In this paper we investigate leader election protocols for single-hop radio networks from perspective of energetic complexity. We discuss different models of energy consumption and its relation with time complexity. We also present some results about energy consumption in classic protocols optimal with respect to time complexity -- we show that some very basic, intuitive algorithms for simplest models (with known number of stations) do not have to be optimal when energy of stations is restricted. We show that they can be significantly improved by introducing very simple modifications. Our main technical result is however a protocol for solving leader election problem in case of unknown number of stations $n$, working on expectancy within $O(\log^\epsilon n)$ rounds, with each station transmitting $O(1)$ number of times and no station being awake for more than $O(\log \log \log n)$ rounds.