6. Explore efficiency and reducing unwanted energy transfers

Starter

Why is boiling water in a saucepan energy inefficient? Through a discussion, ask the students to consider all of the outcomes, i.e., steam, noise, thermal energy and sound energy. What does that mean? What is being lost in relation to the transfer from one store to another? How many transfers are occurring in a boiling saucepan of water and in the surrounding atmosphere?

Main Teaching

Use the handout to expand on the topic of energy efficiency and reinforce learning from the lesson. Discuss Carnot and the heat engine theory. Where and how is energy lost in an engine? Ask the students to resolve the calculations and answer whether an engine can be 100% efficient. Complete the table on the final page. Then, ask the students to make a survey of the ‘energy efficiency ratings’ of the electrical appliances in their environment, school classroom or home. Practice calculating the energy efficiency of an energy transfer into a decimal figure and then converting into a percentage. 

Climate change is causing a rise in the earth’s temperatures. How does energy inefficiency add to this global temperature increase?

Career Film: This is Billy Keywood. Billy is a Graduate Scientist who works for National Nuclear Laboratory.

Expert Film: This is Dr. Tim Gregory, who works as a Chemical Analyst for National Nuclear Laboratory. Tim talks about efficiency and reducing unwanted energy transfers.

Mission Assignment

Use the handout to expand on the topic of energy efficiency. Discuss Carnot and the heat engine theory. Where and how is energy lost in an engine?

Challenge Task: The phrase “energy crisis” is often used. What does this term mean? If energy cannot be created or destroyed, why are we facing an energy crisis? How can we use ides about efficiency to help with the crisis?