The purpose of the article is to justify the theoretical basis of bioenergy in context of the energy conservation law, in particular: the incorrectness of the statement about a concept of renewable bioenergy on basis of the energy conservation law for open systems within the planet Earth, for which the Sun, as a cosmic body, is the only primary source of heat and light, and it will go out after its energy exhausting; to justify classification features for energy resources, which determine their affiliation to bioenergy. Research methods. In the research process were used the following scientific methods: the dialectical method of cognition, which made it possible to investigate processes of accumulation and transformation of solar energy into bioenergy through photosynthesis; the systematic approach for compliance with concepts of bioenergy renewability of the energy conservation law; induction and deduction methods for substation of classification attributes of energy resources, by which their affiliation to bioenergy is determined. Research results. Classification of energy resources, which determines their affiliation to bioenergy was justified. It was proved the incorrectness of a statement about the renewable bioenergy on basis of the energy conservation law for open systems within the planet Earth, for which the Sun, as a cosmic body, is the only source of heat and light, which despite very long period of existence, will finally exhausted its energy at some point. Elements of scientific novelty. It was proposed to eliminate an incorrect statement regarding the renewability of bioenergy on basis of the energy conservation law in open systems, which the solar system applies to. Classification of energy resources, which determines their belonging to bioenergy, was substantiated. Practical significance. There was proposed a vision of the non-renewability of Earth bioenergy resources available for human. It will lead to the formation of a fundamentally new conceptual vision for the development of energy industries and better solutions for environmental conservation. Figs.: 1. Refs.: 59