How green hydrogen is obtained and how it can contribute to the fight against climate change

Green hydrogen, which is obtained from renewable energies, gains prominence as an alternative in the process of decarbonization of Europe. We tell you how this compound is used to obtain electricity.

Europe has begun to walk the path towards an energy transition that allows the decarbonisation of all sectors. In that process, green hydrogen acts as the cornerstone of an energy system that is climate neutral by 2050. But can this compound position itself as an alternative to fossil fuels?

What is green hydrogen?

The universe is composed of 75% hydrogen, but on Earth it is always present in combination with other molecules, such as oxygen to create water. This is an obstacle to its use as a raw material. In order to use it, it is necessary to carry out a chemical process to separate it from the rest of the elements. It is what is known as an energy vector.

The use of hydrogen in industry is not new. So much so that its consumption has tripled since 1975, according to data from the International Energy Agency (IEA).

The problem is that, at present, most of that hydrogen is obtained through the use of hydrocarbons, a highly polluting process. The IEA estimates that hydrogen production for chemical industries and refineries accounts for 6% of global natural gas use and 2% of coal consumption. In addition, it is responsible for 830 million tons of annual carbon dioxide emissions, which is equivalent to the emissions of Indonesia and the United Kingdom combined.

As an alternative, projects are being developed based on the use of green hydrogen obtained through renewable energies.

Decomposing the water molecule: this is how green hydrogen is produced

The best-known method for producing green hydrogen is the electrolysis of water, which consists of breaking down the water molecule into its elements: oxygen and hydrogen. To achieve this, a direct electric current is applied to an electrochemical device called an electrolyzer. The electricity to carry out this process is obtained from renewable sources, such as wind or solar.

This hydrogen is stored in specific tanks and is channeled to be used either as a heat source or as electrical energy through a fuel cell. In this mechanism, hydrogen in the gaseous state is mixed again with oxygen to obtain electrical energy. This means that the only residue from the whole process is water.

A sustainable alternative for transport

One of the main advantages of this compound is its versatility. “Hydrogen is very flexible because it can be transformed into electricity, but also into heat. This allows it to be used not only in fuel cells, but also in other equipment that is already developed such as engines or turbines,” says Eva Llera, professor of the Master’s Degree in Renewable Energies and Energy Efficiency at the University of Zaragoza. To this is added its ease to store it, both in gaseous and liquid state, and transport it.

Green hydrogen has gained strength as a possible ally in some sectors that are very difficult to decarbonize. Thus, its use is studied especially in the production of iron and steel, aviation, maritime transport, long-distance road transport and heat for buildings, according to the scientific journal Science.

“Hydrogen can be a substitute for the fuel in our cars,” explains Javier Brey, president of the Spanish Hydrogen Association (AeH2). “These cars are electric and carry a tank with four or five kilograms of hydrogen and a fuel cell where that gas is transformed into electricity. They have a range of more than 400 kilometers,” he adds.

There are currently around 11,200 hydrogen-powered cars on the roads around the world. Existing government targets call for that number to rise to 2.5 million by 2030, according to the IEA. However, achieving these goals seems like a major challenge and one of the obstacles is that producing this type of hydrogen is expensive.

Cost, a barrier to implementation

The cost of producing green hydrogen is determined by the price of renewable electricity, the investment cost of the electrolyzer and its operating hours. “Public intervention is needed either to make fossil fuels more expensive and hydrogen more competitive or to help make hydrogen cheaper so that costs go down,” Alejandro Núñez-Jiménez, an energy policy researcher at the Swiss Federal Institute of Technology in Zurich, told Newtral.es.

“Right now a kilo of gray hydrogen – one that is obtained by reforming fossil fuels and carries significant CO emissions.₂-, costs between 1.5 and 2 euros, while the price of green hydrogen, the little that is produced, stands at 5.5 euros per kilogram, “says Brey. According to a report by the International Renewable Energy Agency (IRENA), hydrogen produced with renewable electricity could be cost-effective from 2030.

However, it is not the main limitation that hydrogen has ahead as a fuel, the lack of infrastructure is also decisive.” A vehicle that uses hydrogen is not much more expensive than a high-end sedan, around 60,000 euros, what happens is that we do not have a sufficient network of hydrogen service stations, “says Brey.

Source: Newtral