This article aims to rediscover a relatively unknown author to the general public, Slavcho Zagorov, and to revive his ideas. Zagorov was a Bulgarian economist and statistician whose main works date back to 1954 and are mainly devoted to the concept of energy flows in the economy and human metabolism explained through the prism of thermodynamics. His work and career are reminiscent of another Balkan economist, Nicholas Georgescu-Roegen. We first present Zagorov's theoretical work on the importance of energy in economic activity and secondly on the measurement of national income and productivity through energy. Thirdly, we show the relation he establishes between energy and utility. Finally, we discuss his texts in relation to his professional and personal trajectory and point out some preliminary elements of comparison with Georgescu-Roegen's work.