Design News, January 2013

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Silicone Carbide Filled Epoxy Captain Hybrid Could Pure Electrics Emit More Than Hybrids? Researcher says bigger batteries aren't necessarily better. By Charles j. murray, senior Technical editor , electronics &Test michalek says the biggest electric vehicle subsidies are going to the wrong cars. After studying the lifecycle of electrified cars — from the first moment of raw material mining to the final day in the car's life — Michalek and fellow researchers have concluded that hybrids with smaller batteries pollute less than pure EVs. That, of course, flies in the face of everything we now believe. Today, cars with bigger lithium-ion batteries receive three times as much in federal subsidies than hybrids with smaller batteries. Those subsidies, however, are based on the idea that big-battery EVs pollute less, which may not necessarily be so, according to Michalek. "As the battery pack gets larger, the emissions associated with manufacturing can be quite significant," Michalek, an associate professor of mechanical engineering and public policy at Carnegie Mellon University, told Design News. "You have to look at the entire supply chain. Some of the emissions come from the facility where the battery is assembled, but a portion of it is upstream. Some of it comes from the power plants used to create the electricity that runs the equipment." Michalek's conclusions were recently published in an article (http:// in "Issues in Science and Technology," a publication of the National Academies. They were also unveiled in 2011 in a separate study titled, "Valuation of plug-in vehicle lifecycle air emissions and oil displacement benefits" (http:// For both papers, Michalek teamed with jeremy Two Component EP21SC-1 • Exceptional abrasion resistance • Withstands chemical exposure • Paste viscosity • Convenient one to one mix ratio Hackensack, NJ 07601 USA +1.201.343.8983 researchers from Arizona State University and the Rand Corporation. The gist of the studies' conclusions is that there's more to emissions than what comes out of the tailpipe. That's especially so when it comes to vehicles with big lithium-ion batteries. According to the studies, a battery-electric car with a 240 km (144 mile) range is responsible for slightly less than $5,000 worth of "social damages" over its lifetime. The figure is similar for conventional gasburning vehicles. A plug-in hybrid with a 20 km (12 mile) all-electric range, however, comes in at less than $4,000. In arriving at the numbers, researchers considered emissions caused by vehicle operation, as well as by electricity production, gasoline production, battery production, and vehicle production. The bottom line of the study is that smaller battery size is important. Although the studies didn't mention any specific vehicle models, their findings would indicate that a Prius PHV plug-in hybrid with a 4.4 kWh battery would emit less than a Chevy Volt with a 16 kWh battery. Similarly, a Volt would emit less than a pure electric car with a big battery. The irony of all this is that public policy now favors bigger batteries, largely because it's assumed that BEVs pollute less. Subsidies from the federal stimulus package give as much as $7,500 for vehicles with batteries sized at 16 kWh or larger, but $2,500 for smaller, 4 kWh packs. "The larger the pack is, the more public money we're spending on it," Michalek said. "But the truth is, bigger isn't necessarily better." DN Design News | jaNuary 2013 | www.d esign n –22–

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