Hoover Dam – Science Tourist: Water Engineering 2

Hoover Dam by Ansel Adams (1942)
Hoover Dam by Ansel Adams (1942)

Last week I wrote about a pump that used steam power to empty a large lake. This week, the opposite: Hoover Dam created a lake to generate power!

Hoover Dam is built in the Colorado river, on the border of Nevada and Arizona. It’s very much in the middle of nowhere, but Vegas isn’t far away and Hoover Dam tours are one of the main attractions for visitors who quickly tire of the bright lights, casinos, shows, and theme hotels. About 15 minutes into the bus trip you will also have tired of puns on the word “dam(n)”, though, but that’s a sacrifice you’re going to have to make on this dam tour for the rest of the dam day. To give you an accurate experience, I’m going to be making dam puns throughout the rest of this post.

The dam was built during the Great Depression, between 1931 and 1935, which is somewhat encouraging in light of the current global financial situation. Pretty dam awesome things can still be built in hard times. Since 1987, the dam has offset its entire production cost by the sale of electricity, and continues to support its own dam maintenance from energy sales.

The goal of building a huge dam was threefold: to provide water for land irrigation, to control flooding of the river, and to generate electricity. The dam works by blocking the flow of water upstream of the dam, and regulating its outflow. This created a reservoir lake, Lake Mead. If the lake gets too full, the dam can divert spillover water, but due to recent droughts, the dam lake has not been filled to capacity in several years. (Dam climate change!)

Here’s a picture I took of Lake Mead in 2008. The dam tour guide told us that the marina had been moved several times over the previous years to accommodate the receding shoreline.
Lake Mead

I searched Flickr for more recent pictures at the same location, and found this one from 2012. It looks the same as mine from four years earlier.

The low water level of the lake is also very obvious at the dam itself. Mineral deposits on the rock show where the water used to be. When the lake is full, the tower in the dam picture would also be mostly under water.

Inside the lower part of the dam are the dam generators that produce electricity. Pictured below are the ones on the Nevada side of the dam. The wall at the back of the room is the state border with Arizona, and on the other dam side are about as many more generators.

Generators inside the dam

The water on the lake side of the dam is much higher than the river downstream, and in falling from high to low levels through the dam pipes, the water passes on kinetic energy to spinning turbines which power the generators. As explained in the dam museum exhibit, it works by magnetism, not magic:

Not Magic!

On average, the Hoover Dam produces about 4 billion kilo-watt hours per year, enough for 1.3 million people. Even though the dam is on the border of Nevada and Arizona, most of the electricity it generates goes to the more populated state of California. Los Angeles alone uses almost as much dam energy as Arizona does.

Nevada is also home to a solar panel factory (which I believe also runs on solar power, although I can’t find a link right now) and when I asked my tour guide about energy production in the state she was really enthusiastic about it. She said that people in Nevada are very aware that they have more energy than they know what to do with, from the dam and from the sun, and are very supportive of any initiatives to harness and distribute it. It’s a nice thought that so much energy is coming out of Nevada, to balance out the seeming wastefulness of Vegas.

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