# How Plug-In Hybrid Cars Could Be Game Changers

Over the last few months I’ve started thinking about buying a new car. My present car is 7 years old and problems are starting to creep up. New noises appear everyday and my dash lights appear to be failing one after the other. After 120,000 miles, I’m beginning to wonder if its time to get rid of the beast.

Considering my field of interest, I’m thinking its time to get a plug-in or an electric car. I’m thinking a new Chevy Volt or a Nissan Leaf will go well with our second car, a Toyota Prius. I would have considered the Tesla Roadster, but the lack of a backseat is a showstopper.  And there is that little problem that it has one extra zero in the price, which I’m told is not a typo!

Considering my 70-mile daily commute and my present car’s 25-mpg gas mileage, the change should give me some green cred.

All the planets appear to be lining up. Cars with my favorite technology are coming to the market. There is (up to) $7,500 tax credit from the Feds and$5,000 more from my home state of California when you buy these cars. You have a chance at getting the coveted carpool stickers (which are priceless!). Finally, we just bought a home, so “plugging in” is not an issue anymore.

The Leaf

Considering the $10,000 price differential between the Leaf and the Volt ($32,000 for the Leaf vs. $42,000 for the Volt, before taxes), I started paying more attention to the Leaf. With the two tax credits, this car was beginning to look like something that was highly affordable. But a quick Google search and 10 minutes later, it was obvious that the Leaf was not going to work for me. When you see reports that you could end up with 47-50 mile range (under certain commute conditions) before you spend the next 8-20 hours charging the battery, you begin to realize that you get what you pay for. With a daily commute of 70 miles in traffic, with some days stretching to 100 miles, I will need to charge at work and, as of today, there appear to be very, very few charging stations available. I heard this week that, apparently, a typical American takes 8 long trips (greater than 100 miles) a year. Our cars need to have the energy to take us on these trips. The Leaf will have difficulty in being anything but a second or third car. Clearly, at least for me, the low range and the long charging time were going to be issues. Moving on… The Volt The Volt gets us away from the issue of range because it is a Plug-in hybrid (PHEV). With the gas engine as a backup waiting for the battery to run out of juice, you can have your cake and eat it too. Be green for the first 35 miles and forget the range anxiety on longer trips. But at$33,000 for the car ($42,000 base plus CA tax minus the tax credits), this is still one expensive car. The EPA tells us that once you run out of juice, the car is rated as at 37 mpg. So my daily commute of 70 miles would consist of the first 35 miles on the battery and the next 35 miles on gas. Without nitpicking, I would use 1 gallon of gas a day. This costs me, as of today,$4.

I also need to charge the battery (12.9 kWh) at 12 cents a kWh, which means I will spend an additional $1.55 for the electricity. Total cost$5.55 per day. Right now I spend $11.20 a day. I will save about$1,400 every year when using the Volt.

My Subaru cost me $21,000 to buy. With this yearly savings I should get cost parity in … around 8-9 years. This does not include any of the time-value-of-money calculations, which would push this out more. I’m sort of throwing numbers here without seriously checking into them, but suffice to say, it’s not an inexpensive car. Beyond Economics But it’s not all about economics, is it? Being green has never been cheap (Although the corollary does not hold. Meaning, if you are cheap, you can actually pass that off as being green!). The first blog post I made on This Week in Batteries concluded that I could not afford the Volt. Gas prices were at$3 at that time. At $4 the Volt still not inexpensive, but it’s getting to the point where one can start to think about this. The future is uncertain (unless you are the Wall street-type and can pretend that drawing a trend line on past data to predict future price is worth$1 million a year in compensation!) and we don’t know where gas prices are headed.  But there are a few things we can conclude.

First, at present-day battery prices and energy densities, EVs don’t make much sense economically.  They are too limiting in range for use as a primary (or even a secondary car). If you get the range up by packing in more batteries it gets more expensive and you lose a bunch of trunk space to fit the batteries. I would say that we need to triple the energy density of batteries and cut the price by a factor of 4 before we can get serious about this (but you can argue with me on this one).

Second, a plug-in hybrid makes a lot of sense, but you will need to pay for the dual power sources. If you can cut the battery costs by a factor of 2 and maintain the tax credits, the concept becomes economical.

I heard that, apparently, gas consumption would reduce by 70-80 percent if we convert all cars to PHEVs. I, for one, would ask if we even need to work on a pure battery electric vehicle. Maybe the focus of all our efforts should be on getting a PHEV on the road at an economical price.

Irrespective of your views of how the world should operate, I think it is important for us to understand whether or not batteries can actually be made any better.  I shall use this as a launching point to talk about a few issues over the next few months including why we all use lithium batteries today, and what I think will happen to battery energy densities over the next few years. I also think its important for us to appreciate what the theoretical limits are in batteries so that we can temper our expectations.

In the meantime, I’m starting to think about test-driving the Volt. But the dealership tells me that I have to put a deposit down to test drive the car. Maybe I’ll pretend to be a journalist working for GigaOm to see if that gets me anywhere!

Venkat Srinivasan is a Staff Scientist at Lawrence Berkeley National Lab and writes about batteries on his site This Week In Batteries.

Image courtesy of Nissan, GM.