Modeling of combined heat and power generation in the context of increasing renewable energy penetration

Combined heat and power (CHP) can achieve fuel efficiencies of up to 90% and is thus considered as economically advantageous and ecologically sound compared to uncoupled power and heat generation. This advantage is exploited only if CHP plants are operated as much as possible at their optimal operation point. Increasing penetration by variable renewable energy sources and more flexible technologies challenge this optimal operation. With decreasing residual power loads the required share of power in the CHP output combination decreases and a mix of alternative technologies by uncoupled power and heat generation, power-toheat, and storage, can become more efficient than CHP. Using a cost-minimizing investment and dispatch model individual CHP technologies are examined in stylized energy systems with increasing renewable energy penetration. Findings: whereas fuel efficiency of CHP and the share of cogenerated residual power increases, this improvement is offset by decreasing full load hours.