisely, premise applies a number of transformations on energy-intensive activities found in the inventory database ecoinvent according to projections provided by the IAM. Unsurprisingly, the study shows that, within a given socio-economic narrative, the climate change mitigation target chosen affects the performance of nearly all activities in the database. This is illustrated by focusing on the effects observed on a few activities, such as systems for direct air capture of CO 2 , lithium-ion batteries, electricity and clinker production as well as freight transport by road, in relation to the applied sector-based transformation and the chosen climate change mitigation target. This work also discusses the limitations and challenges faced when coupling IAM and LCA databases and what improvements are to be brought in to further facilitate the development of pLCA. [Display omitted] • Prospective LCA can benefit from projections of models such as IAM. • Premise streamlines the production of LCA databases based on prospective scenarios. • Emissions and energy efficiencies of major industries are aligned with IAM scenarios. • Stricter greenhouse gas targets result in larger transformations in the LCA database. • However, such targets result in increased LCA impacts other than global warming. [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]

Anaerobic digestion (AD) is at the interface of biowaste management, energy generation, food production and land-based carbon dioxide removal. Strategic deployment of AD requires careful scoping of interactions with prospective alternative biowaste management, energy generation technologies and land uses to ensure effective delivery of climate neutrality and circularity. There remains a need to assess the greenhouse gas (GHG) mitigation efficacy of AD in the context of future alternative (counterfactual) processes associated with differential rates of decarbonisation across energy, waste management and land (including agriculture) sectors. To address this gap, prospective life cycle assessment (LCA) is applied to AD deployment scenarios across three decarbonisation contexts, using the UK as an example. Food waste prevention and diversion to animal feed always achieve more GHG mitigation than AD, even with sustainable intensification of food and feed production. Compared with maize- or grass-biomethane transport fuel, solar electricity generation can avoid 16 times more fossil energy and afforestation can mitigate six times more GHG per hectare of land occupied. Transport biomethane is currently the most effective biogas use for GHG mitigation, but large-scale combustion of biogas for electricity or industrial heat generation is the most effective long-term option as transport is electrified and bioenergy carbon capture & storage (BECCS) is deployed. Prioritising waste prevention and diversion to animal feed (including via insect meal) instead of maximising AD deployment could simultaneously: offset an additional 10–15% of national GHG emissions; meet an additional 2–4% of national energy demand; free enough arable land to provide 20–21% of national recommended protein and kcal intake. However, AD is likely to remain the best option to manage substantial volumes of residual food wastes and manures that will remain available even if ambitious projections on waste prevention and diet change are realised. [Display omitted] • Consequential LCA of anaerobic digestion (AD) in future decarbonisation contexts • GHG mitigation efficacy of AD declines as energy & transport systems decarbonise • AD-crop cultivation is a highly inefficient land use for energy generation and GHG mitigation • Carbon capture & storage could maintain effective mitigation from large-scale biogas use • Sustainable niche for waste-AD alongside waste prevention & diversion to animal feed [ABSTRACT FROM AUTHOR]

To address global food demand and sustainability challenges, aquaculture has appeared as an essential element in food systems, and an increasing number of national aquaculture policies have emerged over the past decades. However, several of these policies have failed because of an often-argued inability to anticipate their far-reaching implications on environmental and socio-economic variables. To tackle this gap, we propose a step-wise framework to assess the national environmental impacts from aquaculture industries with a prospective and systemic approach. Starting from identifying policy-based national targets, the methodology relies on economic equilibrium modeling to develop realistic future-oriented scenarios of the aquaculture sector, and couples them with life cycle assessment principles. To evidence its operability, we apply the framework to two distinct case countries: Norway and Singapore. Beyond our key findings from the analyses of the policies in both countries, we observed that feed production and usage are important drivers of impacts, hence calling for new and more environmentally-friendly feed options. Our results additionally show that the development of aquaculture following existing governmental policies may not directly reduce greenhouse gases emissions and, hence, not support climate change mitigation objectives. These findings should however be cautioned as potential shifts of diets due to the increasing seafood availability might occur, leading to indirect environmental benefits. We therefore advocate the further expansion of our framework to cover the entire food system, so it can integrate such indirect effects. Meanwhile, we recommend its interim application to support policy-making and help move towards more environmentally sustainable aquaculture systems. • A framework to assess prospective environmental impacts of aquaculture is developed. • It combines economic equilibrium modeling and life cycle assessment at national scale. • It is operationalized to assess aquaculture policies in Singapore and Norway until 2040. • Conclusions for each country are issued, and common findings are discussed. • We call for a wide application of our framework to support aquaculture sustainability. [ABSTRACT FROM AUTHOR]