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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]

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]

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]

An essential part of environmental impact assessment (EIA) is the proposal of mitigation measures, whose effectiveness has a decisive influence on the magnitude of the residual impacts of the proposals. However, the effectiveness of mitigation is not always well known, and sometimes it is even used in a manipulative way. This paper presents a sample of effectiveness values for some mitigation measures commonly proposed in EIA reports, based on information from the academic and grey literature. The aim is to show that the effectiveness of mitigation measures can be highly variable, and may even lead to undesirable effects, and to highlight how this can influence the assessment of residual impacts. As examples, climate change mitigation may have undesired effects; revegetation effectiveness is overrated at least in some regions; wildlife protection measures may be over-optimistic; and sometimes there are complaints after the implementation of mitigation measures for odour, noise or vibration because beneficiaries expected greater effectiveness. Overestimating mitigation effectiveness leads to ignoring the mitigation hierarchy and underestimating residual impacts, which may distort decision-making. The effectiveness of mitigation is often site-dependent and species-dependent, so a lot of information is needed. Feedback from environmental follow-up is necessary, and EIA authorities should make an effort to collect and disseminate this information. Academics, practitioners and environmental authorities need to work hand in hand in this regard. • Overestimation of effectiveness lead to underestimation of residual impacts. • Effectiveness of some mitigation measures is sometimes over-optimistic. • Population complaints related to the effectiveness of mitigation are frequent. • Mitigation effectiveness is often site-dependent and species-dependent. • Feedback from environmental follow-up is necessary. [ABSTRACT FROM AUTHOR]

As the content of the climate policy to meet the 2 °C targets, actions in all economic sectors, including agriculture, are required to mitigate global greenhouse gas (GHG) emissions. Although there has been an ever-increasing focus on agricultural GHG emissions, little is known about the environmental benefits of individual crops, making it challenging to link production to consumption (including trade) and GHG emissions. In this study, we estimated GHG emissions related to rice in 227 countries and three sectors, taking time series data from the Food and Agriculture Organization (FAO) from 1986 to 2017. The results showed that production-based emissions increased by 25.5%, and actual consumption-based presented the same trend while assuming domestic production (no trade) expanded by 45.1%. The reason for the unbalance between the two sectors is that the total transfer volume embodied in the rice trade increased by 151.6% in 32 years. Meanwhile, we found that trade flows increased from low- to high-emission intensity countries, while rice emissions intensity was significantly reduced, contributing to a global GHG emission reduction of an average of 56.3Mt per year. Our results provide a comprehensive, forward-looking assessment of the environmental impacts of global growing rice production and consumption on the main countries and their trading relationships. Thus, besides domestic policies, main importing countries should also consider environmental benefits in developing sustainable international trade to limit the negative environmental impacts of its growing rice consumption. • Differences between production-based and consumption-based GHG emissions are investigated. • GHG transfer embodied in the rice trade regulates the imbalance of production and consumption. • Trade contributed to a reduction of GHG emissions of above 56.3Mt yr−1. • Rice-related emissions deserve more policy attention toward sustainable food systems. [ABSTRACT FROM AUTHOR]

Biomass plays a dual role as an energy source and a solution for climate change mitigation. There are complexities surrounding decentralized electricity generation, and Ghana could not achieve its 10% renewable energy target in 2020. The paper assesses the greenhouse gas mitigation potential and economic impact of electricity from major food crop residues subjected to anaerobic digestion technology in 16 regions and 88 districts in Ghana from 2017 to 2020. Buswell equation was applied to calculate the biogas and methane yield. The environmental impact assessment was expressed as global warming potential, and the economic feasibility was conducted. The results showed that crop residues' annual theoretical and technical potential was 28.92 Mt and 17.24 Mt. The top four residues with the largest share of technical potential were maize (5.41 Mt), yam (3.58 Mt), plantain (3.05 Mt) and cassava (2.39 Mt). Biogas and electricity potentials were 1,912.74 Mm3 and 3,068.34 GWh, which could offset 15.56% of electricity consumption in Ghana. The Ashanti (478.18 GWh), Eastern (430.20 GWh), Bono East (318.29 GWh) and Northern (314 GWh) regions demonstrated the highest electricity potential. Ghana could generate the highest electricity potential of 46.52 GWh in the districts and a minimum potential of 0.89 GWh annually. Power generation potential from anaerobic digestion had a diesel displacement capacity of 923.35 × 10 6 L with a GHG emissions reduction of 2,507.35 kt CO 2 eq. The largest GHG reduction potential was 38.15 kt CO 2 eq at the district level. The findings show that the project is economically viable, with an average net present value of $ 10,105,904 per region and an electricity cost of $ 0.0321/kWh. The study provides critical insights to policymakers and industry developers for decentralized biomass-based electricity generation in Ghana. • A sustainable crop residue assessment is conducted in Ghana. • The total biogas-based electricity is 3,068.34 GWh. • Ashanti region has high electricity (478.18 GWh) than Greater Accra (9.82 GWh). • The total GHG mitigation is estimated as 2507.35 kt CO 2 eq. • The project is economically viable at a cost of $ 0.0321/kWh. [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]

• Public works programs are increasingly used to address food insecurity and poverty. • We study the environmental impacts of Ethiopia's flagship public works program (PSNP). • We combine remote sensing and econometric methods to create a credible counterfactual. • We find that the PSNP increased tree cover over 15 years in participating districts. • Public works programs can support climate change mitigation and adaption efforts. More than one billion people worldwide receive cash or in-kind transfers from social protection programs. In low-income countries, these transfers are often conditioned on participation in labor-intensive public works to rehabilitate local infrastructure or natural resources. Despite their popularity, the environmental impacts of public works programs remain largely undocumented. We quantify the impact on tree cover of Ethiopia's Productive Safety Net Program (PSNP), one of the world's largest and longest-running public works programs, using satellite-based data of tree cover combined with difference-in-differences and inverse probability treatment weighting methodologies. We find that the PSNP increased tree cover by 3.8% between 2005 and 2019, with larger increases in less densely populated areas and on steep-sloped terrain. As increasing tree cover is considered an important strategy to mitigate global warming, our results suggest a win–win potential for social safety net programs with an environmental component. [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]