Plug-in hybrid
A plug-in hybrid electric vehicle (PHEV) or simply plug-in hybrid is a type of hybrid electric vehicle equipped with a rechargeable battery pack that can be directly replenished via a charging cable plugged into an external electric power source, in addition to charging internally by its on-board internal combustion engine-powered generator. While PHEVs are predominantly passenger cars, there are also plug-in hybrid variants of sports cars, commercial vehicles, vans, utility trucks, buses, trains, motorcycles, mopeds, military vehicles and boats.[6]
This article is about hybrid vehicles whose battery may be externally charged. For vehicles that are propelled only by electric motors, using energy stored in rechargeable batteries, see battery electric vehicle. For the more general category of vehicles with plug-in rechargeable capabilities, see plug-in electric vehicle.
Similar to battery electric vehicles (BEVs), plug-in hybrids can use centralized generators of renewable energy (e.g. solar, wind or hydroelectric) to be largely emission-free, or a fossil plant in which case they displace greenhouse gas emissions from the car tailpipe exhaust to the power station. As opposed to conventional hybrid electric vehicles (HEVs), PHEVs generally have a larger battery pack that can be recharged (theoretically) from anywhere with access to the electrical grid, offering enhanced energy efficiency and cost-effectiveness when compared to relying solely on the on-board generator. Additionally, PHEVs can support longer and more frequent all-electric range driving, and their electric motors often have higher power output and torque, are more responsive in acceleration, and overall have lower operating costs. Although a PHEV's battery pack is smaller than that of all-electric vehicles of the same weight, as it must accommodate its combustion engine and hybrid drivetrain, it provides the added flexibility of reverting to the use of its gasoline/diesel engine, akin to a conventional HEV if the battery charge is depleted. This feature helps alleviate range anxiety, particularly in areas lacking sufficient charging infrastructure.
Mass-produced PHEVs have been available to the public in China and the United States since 2010,[7][8][9] with the introduction of the Chevrolet Volt, which was the best selling PHEV until it was surpassed by the Mitsubishi Outlander PHEV at the Volt's end of production in 2019.[10] By 2021, BYD Auto emerged as the largest plug-in hybrid vehicle manufacturer in the world, with cumulative sales over 3.3 million units as of December 2023. The BYD Song DM line of SUVs contributed over 1.05 million units.[11][12][13][2][14][15]
As of December 2019, the global stock of PHEVs totalled 2.4 million units, representing one-third of the stock of plug-in electric passenger cars on the world's roads.[16] As of December 2019, China had the world's largest stock of PHEVs with 767,900 units, followed by the United States with 567,740, and the United Kingdom with 159,910.[16]
Terminology[edit]
A plug-in hybrid's all-electric range is designated by PHEV-[miles] or PHEV[kilometers]km in which the number represents the distance the vehicle can travel on battery power alone. For example, a PHEV-20 can travel 32 km (20 miles) without using its combustion engine, so it may also be designated as a PHEV32km.[17]
For these cars to be battery operated, they go through charging processes that use different currents. These currents are known as Alternating Current (AC) used for on board chargers and Direct Current (DC) used for external charging.[18]
Other popular terms sometimes used for plug-in hybrids are "grid-connected hybrids", "Gas-Optional Hybrid Electric Vehicle" (GO-HEV) or simply "gas-optional hybrids".[19][20][21] GM calls its Chevrolet Volt series plug-in hybrid an "Extended-Range Electric Vehicle".[22][23]
Life cycle energy and emissions assessments[edit]
Argonne[edit]
In 2009, researchers at Argonne National Laboratory adapted their GREET model to conduct a full well-to-wheels (WTW) analysis of energy use and greenhouse gas (GHG) emissions of plug-in hybrid electric vehicles for several scenarios, considering different on-board fuels and different sources of electricity generation for recharging the vehicle batteries. Three US regions were selected for the analysis, California, New York, and Illinois, as these regions include major metropolitan areas with significant variations in their energy generation mixes. The full cycle analysis results were also reported for the US generation mix and renewable electricity to examine cases of average and clean mixes, respectively[178] This 2009 study showed a wide spread of petroleum use and GHG emissions among the different fuel production technologies and grid generation mixes. The following table summarizes the main results:[178]