Danish cogeneration plant and solar collectors in separate sites
This project example is a model of the Danish district heating plant in the city of Ringkøbing. For further information about Ringkøbing District Heating, see our online presentation where you can monitor the daily operation: http://www.emd.dk/plants/rfvv/?english&history
The energyPRO model of Ringkøbing district heating plant includes a natural gas fired CHP, an electric boiler, solar collectors, gas fired boilers and a thermal storage. These units must at all times cover the city’s heat demand. Produced and consumed electricity is traded on the Day-Ahead spot market in West Denmark.
As can be seen in the below figure, the district heating grid is divided into three different sites: “The Rindum central”, “Ringkøbing district heating grid” and “Solar collector field”. The arrows between each site indicates heat flow directions and limitations.
energyPRO calculates the optimal operation of the units in the project, which in this case is by covering the heat demand at the lowest possible price. Since the solar collectors have a low marginal production cost, their production is prioritized before the other units in the system. The solar collectors should therefore produce as much heat as possible supported by the flexibility the heat storage provides. The CHP should be operated in hours with high electricity prices and the electric boiler in hours with low electricity prices.
In the below figure, a graphical representation of the operation can be seen. The figure is composed of five graphs: The top graph shows the solar radiation in every hour for the given location. This is used to calculate the heat production from the solar collectors. The second graph shows the electricity price in West Denmark every hour. The third graph shows the heat production of the different units and the total heat demand. The fourth graph shows the electricity production and consumption, and the last graph shows the storage capacity and content.
From the figure it can be seen that the CHP (green color) is operated in hours with high electricity prices and the electric boiler (orange color) in hours with low electricity prices. The solar collectors (red color) produce as much as possible and the boilers (blue color) covers the rest of the heat demand.
Besides the graphical overview of the operation, it is also possible to generate a number of technical and economic reports. For instance, the report “Operation Income” collects all operational payments, i.e. revenues and expenditures from one year’s operation, as shown in the below figure.