Zero net Energy House

Colonial Solar House: Electric Car

Another large source of carbon dioxide emissions is your car’s tailpipe.  Colonial Solar House was outfitted with more solar photovoltaic modules than it needs in a typical year, so there is some electric energy available to power an electric car or two.  Even if you were to power it with electricity from the grid, an electric vehicle’s net carbon dioxide emissions are less than what a gasoline-powered car produces.     

We own a Chevy Volt and a Tesla Model S. The Chevy Volt has a 40-mile all-electric range, after which it switches over to a gasoline engine. It is described most accurately as a plug-in hybrid. You can recharge it overnight from an ordinary 110-volt outlet, and after it has gone about 40 miles, it operates much like a hybrid (such as a Toyota Prius). We mostly drive it around the Champaign-Urbana area, so we rarely use the gasoline engine.

The Tesla Model S is all electric. It has a much bigger battery pack than the Chevy Volt, giving it a 208-mile range. That easily takes us one way to Chicago, St. Louis, Indianapolis, or Bloomington-Normal, but what about recharging? Tesla has set up Superchargers in all of these cities, and these can recharge the battery to half full in about 20 minutes. And it's free. You can already drive from coast to coast using Superchargers, and Tesla is continuing to expand its Supercharger network. We will likely get a Supercharger in Champaign-Urbana in the future.

All modern electric cars can be recharged at a 240-volt charging station, and these are becoming increasingly common. The Chevy Volt can be fully recharged in 4 hours, the Tesla Model S in about 7 hours. There are three such charging stations in the Hill Street Parking Deck in downtown Champaign, and they are free.

Here I have plugged in my Chevy Volt at the Hill Street Parking Deck.  The car will be fully recharged for free while I have dinner downtown and catch a film at the Art Theater.  The Tesla Model S can also be recharged at 240-volt charging stations like this one.
Here I have plugged in my Chevy Volt at the Hill Street Parking Deck. The car will be fully recharged for free while I have dinner downtown and catch a film at the Art Theater. The Tesla Model S can also be recharged at 240-volt charging stations like this one.

What does it cost?

The Chevy Volt has a base price of $35,000, which seems like a lot for a small car. But there is a $7,500 federal tax credit and a 10% Illinois rebate, which brings the price down to $24,000. Then there are the fuel savings: the Volt costs only about a fourth as much to fuel as comparable gasoline-powered cars. If we assume a gasoline-powered car gets 30 mpg, the fuel savings over 100,000 miles of driving is about $10,000. So the net cost of a Chevy Volt is only about $14,000.

The Tesla Model S is a premium car, so brace yourself for its premium price: the base cost is $70,000 for the 60-kWh model (that's the capacity of the battery pack). Subtract the federal tax credit of $7,500 and the Illinois rebate of $4,000 (that's the maximum) to bring the price down to $58,500. Let's assume that the fuel savings is $10,000, as above, and the net cost of a Tesla Model S is about $48,500. That's still a lot of money, but comparable to other premium cars.

There is another advantage of an all-electric car: maintenance costs. An all-electric car should be cheaper to maintain than a gasoline-powered car—just think of all the things that can go wrong with an engine vs. an electric motor.