Springer Science and Business Media LLC

The use of forest biomass residues to generate electricity can contribute to the sustainability of the energy matrix, circularity in forest production chains and resource conservation. The challenge for biomass power plants is to generate as much energy as possible considering the resources available. This article aims to analyze the eco-efficiency of an electrical energy cogeneration unit from the burning of forest biomass residues, considering the historical evolution of indicators in the period between 2010 and 2019. The results indicate that the plant became more eco-efficient in the period evaluated, producing more energy in relation to the use of biomass (from 0.30 MWh t−1 in 2010 to 0.48 MWh t−1 in 2019), associated with a 55.5% reduction in ash generation for each ton of biomass used. Eco-efficiency also increased when considering the consumption of diesel oil, electricity and water. The main factor responsible for the advance of eco-efficiency indicators was the improvement in the quality of biomass consumed by the plant. An adequate understanding of the efficiency of electricity generation from forest biomass residues is important for reducing costs and environmental impacts, especially in the context of the circular economy.

Water, energy, and food are economic resources whose security and sustainability affect human livelihood. This paper is dedicated to exploring the influence of economic indicators on the security and sustainability of these resources within the water–energy–food (WEF) nexus. The research employed a quantitative approach, gathering data through a structured questionnaire from 282 WEF management professionals in South Africa. The collected data were subjected to statistical analyses, including mean score ranking, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and structural equation modeling (SEM) using EQS and SPSS software. The results of this study highlight the significant impact of economic indicators on the sustainable security of WEF resources. The mean ranking revealed that there is a need to understand people’s economic power for resource sustainability. The CFA and SEM analyses identify four key economic indicators that influence resource security: WEF resource pricing mechanisms, employment rates in the WEF sectors, WEF resource importation, and WEF resource exportation. In conclusion, managing economic indicators within the WEF nexus calls for strategic investment based on comparative advantage. The study provides valuable policy recommendations to support this approach.

Rapid population growth in Kuwait, accompanied with rising standard of living, has resulted in a sweeping increase in the use of passenger vehicles for transportation. Consequently, deterioration of ambient air quality near major roadways has become an issue of public concern. The knowledge of real world road vehicle emission factors is an essential element to the development of any strategy aimed at the reduction of air pollution in urban areas. This work focuses on investigating exhaust emission pollutants from passenger cars for idle and slow acceleration (stop-and-go) traffic conditions. We found that vehicle emissions are minimal during idle mode for all vehicle categories. However, it was interesting to observe that during the slow acceleration mode HC and CO emissions increased for light vehicles with relatively high mileage (higher than 40,000 km). We can conclude from this study that with the growing vehicle ownership, and congestion it causes, the vehicular exhaust emissions is a major sources of air pollution in densely populated centers in the state of Kuwait, where idle and stop-and-go driving cycle is a common occurrence.

Algal biomass is considered as a promising source of alternative fuel energy given its high yield per land area and other potential benefits. Categorized as an advanced generation biofuel feedstock, microalgae are grown in non-conventional ways through different cultivation systems. A preference of a cultivation system may vary depending on a given scenario and its inherent configuration (strength and weakness). Hence, the usage of a specific cultivation system to sustainably produce algal biofuels depends on various factors. Thus, a multi-criteria approach based on analytic hierarchy process (AHP) is proposed for evaluating alternative cultivation systems for sustainable production of algal biofuels. The main criteria considered to evaluate the alternatives based on consultation with a panel of expert and from literature are environmental impact, energy consumption, economic viability, social acceptability, and system robustness. Sub-criteria were identified under each main criterion to further qualify the analysis into relevant sub-factors in the sustainable production of algal biofuels. Three cultivations systems were used as an example to demonstrate the developed decision model using qualitative data and quantitative data. Probabilistic scenarios were analyzed using stochastic approach via Monte Carlo simulation. The results of the stochastic-based AHP showed which cultivation system is preferred for conservative (risk-averse) and optimistic (risk-inclined) scenarios.

Experimental investigation shows that UV/hydrogen peroxide (H2O2) oxidation of a more concentrated phenolic wastewater can lead to economical savings. The savings can be achieved by the lower amount of H2O2 required and time needed to treat the wastewater. Phenolic wastewater can be concentrated by treating the bulk wastewater with activated carbon. The concentrated wastewater that is generated from activated carbon regeneration (assumed to be fully regenerated by steam) can then be treated with UV/H2O2. Experimental results show that H2O2 concentration goes through an optimum value where adding any more H2O2 will result in less effective removal of contaminants. Conductivity of treated wastewater increases sharply then drops down. This could be attributed to the presence of high molecular compounds, inorganic acids, and OH radicals.

As a large number of photovoltaic (PV) modules are approaching the end of their lifespan, the management of end-of-life crystalline silicon PV modules, especially the recycling of solar cells, is imminent. The premise of sufficiently recycling solar cells containing valuable resources from PV modules is to eliminate EVA for bonding glass, solar cells, and backsheet. Compared with physical methods and pyrolysis, the chemical swelling method for separating different layers to recover solar cells has the advantages of low energy consumption and high separation efficiency. However, the toxicity of swelling reagents and the uncontrollable swelling process are major problems. In this context, a novel green reagent dibasic ester (DBE, C21H36O12) was used to separate the glass-EVA layer. In order to expose the solar cells for subsequent resource recovery, the effect of various parameters on the separation of different layers was studied. The mechanism of glass-EVA separation with DBE was examined by FTIR, SEM, and GC–MS. Compared with traditional chemical reagents, the swelling of EVA by DBE is controllable, which can prevent excessive cracking of solar cells and facilitate the recycling of solar cells. This research has crucial implications for the green and sufficient recycling of solar cells from PV modules.

The importance of biomass in combustion processes for the combined production of electrical power and district heat is still rising. In the presented work, CFD is used for the development and optimisation of an innovative combustion chamber for a solid stem-shaped biofuel in the form of compressed biomass bales. The main focus of this investigation is the maximisation of the thermal output of the combustor by an optimisation of the bale burnout and the minimisation of gaseous emissions such as VOCs, carbon monoxide and nitrogen oxide. For this purpose the functionality of a commercial CFD-solver has been extended in terms of the solid phase description and the solid–gas interactions. These sub-routines comprise the description of the solid biomass fuel as a porous bed, the biomass drying, the degradation during devolatilisation and char burnout, as well as the generation of gaseous species and the release/consumption of energy during these three steps. Moreover a simplified model for the prediction of NO x -emissions emanating from the fuel-bound nitrogen has been implemented. The results of this work show that the application of CFD enables a significant reduction of the development costs and the time-to-market of innovative chemical engineering concepts such as solid biomass combustion.