To Plug In—or Not

Having seen John Voelcker’s article “Plugging Away in a Prius” [May], I thought you might be interested in my particular Prius project, which is essentially the opposite of the one in the article.

I have created what he might call the “Plug-Out Prius” and what I call the “PriUPS” project, UPS being “uninterruptible power supply.” I take advantage of a standard Prius (the only modification is a $10 connector) to supply several kilowatts to power my house in the event of a power failure. In effect, it is a “free” generator that is always ready in emergencies.

I think your readers will find it interesting, because many already own or are considering the purchase of a hybrid, and it’s a low-cost mod, unlike the lithium-ion battery pack. If widely adopted, this setup has a number of advantages beyond simply providing emergency power for the individual owner. The project is detailed on my Web site: www.PriUPS.com.

Richard Factor, Kinnelon, N.J.

The author responds: I’ve followed the notion of V2H (vehicle-to-house) emergency power since I first heard it mentioned a couple of years ago. We don’t presently have any plans to cover it, but if further developments warrant, we may well do so in the future.

Incidentally, you may be aware that the now-discontinued (and not very popular) first hybrid version of the Chevy Silverado pickup offered this same capacity, via several 121-volt ac outlets. With its engine running, it was said to provide household emergency power for 32 hours on a full tank of gas. We covered this vehicle in “Top 10 Tech Cars” in the March 2004 issue of IEEE Spectrum.

I hope this plug-in mania will be limited to the technocracy and not spread to the general public, but I fear that since Detroit is making noises along this line, it may very well spread. It is, I admit, one of the solutions to our addiction to oil, but not an optimal one, in my opinion.

Has anyone asked the custodians of our national power grid if they can supply enough kilowatt-hours to charge a vast army of plug-in hybrids? Every summer, for instance, Los Angeles faces brownouts from the use of air-conditioning. What will happen when 3 million hybrids plug in at the same time?

The other aspect is that this approach is merely transferring the automotive pollution to a fixed source: the generating plants, many of which in this country still use coal. Most folks will not invest in a solar-panel array, as Jon Sawyer did [see “Plugging Away in a Prius”], because of the huge investment required and the long payback.

There are no easy answers. I had hoped you would have shed some light on the downside of plug-in hybrids in your article. But it’s good to have you on board, reporting on automotive technology. There are many exciting things happening these days.

Ed Jacklitch, IEEE Life Senior Member, San Jose, Calif.

The author responds: You have touched on issues that are much debated in advanced auto technology circles these days, both the increase in demand for electric utilities and the carbon-dioxide and greenhouse-gas impacts of electrically driven vehicles.

First, it’s worth noting that in the first year of plug-in hybrid electric vehicle (PHEV) production (2010 or 2011), the U.S. Department of Energy’s Energy Information Administration forecasts new (nonautomotive) demand in the United States at 65 000 gigawatt-hours—which is enough electricity to charge about 25 million PHEVs. The first year of Chevrolet Volt production, if projections by GM’s Bob Lutz are accurate at 60 000 vehicles, would be 0.2 percent of this new load.

Hence, if this poses a problem, it is one that will grow slowly and predictably. It’s also worth pointing out that every four or five plasma TVs impose the same grid load as one PHEV, and plasma TVs haven’t raised huge concerns as yet. I’m told that utilities are growing more sophisticated in predicting customer load, with some even modeling customer adoption of new technologies into the future to predict capacity needs.

As for “wells to wheels” greenhouse-gas impacts, a number of studies have attempted to quantify this issue. In particular, I would point you to one jointly issued last year by the Electric Power Research Institute (EPRI) and the Natural Resources Defense Council (NRDC).

The EPRI-NRDC study actually contains two parts, one for greenhouse-gas emissions and one for criteria pollutants (nitrogen oxide, carbon monoxide, hydrocarbon). This work is considered to be the most rigorous, because it looks not only at the current power grid but also what the grid mix is likely to be in the future. This is crucial, since it will probably be 10 to 15 years before sizable volumes of PHEVs are found on North American roads.

The EPRI-NRDC study carefully accounts for many factors, including losses in fuel production, generation, transmission, and distribution. Electricity is produced from diverse sources: coal, nuclear, natural gas, and renewables. Looking at the likely scenarios under which electricity is produced and delivered—now and in the future—the study concludes that greenhouse-gas emissions from PHEVs are lower than those from current hybrids and significantly lower than those from conventional vehicles. Variables in the scenarios include the time of day when charging is done (most utilities are expected to provide sizable incentives for nighttime or off-peak charging), the rollout pace that will lead to noticeable numbers of PHEVs on the roads, and of course, the evolving mix of generating plants and fuel types.

A second study was done by Oak Ridge National Laboratory, in Tennessee, on the impact of PHEV charging on generating capacity: “Potential Impacts of Plug-in Hybrid Electric Vehicles on Regional Power Generation” [PDF]. This model appears to have two flaws. Unlike the EPRI-NRDC study, it posits a huge penetration of vehicles that charge at 6 kilowatts entirely between 5 and 8 p.m. Furthermore, its grid capacity expansion for normal load (not PHEV load) is based on the Energy Information Administration’s Annual Energy Outlook projections. Those include large numbers of new coal-fired plants, which most analysts feel is a very unlikely scenario, due to high construction costs, local resistance, and most of all, uncertainty over future carbon constraints.

Finally, a third study was done by Pacific Northwest National Laboratories [PDF]. It concludes that plug-in hybrids can reduce overall greenhouse-gas emissions, with some regional variations. Regrettably, there wasn’t room in the article to go into the detail I have provided above, although perhaps that might be a suitable topic for a future piece in IEEE Spectrum.