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Hydrogen car: work, problems, advantages

A hydrogen car is a type of car that uses fuel cells to power its engine. These cars have been in development for many years, and the first commercially available models began to appear in 2014. Hydrogen cars offer many advantages over traditional gasoline vehicles, including lower emissions, increased durability and greater autonomy . However, there are also some significant challenges to overcome before these vehicles become mainstream. In this article, we’ll take a closer look at how hydrogen cars work and explore the pros and cons of this emerging technology.

Hydrogen is not renewable, it must be produced

On Earth, hydrogen is not available in natural form. Therefore, this gas cannot be considered a renewable source, at least in its primary form. Rather, it is an energy carrier. Today it is produced by gasification of coal and chemical treatment of hydrocarbons, both unsustainable practices given the large amount of carbon dioxide released into the atmosphere (or by steam reforming of natural gas) a process that consists of the reaction of methane and water steam at a temperature between 700 and 1100°C to produce synthetic gas, a mixture of carbon monoxide and hydrogen, or even through two environmental systems.

In the first case, algae are used in special bioreactors, but also sludge and wastewater. In the second, we rely on the electrolysis of water.

Wind or solar electrolysis is sustainable

During the electrolysis of water, a low-voltage current is passed through the liquid and produces oxygen and hydrogen in gaseous form. In the past, the electricity consumed for this operation cost more than the hydrogen produced; therefore, the energy balance was negative and unsustainable. At least 45 kWh are needed to produce one kilogram of hydrogen, while current technology, aided by the availability of aqueous solutions of renewable alcohols such as ethanol, glycerol and other biomass extracts, pegs the energy requirements at 18.5 kWh. The energy that is increasingly provided by renewable sources (mainly wind and solar) and which in some countries such as Germany is linked to the need to absorb production peaks, optimize the whole system and make hydrogen a source literally “renewable “.

A positive energy balance is possible

The production of hydrogen from renewable sources enables a positive energy balance. This is the point of view of Toyota, for example, the first brand in the world to introduce a standard fuel cell car to the market, which is committed to creating a virtuous supply chain in the Japanese cities of Yokohama and Kawasaki thanks to the Hama Wing high-tech wind farm .

However, to make hydrogen affordable and therefore economically sustainable, further developments are needed. First, the proliferation of refueling points and fleets of cars and buses capable of providing an adequate load for each station. In short, a mode of operation that minimizes financial risks and turns the proliferation of this fuel from a niche technology into a mass solution.

A horizon in which some manufacturers firmly believe, attracted by the goal of producing vehicles with zero emissions (provided that the hydrogen is not extracted, as said, from fossil fuels) and characterized by a generous autonomy, renewable in minutes.

Mirai is filled with hydrogen

A hydrogen car relies on electrochemistry

Hydrogen propulsion systems convert the chemical energy of this fuel into mechanical energy in two main ways: by burning it in an internal combustion engine, as is the case with NASA rockets, the agency’s US space shuttle, or by reacting it with oxygen in a fuel cell to produce electricity.

Vehicles that follow the first strategy are called HICEV (Hydrogen Internal Combustion Engine Vehicle), while the second are called FCEV (Fuel Cell Electric Vehicle). The mobility of the future is indeed reserved for the latter, given the lack of emissions and the affordability of the technology needed to achieve remarkable mileage on a single refuel.

Fuel cells produce energy, but also water

Fuel cells, which are the basis of modern hydrogen cars, are electrochemical devices that make it possible to obtain electricity from the combination of hydrogen and oxygen, without any thermal combustion process. The reaction required for this is based on the idea of ​​breaking down hydrogen molecules into positive ions and electrons; the latter, passing through an external circuit, provide an electric current proportional to the rate of chemical reaction, which can be used for any purpose. This reaction produces a waste, water, which can be discarded into nature, as it is completely compatible with the environment and does not change at all.

Hydrogen must be compressed

The technical problems associated with the use of hydrogen for automobiles are essentially related to its low energy density on a volumetric basis (especially compared to hydrocarbons), which requires either particularly high pressure for storage or, alternatively, cryogenic processing. There is currently no alternative in the automotive sector, as both the adoption of large tanks and storage in the form of ammonia, metal hydrides, synthetic hydrocarbons (such as methanol) or carbon and silicon nanotubes are hardly suitable for use in compact cars. Storage pressure therefore plays a central role in the use of hydrogen for propulsion, although it opens the door to issues related not so much to safety as to the suitability and durability of the system, since compressed hydrogen involves energy expenditure.

A hydrogen car shares the advantages of electric cars

A hydrogen car is an electric car, but equipped with fuel cells instead of ordinary batteries. From a driving point of view, nothing changes, as advantages such as instant thrust, linear flow, lack of jolts when taking off and first-class comfort are not in question.

BMW iX5 Hydrogen

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