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Abstract: Waste heat recovery technologies play an important role in enhancing energy efficiency and supporting sustainable energy production. This study investigates the utilization of waste heat from aluminium production through an Organic Rankine Cycle (ORC) system to generate electricity and heat simultaneously. Based on operational data from an aluminium plant, the system is firstly optimized from both the thermodynamic and economic perspectives. To maximize performance and to identify optimal configurations, a mathematical model is developed and solved using GAMS, capturing the complex interdependencies between the operational, economic and thermodynamic parameters. The environmental impact of the optimized scenarios is subsequently evaluated using a Life Cycle Assessment (LCA), considering a broad range of impact categories. The results indicate a maximum power output of 830.9 kW and a maximum net present value (NPV) of 51.71 M€, confirming the system’s technical and economic viability. The environmental assessment demonstrates the potential of ORC systems as sustainable energy solutions, with significant environmental unburdening under optimized operating conditions (up to -606.0 kg CO2 eq./h). A sensitivity analysis indicates that the greatest environmental benefits occur under the optimal thermodynamic scenario, achieved through the utilization of higher-energy flue gas streams (up to -515.0 kg CO2 eq./h), and under the optimal economic scenario by balancing the electricity and heat prices optimally for simultaneous heat and power production (up to -696.7 kg CO2 eq./h). These findings highlight the importance of the thermal input quality and availability in maximizing ORC performance. With the ability to prioritize electricity, heat, or both, the optimized ORC systems support flexible energy solutions tailored to specific applications and environmental conditions, offering a promising pathway for unburdening the environment through the efficient utilization of industrial waste heat.
Keywords: waste heat recovery, aluminium production, organic rankine cycle, environmental impact, life cycle assessment, sustainable energy solutions
Published in DKUM: 13.06.2025; Views: 0; Downloads: 19
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Abstract: Cover crops can reduce the use of external inputs such as pesticides and fertilisers and can at the same time suppress weeds as well as improve or maintain soil fertility. Cover crops can also modify the microclimate which affects pest populations and diseases. Determining cover crop species and management practices is based on the needs and goals of production. The effects of introducing living mulch (LM) and management strategies on cash crop yield, product quality and energy use were studied in certain European countries (Slovenia, Italy, Germany and Denmark) in different climatic and soil conditions. In Slovenia, in organic production of cauliflower and leek, the effects of two terms of sowing white clover with additive design were compared with a production with black foil and with the usual agricultural practice by hoeing. In the field experiments the effect of LM on arthropod dynamics and activity density was investigated. The results demonstrated that the LM systems with a substitutive design, can be effectively implemented in vegetable production if the value of the ecological services (positive externalities) delivered by LM can counterbalance the yield loss due to the cash crop density reduction. If an additive design is used, the LM should be sown several weeks after the cash crop planting. Different cash crop genotypes (i.e., open pollinated/local cultivars in comparison with the hybrids) performed similarly. Use of human labor (HL) and fossil fuel (FF) energy slightly increased in LM systems (7%). The farmers’ acceptance of the LM techniques was quite high (75% of the interviewed sample). The LM technique did not affect the infestation of cabbage caterpillar Pieris spp., showing no detrimental effect of this technique on this key pest of cabbage. In Denmark, aphid populations were higher in the sole crop system than in the LM system. In Italy, a level of larval parasitization was detected and in the first year the percentage of parasitization was higher in LM (88%) than in sole crop (63%). Overall, the LM positively affected the activity density of Carabid beetles, also increasing the diversity and evenness of species (Slovenia and Italy) or activity density of some taxa (Slovenia and Denmark). Due to numerous agroecological services of cover crops, growing simultaneously with vegetables as LM, this could be promising technique for organic and others production systems in the future.
Keywords: organic vegetable production, cover crops, agroecological service, living mulch, energy consumption, biodiversity, soil arthropod
Published in DKUM: 01.02.2019; Views: 2206; Downloads: 305
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Keywords: organic farming, food production
Published in DKUM: 10.07.2015; Views: 1638; Downloads: 113
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