California’s busy truck corridors present a charging challenge

Published on December 16, 2020 by Hil Anderson

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A considerably larger and more complex electric grid will be needed if California plans to meet the challenge of completely eliminating carbon emissions in the next 25 years, Southern California Edison (SCE) said in a newly released white paper.

About $170 billion will be required to ramp-up solar and wind generation to meet an anticipated surge in demand by 2045. In addition, another $70 billion will be needed to upgrade and expand the statewide system of wires and support equipment that transmits that power and delivers it to newly electrified homes, businesses, and a growing fleet of electric vehicles (EV) ranging from passenger cars to semi-trucks.

“As electricity fuels a larger part of the economy, we must reimagine what the grid should look like in the future and how it will need to function in new ways to meet expanded needs,” SCE President and CEO Kevin Payne said as his company released “Reimagining the Grid,” a 14-page white paper outlining the daunting path that SCE and all of California will take in order to reach its goal of a completely carbon-free energy system.

“Our approach needs to shift from a focus on system-wide reliability standards to one that meets multiple objectives based on specific, localized needs,” said Payne.

A particularly challenging localized need will be California’s transportation corridors, heavily traveled freeways that are currently jammed with diesel trucks moving freight in and out of industrial parks and busy seaports. The SCE report notes that with 30 percent of the nation’s freight imports entering through the harbors in its service territory, transportation corridors will require major increases in fast-charging infrastructure to keep the new fleet of EV trucks moving around the clock.

The paper said, “While light-duty passenger vehicles sit idle for large portions of the day and therefore can be charged for hours at lower voltages … many commercial vehicles are in use throughout the day.” As a result, fast-charging stations for heavy trucks will likely require high-voltage DC current in the range of 250 kilowatts (kW) to 1 megawatt (MW) as opposed to the slower AC current chargers in the 3.3kW-7.2kW range that passenger vehicles require.

“Sites with commercial EV fleets relying on fast charging will stress the existing distribution system’s capacity within these corridors, and aggregate load from all EV charging in the region will push the capacity of the sub-transmission system that links these corridors to the high-voltage transmission network,” the report said. In addition, factories and other industrial sites along the highways will also electrify their operations, which will add to the increase in demand.

For SCE, that would mean at least expanding the capabilities of existing lines and possibly building new ones if that is what it takes to respond to localized increases in demand. “The intention would be to leverage the existing footprint of our AC system,” the company told Daily Energy Insider in a statement. “Depending on the age of the existing equipment, upgrades may be required. However, there are solutions that currently do allow for converting existing AC lines to DC lines.”

Part of the solution will be the creation of new emission-free generation closer to transportation corridors that will not require a lot of new transmission infrastructure at all.
The SCE paper suggested that nearby generation could produce the high-voltage DC power that would be fed directly to truck-charging stations without the need for adding costly new transmission lines and transformer gear; in addition, EV chargers could even be installed on-site at local DC substations.

Energy storage strategically located around densely populated neighborhoods is also part of the decarbonization strategy for transportation corridors, but that technology has not yet been widely deployed. “Transportation corridors will present a novel and demanding set of challenges for SCE in the long run, beyond this coming decade’s planning horizon,” the paper said. “The variability around when and where these new challenges will appear, as well as which grid technologies and architectures will be available to address them, will bring unprecedented complexity to how we plan, design, build and operate our grid in these regions.”

Moreover, grid planners at SCE and the rest of California will also need to accommodate an anticipated boom in residential solar generation and other distributed energy resources that will be chipping into the electricity supply at different times of the day.

The energy requirements for California’s transportation corridors will be different than other SCE service areas, such as suburban neighborhoods and downtown business districts, and the prospects for necessary technology changes and advances become less clear 10 years out. As a result, SCE will be working closely with customers, regulators and the other parties they will be encountering on the journey to 2045.

Payne said: “We cannot do this alone. Stronger alignment, broader reach and deeper collaboration with stakeholders will be key for future grid designs, standards and infrastructure planning.”