Electric car versus hydrogen car: which is more ecological?

Theoretically, the electric car and the hydrogen carThese are two zero technologies carbon : the electric motor drives the car while thehydrogen reacts with oxygen to generateenergy and water in a Fuel cell. Each technology has its advantages and disadvantages: on the one hand, the electric car is easier to maintain and presents less risk of storage, on the other, hydrogen allows a greater autonomy and recharges faster. But what about on an ecological level? Are electric cars and hydrogen cars really that clean?

According to the Canadian Hydrogen and Fuel Cell Association, the carbon footprint overall hydrogen car would be much better, with a carbon footprint of 2.7 kg of CO₂ per kilometer, against 20.9 kg of CO₂ per km with the electric car. One of the arguments put forward by the association is the weight of the batteries: the battery of a Tesla 3 weighs 480 kg, against 88 kg for the tank of a Toyota Mirai running on hydrogen. The hydrogen car also requires less infrastructure (charging stations).

Energy efficiency: advantage over electric

But for Tom baxter, professor of chemical engineering at the University of Aberdeen, this assessment is biased because the association compares hydrogen produced with renewable sources such as wind power to an electric vehicle powered by energy produced by sources fossils. The researcher therefore calculated the energy efficiency of each technology, and the advantage clearly appears in favor of the electric car.

” Take 100 watts of electricity produced by a renewable source such as wind turbine. To power a vehicle with a fuel cell, this energy must be converted into hydrogen [par exemple par électrolyse, ndlr] “. About a quarter of the electricity is lost during this step. The hydrogen produced must then be compressed, refrigerated and transported to the hydrogen station. We lose 10% of energy again. Once inside the vehicle, the hydrogen is converted into electricity, and another 40% of energy is lost. Finally, 5% of energy is lost when electricity is used in the engine to move the vehicle. ” In the end, only 38 watts of the starting 100 watts are used », Concludes the researcher.

In comparison, with the electric car, about 5 watts are lost during transport in the network, 10 watts when charging and discharging the battery, and 5 watts when moving the vehicle. The overall yield is therefore 80%. An analysis of the firm Horváth & Partners cited by Volkswagen arrives at roughly the same conclusions, with an energy efficiency of between 25 and 35% for the hydrogen car against 70 to 80% with the electric car.

Global carbon footprint: advantage of hydrogen

When we take into account the entire life cycle of the car (manufacture, use, recycling and end of life), the Deloitte firm calculate that the carbon footprint of the electric car is 130 to 230 g of CO₂ per km, against 160 to 250 g for the electric car, and 180 to 270 g for a combustion (gasoline or diesel). A difference mainly due to the production of batteries, the extraction of lithium and of metals rare being particularly greedy in energy. But again, it all depends on how the electricity is produced: Deloitte relies on the energy mix current, which still relies mainly on fossil fuels (62% in 2019). When electricity is produced with wind, solar or nuclear power, the results are much more favorable for the electric car.

Cost and infrastructure: advantage over electricity

The argumentecology is not the only advantage of the electric car. The latter would also be much more economical, with a cost price of 2 to 7 euros for 100 km, against 9 to 12 euros for 100 km for the hydrogen car. Likewise, the electric car would be much less expensive to maintain. In addition, the installation of electric charging stations is less expensive than deploying a network of hydrogen stations.

According to Dietmar Voggenreiter, head of the Horváth & Partners study, hydrogen will only be interesting in vehicles requiring a very long range, such as trucks and buses, because the weight of the electric battery then becomes prohibitive.