Name:___________________________________________Date:______________________
Energy Transformations and Efficiency - Analyzing Sankey Diagrams
Learning Target 1.2 - I can interpret energy models (Sankey Diagrams), explain how energy is
transformed to different forms, and evaluate the efficiencies of energy transformations.
Energy efficiency is a measure of how much energy or work is conserved in a process. In
many processes, work or energy is lost as waste heat, vibration, etc. The efficiency is the
energy output divided by the energy input and is expressed as a percentage. A perfect process
would have an efficiency of 100%
Formula:
Efficiency = Energy output / Energy input x 100%
TASK:
For the Sankey diagram of energy use in the USA for 2017, calculate the energy efficiencies
and then answer the questions that follow. Show all work.
EXAMPLE
1. Calculate the energy efficiency of our Electrical Generation?
Efficiency = 12.5 / 37.2 * 100 = 0.333 = 33%
12.5 quads = the energy flow out of the electrical generation box
37.2 quads = the total energy in the electrical generation box
2. Calculate the energy efficiency of the Residential energy usage?
3. Calculate the energy efficiency of the Commercial energy usage?
4. Calculate the energy efficiency of the Industrial usage?
5. Calculate the energy efficiency of the Transportation usage?
6. What is the overall energy efficiency of our entire nation?
7. If you were to make recommendations to the US Government to improve energy
efficiency, where would you recommend changes to make the most impact?
What do think could be done?