translated from Spanish: What is green hydrogen and how it could help clean our CO2 roads and cook with less smoke

The dream of a hydrogen-based green economy seemed to have faded, but it has regained momentum and may be here to stay.
Today this element is seen by many as an effective option to “clean” the smoke of our roads, the so-called “decarbonization”, the great challenge of environmentalists.
The use of hydrogen as fuel is not new: technology has existed for decades. It was used, for example, in 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 leaves only water vapour behind it, rather than the greenhouse gases that come from fossil fuels.
In addition, it is lighter than any other element of the periodic table, so the first aircraft used hydrogen engines in the twentieth century… until a fatal tragedy with a zeppelin occurred in 1937.
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But interest in hydrogen as 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 advocates have high hopes placed on it.
Clean energy for mobility
Some major car brands have been making strong investments in the development of hydrogen-powered engines for years.
Honda, DaimlerChrysler, Ford, General Motors/Opel, Hyundai, Kia, Renault/Nissan or Toyota are just a few of them.
And there are already several countries that propose it as a viable alternative to electric motors.
Japan recently said it wants to become a “hydrogen economy,” and countries like Germany, the United States, France, China or Russia have trains that run on this element.
The International Energy Agency (IEA) praised its qualities at the last G20 summit in a report that it titled The Future of Hydrogen. Seizing today’s opportunities (“The future of hydrogen. Taking advantage of today’s opportunities”).
But how does green hydrogen technology work?
A driver drives the first hydrogen-powered train, from french train manufacturer Alstom, during its first journey on 16 September 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 steam. Thus, it generates electricity or heat in a totally clean way.
However, one of the drawbacks is that to obtain hydrogen as an isolated element – and thus be able to generate hydrogen to make fuel – requires large amounts of energy or use non-renewable sources.
A “relatively green” alternative
The vast majority (almost 99%) hydrogen is produced from hydrocarbons: natural gas and coal, making its own production an abundant source of carbon dioxide (CO2) emissions.
In that case we would talk about a hydrogen fuel that is not green, but which nevertheless represents a “relatively green” alternative to greenhouse gases.
The UK has developed a project — called HyDeploy – at Keele University mixing natural gas with 20% hydrogen in a trial that gained national relevance, as explained by BBC environment analyst Roger Harrabin.
Adding hydrogen reduces the amount of CO2 each time you turn on heating or cooking.
Natural gas can be mixed with hydrogen to make a more “green” energy. It is the first test of its kind in the UK of hydrogen in a modern gas network.
As a fuel, hydrogen works largely in much the same way as natural gas, Harrabin points.
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 laelectrolysis, turning 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.
“The electrolysis of the renewable energy surplus is unequivocally beneficial to the environment, but it is not very efficient,” says the BBC analyst.
“In the near future, it may be cheaper to produce hydrogen from natural gas. However, CO2 is released into the industrial process used to generate hydrogen,” adds Harrabin.
Hydrogen could be generated using surplus energy from renewable energy, the solution? A technology called carbon capture and storage (CCS) that is not yet available on a large scale and that allows to capture the resulting CO2 and store it underground, says the journalist.
An inevitable revolution?
According to a recent report by US financial institution Morgan Stanley, the “revolution” of green hydrogen 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.
Costs are much higher than what natural gas requires, for example, although the gap is likely to narrow as carbon taxes rise to combat climate change in the coming decades, Harrabin predicts.
The independent organization on sustainable development E3G said in a statement: “Getting hydrogen involves massive spending on infrastructure. In many cases, the additional costs make it seem unattractive compared to alternatives (such as renewables).”
The idea of using hydrogen as fuel is not new, but it has resurfaced in the last few years. That’s why some experts, such as Richard Black, from the Energy and Climate Intelligence Unit (ECIU), have a degree of skepticism.
“We should have and will have hydrogen in the mix of energy options, but it is not a miraculous solution for everything, an impression that sometimes follows from what is often said. There is hope, but also a lot ofpublicity,” he told the BBC.

Original source in Spanish