Ultimate Benefits of PHEVs Will Depend on Fuel Economy of Vehicles They Replace

calcar PHEV

Image courtesy of Mike Weston via flickr

Will PHEVs provide the hoped-for benefits that many have ascribed to them? Well, yes, a new study published in ES&T; has found - though the ultimate energy savings and emissions reductions will depend on the fuel economy of the cars they replace.

According to the authors, the U.S.'s spare nighttime electricity capacity could power a large fleet of PHEVs; since they require about 10 hours of nightly charging, Joe Sullivan of the Argonne National Laboratory, one of the authors, nighttime electricity could allow PHEVs to replace up to 34% of today's light-duty fleet - and only consume 13% of the fuel used nationally for electricity generation in the process.Michael Kintner-Meyer of the Pacific Northwest National Laboratory - in a separate study - found that 43% of the fleet could be replaced by PHEVs with existing nighttime capacity. A big advantage of nighttime charging would be that it would help make electricity cheaper by allowing power plants to operate at full capacity, significantly driving down maintenance costs.

Sullivan and his co-author, Craig Stephan of the University of Michigan Transportation Research Institute, also found that PHEVs consumed 25% less energy than hybrids and that they reduced carbon emissions by 25% in the short term. In the future, assuming more PHEVs are introduced into the fleet, they could help slash emissions by up to 50%. What remains unclear is whether - as PHEVs begin to replace today's fleet - the U.S. will obtain greater emissions reductions by replacing the fleet with PHEVs or by replacing inefficient coal-fired power plants with cleaner, more efficient ones.

"If you're replacing poor fuel-economy conventional vehicles, then you're better off supplying electricity for plug-in hybrids. If, on the other hand, people are going to be buying high-fuel-economy conventional hybrids instead, then it would tip the other way," says Stephan.

Via ::ES&T;: Promises of plug-in hybrids (news website)

See also: ::Report: U.S. Power Grid Can Fuel 180 Million Electric Cars, ::The Anatomy of the Plug-In Hybrid—Part 1: What the Heck is it?, ::Toyota Unveils Plug-in Prius