Hydrogen or electric cars? It’s time to clarify

The different terms: electric vehicle, hydrogen fuel cell vehicle and hydrogen vehicles with a battery

These days, when we talk about a hydrogen fuel cell vehicle, we mean a form of electric car. This type of vehicle, commonly known as an FCEV (fuel cell electric vehicle), uses hydrogen to power a 100% electric motor. The solution explored by Renault Group incorporate both a hydrogen tank with a fuel cell and a battery that can be charged on the electric grid. In everyday speech, “electric car” is often used to refer to a vehicle that is powered by a battery alone, and “hydrogen car” for a vehicle with an onboard hydrogen tank as well as a battery. 

The principles and advantages of hydrogen fuel cell cars

A hydrogen fuel cell electric vehicle uses dihydrogen (H2) as fuel. The fuel cell is supplied with this hydrogen, and oxygen from the surrounding air. These gases, upon contact inside the fuel cell, provoke an electrochemical reaction which produces an electric current, heat and water vapor. This electric current is then used to power an electric motor which then propels the vehicle. 

This technology contains numerous intrinsic advantages. Firstly, the vehicle’s exhaust only emits water vapor. Hydrogen-powered vehicles are classified as low-emission cars, as they do not emit any air pollutants or carbon dioxide (CO₂) while driving*. In addition, an electric motor combined with a fuel cell is particularly efficient, resulting in much lower energy consumption than a combustion-powered car. What’s more, filling up the tank with hydrogen only takes three to five minutes — in other words, no more than topping up a combustion-powered version — for several hundred kilometers of range. Another advantage is the nature of the electric motor: its excellent torque offers the driver dynamic and responsive road handling 

In the solutions tested by Renault Group, hydrogen power does not replace the battery, but rather complements it. The Renault Emblème concept car has a dual-energy electric motor powered by a rechargeable battery, sufficient for everyday use, and a hydrogen fuel cell for long journeys. This configuration allows the car to travel up to 1,000 km without recharging, with just two hydrogen refills of less than five minutes each. 

The principles and advantages of 100% electric cars 

In a 100% electric vehicle, electric energy is not produced by a fuel cell, but stored in a battery after charging from an electricity supply, whether this be a public charging station or a plug socket at a private location. The electric motor receives this stored current and uses it to propel the vehicle. As a complement, the electric motor also receives current recovered using its reversal properties, where every deceleration or application of the brakes generates energy that is then transformed into electricity. 

A 100% electric car emits zero exhaust gas: it is carbon-free when being driven and gives off no air pollutants. The efficiency of an electric motor is also three to four times superior to that of an equivalent combustion engine, offering controlled consumption and considerable power. Lastly, these cars have the advantage of being able to access a growing variety of charging infrastructures, whether on the highway, in the city or at home (with the installation of a wall charging station, for example.) 

Hydrogen: a safe technology

The need to keep hydrogen under high pressure requires vehicles to be equipped with advanced safety devices. These are equipped with very high quality materials to ensure the gas circulates safely. Emergency dihydrogen purge circuits as well as protective components prevent shocks or potential leaks from causing accidents. The vehicles under consideration at Renault Group would, for example, feature a system that dilutes and disperses hydrogen in under a minute — an additional safety guarantee for these models classified “zero risk” according to the European regulation (CE) n° 79/2009. You can feel just as confident as in a combustion-powered, hybrid or battery electric vehicle. 

The maturity of the electric car

The technologies used in electric cars and hydrogen vehicles are not at the same stage of development. The principle of electric motors for propulsion dates back to the early days of the automobile. Mass production of this type of electric vehicle began in the 1990s. Over time, improvements in charging infrastructure and increasing battery range have led to the rise of electric vehicles. In 2024, they accounted for 13.6% of sales in Europe. However, it was not until the 2010s that ‘hydrogen’ electric cars equipped with fuel cells were designed.  Today, Renault Group is exploring hydrogen solutions for racing cars such as Alpenglow, passenger vehicles such as Renault Emblème, and commercial vehicles. 

Electric or hydrogen: what about energy storage?

Full electric cars run solely on batteries. Electricity is stored directly within the car, inside the traction battery. This type of vehicle is “filled up” through charging, which quite simply uses current from the electrical grid via charging stations that are increasingly common in public spaces, or using plug sockets at private locations such as the home. 

In terms of energy storage, the hydrogen fuel cell electric vehicle behaves according to very different principles. This kind of vehicle runs on hydrogen, not electricity from the grid. Before filling up the tank, the dihydrogen needs to be stored, which is a challenge in itself: the chemical element is very light, with 11m3 required to store one kilo. Engineers have therefore developed different techniques to reduce this volume and to facilitate the transportation and storing of dihydrogen. There are two main methods currently in use: either the tank pressure is increased, which “compresses” the gas in a reduced space, or the hydrogen is liquified in a container at an extremely low temperature, for the same result in terms of space-saving.

Electric or hydrogen: CO2 emissions comparison

In terms of emissions during driving, battery electric cars and hydrogen fuel cell vehicles generate no CO2 emissions from the exhaust. However, a calculation of their overall CO2 emissions should be carried out to include their entire life cycle, in other words from design to recycling, and should also take into consideration the way in which the vehicle’s energy is transformed to power mobility. 

It is therefore the way in which the energy that propels them is produced which largely explains their low carbon footprint. If the electricity grid is powered by low-carbon power stations (nuclear, renewable energies such as wind, hydroelectric or solar), then the life cycle of electric cars will be environmentally sound. This is why the carbon footprint of an electric vehicle is calculated based on the energy mix of the country where it is charged. In many European countries — Germany, for example, where the production of electricity from renewable energy sources is increasing at a steady rate — the electric car will see its carbon footprint decrease as the percentage of these sources in the energy mix increases. Conversely, trips undertaken by the driver of a combustion-powered vehicle will always have the same carbon footprint over time, regardless of geography. 

For hydrogen fuel cell vehicles, electric energy is created without emissions inside the vehicle using its onboard hydrogen. It is the production of hydrogen that can generate CO2 emissions associated with this type of vehicle. Hydrogen is rare in its natural state on earth. Until now, the simplest technique for producing it has been to reform natural gas through chemical transformation in order to extract the dihydrogen molecule. This can result in higher carbon emissions than when producing electricity using renewable energies. 

However, there are ways to produce low-carbon hydrogen, in particular through water electrolysis. This is the principle of batteries…but the other way round. Electrolysis requires electricity to produces dihydrogen molecules. If this electricity is low carbon (from wind power, solar energy etc.), then we refer to it as ‘green hydrogen’, a forward-looking solution to make this mode of propulsion more environmentally friendly! 

Electric or hydrogen? Why not both

While industrial development of the hydrogen car is more recent than that of the battery-powered electric vehicle, the two technologies will be able to offer complementary approaches, meeting different needs. Electric battery power continues to be the best solution for individuals as things stand. At the current time, hydrogen is aimed first and foremost at business fleets or professionals, especially when their premises possess a hydrogen charging station. This means of propulsion also suits drivers with regular routes, like deliveries for example, with access to a suitable refill station. Hydrogen could be suitable for company fleets or professionals, but this would require the development of a refuelling infrastructure.  

The Renault Emblème demo car has a dual-energy electric motor powered by a rechargeable battery, sufficient for everyday use, and a hydrogen fuel cell for long journeys. This configuration allows the vehicle to travel up to 1,000 km without recharging, with just two hydrogen refills of less than five minutes each. It also achieves an unprecedented 90% reduction in carbon footprint compared to a 2019 Captur combustion engine vehicle. 

Hydrogen and battery electric technologies complement each other rather than compete, and there is one clear winner: the driver! 

*Neither atmospheric emissions of CO2 nor pollutants while driving (excluding wear parts).

**WLTP range: Worldwide harmonized Light Vehicles Test Procedure. The standard WLTP cycle consists of 57% urban driving, 25% suburban driving and 18% highway driving.

*** source : ACEA