2.5

## University of Groningen

Skip to 0 minutes and 12 secondsIn the previous lecture, I introduced you to energy systems and to the energy systems concept. The examples given illustrate that the variety and diversity of energy systems is overwhelming. Different resources, different technologies, different scales, and many appliances are in use. Let's, for example, take a closer look at how we use energy from coal. It all starts at the mine. Here, coal is extracted from the Earth. Coal converted to coke provides the energy to make iron and steel in the blast furnace. Most coal extracted, however, is shipped to power plants, where its heat of combustion is converted into electricity. Electricity is delivered to the transmission grids and then to end users, like you and me.

Skip to 1 minute and 5 secondsEach of these activities we can frame as an energy system and taken together, the chain also can be framed as an energy system. What is basically a system? The structured assemblage of elements and subsystems is the system configuration. In a system representation, we delineate this by the system boundary. Interfaces and interaction is via material and energy flows and via information. Within the system, these link the internal components. Inputs and outputs of the system cross the system boundary and they connect the system with its environment. And note that this environment is yet another system. In summary, any representation of an energy system has a system boundary and inputs and outputs that cross the system boundary.

Skip to 2 minutes and 3 secondsThe representations can be simple or it can contain extensive detail. The definition and the representation allows you to frame energy systems for analysis. Try it for one of your energy systems at home. In the next lecture, I will discuss system decomposition.

# Energy system representation

As a follow-up to the first video, (energy) systems can be represented in various ways. In addition, a large diversity in energy systems demands a method to respresent them uniformly. Different terms, such as a system’s input, output, and boundaries, will be explained which are required for understanding and making system diagrams. As you will see, representations can be very simple, or very detailed.