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  • Foto del escritorNicolás LISO FABBRI

Nicolas Liso Fabbri: What is green hydrogen and how it could help clean our roads of CO2

Actualizado: 4 jul 2021

Some analysts are positive about hydrogen, but also cautious.

The dream of a hydrogen-based green economy seemed to have faded, but it has regained momentum, and this time it may be here to stay. Today this element is seen by many as an effective option to "clean" the smoke from our roads, the so-called "decarbonization", the great challenge for environmentalists. The use of hydrogen as a fuel is not new: the technology has been around for decades.

It was used, for example, on NASA spacecraft. In fact, the first combustion engine in history ran on hydrogen. It has been proposed for all possible industries - it is the most abundant chemical element in the universe - but until recently it had not emerged as a 100% sustainable alternative to generate large amounts of energy.

The key: that when hydrogen burns it only leaves behind water vapor, rather than the greenhouse gases that come from fossil fuels.

Furthermore, it is lighter than any other element on the periodic table, which is why the first aircrafts used hydrogen engines in the 20th century ... until a fatal tragedy with a zeppelin occurred in 1937.

Why zeppelins can be the solution to congested and polluting air travel But interest in hydrogen as a fuel has resurfaced in recent years for the development of batteries and engines, or as "green" energy for domestic use.

The idea of hydrogen as a combustion element is not new.

Critics of this technology fear that it will end up being too expensive for mass use, but its proponents have high hopes for it.

Clean energy for mobility

Some major car brands have been investing heavily in the development of hydrogen-powered engines for years. Honda, DaimlerChrysler, Ford, General Motors / Opel, Hyundai, Kia, Renault / Nissan, or Toyota are some of them.

And there are already several countries that propose it as a viable alternative to electric motors. Japan recently said that it wants to become a "hydrogen economy", and countries such as Germany, the United States, France, China, or Russia have trains that run on this element.

The International Energy Agency (IEA) praised his qualities at the last G20 summit in a report titled The Future of Hydrogen. Seizing today's opportunities.

But how does green hydrogen technology work?

A conductor directs the first hydrogen-powered train, from French train manufacturer Alstom, during its maiden journey on September 16, 2018, near Bremervoerde, Germany.

The mechanism is as follows: hydrogen reacts with air, generating electricity and releasing water (H2O) to the outside in the form of vapor.

Thus, it generates electricity or heat in a totally clean way. However, one of the drawbacks is that obtaining hydrogen as an isolated element - and thus being able to generate hydrogen to make fuel - requires large amounts of energy or using non-renewable sources.

A "relatively green" alternative The vast majority (almost 99%) of hydrogen is produced from hydrocarbons - natural gas and coal, making its own production a plentiful source of carbon dioxide (CO2) emissions.

In that case, we would speak of a hydrogen fuel that is not green but nevertheless represents a "relatively green" alternative to greenhouse gases. The UK has developed a project - called HyDeploy - at Keele University blending natural gas with 20% hydrogen in a trial that became nationally relevant.

Adding hydrogen reduces the amount of CO2 each time the heating is turned on or when cooking.

Natural gas can be mixed with hydrogen to make "green" energy.

It is the UK's first such test of hydrogen in a modern gas network. As a fuel, hydrogen works in much the same way as natural gas.

Hydrogen is produced in a device called an electrolyzer, a device that divides water (H2O) into its components: hydrogen and oxygen.

But it can also be generated without producing any pollution, through electrolysis, converting water into hydrogen and oxygen molecules using renewable sources, such as surplus wind energy. In that case, we would be talking about green hydrogen, a clean process.

Although here we find another problem: its high cost.

Electrolysis of surplus renewable energy is unequivocally beneficial for the environment, but it is not very efficient.

In the near future, it may be cheaper to produce hydrogen from natural gas. However, CO2 is released in the industrial process used to generate hydrogen.

Hydrogen could be generated using surplus energy from renewables.

The solution? A technology called carbon capture and storage (CCS) is not yet available on a large scale and that allows the resulting CO2 to be captured and stored underground.

An inevitable revolution?

According to a recent report by the US financial institution Morgan Stanley, the green hydrogen "revolution" will help reduce emissions in existing industrial processes and also provide fuel for buses, trucks, or ships. But the main drawbacks of hydrogen are cost and availability.

The costs are much higher than those required for, for example, natural gas, although the difference is likely to decrease as carbon taxes are raised to combat climate change in the coming decades.

Independent sustainable development organization E3G said in a statement: "Obtaining hydrogen involves massive spending on infrastructure. In many cases, the additional costs make it seem unattractive compared to alternatives (such as renewable energy)."

The idea of using hydrogen as a fuel is not new, but it has resurfaced in recent years.

That is why some experts such as Richard Black, from the Energy and Climate Intelligence Unit (ECIU), maintain a certain degree of skepticism.

"We will have and will have hydrogen in the mix of energy options, but it is not a silver bullet for everything, an impression that sometimes comes from what is said.

There is hope, but also a lot of publicity ..."

Nicolas Liso Fabbri

Lic. Cr. Nicolas Liso Fabbri

TECHNIC ingenieria & construcción

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