Chapter 28. Chapter 28: Sun, Wind, and Water Energy

What are the characteristics of a sustainable energy source...?

Why You Should Care

Energy is considered sustainable if it cannot or will not be depleted within a timeframe that is meaningful to humans. Solar energy is the prime example of sustainable energy because it is constant (at least for the next few billion years) and incurs relatively little environmental impact to harness. Fossil fuels, which nearly all fall under the categories of oil, coal, or natural gas, are non-sustainable energy sources. Projections of the available supplies of fossil fuels are still being fine-tuned, but it is a safe bet that most of our resources will be depleted in the next century or so. Some projections predict that the majority of oil will be depleted before the end of the 21st century. Furthermore, extracting fossil fuels causes a suite of environmental damage. Today, sustainable energy sources account for a small fraction of the world’s energy usage, but they are seen much more in popular media than unsustainable sources, unless gas prices are particularly high. It is human nature to look to the future with wonder and optimism, but the evidence suggests we can’t find sustainable energy sources fast enough in the present.

5.

Thought Question: The demand for electricity from both renewable and fossil fuel sources is predicted to increase over the next 30 years. Compare the predicted growth of renewable electricity and fossil fuel electricity. How does the growth of each source of electricity relate to the total electricity production worldwide?

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Renewable electricity production is predicted to double over the next 30 years. Fossil fuel electricity is predicted to increase from about 13 trillion kilowatt-hours to 21, an increase of only about 50%. However, the proportional contribution of renewable electricity to world demand will only modestly increase since it is diluted by the large contribution from fossil fuels.

6.

Thought Question: As you will read later, around 20% of the world's electricity is currently produced by hydroelectric dams. Now, refer again to the chart predicting energy consumption. About how much of the world's electricity currently comes from renewable sources? About how much of that renewable electricity comes from hydropower?

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About 18–20% of the world's electricity is produced from renewable sources. Considering about 20% of the world's electricity is produced by hydropower, that suggests that most of the world’s renewable electricity is produced by hydropower.

7.

Thought Question: Examine both graphs. What units are used for each?

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The bar chart predicting electricity production is measured in trillions of kilowatt-hours. The pie chart is measuring the percent of production of renewable energy represented by each source.

8.

Thought Question: Does all of the renewable energy production represented in the pie chart refer to electricity?

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No, most of the renewable electricity comes from hydropower, but biomass represents the largest share of renewable energy production. This suggests that most of the biomass energy is being used as heat from combustion.

9.

Thought Question: How will nuclear power change over the next 30 years?

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Nuclear power also seems to be doubling production by 2035, but it doesn't seem to be meeting much more of the total energy demand proportionally.

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