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The need to limit anthropogenic climate change to 1.5–2 °C, as agreed in the Paris Agreement, requires a significant reduction of CO2 emissions resulting from the use of fossil carbon. However, based on current knowledge, carbon is expected to remain crucial in certain industrial sectors, e.g., the chemical industry. Consequently, it is essential to identify and utilize sustainable carbon sources in the future. In this context, various carbon sources were examined and classified in terms of their disruption of the Earth's (fast) carbon cycle. Furthermore, the examined carbon sources were qualitatively analyzed with regard to their technical readiness level, their energy expenditure, and their current and future availability, as well as legal regulation within the European Union. As a result, only biogenic and mixed carbon from the ambient air can be considered genuinely sustainable within the Earth's (fast) carbon cycle. Mixed carbon streams, e.g., from waste recycling, fall into a gray area. The same applies to certain process-related emissions that originally descend from fossil fuel energy. In terms of energy considerations, technical maturity, and exploitable potentials, prioritizing the utilization of biogenic carbon sources is advisable for the time being, especially for CO2 produced as a by-product originating from biogenic carbon carriers. [ABSTRACT FROM AUTHOR]

Façades with building-integrated photovoltaics (BIPV) have the advantage that they can produce renewable electric energy. Compared with conventional façades, BIPV façades have therefore a valuable additional property that can generally contribute to increasing the degree of sustainability of buildings. A holistic assessment system for BIPV façade systems for office and administration buildings was developed in the framework of the project "MULTIELEMENT II" at the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Kassel, Germany. The aim of this research was a comparison of conventional façade systems with BIPV façade systems regarding different technical, economical, sustainability, and design criteria. This paper discusses the basic conditions for a holistic evaluation of BIPV façades in comparison with conventional façades. A method for the execution of a holistic evaluation and characteristic values for a comparison interpretation of results is presented. Façade systems are evaluated regarding both quantifiable and non-quantifiable properties by means of a Microsoft Excel-based evaluation tool. The tool facilitates the comparison and evaluation of planned or built façades with and without BIPV. The detailed evaluation results aim tofacilitate the certification of BIPV façade systems in the framework of sustainable building certification systems such as the German DGNB. [ABSTRACT FROM AUTHOR]

To improve decision-making, sustainability-based approaches to assessment of options and undertakings demand that we move beyond narrowly defined considerations to address the full suite of requirements for progress towards sustainability. This paper reports on a sustainability assessment exercise that originally focused on burning agricultural residues, primarily peanut shells, for cooking applications in Senegal. The scope of assessment had to be expanded to address the agricultural and energy systems of Senegal, when closer examination revealed a complex set of energy and agricultural system interactions that could undermine the anticipated positive effects of initiatives centred primarily on peanut residue cookstoves. The case highlights the need to be open to expanding the scope of assessment to address underlying and/or unexpected issues that cannot be addressed appropriately at the project scale. In particular, the case illustrates how the assessment of an energy system may serve as an entry point into a deeper exploration of the context in which the energy system is embedded. The analysis also illustrates a situation in which different paths that may be followed, each with its own degree of uncertainty, path dependence, feasibility, fairness, cultural sensitivity, trade-off acceptability and possibilities for public judgement of overall desirability. [ABSTRACT FROM AUTHOR]

Implementing hybrid renewable energy systems in hospitals, as an applicable solution to improve the sustainability of power systems, was studied. Several hybrid renewable configurations with detailed technical and economic information were proposed by HOMER Pro software, and the most cost-effective system was introduced as a combination of PV (350 kW), WT (1 unit, 25 kW), and DG (700 kW), with a total net present cost of USD 3.25 million and cost of energy of USD 0.0543/kWh. To consider all aspects of sustainability for choosing the optimal system, a Multi-Criteria Decision-Making approach, considering technical, environmental, economic, and energy security criteria, was applied using the TOPSIS method. According to ISO 21929, the weighting of the criteria was performed depending on how indicators affected the key areas of protection. By using the TOPSIS technique, a system with a larger renewable proportion, more variety, and less reliance on diesel was chosen. Thus, the optimal choice for this process was the configuration of PV (350 kW)/WT (1 unit, 25 kW)/DG (600 kW)/Bat (100 kWh). Comparing the results of economic optimization with MCDM optimization shows that the COE increased by approximately USD 0.025/kWh in the MCDM approach, while a decline of more than 27% in environmental impacts, as well as reduced reliance on conventional resources, were achieved. [ABSTRACT FROM AUTHOR]