Switching to electric vehicles could save the US billions, but timing is everything

Today, less than 2 percent of the vehicles Americans buy are electric. But within the next three decades, some automotive industry experts expect electric vehicles could make up the majority of U.S. and global car sales.

All told, American drivers log about 3 trillion miles per year, consuming more than 170 billion gallons of gasoline and diesel in the process. Converting all those road miles to electricity would place new demands on the nation’s system for producing and delivering electricity.

As part of a major energy infrastructure study, we are seeking to understand how an increase in electric vehicles (EVs) might change how energy is supplied and consumed. So far, we have figured out the impact of electric vehicles will depend on where you live and when they are charged.

Estimating how much electricity EVs will demand

Using a similar technique featured in our recent paper on hydrogen vehicles, we developed a state-by-state assessment of the amount of electricity that would be needed to charge an electrified fleet of personal cars, trucks and SUVs.

We started by estimating the amount of gasoline every county consumes today. We then converted vehicle miles traveled into electricity requirements based on the efficiency of today’s EVs.

Admittedly, these methods have limitations. The number of miles traveled could change significantly if autonomous vehicles become commonplace and more people rely on Uber, Lyft and other vehicle sharing services, for example. However, we believe our approach provides a good starting point for estimating future electricity demand if EVs become the norm.

Regional impacts

The U.S. electric grid has continually evolved to accommodate new demands throughout the last century. But if the nation’s vehicles were to rapidly become electric, the grid would need to change faster. Depending on local driving habits and the grid infrastructure that’s already in place, our analysis shows that EVs will have different impacts in different regions.

Since Texas and California consume more electricity than any other states, they provide a good snapshot of what a future filled with electric vehicles might look like. In both cases, an increase in EVs would drive consumption higher, with the potential to strain local infrastructure.

If virtually all passenger cars in Texas were electrified today, the state would need approximately 110 more terawatt-hours of electricity per year – the average annual electricity consumption of 11 million homes. The added electricity demand would result in a 30 percent increase over current consumption in Texas.

By comparison, because of a more temperate climate, California might require nearly 50 percent more electricity than it currently consumes if passenger vehicles in the state were fully electrified. That means California would need to generate an additional 120 terawatt-hours of electricity per year.

A tale of two grids

A look at the two states’ grids demonstrates how reliance on EVs for mobility could vary from place to place.

On hot summer afternoons, Texas uses about half of the electricity it generates to power air conditioning to keep buildings cool. The large seasonal variations in electricity demand due to air conditioning means the state has power plants that sit idle throughout many hours of the year. The spare capacity during off-peak hours could make it easier for Texas to meet future electricity demands of EVs.

California’s more temperate climate means the state needs less electricity on summer days, and less demand variability on the grid overall. As a result, California has less generation capacity available than Texas to meet future charging demands from electric vehicles.

In 2018, the Electric Reliability Council of Texas, the organization that manages most of Texas’s electric grid, hit a new peak demand of roughly 73 gigawatts on July 19. Looking at the off-peak hours for July 19, 2018, we found the ERCOT grid had spare capacity to provide more than 350 gigawatt-hours of additional electricity if idled power plants continued to operate throughout the day, not just during peak demand.

Based on our estimates, the charging requirements for a fully electrified fleet of personal cars in Texas would be about 290 gigawatt-hours per day, less than the available surplus of generation capacity. In other words, the Texas grid could theoretically charge a fully electrified vehicle fleet today if vehicles were charged during off-peak hours.