Fundamental and applied research on renewable energy is actively supported for the development of world science and maintaining the energy independence and security of different countries. This section analyzes the publications of scientists from two countries-Ukraine and Poland-in the field of "thermoelectricity," "photoelectricity," and "bioenergy" to find regularities in each state and to determine the prospects for joint research. Ukraine and Poland share a common border and have similar climatic conditions and historical heritage, but Poland is a member of the EU, and its legislation in the field of renewable energy complies with the regulations of the European Community. Ukraine is making every effort to develop renewable energy. Comparison of the state of research in these countries is also an example of the analysis of the situation at the borders of EU countries and may answer questions related to sustainable development, the mass transition to renewable energy, and the refusal to use fossil fuels and nuclear power plants. The analysis is based on the results of data published in the international scientific databases Web of Science and Scopus. The most advanced areas of research in each country are identified, analyzed, and aimed at practical application.