As far as automobiles are concerned, electric power is undoubtedly the future. The source and repository of said electric power for the future has the house divided. While battery-powered electric vehicles (BEVs) have managed to gain considerable momentum in most parts of the world, it’s hydrogen fuel cell electrics (FCEVs) that, at least on paper, appear to be the most sustainable form of mobility. So just what are the critical differences between battery electrics (powered using lithium-ion batteries) and hydrogen electrics (powered utilising a fuel cell)?
How it works
FCEVs are not to be confused with hydrogen combustion cars, which use hydrogen as propulsion agents. With an FCEV and a BEV, the source of power continues to be electricity. However, an FCEV produces electricity on the run through the chemical reaction between hydrogen and oxygen, using a fuel cell.
Hydrogen is stored on-board much like petrol is stored in an internal combustion car, and the fuel cell sends the electricity generated through the chemical reaction to the electric motor(s) in the vehicle. With BEVs, electricity is stored in a lithium-ion battery, much like any consumer electronic device, and transferred directly to one or multiple electric motors that propel the vehicle.
Range and efficiency
As things stand, the advantage lies with hydrogen-powered EVs. Hydrogen provides hundreds of times as much energy per kilogram, which gives a vehicle a much longer range without making it considerably heavier – a crucial impediment for BEVs, which cannot extend their range without adding to the vehicle’s weight.
Simply put, li-ion batteries aren’t as power dense as a tank full of hydrogen. An incremental change in the size of a hydrogen tank can add to the range considerably. In comparison, an increase in the size of a li-ion battery proves to be a self-defeating concept as the extended range must also cater to the added weight, reducing overall efficiency.
With solid-state batteries on their way, BEVs are looking at a range of roughly 1000km – a game-changer when you consider that there’s no breakthrough on the horizon for FCEVs. Not only can solid-state batteries hold more charge, but they also take about half as long as a current-generation li-ion battery to be fully charged.
While this is longer than the refueling time for an FCEV, the added range spotlight li-ion batteries. But the consensus is that FCEVs are better for long-distance journeys, while BEVs are preferable for shorter runs. At present, the average FCEV can outrun the average BEV by about 160km before running out of juice.
Although the overall range of a BEV and an FCEV may be relatively comparable, it’s the refuelling time where FCEVs edge ahead. Filling up a tank with hydrogen takes as much time as filling it up with petrol, thereby saving precious minutes, which can be subtracted from the overall duration of your journey.
While fast charging a Tesla Model S can give you 80% power in half an hour, a regular AC charger takes up to 5 hours to fully charge an EV. Considering that a li-ion battery can only take a limited number of fast charging cycles, and hydrogen comes out as the winner in terms of sheer practicality.
Its power density and refueling times are two main reasons hydrogen revolutionizes the commercial vehicle industry. Long-haul transport trucks cannot have heavy batteries as it will force them to reduce their cargo weight. A smaller battery would reduce the range considerably and add to the overall time required to deliver cargo.
In terms of durability, BEVs are at a disadvantage. While most BEV manufacturers offer up to 8 years or 160000km of warranty on their lithium-ion batteries, the batteries themselves can only take a limited amount of charging cycles before they start to lose their ability to retain electric charge despite being protected by thermal management systems and battery buffers (which prevent the battery from being fully charged or depleted, thereby extending its lifespan).
At the end of its life cycle, a lithium-ion battery offers considerably less range, and while it is replaceable, it is always an expensive proposition. Far more costly than replacing a fuel cell.
On the other hand, a fuel cell has an estimated life span of 5000 hours, or 240000km, giving it the upper hand. However, research has proven that short-distance driving puts severe stress on a fuel cell’s membrane, which reduces its lifespan.
Continuous driving, wherein a fuel cell isn’t wetted and dried constantly, would allow a fuel cell to last almost eight times as long as it does on average. Therefore it’s far more suited to long-distance journeys where it isn’t required to make frequent pit stops.
After a century of using inflammable fluid as fuel, it’s a wonder why we look at hydrogen as a dangerous form of propulsion. Hydrogen cars like the Toyota Mirai, the Honda FCX Clarity, and the Hyundai Nexo have been deemed perfectly safe to drive and have recorded no significant incidents. The same cannot be said for BEVs over the years.
However, the storage and transportation of hydrogen and the refueling process pose certain risks, according to a journal published by the International Journal of Hydrogen Energy. Refueling stations can use renewable sources to produce hydrogen on-site to counter the additional costs and threats inherent in transporting hydrogen.
In reality, the dangers of hydrogen-powered cars remain primarily theoretical. Hydrogen has been transported for industrial use for decades, and there have been no notable incidents with the major FCEVs on the road. However, since compressed hydrogen poses a greater risk than a lithium-ion battery, a BEV is a comparatively safer option.
This point goes to FCEVs. Hydrogen cars filter air as they drive, leaving clear air in their slipstream. With excellent production of green hydrogen (that is, hydrogen produced using renewable energy sources) for commercial and passenger vehicles, FCEVs are the more sustainable EVs. Unlike BEVs, they don’t leave heaps and heaps of (partially recyclable) battery waste.
India isn’t the only country with an underdeveloped hydrogen infrastructure. In fact, except for Japan and Germany, most countries are yet to build a good network of hydrogen stations.
According to a research journal “Compendium of Hydrogen Energy”, published by J. Wind, “About 200 hydrogen refuelling stations have been installed worldwide; around 85 of these are located in Europe and approximately 80 in the US (mainly California)”.
This is a direct consequence of very few passenger cars FCEVs are being manufactured (Toyota, Honda, and Hyundai are the only key players). Even fewer infrastructure companies worldwide are willing to invest in the transport and the setting-up of hydrogen refueling stations. It’s a chicken-and-egg problem that can be solved partially through government policy.
At the moment, India has no FCEVs on sale and, consequently, no hydrogen refueling stations. If a brand were to introduce FCEVs in the market, there would be few to no takers, given the glaring infrastructural shortcomings.
With the government’s proposed “National Hydrogen Mission” and Reliance announcing the construction of two gigafactories dedicated to renewable hydrogen, it’s clear that India wants to be a global hub for manufacturing and exporting green hydrogen.
However, it is premature to speculate whether that green hydrogen will be channeled to develop its hydrogen refueling infrastructure.
India also plans to produce lithium-ion cells independently, without relying on imports – a move that will make EVs considerably cheaper and easier to adopt.
Brands like Tata Chemicals, Exide Industries, and TDSG are emerging as India’s biggest suppliers of lithium-ion batteries, and battery tech is projected to get much cheaper in the coming years.
At present, BEVs have gained a lot more momentum than FCEVS. All car manufacturers aim to go completely electric by 2030-2035, but few have talked about taking the hydrogen route.
However, several prominent players like Toyota, VW, GM, Hyundai, and Honda aren’t ruling out hydrogen as the future fuel. They will continue to develop FCEV technology parallelly, albeit in a smaller capacity, until FCEVs gain greater acceptance and renewable hydrogen becomes cheaper to produce.