Plug-in hybrid vehicles can greatly impact emissions and petroleum dependency
By Margery Conner, Technical Editor -- EDN, August 16, 2007
Gasoline prices have soared, greenhouse-gas emissions are environmental concerns, and particulate emissions continue to have a health impact. It’s clear that, even five years from now, the profile of our almost-exclusively gas-powered-automobile-based transportation system must change. Government regulations and public concern about foreign-oil dependency will demand it. One possible scenario has the US public switching to PHEVs (plug-in hybrid electric vehicles)—cars that rely on a battery with a range of 40 to 70 miles for their usual daily commute, with a small engine that can power the battery for an extended range. But do PHEVs just shift the pollution and fuel used to the nation’s electrical grid?
To answer that question, the EPRI (Electric Power Research Institute) and the NRDC (Natural Resources Defense Council) last month released a study, “Environmental Assessment of Plug-In Hybrid Electric Vehicles”. The study concludes that PHEVs and the grid—both as it exists now and as it evolves by 2050—will work well together, with the adoption of PHEVs reducing US dependence on petroleum by 90% and reducing greenhouse emissions by 80%.
In the question-and-answer session that followed the organizations’ introduction of the study, an audience member raised a question about the viability of PHEVs themselves; many question whether any battery today can meet the safety and durability requirements of combined deep cycling of the battery over lifetime distances of 100,000 miles. Representatives from General Motors and Edison International in attendance said that the history of battery development shows that new battery technologies consistently exceed the industry’s initial expectations. For example, a partnership of Saft and Johnson Controls has demonstrated a battery that withstands the equivalent of seven years of deep cycling with a capacity loss of only 6 to 7%.
