The Sacramento Municipal Utility District unveiled its newest and most high-tech electrical substation in Downtown Sacramento, which serves the grid that includes the Capitol, capital offices and the skyscrapers along Capitol Mall.
Downtown is historically one of the utility’s most resilient grids, and the $94 million new substation should make it even more resilient, said SMUD CEO Paul Lau.
“We have never built anything like this before,” Lau said Thursday. “It will serve Downtown for many years to come.”
The utility recently built a similar capacity substation in the Franklin area on 17 acres. This new Downtown Station G sits on just 1.5 acres at Eighth and G streets.
The Downtown substation cost more than double what a larger-acreage substation would cost, but it is the nature of Downtown real estate being precious that forced the utility to go high-tech.
To be able to concentrate capacity into a small space, it uses gas-insulated switchgear to take the 115,000-volt high-voltage transmission lines into the substation. All the high voltage coming into the station and all the distribution going out of the substation are undergrounded in vaults.
The new substation also is a major connection for the Sacramento Regional Transit District’s electric light rail trains.
Station G takes up half a city block. It is on the same block as the previous station that served Downtown at Seventh and H streets. That historic station, whose building dates from 1894, is now being developed into a new Station H that will be part of the network that powers the Downtown Railyards. Station H should come on line in 2025.
The site was a difficult one to work with because it was in part of Downtown that was raised with fill dirt in the late 1800s to prevent flooding. The entire substation has some 400 pilings below it as well as a lot of concrete to make up for the weakness of the fill dirt. Because it’s close to the river, most connections are hardened to be able to be submersed.
The four massive electrical transfomers that step down the electricity to distribution level are all raised above grade to avoid flooding. Those four transformers are all surrounded on two sides by massive concrete blast walls, so that should one of them fail, they don’t take out the other ones. And any one of the transformers can power its entire network, with the others there to provide redundancy and resilience, said Rob Kerth, a member of SMUD board of directors and an engineer.
“Most people in Sacramento take this kind of thing for granted, and they don’t know how proud they should be about this,” Kerth said.
The station has no employees assigned to it. It is managed and monitored remotely, and many fixes can be handled remotely.
There are more than 2 miles of conduit on the site, and many more miles of wiring. Everything in the substation is grounded with massive wires, and it's covered above by lightning rods and lightning-attracting cables that protect the switchgear and transformers, Kerth said.
The substation project was built by contractors Wilson Construction Company of Canby, Oregon, and Roebbelen Contracting Inc. of El Dorado Hills.
The new substations will help SMUD support electrification as the district and the state phase out carbon-emitting energy, Lau said. It is SMUD’s goal to get to zero carbon by 2030.
