The threat of a catastrophe at California’s Oroville Dam appears to be over. California’s Department of Water Resources (DWR) lifted the evacuation order that last week moved some 180,000 residents out of the area that could be flooded if the water level topped the 770-foot dam.
But the dam’s troubles have also temporarily brought down one of the state’s major renewable energy assets, likely replacing some 819-MW of carbon-dioxide free hydro generating capacity with kicked up natural gas generation for some period of time. Oroville, the highest dam in the U.S., is a major electricity generator in addition to providing flood control on the Feather River upstream from Sacramento and irrigation to the San Joaquin Valley.
The plant houses the Edward Hyatt power plant. Two 22-foot-diameter penstocks feed three conventional hydro turbines and three pumped storage generators, which are connected to a catchment at the foot of the dam. When the state-built dam and power plant went into service in 1968, it was the largest underground power station in the U.S.
During relicensing at the Federal Energy Regulatory Commission in 2005, local environmental groups raised the issue of upgrading the emergency spillway, which was used last week when the standard spillway suffered major erosion. The emergency spillway also had erosion problems last week, which led to the evacuation order.
The Los Angeles Times quoted Metropolitan Water District manager Jeffrey Kightlinger, “They did look at that issue and they determined that [the existing spillway] did meet the appropriate guidelines. In the FERC guidelines, they talk about how you don’t put a lot of funding and concrete, etc. into emergency spillways because presumably they will rarely if ever be used.”
Het Shah, an analyst at Bloomberg New Energy Finance, said, “Gas generation probably needs to pick up the slack from what you lose at the Oroville Dam. You need two gas facilities to fill that gap.” Bloomberg noted that the closure of the plant “comes at a time of low seasonal demand for natural gas in California.” There has been no word from the CAISO (CAISO) or the DWR on restarting the generating plant.
The CAISO de-energized three 230-KV power lines in the Ororville area during the emergency. The grid manager said no other problems occurred on the grid related to the Oroville outage.