Question of the Day - 05 October 2017

As discussed in yesterday’s QoD, Lake Mead fell to a record-low surface elevation of 1,071.61 feet in July 2016 and the electrical plant was designed in the early ’30s to have to be shut down if the water level ever fell below 1,050 feet. The low water pressure causes the turbines to vibrate and can cause serious, even irreparable, damage if they continue to run.

Does this mean that when or if the surface level of the reservoir drops another 25 or so feet, no electricity will be produced by this prodigious generating station?

No. It doesn’t. The Bureau of Reclamation, which manages the dam and operates the power plant, has been taking important steps to keep the generating station alive. 

First, the below-1,050-foot level is uncharted territory; the lake has never fallen that low before. Second, more efficient equipment will allow power to be produced if the water level drops, engineers estimate, to the 950-foot level and possibly even lower. A major investment (upwards of $15 million since 2011) has been made in wide-head turbines, stainless-steel wicket gates, and digital controls to help wring every last drop of water out of a shrinking resource.

Wide-head turbines are specifically designed to operate smoothly at low reservoir levels and low water pressure. Five of Hoover Dam’s 17 turbines have been fitted with wide-head models.

The new wicket gates, essentially the plugs at the bottom of the intake-tower bathtubs, allow for more precise control of water flowing through the turbines; they also reduce leakage. This ensures that all the water flowing through the dam generates as much power as possible. 

The digital controls enable operators to precisely position the wicket gates.

Electricity from Hoover Dam, around $1.80 per megawatt hour, is extremely inexpensive, compared to other technologies and areas in the world. Construction costs for the dam were paid off 30 years ago and the water is courtesy, for the most part, of Mother Nature. To maintain the system, engineers and authorities are learning how to do more with less.