Does the future belong to plug-in hybrids?

It was in 1997 that Toyota launched the first hybrid car for the general public. That is, a Prius, which combined electric propulsion, for short distances, and a combustion engine, a solution considered the most effective to reduce greenhouse gas emissions from light vehicles.

It is true that, on paper, a “hybrid” offers two major advantages: it reduces pollution by reserving the combustion engine for high-speed running intervals, and it recovers some of the energy in the deceleration phase, such as 100% electric cars.

At the time, Toyota was a pioneer. It was only at the beginning of the millennium, in a context of the fight against air pollution and greenhouse gas emissions, that other manufacturers began their turn. But shyly, the ads are all about electric vehicles, which look promising for a bright future.

This was before, in early July 2018, the Environment and Energy Management Agency (Ademe) stepped on the plate. In collaboration with the French Petroleum-New Energy Institute (Ifpen), it publishes a report called simply Economic, Energy and Environmental Study for French Road Transport Technologies (E4T): an analysis of the main trends in the vehicle electrification, its efficiency and its ability to reduce the environmental impacts of transport.

Its first conclusion is not surprising: in 2030, thermal power “will face strong competition from electrified technologies.” Yes, but experts also point out that by 2030, the rechargeable hybrid – that is, with power supply – could provide a “more relevant solution” than the all-electric car to reduce CO2 emissions.

>> Read also: Electric, autonomous, connected … what will your car be like in 10 years?

Hybrids have an “ecological debt”

Because the big handicap of the electric car lies in the very energy-intensive manufacture of its battery: a step that alone represents up to 40% of the total greenhouse gas emissions of the vehicle throughout its useful life!

In fact, in order to have a fair assessment of the environmental impact of a vehicle, it is necessary to take into account the emissions it produces when driving, but also those that were emitted during its production! That is, during the use phase, each electric car has to repay an initial “green debt”: in France, a fully electric city car like the old Renault Zoé version has to travel more than 50,000 km before it is more climate-friendly that a thermal car of comparable size …

However, other impacts must also be added to this CO2 meter, linked to the use of rare metals: the extraction and transformation of lithium and cobalt used in the battery, or rare earths in the engine and electronics, have the price of high environmental pollution in producing countries.

And here’s the great advantage of the rechargeable hybrid: it has a much smaller battery and therefore comes out with a lower ecological debt. To the point of turning it into the new panacea? Not yet.

Because this technology has three limits that must be overcome by 2030. Complex, it remains a prerogative of sedans or SUVs: large vehicles highlighted by the abyss that separates their sobriety shown and their actual consumption. But new, more virtuous models could change the situation, such as the BMW i3 REx or the Toyota Prius Plug-in, which won five stars in the eco-test conducted by the powerful German Motorists Association (Adac).

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Good reflections to acquire in drivers

Second limit: the behavior of drivers. Because the environmental behavior of this type of vehicle is closely linked to its actual use. However, the right reflections are not yet there: a study conducted between 2012 and 2016 among owners of plug-in hybrid vehicles showed that they are only used in electric mode for 30% of the time normally expected, users forgetting refill the drums! This increases fuel consumption by the same amount, as the internal combustion engine runs even on short journeys.

Finally, the last limitation: due to its complexity, the rechargeable hybrid is an expensive technology. Therefore, its adoption will be conditioned by a significant drop in prices in 2030 (a Prius costs about € 40,000, or € 6,000 more than a non-rechargeable model). Otherwise, this technology could be duplicated on your right by another, much more affordable: the mild hybrid or microhybrid.

These booming vehicles are based on the addition of a small 48 V battery that allows significant fuel savings when accelerating in the city. However, their environmental history is still much lower than that of their cousins.

By advancing the rechargeable hybrid as a transition solution for 2030, Ademe is actually pointing out the danger of the current all-electric race, which leads to weighing the ecological weight of the battery. Let’s face it: to double the range of its new Zoe (from 200 to 400 km), Renault has almost doubled the capacity of its battery (from 23 to 41 kWh), increasing the ecological impact of its construction …

Hence this observation: if 100% electric cars seem virtuous for daily commuting, in terms of longer distances, it is the hybrid that would make the transition possible, until the most efficient solutions (hydrogen or biofuels of second generation) are maturing.

Therefore, environmental balance invites plug-in hybrids to take over. It remains to be seen whether, in practice, industrial logic and public policy will go in this direction.

>> Read also: Electric car: is it true that a battery needs 225 tons of raw materials?

According to Science & Life Questions & Answers n ° 34

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