With the drop in water levels at Lake Mead, how has the lower water pressure impacted the production of electricity at Hoover Dam?
Hydropower accounts for nearly 20% of total electricity produced globally. It’s not only one of the cleanest forms of energy production, it’s also one of the most widely used and cheapest renewable energy sources (not including the initial costs of dam infrastructure). The U.S., China, Canada, and Brazil are the largest producers of hydroelectricity.
When it came on line in 1936, iconic Hoover Dam was the largest concrete structure and the largest hydro plant in the world. Control of the Colorado River was the prime motivator for the dam; electricity was produced to repay the 50-year construction loan, finance the multimillion-dollar annual maintenance budget, and produce power for the growing southwestern U.S.
Hoover Dam can produce up to a little more than 2,000 megawatts of electricity and a yearly average generation of 4.5 billion kilowatt hours, servicing upwards of eight million people in southern Nevada, Arizona, southern California.
Generating electricity from water uses the same principle as from wind: Install a turbine in the path of the flow. Flowing water or blowing air causes the propeller-like turbine to spin; the turbine turns a metal shaft in a generator, the motor that produces electricity.
Pipes direct water from Lake Mead down to the bottom of the dam. The water picks up speed as it falls; gravitational energy turns the turbines. As your question states, the amount of energy generated depends on the pressure of the water falling down this pipe.
This process, of course, drains water from the reservoir and, along with evaporation, requires water to be replenished to keep the cycle going. But with the drought, that’s not happening.
As we’ve discussed a number of times in previous QoDs, Lake Mead fell to a record-low surface elevation of 1,071.61 feet in July 2016. However, in July 2015, the dam was “derated” from 2,074 to 1,592 megawatts and was providing power only during periods of peak demand for Vegas, L.A., and other southwestern cities.
Under its original design, the dam can no longer generate power once the water level falls below 1,050 feet.
We’ll address the current outlook for Hoover Dam electricity output in tomorrow’s answer.
