Evaluation of operating modes of micro-cogeneration units and a modification of the load profile

Because of the high energy efficiency of the coupled production of thermal and electrical energy, cogeneration is a key technology of the German climate protection plan. This paper focuses on the optimized use of cogeneration plants with a low scale of thermal and electrical power output (micro-cogeneration units) to supply residential buildings with thermal and electrical energy. The operating behavior of micro-cogeneration units depends on the concept of the heating system, the operating mode and the building´s load profile. Different operating modes are developed, analyzed and compared in terms of energy efficiency and economic efficiency. A special heat and electricity driven operating mode is introduced and compared to existing alternatives like operating the cogeneration unit with a thermal storage unit or using the ability to modulate the power output. In addition, the energy efficiency and economic efficiency potential of preheating service water of washing machines and dishwashers is evaluated. The simulations and evaluations are executed for a poorly insulated apartment building in the Ruhr area in Western Germany.