The requirement and supply of reducing power and ATP for the growth-associated synthesis of polyhydroxybutyrate (PHB) and the non-PHB biomass were balanced. By using glycerol, glucose, fructose, octanoate or oleate, the net balances of the PHB synthesizes result in an energy surplus which might contribute to growth. The calculated yields amount up to 90% PHB in cells correlating inversely to the P/O-quotient. The growth-associated PHB production contributes to two metabolic processes: supplying energy for growth and accumulating storage material.