Often presented as the ideal energy source, hydrogen does have many arguments in its favour. But it is important not to misinterpret its possibilities bearing in mind the current realities of the sector. It will take time for it to deliver on its promises.
While it may be seen as a futuristic solution, hydrogen has a long history. The method by which this fuel can be used in combustion engines was first tested in the 19th century. However, what we mean by “hydrogen-powered vehicle” these days is an electric vehicle whose battery is recharged by a “fuel cell” using hydrogen gas. Within the fuel cell the hydrogen stored in tanks reacts with oxygen in the air: this reaction produces electricity and the only byproduct produced in the system is water.
For drivers of this kind of vehicle, filling up with hydrogen gas is faster than recharging the batteries. When comparing equal masses, hydrogen offers a greater range than lithium-ion batteries. For automakers, fuel cells offer a chance to reduce their dependence on producers of battery cells in Asia. Hydrogen clearly has many arguments in its favour as the future of clean mobility.
Green Hydrogen – The Ideal Energy Source
Though it is abundant throughout the universe, hydrogen is not found on Earth in its isolated state. It is necessary to break apart molecules to extract it, requiring an industrial process. While a fuel cell combines hydrogen and oxygen to produce water and electricity, it is also possible to obtain hydrogen and oxygen by submerging electrodes in water. If this electrolysis is performed using renewable energy, the resulting gas is called green hydrogen. This is the foundation for a clean sector. On 8 July 2020, the European Commission presented its strategy for hydrogen production with no negative climate impact. There is a future for green hydrogen.
Transformation Needed in the Hydrogen Sector
Today 95% of industrial hydrogen production* worldwide is powered by fossil fuels. While cost-effective, this process produces an incredible amount of CO2. The resulting gas is known as grey hydrogen. Envisioned as an electricity storage method, green hydrogen is positioned as the intermediary in the power-to-H2-to-power chain. The yield is between 20 and 30%. That means four times as much electricity is used for the initial electrolysis as is available for use from the fuel cell. This could be a non-issue if a world with superabundant electricity – the dream of the ITER project (International Thermonuclear Experimental Reactor) – eventually becomes a reality.
Still to Come: Safety and Profitability
Another significant challenge is that all the elements needed for a fuel-cell vehicle and the green hydrogen sector are currently extremely expensive. Scaling up their production would reduce the cost per unit. Then there is the need to seal off the hydrogen circuits. This is a gas that explodes when its concentration in the air is between 4 and 77%, so any leaks could pose a safety risk.
Unlike methane, it is not possible to odorize hydrogen, as a fuel cell requires the gas to be extremely pure. Thus, any leaks would have to be detected by sensors. Hydrogen-based mobility will also require the creation of a network of refuelling stations. All these challenges can be overcome, given the requisite time and resources. For all these reasons, however, hydrogen-powered heavy goods vehicles are not likely to take to the roads in large numbers before 2030.
* Source IFP Energies Nouvelles