In the previous lesson we learned about the difference between primary and secondary energy. As a refresher, by definition, “primary energy (PE) is an energy form found in nature that has not been subject to any human engineered conversion process. It is energy contained in raw fuels and other forms of energy, including waste, received as an input to the system. Primary energy can be non-renewable or renewable.” 1Wikimedia Foundation. (2021, August 30). Primary energy. Wikipedia. Retrieved September 21, 2021, from https://en.wikipedia.org/wiki/Primary_energy#:~:text=Primary%20energy%20(PE)%20is%20an,be%20non%2Drenewable%20or%20renewable.
The graph below, published by the web publication Our World in Data, plots global direct primary energy consumption from 1800-2020. The direct primary energy sources include:
- Traditional biomass
- Coal
- Oil
- Gas
- Nuclear
- Hydropower
- Wind
- Solar
- Other renewables
- Modern biofuels
On the plot, global energy consumption is measured in terawatt-hours (TWh). Energy consumption on such a large scale is often measured in terawatt-hours, and one terawatt-hour is equivalent to one-trillion watts per hour or 3.6 * 1015 joules.
Using the interactive graph, answer the series of questions that follow to gain a better perspective on the changes in global primary energy sources consumed over time. To view primary energy consumption in percentages first check the ‘relative’ box in the upper left hand corner. From there you can toggle your mouse throughout the chart to view percentages for each year.
Traditional biomass is plotted on the graph. Prior to the use of fossil fuels and modern renewables, humans primarily relied on biomass to satisfy their energy consumption needs. By definition, biomass is “plant or animal material used as fuel to produce electricity or heat.”2Wikimedia Foundation. (2021, September 11). Biomass. Wikipedia. Retrieved September 21, 2021, from https://en.wikipedia.org/wiki/Biomass. Biomass is a renewable energy source.
What do you think was the primary global biomass source in the 1800’s?
Starting in 1800, estimate the successive doubling time for energy consumption. (i.e., how long did it take to double the first time, then how long to double again, etc.). Much of the chart has been completed – calculate the numbers for the blanks in the table below where you can refer to them (TWh rounded to nearest 100s).
| Year | Consumption, TWh | Time to double, years |
|---|---|---|
| 1800 | 5,600 | No data to determine |
| 1900 | 12,100 | 100 |
| 40 | ||
| 1960 | 40,600 | 20 |
| 1978 | ||
| 159,000 | 41 |
