|
|
| Fig. 1: A water wheel in Indiana that originally powered a grist mill. (Source: Wikimedia Commons) |
Hydropower has a long history. Human beings have already learnt to take advantage of the free energy the rivers produced from many centuries ago. In many agricultural civilizations, dwellers used forces produced by water wheels to process their grains. Figure 1, for example, shows a waterwheel furnishing power for a mill in the US. In the 19th century, hydropower became an electricity source. In 1882, the first hydroelectric power plant started running in the US. [1] Since then, hydroelectricity has been one of US's main sources of clean energy, facilitating industries and human lives.
Using the report from U.S. Energy Information Administration's Electric Power Annual, we can find how much electricity was generated from each source. [2] The amount of hydroelectricity generated in the U.S. from 2011 to 2020 is listed in Table 1, and also plotted in Fig. 1. [2] Adding the amount of hydroelectricity generated from 2011 to 2020 up, we get 2.806 × 109 MWh. We then divide this number by ten and get an average of 2.806 × 108 MWh per year.
Converting to Joules per year, we then obtain
This is the amount of energy hydropower produces in the US per year.
|
|||||||||||||||||||||||||||||||||
| Table 1: The Amount of Hydroelectricity Generated From 2011 to 2020. [2] These data are also plotted in Fig. 2. |
 |
| Fig. 2: Amount of hydroelectricity generated in the U.S. from 2011 to 2020, from Table 1. [2] (Source: T. Chen) |
In Fig. 2, we see that the amount of hydroelectricity generated fluctuates overtime, and does not stably increase. This is because if we want to keep the amount of hydropower generated increasing, we have to build more water dams and "exploit" more rivers. However, all qualified rivers are already dammed. Therefore, we should not expect a significant rise in hydroelectricity generated in the future.
After calculating the amount of hydroelectricity generated in the US per year, we explore its price. Here, we use "Table 2.4. Average Price of Electricity to Ultimate Customers" in the Electric Power Annual. The average prices of electricity from 2011 to 2020, measured in cents per kilowatthour, is 10.307 cents per kilowatthour, which means 0.10307 US dollars per kilowatthour. [2] However, the price of electricity vary for customers living in different places, and also changes over time. Also, these prices are results of regulation and negotiation between government and the utilities. Therefore, the price is not a good way of measuring the value of hydroelectricity in the US.
Hydroelectricity in the US, much cleaner than traditional forms of generating electricity like burning coal, maintains its stable presence in a lot of US people's lives. However, as a lot of rivers which are qualified in generating hydroelectricity are already dammed, the amount of hydropower generated in the future will not be significantly increased. If human beings want to take advantage of more clean energy, they should focus on exploring other forms instead of hydroelectricity.
© Tianyi Chen. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] C. Nunez, "Hydropower Explained," National Geographic, 13 May 19.
[2] "Electric Power Annual," U.S. Energy Information Administration, March 2022, Tables 3.1.B and 2.4.