Answer to Question #133127 in Optics for Elvis

Question

Explain the term energy chain
i. Describe the energy chain which occurs at a power station which uses coal as fuel.
ii. Account for energy losses if production of electrical energy is not at 100%.

Answer 1

Term “energy chain” can be explained as trail that energy takes as it changes from one form into another.

i. Sun → Plant biomass → Coal → Power Station → Electricity

ii. When energy is transformed from one form to another, or moved from one place to another, or from one system to another there is energy loss. This means that when energy is converted to a different form, some of the input energy is turned into a highly disordered form of energy, like heat. Whenever electrical energy is transported through power lines, the energy into the power lines is always more than the energy that comes out at the other end.

Electricity use is a good example that illustrates energy loss in a system. By the time the energy associated with electric power reaches the user, it has taken many forms. Initially, the process begins with the creation of the electricity through some method. For example, the burning of coal in a power plant takes the chemical energy stored in the coal and releases it through combustion, creating heat that produces steam. From here the steam moves turbines and the mechanical energy here turns a generator to produce electricity. A typical coal fired electrical plant is around 38 % efficient, so ~1/3 of the initial energy content of the fuel is transformed into a usable form of energy while the rest is lost. Further losses occur during the transport of this electricity. Finally, the electricity reaches its destination. This electricity could reach an incandescent light bulb wherein a thin wire is heated until it glows, with a significant amount of energy being lost as heat. The resulting light contains only about 2% of the energy content of the coal used to produce it.