An anonymous reader quotes a report from Ars Technica: Two researchers at the University of California, Davis -- Yanning Li and Alan Jenn -- have determined that nearly two-thirds of [California's] feeder lines don't have the capacity that will likely be needed for car charging. Updating to handle the rising demand might set its utilities back as much as 40 percent of the existing grid's capital cost. Li and Jenn aren't the first to look at how well existing grids can handle growing electric vehicle sales; other research has found various ways that different grids fall short. However, they have access to uniquely detailed data relevant to California's ability to distribute electricity (they do not concern themselves with generation). They have information on every substation, feeder line, and transformer that delivers electrons to customers of the state's three largest utilities, which collectively cover nearly 90 percent of the state's population. In total, they know the capacity that can be delivered through over 1,600 substations and 5,000 feeders.[...]
By 2025, only about 7 percent of the feeders will experience periods of overload. By 2030, that figure will grow to 27 percent, and by 2035 -- only about a decade away -- about half of the feeders will be overloaded. Problems grow a bit more slowly after that, with two-thirds of the feeders overloaded by 2045, a decade after all cars sold in California will be EVs. At that point, total electrical demand will be close to twice the existing capacity. The problems aren't evenly distributed, though. They appear first in high-population areas like the Bay Area. And throughout this period, most of the problems are in feeders that serve residential and mixed-use neighborhoods. The feeders that serve neighborhoods that are primarily business-focused don't see the same coordinated surge in demand that occurs as people get home from work and plug in; they're better able to serve the more erratic use of charging stations at office complexes and shopping centers. In terms of the grid, residential services will need to see their capacity expand by about 16 gigawatts by 2045. Public chargers will need nine gigawatts worth of added capacity by the same point. The one wild card is direct current fast charging. Eliminating fast chargers entirely would reduce the number of feeders that need upgrades by 12 percent. Converting all public stations to DC fast charging, in contrast, would boost that number by 15 percent. So the details of the upgrades that will be needed will be very sensitive to the impatience of EV drivers.
Paying for the necessary upgrades will be pricey, but there's a lot of uncertainty here. Li and Jenn came up with a range of anywhere between $6 billion and $20 billion. They put this in context in two ways. The total capital invested in the existing grid is estimated to be $51 billion, so the cost of updating it could be well over a third of its total value. At the same time, the costs will be spread out over decades and only total up to (at most) three times the grid's annual operation and maintenance costs. So in any one year, the costs shouldn't be crippling. All that might be expected to drive the cost of electricity up. But Li and Jenn suggest that the greater volume of electricity consumption will exert a downward pressure on prices (people will pay more overall but pay somewhat less per unit of electricity). Based on a few economic assumptions, the researchers conclude that this would roughly offset the costs of the necessary grid expansion, so the price per unit of electricity would be largely static. The findings have been published in the journal Proceedings of the National Academy of Sciences (PNAS).
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