A significant development of the photovoltaic market in the European Union has been observed recently. This is mainly due to the adopted climate policy and the development of photovoltaic technology, resulting in increased availability for consumers at lower prices. In the long run, increased installed PV capacity is associated with an increased amount of photovoltaic waste generated at the end of life. Since this waste belongs to the group of WEEE (waste electrical and electronic equipment) waste, it is subjected to high recovery levels. Existing installations for the highly efficient recycling of PV panels are just proofs of concept. However, the situation will change in the near future, and it will be necessary to implement a full-scale waste management system dedicated to PV waste. The paper estimates mass streams of photovoltaic waste generated by 2050 in individual EU countries. Consequently, the characteristics of the European market of waste PV panels are considered together with the demand of individual Member States for installations. The estimation enables the fulfillment of the Directive on WEEE recovery rates.

The present paper describes the problem and effects of water scarcity and the possibility of rational use of this resource in the idea of a Circular Economy (CE) and sustainable development. Rational water management requires innovation, due to the growing demand for this raw material. It seems that water is widely available, e.g., in Poland, there is no problem with drought. Unfortunately, Polish water resources are shrinking and modern solutions, as well as the construction of new and modernisation of old infrastructure, are some of the few solutions that can protect against a shortage of potable water. Water is also an essential resource for economic development. It is used in every sector of the economy. Limited water resources lead to an inevitable energy transformation because, in its present state, the Polish energy industry consumes huge amounts of water. Due to the above statements, the authors propose a solution in the form of an interactive shower panel that contributes to more rational water management (e.g., in households or hotels) based on the latest technological achievements. This device enables the creation of water consumption statistics based on accurate liquid flow measurements and the transfer of data to the user’s mobile device. This innovation aims to make the user aware of the amount of water used, which in turn can contribute to lower water consumption.

In this article, an investigation of a free-piston Stirling engine-based micro-cogeneration (μCHP) unit is presented. This work is a step towards making the system calculations more reliable, based on a data-driven model, which enables the time-domain simulation of the μCHP behavior. A laboratory setup was developed that allowed for the measurement of a micro-cogeneration unit during long-term operation with a variable thermal load. The maximum efficiency of electricity generation was equal to 13.2% and the highest overall efficiency was equal to 95.7%. A model of the analyzed μCHP system was developed and validated. The simulation model was based on the device’s characteristics that were obtained from the measurements; it enables time-domain calculations, taking into account the different operating modes of the device. The validation of the system showed satisfactory compliance of the model with the measurements: for the period modeled of 24 h, the error in the heat generation fluctuated in the range 0.31–4.50%, the error in the electricity generation was in the range 2.48–4.70%, the error in the natural gas consumption was in the range 0.26–4.59%, and the engine’s runtime error was in the range 0.14–8.58%. The modelling process is easily applicable to other energy systems for detailed analysis.