Two-stage joint equilibrium model of electricity market with tradable green certificates

Renewable portfolio standard (RPS) with tradable green certificate (TGC) scheme has important influences on the market equilibrium outcomes and generation firms’ strategic behaviors. The main objective of this paper is to investigate that under the RPS with TGC scheme, who and how to exercise the market power, and to what extent market powers are exercised in the electricity wholesale and TGC markets. This is achieved by firstly proposing a two-stage joint equilibrium model based on the oligopolistic competition equilibrium theory. The model is then formulated as an equilibrium problem with equilibrium constraints (EPEC) by using the backward induction method, which is further solved by the nonlinear complementarity approach. Finally, simulation results show that renewable firms tend to withhold some of TGCs to raise the TGC prices when the RPS is relatively low, otherwise they choose to cut down their electricity output to reduce the volume of TGC and raise the TGC price. Moreover, facing the increasing TGC price, fossil fuel firms tend to withhold their electricity output to decrease the demand of TGCs and lower the TGC price. This study has meaningful implications for design of the electricity markets with TGC market.