CalCars Weighs In on GM Series/Toyota Parallel PHEV Debate

[OKIsItJustMe]

http://www.greencarcongress.com/2008/03/calcars-weighs.html#more

CalCars Weighs In on GM Series/Toyota Parallel PHEV Debate

7 March 2008

Guest piece by Ron Gremban, CalCars

GM and Toyota have been taking public shots at each other, each claiming that their plug-in hybrid (PHEV) technology—not yet brought to market—is the best, and implying that the other's plans are poorly thought out, to say the least.

We at CalCars, if anything, are thrilled to see the two biggest automakers in the world touting their upcoming PHEV wares and paying significant attention to each other's. But what is the science behind the dispute? What follows is a discussion that is aimed at engineers, but we think will be quite informative also to non-technical audiences. Thanks to Dr. Andy Frank of UC Davis and Efficient Drivetrains Inc. for his helpful review and comments.

A preview of my conclusion: It turns out that different battery sizes have different optimum PHEV architectures, and each company’s claims are basically accurate, but only for its vehicle’s battery size. Since each type of PHEV has its own advantages, disadvantages, costs, and optimum driving regimes, our expectation is that during the first few years—maybe a decade—of PHEV production, all types of PHEVs will compete well in the marketplace.

Then, eventually—as batteries become a cheaper, longer-life, commodity item, liquid fuels become more dear, renewable electricity generation proliferates, and CO₂ emissions are increasingly targeted—the PHEVs with the most EV power and range will come to dominate.

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