Study finds benefits of plug-in vehicles depend on battery size

Sep 26, 2011

Thinking about buying a new plug-in vehicle? You may want to check the size of its battery first.

Carnegie Mellon University's Jeremy J. Michalek and co-authors report that plug-in vehicles with small battery packs and hybrid electric vehicles (HEVs) that don't plug in can reduce life cycle impacts from air emissions and enhance oil security at low or no additional cost over a lifetime. But plug-in vehicles with large battery packs are more costly and may have higher or lower emissions than HEVs depending on where and when they are plugged in.

In a study appearing this week in the , Michalek argues that electrified vehicles with smaller battery packs are more efficient in reducing societal costs for health care, environmental damages and .

"Current provides larger subsidies for vehicles with larger battery packs, assuming that larger is better," said Michalek, an associate professor of engineering and public policy and mechanical engineering at CMU. "While larger battery packs allow plug-in vehicles to drive longer distances on electric power instead of gasoline, they are also expensive and heavy, they are underutilized when the battery capacity is larger than needed for a typical trip, they require more charging infrastructure and they produce more emissions during manufacturing."

U.S. policy has been pushing the to investigate alternatives to fossil fuels. The American Recovery and of 2009 provides up to $7,500 in tax credits for up to 200,000 plug-in vehicles.

"Because vehicles with larger battery packs are more expensive, fewer of them can be subsidized, and that can result in lower total benefits," said Michalek, who recently received a $400,000 grant from the National Science Foundation (NSF) to analyze how public policy could help determine the types of vehicles built in coming years and how consumers might respond to these vehicles.

"It's possible that in the future plug-in vehicles with large battery packs might offer the largest benefits at competitive costs if the right factors fall into place, including sufficiently low cost batteries, high gasoline prices, low emission electricity and long battery life," said study co-author Mikhail Chester, assistant professor of sustainable engineering at Arizona State University. "But such a future is not certain, and in the near term, HEVs and plug-in vehicles with small battery packs provide more emissions benefits and oil displacement benefits per dollar spent."

"With increasing energy and environmental constraints, transitioning from conventional gasoline vehicles to hybrid and plug-in vehicles offers an opportunity for improving energy independence and air quality while helping to address global warming," said study co-author Constantine Samaras, an engineer at the RAND Corporation.

Michalek's research is aimed at understanding tradeoffs in the capabilities of new technologies and to predict what near- and long-term strategies should be.

"Given the major spending cuts under debate in Washington, it is important that we get the most benefits out of spending designed to improve the environment and energy security," Michalek said. "In the near term, HEVs and plug-in vehicles with small battery packs offer more cost-effective benefits. More research on batteries — especially lowering cost — and a transition to a cleaner electricity grid are needed to pursue a future where large battery packs may also be able to help address climate change, air pollution and oil dependency at competitive costs."

Explore further: Electromobility, efficient and safe: Visio.M consortium presents new electric car

Related Stories

Kia unveils plug-in hybrid concept car

Feb 10, 2010

Kia Motors America introduced its new Ray plug-in hybrid concept vehicle Wednesday that is designed to travel up to 50 miles on one battery charge.

Study: Are plug-ins the next wave of hybrid vehicles?

Sep 25, 2007

Is America ready for rechargeable cars? Teams of researchers at the University of Michigan and Pacific Northwest National Laboratory will explore this question and others with $2 million from the U.S. Department of Energy's ...

Pulling the plug on hybrid myths

Nov 19, 2009

(PhysOrg.com) -- Whether you call them myths, urban legends, fables or old wives' tales, there's a lot of misinformation out there about plug-in electric hybrid vehicles. These vehicles, abbreviated PHEVs, ...

Best for batteries: Not too hot, not too cold

May 16, 2011

(PhysOrg.com) -- Thermal management is crucial in the development of new car batteries; NREL's Large-Volume Calorimeter helps prepare for a surge in electric vehicles.

Recommended for you

First-of-a-kind supercritical CO2 turbine

9 hours ago

Toshiba Corporation today announced that it will supply a first-of-a-kind supercritical CO2 turbine to a demonstration plant being built in Texas, USA. The plant will be developed by NET Power, LLC, a U.S. venture, together w ...

Drive system saves space and weight in electric cars

Oct 17, 2014

Siemens has developed a solution for integrating an electric car's motor and inverter in a single housing. Until now, the motor and the inverter, which converts the battery's direct current into alternating ...

Dispelling a misconception about Mg-ion batteries

Oct 16, 2014

Lithium (Li)-ion batteries serve us well, powering our laptops, tablets, cell phones and a host of other gadgets and devices. However, for future automotive applications, we will need rechargeable batteries ...

Turning humble seaweed into biofuel

Oct 16, 2014

The sea has long been a source of Norway's riches, whether from cod, farmed salmon or oil. Now one researcher from the Norwegian University of Science and Technology (NTNU) researcher hopes to add seaweed ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

that_guy
5 / 5 (3) Sep 26, 2011
Good research. I'm drawing that this study shows that regular (No plug in) hybrids, or full electrics with only just enough range to get through the day are currently the most effective options for the society at the moment.

I think that implementing their suggestions may have unintentional positive consequences - for example, even though each car will have fewer batteries, by focusing on the low hanging fruit, it will increase the rate of hybrid adoption, and infuse more money and competition available for advanced and cost effective battery solutions - Thus getting us to better long range plug-ins sooner. Win-win.