EDF Climate 411 Blog - July 30, 2007
Plug-In Cars: The Lowdown

This is Part 1 of a three-part series on Vehicle Fuels and Technology.

1. Plug-in Cars: The Lowdown
2. Hydrogen Fuel Cell Vehicles
3. Fossil Fuels and Biofuels

Plug-in Hybrid Electric Vehicles, or PHEVs, have been in the news a lot lately. It's an appealing idea - virtually no emissions, just plug in your car at night and go. Plus the batteries that drive them could store electricity for homes and offices. When cars are parked and plugged in, the electric utility could draw on stored battery power during times of peak demand (with compensation to the car owner).

But will plug-in cars really be ready for widespread use by 2010?

Toyota Prius Plug-in
Toyota Prius, plug-in version.

Reading the news, you might think that PHEVs are just around the corner. Toyota just displayed a plug-in version of its Prius. A recent study by the Electric Power Research Institute (EPRI) and the Natural Resource Defense Council (NRDC) says that if plug-in cars are in widespread use from 2010 to 2050, the reduction in greenhouse gas emissions could be dramatic.

Certainly people are trying to make it happen, spurred by inventor/advocates such as Felix Kramer of CalCars.org and others. The Austin City Council has launched a $1 million campaign to promote plug-ins. Google's philanthropic arm is donating $10 million towards the development of the technology. General Motors made a splash with its Chevy Volt concept in January. Ford has joined the party with a plug-in prototype of its Edge SUV.

Chevy Volt
Chevy Volt.

But as our automotive expert John DeCicco points out, there are some daunting technical issues. In a briefing [PDF] before the U.S. Senate, Advanced Automotive Batteries president Menahem Anderman estimated that plug-ins won't be generally available for another 10 years. Honda manager John German, also in Senate testimony [PDF], said that the problems with plug-ins were so difficult that Honda wasn't even going to try.

So what's going on? Are plug-ins around the corner, 10 years away, or not realistic at all?

The bugaboo is the battery. Here's a summary of the problems, based on Anderman's analysis:

  1. The plug-in battery will be about 3 to 5 times the size of today's non-plug-in hybrid batteries, essentially filling the cargo space of an average sedan.
  2. The weight of this battery will add 200 to 300 lbs. to that of the car, putting a drag on performance and efficiency.
  3. The lithium batteries needed to provide adequate performance for plug-ins raise a serious concern about hazardous failure, such as a fire in a home garage, because they need much deeper, full charging than the smaller batteries of today's hybrids, which are always kept at an intermediate state of charge.
  4. The cost of this plug-in battery (at pack level) to carmakers, using present technology, will be 3 to 5 times the average cost of today's hybrid batteries, i.e. around $5,000 to $7,000 per pack.
  5. The life of any battery technology, lithium or otherwise, when used in a plug-in car is not known. There's a good chance that battery life will be short, meaning costly replacements over the life of a vehicle.

Ford Edge
Ford Edge.

John German points to market problems, as well. He says that unless battery prices drop considerably, the vehicles will be too expensive for broad acceptance. So Honda has instead chosen to focus on hydrogen fuel cell technology (the subject of Part 2 in this series).

German closes his statement with some good advice about how the government can help:

It is impossible to predict the pace of technology development and when breakthroughs will or will not occur. Accordingly, technology-specific mandates cannot get us where we need to go. In fact, previous attempts to mandate specific technologies have a poor track record, such as the attempts in the 1990s to promote methanol and the California electric vehicle mandate. The primary effect of technology-specific mandates is to divert precious resources from other development programs that likely are more promising. If there are to be mandates, they should be stated in terms of performance requirements, with incentives and supported by research and development.

So will plug-in hybrids eventually become mainstream? Possibly, but only with sufficient investment in the development of battery technology. Since we can't know for sure which technologies will work out, it's best to push ahead on all fronts - including making better use of the technologies already at hand - and not put all our eggs in the plug-in basket.

The author of today's post, Sheryl Canter, is an Online Writer and Editor Manager at Environmental Defense.

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