Heat Resources of Rivers in the Odra River Basin as a Potential Element Implement for Sustainable Development in Poland

Seeking solutions that expand the energy market with new possibilities is a natural approach in the context of greenhouse gas emissions and associated climate change. One renewable energy source is water, which, in addition to kinetic energy, can also serve as a source of heat. Having up-to-date hydrological data is crucial for assessing the scale and rate of water circulation in the environment, and subsequently its potential for economic use. This study reconstructs water temperature with the application of the hybrid air2water model for several dozens of rivers in the Odra basin (Central Europe) and, on this basis, estimates heat flux and subsequently its predictability across different temporal scales. The average annual heat flow of all the analyzed rivers was 3.36 × 106 GJ and varied widely, from 0.09 to 51 × 106 GJ, depending on the size of the river. On an annual scale, the heat flow corresponds to the distribution of seasonal changes in key variables (river discharge and water temperature) characteristic of rivers in the temperate zone. The lowest average heat flow was recorded in January (0.74 × 106 GJ), and the highest in July (5.73 × 106 GJ). Considering the obtained results and the spatial distribution of the river network in the analyzed area, it can be concluded that the energy transported by river systems may be regarded as a potential heat source. This is significant in the context of expanding opportunities for obtaining clean energy, which aligns with the current framework of the European Union’s policy aimed at achieving climate neutrality.