Sustainable development is one of the fundamental and most important objectives of the worldwide policy. The conducted research shows that sustainable development (SD) is increasingly important in the consciousness of the EU countries, which can be viewed through a prism of the undertaken projects. This paper raises the issue of clusters and their significance in the development of a sustainable economy. The article explores trends in the European Union policy related to sustainable development and clusters. The purpose of this study is to find an answer to the following questions: How can clusters contribute to sustainable development and what are the key factors that ensure this process? To achieve the goal of the article a systematic study of the literature and reports was carried out. Moreover, the analysis of the activity of European clusters in the context of sustainable development was performed. Next, the examples of cluster projects focused on sustainable development were presented. It was shown that the clusters contribute a smarter and sustainable development by succeeding in technological and scientific results, developing new technologies for emerging industries, creating new business activities, enticing major technology companies, and connecting local firms into world-class value systems. Furthermore, the clusters participate actively in sustainable development as they promote knowledge creation, joint learning, technology transfer, as well as collaboration, and sustainable innovations. Finally, clusters facilitate the sustainable upgrading of small and medium enterprises and encourage the participation of stakeholders in the process of sustainable development.

Sustainable Development Goals require holistic actions, including activity at the intersection of urban planning and environmental engineering. Turning our cities towards transit‑oriented development might help in reducing pollutant emissions caused by individual transportation modes that rely on crude oil. This research presents how the use of geospatial network analysis can support local decision makers in the evaluation of potential public transport accessibility by citizens in the case of a Central European city – Wrocław (Poland). The obtained results indicate differentiation in access to railway stations and stops, which results from pedestrian path networks and the number of entrances to railway stations. The visualization of serve area shows which parts of the city are excluded from comfortable access to public transport and in that way high‑ light where future actions should be taken.

The application of hydroponic cultivation fertilized with biologically nitrified synthetic urine can produce nitrate-rich fertilizer for lettuce (Lactuca sativa var. capitata L.). The mounting water crisis and depletion of natural resources makes nitrogen recovery from human urine a practical option. Nitrified urine can be used in indoor vertical hydroponic cultivation and is characterized by a high degree of element recovery. Because of its high ammonium content, hydrolyzed fresh urine may be toxic. A nitrification sequencing batch reactor with suspended activated sludge biomass ensured urine stabilization and biological conversion into nitrate-rich fertilizer. The diluted nitrate-rich fertilizer was then supplied for soilless cultivation. The results show that diluted nitrified urine is an excellent source of bioavailable nitrogen and phosphorus and, with proper enrichment with microelements, could replace commercial fertilizers in hydroponic systems. The yield and quality parameters of lettuce cultivated with enriched urine were comparable to those obtained with a commercial fertilizer. The mass balance calculation showed that industry-scale lettuce production can be based on urine fertilizer collected from a few hundred people for a single unit.

Climate change forces policy-makers to undertake actions to reduce human impact on socio-environmental system. One of the directions is to shift into low-carbon economy, also by increasing the role of renewable energy sources (RES) in energy sector. Therefore, there is a need to support local stakeholders with a knowledge-based approaches in order to implement RES more effectively. There are some systems assessing natural potential for RES installations, however, legal regulations are not always making it possible everywhere. The aim of this research is to expand existing functions of the decision support system for hybrid RES by the feasibility assessment of selected locations due to legal regulations. The developed tool was applied and presented on the case of a selected Polish region. The RES potential is assessed based on the universal databases (Global Wind Atlas, Global Solar Atlas, CORINE Land Cover), however, it was customized to local legal regulations, which allows the solution to be more practical and helpful for implementation in a low-carbon economy. Promotion of decision support systems for RES planning may constitute effective solution to reach goals set in the European Green Deal.

The purpose of the article is to assess the possibility of applying the circular business model to wine farms in Poland. The focus is on the economic aspects of producing grape seed oil as one of the waste products generated in the wine production chain. The manufacturing potential of grape seed oil in Poland was estimated based on the production resources and the processing capacity of wine farms. The profitability of oil production was determined for selected farms located in Lower Silesia. The data were obtained through interviews with wine producers participating in the “Cooperation” research project of the Rural Development Program. In the case of small wine farms, the scale of wine production does not allow achieving the level of oil production to cover its manufacturing costs. Large wine farms producing more than 10 thousand litres of wine may be interested in this type of production. The transition into the circular business model for wine farms based on grape seed oil production will, therefore, require establishing producer groups or developing relationships based on competition between wine producers.

COVID-19 was a unique event that globally influenced socio-economic systems in many dimensions. One of them was transportation and mobility patterns, especially during lockdown introduced for the sake of public health. Although restrictions were rather universal within each country, cities were characterized by different mobility patterns. The aim of this study was to analyse changes in mobility patterns in response to COVID-19 and define similarities in urban transportation resilience. For this purpose COVID-19 – Community Mobility Reports were used. Results show that work-related mobility was the most influenced in the long term. Bigger cities needed more time to revert to pre-pandemic level. During the first month of lockdown mobility associated with workplaces as well as grocery and pharmacy presented similar decrease. The biggest decrease characterises mobility connected with retail and recreation. Although it met pre-pandemic patterns around the summer 2020, it required almost one more year to reduce fluctuations.