Electrically connecting a vehicle along the roadway while it is moving is a cost-effective pathway to vehicle electrification, according to a new study by NREL. The study also found that PHEVs could become cost-effective if their battery cost goes down to $300/kWh or if their battery life improves by a factor of 10.

Titled “Technology Improvement Pathways to Cost-effective Vehicle Electrification”, the US National Renewable Energy Laboratory (NREL) study evaluates a variety of scenarios aimed at making electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) cost-effective.

The study conclusions are based on a comparison between conventional vehicles on the one hand and the following vehicle electrification scenarios on the other: sizing the battery to last for the life of the vehicle; assuming that the battery will be replaced during the life of the vehicle; assuming that the vehicle will be able to recharge after every trip rather than just at the end of the day (opportunity charging); assuming both battery replacement and opportunity charging; assessing the case of a vehicle that plugs-in dynamically, connecting electrically along the roadway while moving.

Cost-effective electrification pathways

The study indentified the following cost-effective pathways to vehicle electrification:

• Dynamic plug-in: The case of a vehicle that plugs-in dynamically, connecting electrically along the roadway while moving, similar to the way trolley buses or streetcars currently do, reduced total cost to the consumer and fuel use. The authors found that on the consumer side, this solution would be cost-effective even when assuming an extra $1,000 cost for the connection mechanism to be borne by the car owner. “The cost is low because it gains the low cost electric mode operation similar to a battery PHEV without the cost, wear, efficiency losses, and weight of a large battery”, reads the study. According to the authors, this case may warrant further investigation.

• Reduced battery costs make PHEVs competitive to today’s vehicles: If the battery energy cost comes down from $700/kWh to around the DOE (Department of Energy) target of $300/kWh, PHEVs get closer to breaking even with today's vehicles.

• 10-fold improvement of battery life makes PHEVs cost-effective: A third pathway to cost-effective vehicle electrification is to improve battery life. In this case, PHEVs become cost-effective by improving their battery life by a factor of 10.

Other findings of the study

The paper found that increasing the battery power resulted in extra battery costs in PHEVs and EVs that outweighs the gasoline cost savings. Moreover, battery replacement was found to have minor overall improvements in cost-effectiveness, as resulting advantages such as reduced upfront cost and weight of vehicles was balanced out by increased battery wear.

The possibility of opportunity charging was found to have different implications on PHEVs and EVs. It decreased the gasoline consumption, and thus gasoline cost of PHEVs, but at a greater increase in battery cost, since it lead to an increase in the use of the battery. On the other hand, opportunity charging decreased the cost of EVs, as it reduced the depth of discharges and the amount of battery wear, thus reducing the amount that the battery has to be oversized to last the required life.