After I turned on my solar panel system and discovered that it does, indeed, provide significant power even in the tail end of winter, I got on a kick of examining various cars driven primarily or entirely by electricity.
This is not, realistically, something I’m going to pursue. I currently drive a 1997 Toyota Supra Turbo, and it would be hard to give that up. Not that I drive much anymore, I currently put 1400-1800 miles a year on my car, which is why it only has 81,000 miles on it after 17 years.
Still, the idea of driving something that theoretically was powered by my roof, not a limited supply of fossil fuel, rather tickles my imagination. That’s probably theoretical, since my projected annual solar production is supposed to be a bit less than my current house consumption, even if it’s well outpaced consumption so far. In reality, I’d almost certainly still be paying utility rates to run an electric car, not getting the power for free from my roof.
This is even more true of most people and their 10-15k a year drives. I consumed 9,200 kWh last year. Transport with the most efficient electric cars today would add another ~400 kWh for me, and ~4,000 kWh for most people. That energy cost for transport, incidentally, goes up a lot if you figure it for a gas car, to about 16,000 kWh.
One of the interesting things about those figures is that that electric cars are much more energy efficient than gasoline ones, not merely better in terms of emissions and such. The EPA publishes “MPGe” numbers for electric cars and plug-in hybrids running in pure electric mode, and those generally run from 90-110 MPGe. That’s based on the energy content of a gallon of gas, which is 33.7 kWh.
Why is this? It’s not weight or aerodynamics, an Accord Plug-In gets 115 MPGe vs. 29 for the gasoline version, which is 500 pounds lighter. It’s waste heat. An internal combustion engine is essentially a device for turning heat from burning gasoline into kinetic energy, and a lot of that energy goes into waste heat, which is why cooling systems are so critical.
Of course, the same is true for a big power plant. Typically about 67% of the energy of a power plant goes into waste heat. There are some natural gas combined cycle plants than cut that to about 55%, but 67% is more typical. I’ll ignore transmissions losses because they’re quite small, and we’re not counting distribution cost of fuel against cars either. Taking that into account, the Accord Plug-In’s efficiency on electricity is about 38 MPG. Combined efficiency when running on gas is about 46 MPG, higher than my estimate of the real fuel efficiency in electric mode.
On the other hand, even if running on electricity may not be as efficient overall as burning gasoline locally, electricity allows for non-gasoline power sources. Like my roof. That does mean either an electric or “plug in” hybrid, rather than just a hybrid. The “plug in” moniker meaning that the car has a large enough battery to operate in all-electric mode. Usually not far, often 20 miles or less, but regular hybrids with their much smaller batteries can’t do that at all.
The next question is, would you want to drive the car? I’ve long associated electric or hybrid with tiny, underpowered cars, but that’s no longer the case.
There’s the Chevy Volt. My knee-jerk reaction to the Chevy brand is “no,” based on repair records and relatively crappy ergonomics of Chevy rentals I’ve driven. It’s an interesting car, though, since it’s really a pure electric car with a built-in gas generator to recharge the battery, unlike most hybrids where the gasoline engine drives the wheels directly. 149 HP isn’t exciting, the electric range is 38 miles, 98 MPGe on electricity, 37 MPG on gas. The cheapest of the larger electrics at $28k after tax credit.
I mentioned the Honda Accord Plug-In, which is fairly similar to the regular Accord. 195 HP, electric range of 20 miles, 115 MPGe on electricity, 46 MPG on gas. About $37k after tax credit. If I weren’t already spoiled by my Supra, I’d seriously consider a plug-in Accord.
There’s the Tesla S, which is a prime example of what electric cars can be. It’s a luxury sedan like the Accord. The least-expensive P60 has 300 HP, range of 240 miles, and 89 MPGe. The big issue of course is that electricity is the only option, so range critical where it isn’t with hybrids. Tesla’s putting up Supercharger stations around the country that will rapidly charge your vehicle for free, though you have to pay extra for access to the Supercharger network if you’re buying a P60 instead of a P85. It’s possible at present to cross the country or go up or down either coast via the network, but there are still lots of areas that are out of reach. Including the the Supercharger access, which I see as required, and including the tax credit, a P60 is about $66k.
Personally, I wouldn’t touch a Tesla S. I kept running into reports of serious ongoing kinks. For example, people at Edmund’s have been driving an S for a while, and Tesla has had to replace the battery once and the powertrain twice in the first 20,000 miles. That, and Tesla requires that you sign up for $600 / year maintenance, or they void the warranty. That’s nontrivial. Still, it’s a clear example of what’s possible.
Porsche has a plug-in hybrid sedan as well. I know “Porsche sedan” is weird, but it’s meant to compete with the BMW luxury cars, and incidentally the Tesla S P85. 400+ HP (!) which as you might expect is mostly a powerful gasoline engine. Efficiency is underwhelming at about 46 MPGe on electricity, 15 mile range on electricity, and only ~26 MPG on gas. Still, I’m sure this car would give me an experience like my Supra… for $95k or so, depending on options and accounting for the tax credit.