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The increasing demand for energy and commodities has led to escalating greenhouse gas emissions, the chief of which is represented by carbon dioxide (CO2). Blue hydrogen (H2), a low-carbon hydrogen produced from natural gas with carbon capture technologies applied, has been suggested as a possible alternative to fossil fuels in processes with hard-to-abate emission sources, including refining, chemical, petrochemical and transport sectors. Due to the recent international directives aimed to combat climate change, even existing hydrogen plants should be retrofitted with carbon capture units. To optimize the process economics of such retrofit, it has been proposed to remove CO2 from the pressure swing adsorption (PSA) tail gas to exploit the relatively high CO2 concentration. This study aimed to design and numerically investigate a vacuum pressure swing adsorption (VPSA) process capable of capturing CO2 from the PSA tail gas of an industrial steam methane reforming (SMR)-based hydrogen plant using NaX zeolite adsorbent. The effect of operating conditions, such as purge-to-feed ratio and desorption pressure, were evaluated in relation to CO2 purity, CO2 recovery, bed productivity and specific energy consumption. We found that conventional cycle configurations, namely a 2-bed, 4-step Skarstrom cycle and a 2-bed, 6-step modified Skarstrom cycle with pressure equalization, were able to concentrate CO2 to a purity greater than 95% with a CO2 recovery of around 77% and 90%, respectively. Therefore, the latter configuration could serve as an efficient process to decarbonize existing hydrogen plants and produce blue H2.

Abstract The sustainable indicators are characterized by a low degree of aggregation and a high amount of information. An indicator must show a synthetic representation of a real environmental, by using a value or a parameter, so that they can be easily used by policy makers. It is necessary to connect, therefore, the various systems in an appropriately integrated sustainable system. The indicators need to be aggregated based on the structure of the data. Each indicator must to be defined through a weight with reference to another weighted indicator. In this paper is illustrated the calculation of the assigned weights that uses a procedure based on fuzzy logic and to define a model that allows us to estimate the sustainability of a city. The final result is, therefore, a combination of values assigned by expert opinion for the various criteria, processed using fuzzy logic to obtain a weight with significant objectivity and as it is possible to estimate the sustainability of the city through the weights.

Abstract In recent years, distributed energy systems (DESs) have been recognized as a promising option for sustainable development of future energy systems, and their application has increased rapidly with supportive policies and financial incentives. With growing concerns on global warming and depletion of fossil fuels, design optimization of DESs through economic assessments for short-run benefits only is not sufficient, while application of exergy principles can improve the efficiency in energy resource use for long-run sustainability of energy supply. The innovation of this paper is to investigate exergy in DES design to attain rational use of energy resources including renewables by considering energy qualities of supply and demand. By using low-temperature sources for low-quality thermal demand, the waste of high-quality energy can be reduced, and the overall exergy efficiency can be increased. The goal of the design optimization problem is to determine types, numbers and sizes of energy devices in DESs to reduce the total annual cost and increase the overall exergy efficiency. Based on a pre-established DES superstructure with multiple energy devices such as combined heat and power and PV, a multi-objective linear problem is formulated. In modeling of energy devices, the novelty is that the entire available size ranges and the variation of their efficiencies, capital and operation and maintenance costs with sizes are considered. The operation of energy devices is modeled based on previous work on DES operation optimization. By minimizing a weighted sum of the total annual cost and primary exergy input, the problem is solved by branch-and-cut. Numerical results show that the Pareto frontier provides good balancing solutions for planners based on economic and sustainability priorities. The total annual cost and primary exergy input of DESs with optimized configurations are reduced by 21–36% as compared with conventional energy supply systems, where grid power is used for the electricity demand, and gas-fired boilers and electric chillers fed by grid power for thermal demand. A sensitivity analysis is also carried out to analyze the influence of energy prices and energy demand variation on the optimized DES configurations.

Background: Sodium oxybate (SMO) has been shown to be effective in the maintenance of abstinence (MoA) in alcohol-dependent patients in a series of small randomized controlled trials (RCTs). These results needed to be confirmed by a large trial investigating the treatment effect and its sustainability after medication discontinuation. Aims: To confirm the SMO effect on (sustained) MoA in detoxified alcohol-dependent patients. Methods: Large double-blind, randomized, placebo-controlled trial in detoxified adult alcohol-dependent outpatients (80% men) from 11 sites in four European countries. Patients were randomized to 6 months SMO (3.3–3.9 g/day) or placebo followed by a 6-month medication-free period. Primary outcome was the cumulative abstinence duration (CAD) during the 6-month treatment period defined as the number of days with no alcohol use. Secondary outcomes included CAD during the 12-month study period. Results: Of the 314 alcohol-dependent patients randomized, 154 received SMO and 160 received placebo. Based on the pre-specified fixed-effect two-way analysis of variance including the treatment-by-site interaction, SMO showed efficacy in CAD during the 6-month treatment period: mean difference +43.1 days, 95% confidence interval (17.6–68.5; p = 0.001). Since significant heterogeneity of effect across sites and unequal sample sizes among sites ( n = 3–66) were identified, a site-level random meta-analysis was performed with results supporting the pre-specified analysis: mean difference +32.4 days, p = 0.014. The SMO effect was sustained during the medication-free follow-up period. SMO was well-tolerated. Conclusions: Results of this large RCT in alcohol-dependent patients demonstrated a significant and clinically relevant sustained effect of SMO on CAD. Trial registration: ClinicalTrials.gov Identifier: NCT04648423

AbstractFloating photovoltaic system for reservoirs is a recent innovative technology that is highly advantageous in reducing evaporation while generating solar power. In addition, the integration of floating photovoltaic systems with the existing hydroelectric power plants will increase renewable power production. The present study aims to assess the electrical performance of floating photovoltaic systems in major reservoirs with existing hydroelectric power plants in India. The reservoirs with large water surface area were selected for the study, and a model floating photovoltaic system with a 5-MW capacity was designed for the selected reservoirs. The numerical analysis showed that installing floating photovoltaic systems will result in an annual energy yield of 160 GWh. Further, the systems also save 1.40 million cubic meters of water per day and also help in generating additional energy of 514.80 MWh/day from the saved water through its integration with hydroelectric power plants. A single-axis tracking mechanism to the floating photovoltaic systems will increase the annual energy generation by 11%. The detailed cost analysis and carbon emission analysis were also carried out. The results indicate that the tracking mechanisms increase the total installation cost of the systems. The annual carbon emission reduction from the floating photovoltaic systems accounts for about 3.30 million tons of CO2. The obtained results highlight the suitability of this innovative technology for installation in Indian reservoirs and its effectiveness in reducing evaporation and carbon emission. Graphic abstract

In this paper we argue for the need to apply a cognitive approach to understand deep dynamics and determinants of technological evolutions. After examining main contributions from innovation studies to the conceptualization of innovation and change in complex socio-technical environments, we highlight the contribution coming from the application of the cognitive approach to evolutionary studies on technologies and we introduce the concept of technological memory as an interpretative tool to understand those changes. We discuss our hypothesis with reference to several observations carried out in different local contexts – Mexico, India and Italy – in relation to technological change in the water sector. In those cases deliberate attempts to substitute traditional technologies with modern ones led to interesting trajectories of change ranging from the collapse of old technologies to the development of multifaceted hybridization patterns. Tema. Journal of Land Use, Mobility and Environment, 2014: INPUT 2014 - Smart City: planning for energy, transportation and sustainability of the urban system

PurposeThe pressure of globalization has raised social concerns related to the protection of the environment, forced companies to use sustainability as a strategic weapon to fulfill the legal obligations and achieve overall competitiveness. It is reported that small- and medium-sized enterprises (SMEs) are globally responsible for approximately 70 percent of the industrial pollution, justifying urgent attention to the operations of these businesses. The purpose of this paper is to analyze the impact of sustainability orientation (SO) and supply chain (SC) integration implemented by SMEs on their sustainable procurement (SP) and design. Moreover, this study examines how SMEs’ SP and design affect their environmental and cost performance (CP).Design/methodology/approachThe authors develop a comprehensive model to test the relationships among SC, SC integration, SP, sustainable design (SD), environmental performance (EP) and CP at the SMEs level. The authors investigate the relationships of the mentoned factors by a data set that is collected from 358 Indian manufacturing SMEs.FindingsThe results indicate that in the SMEs’ context: SO positively influences both SP and SD; external integration positively affects SP; internal integration positively affects SD; SP positively influences EP and has not impact on CP; and SD positively influences both EP and CP.Originality/valueThis study provides a broad view of the relation between driving factors that may direct SMEs toward a better sustainability performance and offers practical managerial insights into these important business entities.

Syngas (CO, CO2, and H2) has attracted special attention due to the double benefit of syngas fermentation for carbon sequestration (pollution reduction), while generating energy. Syngas can be either produced by gasification of biomasses or as a by-product of industrial processes. Only few microorganisms, mainly clostridia, were identified as capable of using syngas as a substrate to produce medium chain acids, or alcohols (such as butyric acid, butanol, hexanoic acid, and hexanol). Since CO plays a critical role in the availability of reducing equivalents and carbon conversion, this work assessed the effects of constant CO partial pressure (PCO), ranging from 0.5 to 2.5 atm, on cell growth, acid production, and solvent production, using Clostridium carboxidivorans. Moreover, this work focused on the effect of the liquid to gas volume ratio (VL/VG) on fermentation performances; in particular, two VL/VG were considered (0.28 and 0.92). The main results included—(a) PCO affected the growth kinetics of the microorganism; indeed, C. carboxidivorans growth rate was characterized by CO inhibition within the investigated range of CO concentration, and the optimal PCO was 1.1 atm (corresponding to a dissolved CO concentration of about 25 mg/L) for both VL/VG used; (b) growth differences were observed when the gas-to-liquid volume ratio changed; mass transport phenomena did not control the CO uptake for VL/VG = 0.28; on the contrary, the experimental CO depletion rate was about equal to the transport rate in the case of VL/VG = 0.92.