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Scientific American Validates PHEVs w/Romm & Frank Article
Mar 16, 2006 (From the CalCars-News archive)
This posting originally appeared at CalCars-News, our newsletter of breaking CalCars and plug-in hybrid news. View the original posting here.
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Although Scientific American is a consumer publication, its editorial processes are more like those of rigorous professional scientific/academic journals. Anything that goes into this 161-year-old magazine is exhaustively examined and "vetted."

Thus, it's a major signal that hybrid cars have arrived when an article called "Hybrid Vehicles Gain Traction" appears on pages 72-79 of the April 2006 issue (now on new-stands). That's also true for plug-in hybrids when the cover promotes the article with the phrase "Plugged-In Hybrid Cars." This article provides a superb overview of hybrid technology, Then it positions PHEVs as the logical outcome of the evolution of advanced technology vehicles, and explains their benefits. We present a few excerpts below.

The article is written by two leading experts on energy/transportation policy and practice:

  • Josep J. Romm, principal with Capital E­mission, a consulting firm providing "integrated intelligence and strategic investment advice on distributed energy." He's an MIT-trained physicist, former US Energy Dept. Acting Assistant Secretary, and author of "The Hype about Hydrogen: Fact and Fiction in the Race to Save the Climate.
  • Andrew A. Frank, Mechanical and Aeronautical Engineering Professor, University of California at Davis and Director of the Advanced Hybrid Vehicle Research Center , He a University of Southern California-trained engineer, the creator of the first and the most plug-in hybrid prototypes, and a long-time advisor to CalCars.

We encourage you to get the article (with not-to-be-missed graphics) -- for yourself and others. Newsstand price is $4.95. Online, you can register and pay $5 with a credit card to download a PDF of the article (you can also get the cover and table of contents). At, look for the link to the April 2006 issue. Here are some selections:

TITLE: "Hybrid Vehicles Gain Traction" As car buyers turn to fuel-sipping gasoline-electric hybrid vehicles, a new generation of greener hybrids is just coming over the horizon

By then [2010], next generation technology, called plug-in hybrids will offer motorists still better fuel efficiency as well as other perks: low-cost battery recharging overnight by simply connecting a 120-volt plug to an electrical outlet at home or work, very few trips to the gas station each year, and even the chance to sell surplus power back to the electric grid. Beyond the consumer benefits, however, the new plug-ins would help reduce the release of greenhouse gases by displacing emissions from millions of tailpipes to utility power plants. Today these facilities burn domestically supplied coal or natural gas, and in the future they should generate cleaner electricity from energy sources such as wind, solar or even advanced fossil-fuel systems that capture carbon dioxide for underground storage.

Some makers of full hybrids, such as Toyota and Ford, have replaced the standard Otto cycle engine used in most gasoline-powered cars with a more fuel-thrifty configuration based on the Atkinson cycle. A modern Atkinson cycle engine uses electronic controls and intake-valve timing to achieve greater expansion of the fuel/air mixture burning in the cylinder, thereby allowing the power plant to make more efficient use of the fuel. Engineers had only rarely used the Atkinson cycle before because its greater fuel economy comes at the expense of power output; however, in a hybrid, the electric motor can make up for the lost power. In highway driving, the Atkinson engine, combined with the energy savings from braking regeneration, can yield an overall hybrid system efficiency better than that of the modern diesel engine -- the leading internal combustion engine in this regard.

Plug-in hybrid electric vehicles combine the best of electric and hybrid-drive technologies...What is more, these plug-in hybrids should not be much more complex, heavy or pricey than present hybrid models. First, their internal combustion engines will shrink as their electric motors and batteries grow. Second, batteries and electronic components have been steadily dropping in price.

A conventional auto costs about 12 cents a mile to operate at current gasoline prices. A plug-in hybrid could run on electrons at three cents a mile using electricity costing about eight cents a kilowatt-hour, the current average residential rate. And given that half of American cars travel only 25 miles a day or less, a plug-in with a battery capable of providing power for a 20-mile range could cut petroleum-based fuel consumption by as much as 60 percent. Even a long-distance commuter driving a plug-in hybrid could go most of a typical day on less expensive electricity stored in an advanced batter that was topped up overnight via a conventional wall socket and partially recharged at work during the day.

Plug-in hybrids offer other unique benefits....One can speculate that a utility might lease a plug-in hybrid to a consumer or business willing to leave the vehicle connected when it was not on the road and to permit the utility to control when the vehicle's batter was charged and discharged depending on its generation or voltage-regulation needs. Such an arrangement would help utilities with load balancing, for instance.

For policymakers concerned about global warming, plug-in hybrids hold an edge over another highly touted green vehicle technology -- hydrogen cars. Plug-ins would be better at utilizing zero-carbon electricity because the overall hydrogen fueling process is inherently costly and inefficient. Any effective hydrogen economy would require an infrastructure that could use zero-carbon power to electrolyze water into hydrogen, convey this highly diffuse gas long distances, and pump it at high pressure into the car -- all for the purpose of converting the hydrogen back into electricity in a fuel cell to drive an electric motor. The entire process of electrolysis, transportation, pumping and fuel-cell conversion would leave only about 20 to 25 percent of the original zero-carbon electricity to drive the motor. In a plug-in hybrid, the process of electricity transmission, charging an onboard battery would leave 75 to 80 percent of the original electricity to drive the motor. Thus a plug-in should be able to travel three to four times farther on a kilowatt-hour of renewable electricity than a hydrogen fuel cell could.

If current trends in fuel costs and concerns about climate change continue, we expect a broad market transition around the year 20020, when hybrids are likely to become a option for most models. Relatively soon thereafter, we believe plug-in hybrids will probably become the dominant alternative-fuel vehicle, with the speed of that progress determined primarily by oil price rises and government policy on climate change and energy security. Whenever the world's transportation system finally moves to replace oil as its main power source, the most plausible car design would be a flexible-fuel, plug-in hybrid vehicle running on a combination of zero-carbon electricity and a biofuel blend. If the performance of batteries were to improve substantially at some point, drivers might then gradually switch to all-electric cars. It makes senses for us to adopt this highly practical personal transportation technology as expeditiously as possible.

- The Car and Fuel of the Future, Joseph Romm, Report for the Natiional Commission on Energy Policy. Available at:
- Driving the Solution: The Plug-In Hybrid Vehicle. Lucy Sanna in EPRI Journal Fall 2005. Available at or­docs/­CorporateDocuments/­EPRI_Journal/­2005-Fall/­1012885_PHEV.pdf
- To learn more about plug-ins, visit
- To learn more about hybrids, visit
- Andrew A. Frank's technical articles on plug-ins can be found at

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