Tesla road tripping

We took a three-week, 3,857-mile road trip a month ago to visit eight US National Parks and to see friends in Colorado and Utah. Here are some Bryce Canyon hoodoos for you to look at:

The parks visit had been on our list for a long time. Besides that, we wanted to see if you could make a long road trip in a Tesla. Was there enough charging infrastructure? How much hassle would it be to stop and charge up?

Mostly, it was fine. The major interstates have plenty of Tesla superchargers. The navigation system will plan out your recharging stops on long drives, or you can figure out when you are likely to want bathroom and meal breaks, and choose your own charging stops to suit. We’d typically stop for forty-five minutes or so to add electrons, every three or four hours.

Lots of hotels, including several of the National Park lodges, have slower chargers available in their parking lots, as well. That’s an advantage: You can pull in, check in, plug in, go to bed, and wake up to a full battery the next morning. Even better, you have to pay for the electrons you get from the Tesla superchargers, but the “destination” chargers at the hotels are typically free. That’ll no doubt change one day, but it’s a nice perk for electric vehicle owners right now.

Once we got home from the trip, I fired up Microsoft Excel to figure out how much we’d spent, and how that compared to a car with an internal combustion engine. The numbers were interesting.

We spent a total of $330.70 buying electrons on the road. (Remember, we got some for free at those destination chargers). That means we were able to drive 11.7 miles for every dollar we spent.

I eyeballed the prices on the filling station placards as we passed them by. The modal price of a gallon on our trip was $3.50 or so. A little arithmetic says we got the equivalent of 40.8 mpg on the trip in our comfortable Model S sedan. I’m writing this post in late November 2021. The average price of a gallon of gas in California today is $4.71. At that price, we got an implied 54.9 mpg.

That’s pretty good news. On our trip, using the public charging infrastructure, our late-model Tesla sedan cost us about the same to fuel as a new car that gets good gas mileage would have. Upkeep costs are much lower, since there’s no internal combustion engine or transmission to maintain — the only fluid we have to worry about is for the windshield wipers.

We don’t normally rely on the public charging infrastructure, however. We have a 50A, 240V charging station in our garage. We’re PG&E customers in California on the EV-A rate schedule. We pay eighteen and a half cents for a kilowatt-hour of electrons, off-peak, and of course we charge off-peak. I’ve measured our mileage in the Tesla; we get about 3 miles per kWh.

That translates to 16.2 miles per dollar when we use our home charger. At a $3.50/gallon price for gas, that’s equivalent to 56.8 mpg. At today’s $4.71, it’s an implied 76.4 mpg. In California, a Tesla is much cheaper to fuel than a gas-fueled car.

Our situation is still more complicated. We’ve got solar panels on the roof and are on a net energy metering (NEM) plan. We sell electrons we make to our utility in the daytime and buy them back if we need them at night. Basically PG&E is a giant storage battery for our rooftop solar system.

A precise analysis of operating costs with rooftop solar is tricky — you need to figure out if you’re charging with electrons from your own panels, or getting them from the grid, and when. In our case, we charge the car off-peak, which is at night, which is when it’s dark out, so we have to get those electrons from the grid. We use our daytime generating capacity to run the rest of the house. Anything we don’t use ourselves in the daytime gets sold to PG&E at their NEM rates.

But this gets to the real advantage of an electric car. The economics are attractive, as I’ve shown, but the main thing is that we’re not spitting out new carbon dioxide from our tailpipe. We’ve decarbonized substantially by installing solar. Utilities, including PG&E, are steadily moving their generating capacity from fossil fuels to renewables. As they do so, the carbon footprint of a great American road trip will drop to zero.

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Mike Olson

Berkeley-based techie with an interest in business. Worried about the world.