In this paper we analyze interactions of two energy policy instruments, namely a White Certificates (WhC) scheme as an innovative policy instrument for energy efficiency improvement and energy taxation. These policy instruments differ in terms of objectives and final impacts on the price of electricity. We examine the effect of these policy instruments in the electricity sector, focusing on electricity producers and suppliers in a competitive market. Using microeconomic theory, we identify synergies between market players and demonstrate the total effect on the electricity price when suppliers internalize the behaviour of producers in their decisions. This model refers to an ideal market situation of full liberalization. The cases we examin...