Evaluation of building energy systems with an increase of renewable energy sources in the grid – Evaluation methods and simulation based examination

Sebastian Stinner
E.ON Energy Research Center – RWTH Aachen
Institute for Energy Efficient Buildings and Indoor Climate (EBC)
Section: Energy concepts for buildings and city quarters
Phone +49 241 / 80 49 798 – sstinner@eonerc.rwth-aachen.de

Univ. Prof. Dr.-Ing. Dirk Müller
E.ON Energy Research Center – RWTH Aachen
University Institute for Energy Efficient Buildings and Indoor Climate

Short discription of the subject

Background and Motivation
Caused by the increasing feed-in of renewable energy sources (especially photovoltaics and wind power) problem in the stability of the low-voltage grid can occur. In such systems both the loads (consumers) and the generation is volatile. This leads to a need for plants that can use or generate controllable energy to support the renewable energies. These plants could be on the one hand micro-/mini-cogeneration units to generate electricity in times when there is no renewable electricity in the grid. This can be energetically beneficial, if a high share of the generated heat can be used. Additionally, the use of heat pumps in times of overproduction from renewable energies can help to stabilize the electrical grid. The overall efficiency is again dependent on the usage of the generated heat. Thus, load-shifting potentials and storage capacities on the heat side have to be analysed in detail. All those points have to be included into a consistent evaluation method for systems with a higher share of renewables. Many details have to be clarified and a comparison to the existing evaluation methods has to be done. One major point in this evaluation is the different value of electrical energy at different times.

Research Methods
In the scope of the research project, different systems including renewable energy sources have to be considered in a simulation study. The simulations are implemented in the modelling language Modelica with libraries built up by the institute. With this tool, it is possible to describe different parts of the system, like user behaviour, plants, storages and building physics. This allows the users of the software, to vary different parameters and analyse building systems under different boundary conditions. With an intelligent variation of parameters, their influence on the total efficiency of the system should be analysed. To model the systems engineering properly, especially concerning the dynamic behaviour of the plants in future energy systems, Hardware-in-the-Loop (HiL) tests will be arranged to determine different plant behaviour under dynamic boundary conditions. Especially start up and shutdown behaviour and additionally the behaviour concerning different return temperatures should be analysed.

Expected Result
The aim of the research project is a consistent evaluation method for building energy systems concerning the energy efficiency, but also the grid compatibility. Buildings and their systems engineering should not only be evaluated due to their efficiency, but also due to their usability for a stabilization of the electrical grid. The evaluation method should be holistic and consider all aspects concerning buildings as consumer and producer of electrical and thermal energy. Especially the usability of the building as storage should be accounted for.

Short CV

Since 12.2010Research associate (Doktorand); Institute for Energy Efficient Buildings and Indoor Climate; E.ON Energy Research Center – RWTH Aachen
10.2005 – 10.2010Diploma studies; Computational Engineering Science (Mechanical engineering); Field of energy- and process engineering

Focus of interests and research


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