Sizing and economical evaluation of residual load driven CHP and thermal storage systems in residential buildings

摘要

The integration of renewable energy sources into the electrical grid will result in higher fluctuations in power production. These fluctuations can either be covered in a centralised or decentralised manner. Since most residential buildings in Germany still have a significant heat demand, decentralised CHP and electric heating devices could contribute to balancing the grid while ensuring the heat supply of the building. Moreover, a combined CHP and electric heating system is able to adapt to future electricity grid needs, where a change from a positive residual load to a considerable share of negative residual loads is expected. In this paper, we first investigate the dimensioning of residual load driven CHP systems in residential buildings. Standard sizing approaches for CHP systems lead to small CHP units which only cover parts of the heat demand. Additionally, these approaches limit the grid balancing potential. Therefore, we introduce an iterative, simulation-based sizing method, ensuring a major CHP heat generation share. To represent the considered energy system we set up a dynamic simulation environment comprising both buildings and heating devices. Based on this simulation environment an ecological evaluation of the decentralised grid balancing technologies is performed. Additionally to the technical evaluation, we present a method to determine the economic potential of the shown decentralised approach which is independent from the current electricity market design. Both the technical and economic potential are evaluated in comparison to a centralised balancing approach. The simulation results show that a reasonable balancing of the electricity grid is possible. Especially large CHP units in buildings with higher heat demand are able to contribute. From an economical perspective decentralised CHP systems show higher supply cost than centralised power plants.