Petrol, electric and hydrogen: all-round pollution | FormulaPassion.it

When alternative vehicles are discussed in conversations between enthusiasts, whether they are electric, hybrid, hydrogen or biofuel-powered, the importance of assessing greenhouse gas emissions throughout the life cycle is often stressed. In fact, the data relating to emissions often refer only to the use of the car, neglecting processes such as energy supply, the production of the car and its subsequent disposal. At the end of 2022 ADAC, the German automobile club and the largest in Europe, published the results of the studies carried out to estimate the overall emissions of the various technologies offered by the market, using the LCA. This is the tool Life Cycle Assessment, software developed by the Joanneum research center in Graz on commission from the FIA ​​with the support of the German, Swiss and Austrian automobile clubs. The LCA is available to the public to carry out comparative analyzes also in different temporal contexts, in detail in 2022, 2030 and 2050, and has also been used by ADAC to conduct its investigation.

When it comes to environmental impact, it is appropriate to distinguish between different aspects, such as pollutants harmful to human health or agents that contribute to global warming. The results of the ADAC survey were expressed in terms of grams of CO₂ equivalent, weighing the impact of the three main substances responsible for the greenhouse effect: carbon dioxide, methane (generated for example from gaseous fuels) ed nitric oxide (deriving among others from biomass crops and combustion engines). The study considers a wide variety of propulsion technologies:
–heat engine diesel, petrol and natural gas (methane)
–plug-in hybridwith an electric journey equal to 30% of the total, taking into consideration both a recharge with current produced with the current German energy mix and with entirely renewable sources such as wind power
–battery electricalso in this case both with recharging from the German energy mix and with 100% renewable sources
–hydrogen fuel celldistinguishing between production via reforming and distillation powered by renewable electricity
–fully sustainable e-fuel diesel fuel, whose carbon content is derived from carbon capturing or from the cultivation of biomass and with hydrogen produced through wind energy.

All estimates were conducted on vehicles of similar size, performance and weight, outlining what has been defined as the “Golf class”. The values ​​have been calculated over a sixteen-year life cycle, with an estimated mileage of 15,000 kilometers per year. As far as electric vehicles are concerned, a 55 kWh battery was taken as a reference, the life of which, as stated in the ADAC press release, based on recent experiences was set equal to that of the vehicle, without taking into consideration any replacement.

As can be seen from the table, the final result is the result of various polluting contributions: production of vehicle, battery, fuel cells and hydrogen tanks; maintenance; use of the vehicle; energy supply and consumption; end of life. For electric cars, the production of the vehicle alone (excluding the powertrain) is similar in emissions to other technologies, but the battery alone is responsible for an impact almost 40 times greater than that of a vehicle powered by a combustion engine. Overall, the production of the entire vehicle results in 35.5 g/km of CO₂ equivalent for the petrol car, 53.7 g/km for the hydrogen one and 58 g/km for the battery one. However, the disadvantage for the electric one is more than compensated by the lower polluting emissions associated with the energy needed to use the car, which remains the main contribution to total emissions. ADAC estimates that an electric car charged with the current energy mix equals the calculation of emissions with the diesel/petrol counterpart between 45,000 and 60,000 kmwhich could drop to 25-30,000 km in the case of electricity produced entirely from renewable sources.

Among the other items in the table, it is appropriate to focus on the end of life, to which negative values ​​are assigned. It is a form of compensation, associated with the fact that for materials such as steel, aluminum and copper it is estimated a 60% recycling, thus avoiding the extraction of new raw materials and saving further emissions. ADAC also estimates that 3% of electric vehicle batteries are reused, while 97% are recycled for other applications.

The survey also distinguishes between emissions associated with energy supplyi.e. the extraction and transport of fuel or the production of electricity and hydrogen, and those emitted by the vehicle while driving. Consumption on board is obviously nil for battery and fuel-cell vehicles, while it is more than halved for the plug-in hybrid compared to the petrol counterpart. On the other hand, a more thorny issue is that linked to the impact of energy supply, strongly influenced by the use or otherwise of renewable sources. For example, the current German energy mix for car charging is responsible for around 482 g/km of CO₂ equivalent, which, however, is estimated to drop to 32 g/km in 2050. For energy supply alone, the production of hydrogen through reforming is the technology with the greatest impact, followed in order by electric and hybrid recharged with the energy mix current.

Then there is the particular case of biomethane, the supply of which is marked by a negative value. The carbon dioxide released during combustion is in fact partly compensated by that taken from the atmosphere during its production, whether through carbon capturing or the planting of new plants.
However, overall pollution also depends on the vehicle’s “thirst” for energy. As it transpires from another table contained in the ADAC report, battery-electric is the most energy-efficient form of transport, thanks to the excellent efficiency of the powertrain with a consumption of around 0.5 kWh/km. Then follow in order the hydrogen fuel cell and the plug-in hybrid, while the diesel e-fuel turns out to be slightly more efficient than traditional diesel.

Overall, the ADAC report shows that at present no technology, even if supported by entirely renewable sources, still has zero impact. Electric powered by renewable sources proves to be the best option on the table, with an overall slightly lower impact than sustainable hydrogen. The class is placed third in order of emissions the class of e-fuels, however considerably better than the hybrid, battery or fuel-cell powertrains supported by the current energy mix. As far as hydrogen is concerned, in fact, according to the latest report by the International Energy Agency, 99% of global production in 2022 is associated with non-renewable sources. On the other hand, on the subject of electricity, it should also be considered that Europe still has a particularly virtuous energy mix compared to the rest of the world, for which more in-depth analyzes would be needed. Also for this reason ADAC emphasizes the invitation to pursue the objective of technological neutrality, emphasizing how sustainable mobility cannot be the prerogative of a single technology.