Castaic Lake Hydroelectric Power Plant Facility

Castaic Power Plant Tour, September 14, 2012

In the parking area Lois checked off the names of arrivals. Waiting for the final guests, I had 10 minutes to visit with some former colleagues from Flowserve before start of tour. Incidentally, this plant belongs to a short list of the world’s largest pumped-storage installations and is mentioned in Paul Cooper’s Pump Handbook Fourth Edition – who was also in attendance.

The plant tour was arranged by Lois Terada representing the ASME and AIAA of the San Fernando Valley, courtesy of the Los Angeles Department of Water Power which operates the facility. Public tours of this power plant are rare and when I found out about the opportunity, I wasted no time signing up. After posting a blog about it, the reservation list filled up immediately.

We divided into two separate groups for the plant tour and ours was led by Chief Mechanical Engineer Kent Cotterell. I enjoyed hearing about the plant operation and history from the viewpoint of an engineer who has seen a good portion of it firsthand. For instance, in discussing the hydroelectric mode of operation, friction loss in the 7.2-mile long 30-foot diameter water conveyance tunnel from Pyramid Lake establishes the upper limit on the plant’s electrical output. For reasons not fully understood the tunnel’s hydraulic resistance losses measure higher than anticipated. It’s interesting to ponder what hydraulic phenomenon might be causing this. After all, comparative hydraulic resistance measurements taken on other conduits of this size and length would be scarce to non-existent.

In a facility like this, the size of equipment and infrastructure can only be characterized as “massive.” The plant at full load discharges 480 tons of water per second. The 120-foot diameter 400-foot tall surge chamber could hold the volume of 50 Olympic-size swimming pools. Each individual electrical phase contactor (think of one prong connecting into an outlet receptacle) for an individual motor-generator lead is housed in a tall filing cabinet-sized enclosure. Each of the six 20-foot diameter pump-turbine runners weighs 77 tons, way heavier than a Caterpillar D9 bulldozer. And a generator rotor? 550 tons.

This 1250 MW power plant is tucked away at the upper end of Castaic Lake in northwest Los Angeles County. In only 5 minutes a 250 MW hydroelectric turbine unit can be brought online from complete standstill to full power. No other major source of power can ramp up this quickly. No fuel storage tanks. No coal yard. No smoke stacks. No rising plumes of steam. This is clean pumped-storage hydroelectric capable of supplying power to over 1.4 million homes.