Energy Flows. It Is Not and Cannot Be Recycled

[Bernard NebelKeymaster]

 

With all the discussion about recycling, students often get the idea that energy can be recycled. This is a misconception that is important to erase. Stress basic observations:

1. Heat always flows toward a cooler place. A hot object always cools off as heat flows from it into cooler surroundings. The only way to make an object hotter is to place it against or over a hotter source so that heat flows from the hotter source into the cooler object. (Or otherwise add energy to it such as with microwaves.)
2. Stress the observations that every action that involves energy, some energy is changed to heat. For example, consider light bulbs and electric motors.  Invariably, that heat goes off to a cooler place and cannot be retrieved.

From these two basic observations, we should see that used energy cannot be gathered up and reused/recycled. It invariably makes its way (flows) from a source (the sun) to a cooler place, which is eventually outer space.

Like water flowing down a mountain over successive waterwheels, energy may perform many tasks in the course of its flow, prime among these is photosynthesis, which effectively uses solar energy to synthesize biomass from raw ingredients in the environment, mainly carbon dioxide and water. This biomass, in turn, supports all animal life including human life on Earth.

Please post questions that this discussion brings up.

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