A new study by a team of researchers from Carnegie Mellon University and Ford’s Research and Advanced Engineering unit addresses the optimal powertrain mix for the US parc of mid-size light passenger vehicles to reduce greenhouse gas emissions at an affordable cost while maintaining current driving patterns, with and without workplace charging infrastructure.
Optimal design and allocation of electrified vehicles and dedicated charging infrastructure for minimum life cycle greenhouse gas emissions and costs published in Energy Policy’s 51st edition of December 2012.
The abstract of the study says electrified vehicles can reduce greenhouse gas (GHG) emissions by shifting energy demand from gasoline to electricity, but confirms, as have other studies, that GHG reduction potential depends on various parameters, including in this case vehicle design, adoption, driving and charging patterns, charging infrastructure, and electricity generation mix.
The researchers constructed an optimisation model to study these factors by determining the optimal design of conventional vehicles, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs) with optimal allocation of vehicle designs and dedicated workplace charging infrastructure in the fleet for minimum life cycle cost or GHG emissions over a range of scenarios.
They focused on vehicles with similar body size and acceleration to a Toyota Prius under US government 5-cycle driving conditions, and found that under the current US grid mix, PHEVs offer only small GHG emissions reductions compared to HEVs, and workplace charging is insignificant.
“With grid decarbonisation,” they conclude, however, “PHEVs and BEVs offer substantial GHG emissions reductions, and workplace charging provides additional benefits. HEVs are optimal or near-optimal for minimum cost in most scenarios. High gas prices and low vehicle and battery costs are the major drivers for PHEVs and BEVs to enter and dominate the cost-optimal fleet. Carbon prices have little effect. Cost and range restrictions limit penetration of BEVs.”
