Clean power for electric cars?
Regarding the May 5 editorial, "A yellow light for electric cars": I was surprised to read the questions raised by this editorial regarding plug-in hybrid electric vehicles (PHEVs). Specifically, whether electric utilities will be able to build enough power to charge the vehicles and whether the environmental benefits of PHEVs will be negated when the vehicles are charged from electricity generated from fossil fuels?
The Electric Power Research Institute (EPRI) and the Natural Resources Defense Council (NRDC) answered these and other important questions regarding widespread deployment of PHEVs in a landmark analysis published in July 2007. That study, the most comprehensive analysis on the subject to date, models the penetration of new vehicles (allowing new vehicle technologies to enter the market and replace older vehicles over time) in parallel with the continuous evolution of new, cleaner generation in the electric sector.
In the nominal – yet aggressive – scenario, the additional electricity demand attributable to the vehicles is 8 percent, requiring a capacity expansion of 3 percent. Why is there such a large discrepancy in these results with those cited in the Britain? The British study assumed that all 27 million petroleum-drive vehicles in the country would immediately be transformed into full-electric vehicles with half of them charging simultaneously overnight.
By contrast, in the nominal scenario of the EPRI-NRDC study, PHEVs account for 62 percent of the vehicle fleet by 2050, and are assumed to charge primarily but not exclusively at night at a lower rate than assumed in the British study. To place the British results in context, if we could have 10 million PHEVs materialize overnight in the US today, electricity demand would increase by less than 1 percent.
The environmental benefits of PHEVs are similarly impressive. Even when charging solely from older, coal-fired power plants, the CO2 footprint of a mile driven by electric power is 30 percent less than a conventional gasoline vehicle. Of course, electricity used to charge PHEVs will come from a variety of generation technologies – including coal, natural gas, nuclear and renewable sources – and these technologies are improving in their environmental performance and efficiency over time.
As a result, the EPRI-NRDC study found that in 2050 PHEVs will lead to a net decrease in CO2 emissions greater than 450 million metric tons, equivalent to avoiding the carbon emissions from more than 80 million vehicles on the road today. In addition, petroleum use in the US would decline by nearly 4 million barrels per day.
There will be no overnight transformation to electric drive. However, it is clear that the road ahead for PHEVs has a "green" light.
Eladio M. Knipping, Ph.D.
Senior technical manager,
Electric Power Research Institute (EPRI)
There is a lot of confusion about "green" energy options. Some say biofuels (such as ethanol) and batteries can reduce carbon dioxide (CO2) emission, and some say biofuels and batteries will either have no effect or increase CO2 emission.
You have to look at the big picture to make sense of these seemingly conflicting stories. Biofuels, batteries, and hydrogen fuel cells do not reduce (or at least, not significantly) CO2 emissions if they are not part of a bigger energy change. Any of those three technologies can dramatically reduce CO2 emission as part of a general energy overhaul. To reduce CO2 emission in transportation, we must dramatically reduce the use of fossil fuel for electric power generation. All three techniques currently require electric power, so for green transportation you must have green electric power generation. For biofuels, it would be best to also use biofuels in the farming industry. For hydrogen fuel cells, substantial research needs to be performed in hydrogen production without fossil fuels (among other issues).
Batteries and biofuels are poised to make a significant impact on CO2 emission. If we want to reduce CO2 emission, we must take a two-pronged approach: greener electric power generation and greener transportation fuel.
Oak Ridge, Tenn.
The tone of this editorial suggests those hopeful for a shift from dependence on fossil fuels for transportation lack a corresponding hope that utilities will move toward more sustainable sources of solar, wind, geothermal, and biomass.
I think that these people recognize the need for point-of-use power generation from sustainable sources. Governments won't need to "force" plug-in vehicle owners to recharge during lower use times; lower-cost night rates and time-of-use metering will provide all the incentive those concerned about the environment and the costs of transportation need.
This won't happen overnight, but through a thoughtful, long-term view of the changes needed to encourage conservation, they will lessen dependence on fossil fuels, and recognize that "clean coal" is not the answer to our energy needs.
Bruce A. Johnson
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