Hydrogen car: operation, problems, advantages

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

Hydrogen cannot be regenerated, it must be created

On Earth, hydrogen is not available in its natural form. So this gas cannot be considered a renewable source, at least in its primary form. Instead, it is a carrier of energy. Today it is produced by the gasification of coal and the chemical treatment of hydrocarbons, both unsustainable practices, due to the high amount of carbon dioxide released into the atmosphere (or by steam reforming of natural gas ) is a process that involves reacting methane and water. steam at temperatures between 700 and 1,100°C to produce syngas, a mixture of carbon monoxide and hydrogen, or even, through two environmentally friendly systems.

In the first case, algae, but also sludge and waste, are used in special bioreactors. 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 passes through the fluid and produces oxygen and hydrogen in gaseous form. Previously, the electricity used for this operation was more than the amount of hydrogen produced; the energy balance is therefore negative and unsustainable. It takes at least 45 kWh 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, fixes the energy requirement at 18.5 kWh. The energy that is mainly 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, to optimize the entire system and make the hydrogen source. literally “changeable”.

A positive energy balance is possible

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

However, for hydrogen to become affordable, and therefore economically sustainable, further developments are needed. First, the distribution of refueling points and fleets of cars and buses that can ensure sufficient load for each station. A method of operation, in short, that reduces financial risks and brings the distribution of this fuel from a niche technology to a mass solution.

A horizon in which some manufacturers firmly believe, attracted by the goal of creating vehicles with zero emissions (as long as hydrogen is not obtained, as it is said, from fossil fuels) and characterized by a generous autonomy, which can be changed in minutes.

A Mirai is filled with hydrogen

The hydrogen vehicle relies on electrochemistry

The hydrogen propulsion system converts the chemical energy of this fuel into mechanical energy in two basic ways: by burning it in an internal combustion engine, as in the case of NASA rockets, the American spacecraft agency, or by it reacts with oxygen in the fuel cell. to produce electricity.

Vehicles that follow the first strategy are called HICEV (Hydrogen Internal Combustion Engine Vehicle), while the second is called FCEV (Fuel Cell Electric Vehicle). The movement of the future is actually reserved for the latter, due to the absence of emissions and the access to the technology necessary to achieve incredible mileage with a simple refueling.

Fuel cells produce energy but also water

Fuel cells, at the heart 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 hydrogen molecules into positive ions and electrons; the latter, passing through an external circuit, provides an electric current proportional to the speed of the chemical reaction, which can be used for any purpose. This reaction produces waste, water, which can be rejected by nature because it is completely compatible with the environment and does not change.

Hydrogen must be compressed

The technical problems associated with the use of hydrogen for the vehicle are essentially related to its low energy density on a volumetric basis (particularly compared to hydrocarbons) which requires a particularly high pressure for storage, or, alternatively , cryogenic treatment. At the moment, there is no alternative in the automotive sector, because the adoption of large tanks and the storage in the form of ammonia, metal hydrides, synthetic hydrocarbons (such as methanol) or nanotubes, both carbon and silicon, are hardly suitable for for use in compact cars. Therefore the storage pressure plays an important role in the use of hydrogen for movement, although it opens the door to questions about less security such as compatibility and stability of the system, since compression hydrogen involves the expenditure of energy.

The hydrogen car shares the advantages of electric cars

A hydrogen car is basically an electric car, but with fuel cells instead of regular batteries. From a driving point of view, there is no change, because advantages such as quick push, linear flow, the absence of jerks when taking off and first-class comfort are out of the question.

BMW iX5 Hydrogen

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