Mouse over the image to see the key components of a plug-in hybrid electric vehicle (PHEV). Graphic courtesy of the National Renewable Energy Laboratory, U.S. DOE
Plug-in hybrid electric vehicles (PHEVs) offer a choice of fuels. PHEVs have both an internal combustion engine and electric motor. These vehicles are powered by an alternative fuel or a conventional fuel, such as gasoline (petrol), and a battery, which is charged up with electricity by plugging into an electrical outlet or charging station.
The amount of electricity a PHEV can store in its battery can significantly reduce the vehicle’s petroleum consumption under typical driving conditions.
Different Kinds of PHEVs
There are two basic PHEV configurations:
Series PHEVs, also called Extended Range Electric Vehicles. Only the electric motor turns the wheels; the gasoline engine only generates electricity. Series PHEVs can run solely on electricity until the battery needs recharging. The gasoline engine will then generate the electricity needed to power the electric motor. For shorter trips, these vehicles might use no gasoline at all.
Parallel or Blended PHEVs. Both the engine and electric motor are mechanically connected to the wheels, and both propel the vehicle under most driving conditions. Electric-only operation usually occurs only at low speeds.
PHEVs also have varied battery capacities, allowing some to travel farther on electricity than others. PHEV fuel economy, like that of electric vehicles and regular hybrids, can be sensitive to driving style, driving conditions, and accessory use.
Benefits and Challenges
Less Petroleum Use. PHEVs are expected to use about 40 to 60 percent less petroleum than conventional vehicles. Because electricity is produced primarily from domestic resources, PHEVs reduce petroleum dependence.
Less Greenhouse Gas (GHG) Emissions. PHEVs are expected to emit less GHG emissions than conventional vehicles, but the amount generated partly depends on the fuel used at the power plants that generate the electricity used to recharge the car’s battery. A PHEV will lead to less GHGs if its electricity comes from nuclear and hydroelectric plants rather than coal-fired power plants. Electricity powered by renewable energy sources such as solar or wind is optimal.
Higher Vehicle Costs, Lower Fuel Costs. PHEVs will likely cost $1,000 to $7,000 (USD) more than comparable non-plug-in hybrids. Fueling a PHEV will cost less because the cost of electricity is much lower than the cost of gasoline per mile, but fuel savings will not entirely offset the increased vehicle cost. Many governments provide incentives to consumers for qualifying PHEVs.
Charging Takes Time. Charging the battery typically takes several hours, but a "quick charge" to 80% capacity may take as little as 30 minutes. However, PHEVs can be driven without being plugged in. They can be fueled solely with gasoline but will not achieve maximum range or fuel economy without charging.
Measuring Fuel Economy. This will be a challenge because PHEVs run on both electricity and liquid fuel, and it is unclear what percentage of time each will be used during the average driver's daily travel.
IA-HEV Work on PHEVs
Task 15, Plug-in Hybrid Electric Vehicles (PHEVs) encourages the development and commercialization of PHEVs. Task 18, EV Ecosystems is developing an international roadmap to establish a blueprint for infrastructure for plug-in electric vehicles in EV cities of the future. Finally, Task 20, Quick Charging is addressing the technologies available, issues surrounding deployment of quick-charging infrastructure, and establishment of standards for quick charging of plug-in electric vehicles, which includes PHEVs.