Shortcut Evaluation of Chemical Carbon Dioxide Utilization Processes

Chemical utilization of carbon dioxide seems to be an attractive option for the mitigation of greenhouse gas emissions. However, the respective processes themselves cause substantial greenhouse gas emissions. To achieve a good CO₂ balance, it is necessary not only to fix carbon but also to do this efficiently in terms of reactant supply and energy demand. An evaluation of the CO₂ balance requires detailed process simulation for the utilization reaction and the supply chain. To allow a quick evaluation of the potential to mitigate emissions, a number of estimation methods are presented.     

以蛋白质观点探讨台湾地区大豆与绿藻之碳足迹

以减碳与考虑粮食问题为背景,拟以蛋白质供给观点,应用生命周期评估方法探讨大豆与绿藻之个案比较,分析台湾大豆与绿藻供给之生命周期能源消耗与碳足迹,并从粮食与减碳等双重观点进行价值探讨.个案大豆与绿藻的生命周期盘查,从摇篮到大门之碳足迹,生产1t蛋白质之大豆所需之碳足迹略低于绿藻,为5.379tCO2-eq.,而绿藻在培养阶段仍有0.7～0.9tCO2-eq.之减碳量.整体来说,以同样生产1t蛋白质,大豆在碳排放略低绿藻,然而随着绿藻培养技术的提升,其单位面积产值将有机会大幅提升,其减碳效益仍有机会提高.     

Development of a greenhouse gas accounting GIS-based tool to support local policy making—application to an Italian municipality

Climate change is the issue of the century and, according to Agenda 21, local actions are essential to impact global mitigation of greenhouse gases (GHG) emissions (“think globally, act locally”). However, in order to plan and implement effective, sustainable actions, local authorities need detailed information on their GHG emissions and their sources. This paper presents the work that led to the development of a GIS-based tool for local GHG accounting, which provides data for local decision-makers in an innovative manner different from traditional GHG inventories. The original aspects of the study are the geo-referencing of all results and the possibility of calculating all emissions (carbon sources) and removals (carbon sinks) with input data of different accuracy.     

基于行为足迹的多模态融合身份认证

针对单模态身份认证方法存在特征单一容易被伪造和攻破的问题,提出基于用户行为足迹的多模态特征融合隐式身份认证方法.在移动设备中采集用户使用设备时的触摸压力、触摸轨迹、加速度等传感器数据,利用特征选择技术提取触摸屏交互、移动模式、物理位置等特征并对其进行训练与融合,最终通过多模态特征融合模型实现用户身份认证.实验结果表明,...     

Using harmonised life-cycle indicators to explore the role of hydrogen in the environmental performance of fuel cell electric vehicles

This work uses harmonised life-cycle indicators of hydrogen to explore its role in the environmental performance of proton exchange membrane fuel cell (PEMFC) passenger vehicles. To that end, three hydrogen fuel options were considered: (i) conventional, fossil-based hydrogen from steam methane reforming; (ii) renewable hydrogen from biomass gasification; and (iii) renewable hydrogen from wind power electrolysis. In order to increase the robustness of the life-cycle study, the environmental profile of each hydrogen option was characterised by three harmonised indicators: carbon footprint, non-renewable energy footprint, and acidification footprint. When enlarging the scope of the assessment according to a well-to-wheels perspective, the results show that the choice of hydrogen fuel significantly affects the life-cycle performance of PEMFC vehicles. In this regard, the use of renewable hydrogen –instead of conventional hydrogen from steam methane reforming– is essential when pursuing low carbon and energy footprints. Nevertheless, the identification of the most favourable renewable hydrogen option was found to be conditioned by the prioritised life-cycle indicators.     

Techno-economic and environmental assessment of methanol steam reforming for H2 production at various scales

According to global trend of transition to a hydrogen society, needs for alternative hydrogen (H₂) production methods have been on the rise. Among them, methanol steam reforming (MSR) in a membrane reactor (MR) has received a great attention due to its improved H₂ yield and compact design. In this study, 3 types of economic analysis – itemized cost estimation, sensitivity analysis, and uncertainty analysis – and integrative carbon footprint analysis (iCFA) were carried out to investigate economic and environmental feasibility. Unit H₂ production costs of MSR in a packed-bed reactor (PBR) and an MR for various H₂ production capacities of 30, 100, 300, and 700 m³ h⁻¹ and CO₂ emission rates for both a PBR and an MR in H₂ production capacity of 30 m³ h⁻¹ were estimated. Through itemized cost estimation, unit H₂ production costs of a PBR and an MR were obtained and scenario analysis was carried out to find a minimum H₂ production cost. Sensitivity analysis was employed to identify key economic factors. In addition, comprehensive uncertainty analysis reflecting unpredictable fluctuation of key economic factors of reactant, labor, and natural gas obtained from sensitivity analysis was also performed for a PBR and an MR by varying them both simultaneously and individually. Through iCFA, lowered CO₂ emission rates were obtained showing environmental benefit of MSR in an MR.     

Life cycle sustainability assessment of pumped hydro energy storage

At present, pumped hydro energy storage plays the dominant role in electrical energy storage. However, its development is clearly restricted by the topography and adverse impacts on local residents. Underground pumped hydro energy storage (UPHES) using abandoned mine pits not only can effectively remedy these drawbacks but is also constructive to the management of abandoned mine pits. In this paper, we firstly conduct a comprehensive analysis of conventional pumped hydro energy storage (CPHES) and UPHES, using life cycle sustainability assessment (LCSA). Sustainability indicators in this paper include economic indicators, environmental indicators, and social indicators. Among all the indicators, blue water footprint (BWF) and ecological footprint (EF) are included for the first time to assess the social performance of CPHES and UPHES. Then, this paper employs multi-attribute value theory (MAVT) and scenario analysis to evaluate the overall performance of energy storages. The results show that CPHES has better performance in economy and environment than UPHES because of the economies of scale, while the UPHES has better performance in social sustainability impact because of the absence of stages of excavation and backfilling. When using MAVT methodology, only when the weight for social indicator is three times higher than that of economy and environment; ie, the weight for social dimension is 0.6, and the weights for environmental and social dimension are 0.2; the score of UPHES is higher than CPHES.     

Ecological and Economic Evaluation of Hydrogen Production by Different Water Electrolysis Technologies

The economic and ecological production of green hydrogen by water electrolysis is one of the major challenges within Carbon2Chem® and other power-to-X projects. This paper presents an evaluation of the different water electrolysis technologies with respect to their specific energy demand, carbon footprint and the forecast production costs in 2030. From a current perspective alkaline water electrolysis is evaluated as the most favorable technology for the cost-effective production of low-carbon hydrogen with fluctuating renewables.