FRANCESCO RODELLA | Tungsteno
Cleaner air and less noise in our cities; water vapor coming out of exhaust pipes instead of harmful gases; electric propulsion of vehicle engines instead of combustion. Will this recurring dream of our society, which requires the transport sector less CO2 emissions, come true one day? In this long transition that has already begun, to the alternative of electric battery cars is added that of vehicles powered by fuel cells (hydrogen), newly arrived at the competition in the car market for individuals. We review the strengths and weaknesses of each technology.
First of all, it should be pointed out that not just battery-powered cars, but also hydrogen cars, are electric vehicles, clarifies Carlos Merino from the National Hydrogen Centre. In the first type, "the energy is stored in the [lithium] battery, which directly feeds the engine," he explains. In the second case, "what we have is a tank with hydrogen at very high pressure. That hydrogen reaches the fuel cell, which together with the air in the atmosphere produces electricity through an electrochemical reaction." The electricity generated is used to power an engine that functions in the same way in both types of vehicles.
Shorter refuelling times and the non-dependence of the lithium battery, favor the hydrogen-powered vehicle. Credit: Wikimedia Commons.
Two views of the electric car with much in common
José María López, director of the University Institute for Automotive Research (INSIA), adds that in the fuel cell model, batteries are also usually integrated to cover the power peaks, a type of "hybrid" configuration. Both technologies are already commercially available.
The advantages of electric vehicles can be varied. One is the reduction of the carbon footprint compared to conventional means of transport, as noted in a recent report by the former Minister of Industry (2008-2011) and current professor Miguel Sebastián. This characteristic, he says, occurs when the electricity used to power them is produced from a mix that includes renewables. Another benefit, adds Sebastián, is that "the electric vehicle is, from a technical point of view, more efficient per km travelled." And we must not forget the economic advantages, he says. In this sense, electrification makes it possible to reduce the energy dependence on other countries, according to the former minister.
In Spain, with at least 30 models for sale, the battery-powered electric car market is more mature than the hydrogen fuel cell market, also favored, in the case of large cities, by a diversified offer of this type of vehicles for car sharing. On the other hand, among hydrogen fuel cell vehicles, only the Hyundai Nexo is currently available for purchase in this country.
Both fall into the category of zero emissions vehicles according to the criteria established by the Directorate General of Traffic (note: this is different from talking about carbon neutrality, since, in order to do so, one must also take into account the emissions generated in the production of the energy necessary for them to run and in the manufacturing process). But this is not the only point in common: both are silent and require little maintenance, says López.
Electric car: the leader in energy efficiency
One of the best features of battery-electric vehicles is their "very high performance" (i.e. output energy relative to input energy), says López. This performance can be as high as 80-85%, which means that "right now there is no other technology in vehicle propulsion that surpasses it," he adds. In the case of hydrogen vehicles, this feature is less impressive for now, but it has room for growth, adds the expert.
In terms of disadvantages, the need for sufficient lithium to support the increased demand for batteries for electric vehicles powered by them could become a problem, as it is a limited element located in specific areas, says López. In addition, it must be taken into account that to guarantee autonomy, it is necessary to increase the weight of the vehicle, which can represent an obstacle. What’s more, the amount of time required to recharge the batteries is still too long to make long-distance trips convenient.
The small number of hydrogen generators available becomes a limit for the extension of hydrogen electric vehicles. Credit: Joseph Brent.
Hydrogen: a faster and cleaner refuelling
Hydrogen, on the other hand, guarantees refuelling times "similar to those of a traditional fuel," which are around five minutes, as well as a range that can already exceed 600 kilometres, according to Merino. Another particularly interesting aspect, in his opinion, is that in this case the necessary fuel, i.e. hydrogen, can be produced without the need to import it from abroad and can be generated from clean sources.
However, both he and Lopez agree that the lack of infrastructure for recharging fuel cells is a fundamental limit at this time, at least in Spain, where the number of hydrogen generators available can be counted on the fingers of both hands. We must also remember an important aspect affecting both technologies: the cost, which can be significant. This is especially true for hydrogen cars, as shown by the current value of the Hyundai Nexo, available starting from 72,000 euros according to the Korean brand's website.
Rivals or complementary
Will one ever take the lead over the other? Currently, the presence of more developed infrastructure makes the take-off of the battery-powered electric car more attainable, says the director of the INSIA, although he qualifies this by noting that many brands are already betting "clearly" on hydrogen. Merino, on the other hand, points out that there are places, such as California or Japan, where there is already a more developed infrastructure for refuelling with this element, which also facilitates vehicle sales, and he anticipates that both technologies "will share the market, especially in the light vehicle and passenger car sector."
Both experts agree that it is in the extra-urban mobility of heavy vehicles (such as trucks or long-distance buses) where hydrogen technology can possibly have the advantage over battery technology because of its better range and faster refuelling. However, this will depend on political decisions that will determine the way forward. Looking ahead, there are still many questions to be answered, but we have been given a glimpse of the future of low or zero emission mobility.
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Tungsteno is a journalism laboratory to scan the essence of innovation. Devised by Materia Publicaciones Científicas for Sacyr’s blog.