Energy flow in our technological society
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Bernard Nebel.
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Does the concept of energy flow apply to our technological society? Yes it does! We only add steps in the ultimate flow from the sun to outer space.
Major sources of energy used in today’s world are coal, crude oil (refined into gasoline and other liquid fuels), and natural gas. All of these fuels are basically deposits of biomass from ancient photosynthesis that we find buried in the earth. These deposits are limited in amount and as they are mined and burned, they are gone forever as the heat makes its way to outer space. Further, their mining causes extensive environmental damage. See:
http://earthjustice.org/slideshow/images-of-mountaintop-removal-mining
Further, their burning invariably adds carbon dioxide to the atmosphere, a major concern regarding climate change.
Electricity is part of the flow
Many students are likely to think of electricity as a unique energy source exempt from such problems. It is not. It is not, because generating electricity requires energy to turn the generators, and the energy input required is actually greater than the energy output as electricity. The following video shows the principles involved:
Most of the electricity used in the world comes from burning coal or oil, to boil water to produce steam, which drives turbogenerators.
Type into your browser: coal burning power plant images
Turbogenerator images
In short, electricity is part of the energy flow. Note the multiple changes between kinetic energy (K) and potential energy (P) in the course of production and use of electricity.
sunlight (K) > photosynthesis, potential energy in biomass (P) > burning to release heat (K) > boil water to produce steam pressure (P) > drives turbogenerator > electricity (K) > further changes depending on what electricity is used for but all eventually result in heat, which makes it way to outer space
Renewable energy
Revisit renewable energy (inexhaustible energy sources) described under Lesson C-1.
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