advantage or obstacle in decarbonizing roads?

This article originally appeared in our newsletter Mobility decipherment of December 17, 2020. To receive the next articles by email as soon as they are published, subscribe now.

At the end of the year, at a time when the car is becoming electric, hybrid vehicles look like a wonderful Christmas present1, right? According to manufacturers and public authorities, they significantly reduce CO2 emissions without compromising our uses: long range, fast recharging (with gasoline or diesel) if necessary. Only, as with many things, the reality is not so simple.

Let’s start with a brief reminder of semantics: there are non-rechargeable hybrid vehicles2 and rechargeable hybrid vehicles (PHV) 3. Non-rechargeable hybrid vehicles are an incremental improvement over conventional internal combustion vehicles with greater electrification, which mainly allows energy recovery, but so far they are supplied exclusively with petroleum-derived fuels. While Plug-in hybrid vehicles have dual thermal and electric motorization, which allows them to circulate in one way or another, depending on the charge of the battery which generally allows a range of about 40-70 km in electric mode. It is, therefore, this second category of vehicles that interests us here. Why don’t plug-in hybrid vehicles deliver the expected CO2 savings? Firstly because approved emissions (via NEDC or WLTP cycles) do not reflect actual emissions at all. According to a recent study by the ICCT & Fraunhofer Institute, actual emissions from a plug-in hybrid vehicle are 2 to 4 times higher than certified. [1] ! Besides, Hybrid vehicles are inherently heavier (and more expensive) than their internal combustion counterparts, because they contain two motors (thermal and electric). However, any additional weight on board involves additional energy consumption and therefore a loss of energy efficiency for equal use. It seems like driving essentially in combustion mode in a plug-in hybrid vehicle results in higher emissions than the equivalent combustion modelas demonstrated by the NGO Transport & Environment (chart below) [2]. It is therefore necessary to favor the lightest possible vehicles, as we explained in a previous article.

Comparison of emissions from unladen hybrid vehicles (PHEV) and their thermal equivalent (ICE) – gCO2 / km

Transport and Environment

Last but not least, the effective electric mileage rate of plug-in hybrid vehicles is actually much lower than their theoretical rate : according to the ICCT, only 37% of the kilometers are done in electric mode compared to 69% according to the NEDC cycle for private cars, and 20% compared to 63% for company cars. This also contributes to emissions being much higher than certified emissions.

Should we throw the plug-in hybrid vehicle in the trash? No, obviously (the trash is too small). They allow it decarbonize certain specific segments for which the electric vehicle is unsuitable, for example for taxis, or people who often make long business trips and short personal trips4. But in the vast majority of cases, the electric vehicle can meet 90-95% of the needs. Therefore, we must accept rethink your relationship with the car and mobility in generalwith a short-range electric vehicle for daily use, and alternative means for exceptional trips such as holiday outings: range extender, train, car rental … hybrid?

————— 1. Mainly for manufacturers who find this a very convenient way to meet their European regulatory obligations (the famous average target of 95 gCO2 / km). 2. MHEV for soft hybrid electric vehicle in English or FHEV for full hybrid electric vehicle. 3. PHEV for plug-in hybrid electric vehicle in English. 4. Keep in mind that a vehicle running on biomethane or carbon-free hydrogen could be an alternative.

Article written by Nicolas Meunier (Consultant)

Sources: [1] ICCT and Fraunhofer Institute [2] Transport and Environment

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