In recent years, Poland has experienced a significant increase in the installed capacity of solar and wind power plants. Renewables are gaining increasing interest not only because of Poland’s obligations to European Union policies, but also because they are becoming cheaper. Wind and solar energy are fairly-well investigated technologies in Poland and new reports are quite frequently added to the existing research works documenting their potential and the issues related to their use. In this article, we analyze the spatial and temporal behavior of solar and wind resources based on reanalysis datasets from ERA5. This reanalysis has been selected because it has appropriate spatial and temporal resolution and fits the field measurements well. The presented analysis focuses only on the availability of energy potential/resources, so characteristics intrinsic to energy conversion (like wind turbine power curve) were not considered. The analysis considered the last 40 years (1980–2019) of available data. The Spearman coefficient of correlation was considered as a complementarity metric, and the Mann–Kendal test was used to assess the statistical significance of trends. The results revealed that: The temporal complementarity between solar and wind resources exists mostly on a seasonal scale and is almost negligible for daily and hourly observations. Moreover, solar and wind resources in joint operation exhibit a smoother availability pattern (assessed based on coefficient of variation). Further findings show that the probability of ‘resource droughts’ (periods when cumulative generation was less than arbitrary threshold) lasting one day is 11.5% for solar resources, 21.3% for wind resources and only 6.2% if both resources are considered in a joint resource evaluation. This situation strongly favors the growth of local hybrid systems, as their combined power output would exhibit lower variability and intermittency, thus decreasing storage demand and/or smoothing power system operation.

Modeling the reliability of storm water drainage systems encounters a number of methodological difficulties, especially in the selection of a reliable rainfall scenario. Many methods for creating reference hyetographs are described in the literature. The aim of the work was the analysis of the shapes of local precipitation hyetographs and the verification of the reference shapes of rainfall hyetographs used for the drainage systems designing and modeling its operation in Poland (Euler type II and DVWK models). The research material was represented by historical records of rainfall data from the measuring station located in Jelenia Góra (Poland). Rainfall were grouped due to the similarity of physical features, using various methodologies: Huff, cluster analysis using the Ward and k-means methods. The k-means method proved to be especially useful for selecting precipitation in terms of shape hyetographs. The statistical analysis of the similarity of the rainfall hyetograph shapes was performed within the separated genetic clusters, based on the parameters of mass distributions and unevenness over time. The comparative analysis allowed for the positive verification of the Euler type II and DVWK models for the tested station.

Water scarcity and climate change led to changes in water management, especially in urban areas. RainWater Harvesting (RWH) is a promising technique that allows the collection and reuse of rainwater, as well as protecting sewage systems from overload. This article reviews the current state of RWH in Europe, including advantages, implementation, potential efficiency, usage requirements, quality, and treatment processes. The main findings include the importance of RWH as a sustainable water management technique, the historical background and renewed interest in RWH systems in recent years, the positive impact of RWH on reducing energy consumption and greenhouse gas emissions, the versatility of rainwater usage, and the potential cost savings and benefits in various regions. RWH systems are gaining popularity in Europe, particularly in Germany, Austria, and Switzerland. Climate change and precipitation patterns affect rainwater availability and quality. RWH can be used for various purposes, including drinking, but requires proper purification for health safety. It is also being implemented in new locations like airports and large buildings. RWH systems have a high potential to overcome undesired results of climate change. Among that, numerous aspects still need to be considered in the future that allow the application of RWH systems on a larger scale.

This paper analysed from the statistical point of view the trends in observed air temperature in major Polish cities and presented a qualitative analysis of their potential impact on the operation of the selected renewable energy sources. It also reviews the relation between the air temperature and observed electrical load as well as changing numbers of cooling and heating degree days. The method involved a statistical analysis of historical mean daily temperature observed in 19 major Polish cities over the 1968-2018 period. The air temperature change impact on renewable energy sector in Poland, by affecting the heating and cooling demand, the electrical load and the renewables working conditions both, on supply and demand side. The analysis reports that the mean daily temperature in all major polish cities is exhibiting a statistically significant increasing trend, up to 0,52 °C/decade. The observed increase in air temperature reduces the heating demand in Poland, beneficially for the environment and renewable supply. Increasing cooling needs in summer raises the energy consumption and indoor thermal stress. The climate warming affects the operation conditions, energy source, driving force, capacity and efficiency of renewable energy sources. The investigated changes were favourable and unfavourable depending on the renewable technology and operation mode, and were stronger on the demand side than on the supply side.