Study Results: PHEV Cars Can Be Expensive and Contribute to Big Pollution If They Rarely Charge

JAKARTA - Plug-in hybrid electric vehicle (PHEV) vehicles are often seen as the most realistic solution among pure gasoline-powered cars and battery-based electric cars. This technology combines an internal combustion engine and an electric motor, so it is claimed to offer better efficiency and more responsive performance than conventional hybrids.

However, these advantages turn out to depend heavily on how the owner uses them. A recent study from China, which will be published in the scientific journal Transport Policy, confirms that if users rarely or even never charge, PHEVs are potentially an inappropriate choice.

Launching from The Drive, Tuesday, January 13, this study surveyed 500 PHEVs used daily in Shanghai by considering various charging methods and habits. Researchers explained how PHEV operation can be simplified into two main modes.

The first is Charge Depleting (CD), which is when the battery is drained due to use and the vehicle makes maximum use of electric power, both in pure electric driving mode and instant torque assistance.

The second is Charge Sustaining (CS), when the battery is weak and the gasoline engine works almost all the time, leaving only a small amount of energy to maintain battery power through the engine supply as well as regenerative braking.

In optimal conditions, PHEVs operate more frequently in CD mode. This does show a significant increase in efficiency compared to regular hybrids, at least in laboratory tests.

However, the study found indications that PHEVs with batteries in a high-charge state are able to produce nitrogen oxide (NOx) emissions 40 to 60 percent lower than gasoline vehicles in urban use cycles. However, the figure in the real world turned out to be smaller, with a decrease of only about 20 percent.

The problem occurs when the battery is depleted and the vehicle enters CS mode, especially when the user rarely charges. In the worst-case scenario, when the owner never charges the PHEV, emissions actually jump sharply.

The study noted an increase in emissions of 62 percent for NOx, 70 percent for hydrocarbons, and 46 percent for carbon dioxide, compared to when the vehicle operates in CD mode. In addition to emissions, the weight factor is also in the spotlight.

When the battery is empty, PHEVs carry a heavy battery pack without a comparable electric power contribution, so the internal combustion engine has to work harder and longer. As an illustration, the gasoline-powered version of the Mitsubishi Outlander weighs around 3,900 pounds, while the plug-in hybrid version reaches 4,600 pounds.

The Kia Niro PHEV is also recorded to be 250 pounds heavier than its conventional hybrid variant. In conclusion, PHEVs still offer advantages, but must be in line with the charging routines of their owners so that the benefits are really felt.

Unlike pure EVs that "force" users to be disciplined in charging because the vehicle will not run without electricity, PHEVs can still be used without charging, but with the consequences of higher operating costs, decreased efficiency, and increased pollution.