Wednesday, November 17, 2004
Is there truth in "The Truth About Hybrids"?
Over at The Marginal Revolution, Tyler Cowen wonders if this article is a serious reason to dismiss the potential of hybrids.I don't think so, because the "truths" are more like half-truths. Some examples:
- "Because of the low speeds involved, the city portion of the EPA’s test is accomplished in battery-only mode. As the gasoline engine is off-line for a significant part of the test, the eventual mileage figure is grossly inflated."Mostly true, I suspect. However, a hybrid has far greater potential for minimizing losses from engine throttling and torque converters. A non-hybrid needs the engine to be idling all the time it is powered, and has to accept the friction losses in the torque converter or clutch; the hybrid does not.
- "What’s more, all energy-draining, electrically-powered accessories (including AC) are switched off during both the urban and highway tests."The same is true for tests on non-hybrids. Further, hybrids have the potential to run the accessories when the engine is off. The latest model Prius has electric air conditioning which runs off the traction battery.
- "Few people realize that a hybrid’s power train adds roughly 10% to the weight of a car."The weight of a Prius is over 2760 pounds. The author is asking us to believe that the battery (99 pounds), motor and electronics, minus the weight savings from a smaller engine, still amount to more than 250 pounds. I don't. Besides, weight is only marginally relevant to efficiency when regenerative braking enters the picture.
- "Even fewer realize that manufacturers try to offset the weight penalty-- and add to the hybrid’s headline-grabbing mileage figures-- by the extensive use of non-hybrid gas-saving technology."Apparently the author, despite his claimed 30 years of experience in Detroit, does not realize that the same features are coming to conventional vehicles for the same reasons. 42-volt electrical systems, integrated starter-generators and electric AC will be standard equipment.
- "Gas - electric hybrid engines use several large batteries. Creating these power cells requires a couple of hundred pounds of heavy metals-- not to mention the copper used in the large electric drive motors and the heavy wires they require."Where to begin, where to begin...
- Where Mr. Elton would put "a couple hundred pounds of heavy metals" in a 99-pound battery is a very interesting question. If the hybrid powertrains incorporate negative matter, it is a much bigger advance than mere fuel savings!
- Did I miss news of a copper shortage? If push comes to shove, the major conductors from the battery to the engine compartment could easily be changed to aluminum.
Where these objections do not contradict published fact, they are risible.
- "Disposing of the batteries when they outlive their usefulness also raises environmental challenges."Every standard automobile has a lead-acid battery under the hood. These batteries are the most consistently recycled articles in the nation. Lead is cheap compared to nickel; is there any reason to believe that a hybrid's NiMH batteries would be thrown away?
- "And then there are the safety problems related to the gas - electric hybrid engine’s high voltages and amperages. While Federal Motor Vehicle Safety Standards (FMVSS) regulate a passenger vehicle’s basic crash protection, there are no federally mandated procedures remain for the protection of rescue workers at the site of an accident involving a hybrid-powered vehicle."One hopes that a battery firmly mounted behind the passenger seats and cabling routed through the floor pan, combined with fusible links and other standard safety measures, are sufficient to keep rescue workers from making dangerous mistakes. In the case of the Prius, the battery is cut off when the air bag deploys.
