The oil crisis and prices soaring in the 1970’s raised awareness about the energy problem and environmental concerns about the impact of the fossil fuels. This sparked a public debate that is still going on about the energy vectors that are increasingly focusing on a sustainable energy supply based on renewable energy sources, used initially as a complement and then as an alternative to fossil energy sources, which until then had been used almost exclusively.
These considerations were due to the growing awareness of the limited availability of fossil resources brought about by the oil crisis at that time and the logistical problems both of acquisition and transport (Suez Canal crisis) that today they are once again like a spectre due to the war that broke out between Russia and Ukraine, whose main focus is energy supply. In addition, the environmental problems and damage caused by the use of fossil fuels were highlighted in the “Club of Rome” report in 1972. In this context, climate change caused by the industrial CO2 emissions is reaching by now dramatic proportions.
In the case of fossil energy carriers, some new deposits have been found, but their exploitation is more laborious and expensive than in the case of the already existing ones, such as the case of Vaca Muerta, whose financial difficulties constantly arise.
Moreover, detailed research into this has shown that the economic damage due to CO2 emissions resulting from human activities will be more expensive in a longer term. Will be greater
The use of renewable energy sources could minimize, delay and solve these problems. However, especially in the case of wind and solar energy, these resources fluctuate between periodic and aperiodic changes and are very often not available at locations close to demand. Only the large-scale energy storage can balance these discontinuities over days or even weeks.
Pumped hydroelectric power plants or a compressed air power plant can serve as a storage system. Both methods use potential energy, for electricity storage at a large scale during several days or even weeks. But vectors able to store higher energy density must be found. This is possible through storage using chemical energy: Hydrogen is the main vector.
So as to do this, both liquid and gaseous hydrogen and the possibility of combining this with fuel cells offer high efficiency for various application fields that range from land, sea or air transport vehicles to grid electrification. A political decision of the energy transition should be taken to carry this out, a decision to be considered and discussed more intensively. But energy transition should not be understood as restricted to the change of the origin of electricity. It should mean the renewal of all type of energy, including the electricity, the heat and the oil. In the future, energy consumption will be increasingly coupled and will combine different types of energy through conversion.
In this context, hydrogen will be of key importance as it can be produced by different means from all the renewable primary energies. It can also be stored by different phases (liquid or compressed gas )and processes (by compounds chemistry), and it can be converted without polluting emissions into electricity, heat or fuel mobility as well. Due to this multi-purpose application, the cost of hydrogen can be relative.
Hydrogen can be used as fuel for mobile applications, as feedstock for production processes in the chemical or food industry, for domestic heating or back-up power supply as well as control of the power range in the electricity grid. Due to this multiple applicability, the economic and commercial use of hydrogen is obvious. Every application calls for continuous availability and therefore, large-scale electrolysis that must be operated with adaptive power and has problems when it comes to the typical fluctuation of renewable energies.
It is worth mentioning that the hydrogen will boost the need of development of the whole production chain, improving in this way the national economies and the creation of genuine jobs through:
-The exploitation of renewable energies for power production.
– The use of hydrogen as a means of energy storage.
-Its distribution for electrification and for the production of electric energy as a means of energy storage.
-For its further use, for example, as feedstock for the chemical industry.
-As clean fuel for long-range vehicles.
Moreover, hydrogen can be blended with natural gas, but only for further thermal use. This has been developed in some countries including Argentina, where the use of GNC-H2 mixtures for automotive use has been investigated and experimented with, on the initiative of entities such as CONICET, the National Atomic Energy Commission and the intervention of universities.
It should be taken into account that hydrogen must be pure for its high energy -efficient use (as fuel in electric vehicles with fuel cells).
Different techniques and components for various hydrogen applications are still under research and are in the development stage. Some of them are ready for series production or simply on the market, e.g. for mobility or uninterrupted energy supply; others are still in the field test phase. But with continuous developments synergy effects are to be expected, and the expansion of infrastructure as well.
Production prices play an important role in the economic use of hydrogen. The essential process for a sustainable production of hydrogen is electrolysis with electricity coming from renewable energy sources. The large-scale electrolyser of a dozens of megawatts enables new dimensions for a hydrogen central production.
The range of hydrogen applications is broad-based and new potentials will be developed in the future. However, hydrogen as an energy vector has not been able to go beyond the limit of penetration in the market of hydrogen yet.
The adoption of new technologies in the energy field, and especially in the hydrogen economy, brings about technological changes that are often compared to evolution. In this regard, innovations are mutations that prevail in the market by selection or disappear in most cases.
In contrast to mutation, innovations in technology are not the result of a random process, but they are rather due to a special problem or challenge. Anyway, a new technology has to be established in the market and society. Therefore, mere novelty is not enough. In the history of technology there have been several innovations that shone but only briefly and then they were forgotten. But undoubtedly, the use of hydrogen as energy carrier, will be an outstanding innovation with a significant impact on the economy and society.
In this respect, hydrogen is an important option for the global transport market as well as for energy storage. The undertakings, carried out in different parts of the world and especially with focus on Latin America are very interesting. In our country as in the rest of South America there are suitable conditions for the use of energies like the solar or the wind one that have led to a regional development that although it is not comparable to other parts of the world it is worth noticing. Wind energy projects in Uruguay and Brazil have not only allowed intervention in the electricity grid, but have also boosted the economy and the development of the implementation of hybrid and electric vehicles.
In our country, agreements signed at the beginning of 2022 enable the development of green hydrogen production plants based on renewable energy that can not only be used as fuel but also in the petrochemical industry to obtain various compounds, being the ammonia one of the most important ones. There is a similar situation in Chile where there is an agreement for the implementation of a green hydrogen production plant in Punta Arenas area.
It is also worth mentioning the production of synthetic fuels from green hydrogen and the CO2 capture that through processes known as Fisher-Tropsch, make it possible to obtain synthetic fuels (called e-fuels) specifically for current internal combustion engines in the automotive, maritime and aviation sectors. In the case of the latter sector, a change in the power unit (turbine) is practically impossible on a commercial level. Nobody would think of using batteries to cross the Atlantic and it is not technically possible. In this case, a synthetic fuel obtained from green hydrogen and CO2 capture allows a CO2 neutral contribution. The same can be applied to the shipbuilding industry. As regards the automotive industry, the fuel cell solution, using hydrogen and oxygen for electrical conversion, is a feasible solution as it does not have a negative impact on the payload of the transport or on the autonomy.
Hydrogen is produced from hydrocarbons or directly from water. Hydrocarbons are available as fossil fuels or biomass. Hydrogen can be extracted from water by electrolysis, thermochemically and by photobiology or photocatalytic processes. The separation of hydrocarbons is mainly done by steam reforming. In addition, there are other processes such as partial oxidation. Energy, provided as electricity, heat or light is required for both hydrocarbons and water. Electricity and heat can be made available in many different ways.
The method of production is crucial as it affects the price of hydrogen. The emissions and environmental impact of any upstream process must be attributed to the hydrogen produced.
At the present time, the dominant production technology is the one coming from fossil fuels. electrolysis plays only a minor role. Thermochemical, photocatalytic or photobiological processes are still under development. In the long run, the fossil fuels will not be used any longer as hydrogen sources because of their limited availability and the CO2 accumulates as a co-product during production .
The priority and objective is therefore obtaining hydrogen in the cleanest possible way, that is , to be able to use electrolysis but based on renewable sources or the reforming of natural gas with CO2 capture(Blue Hydrogen).This is how a range of colours according to the method of obtaining hydrogen can be distinguished; they go from the black hydrogen to the golden one, passing through the brown, grey, turquoise, blue, yellow, pink, green and golden, the latter one through biomass. That is, there is a colour for each energy source and process used in the manufacture of this renewable gas. This is, therefore, how hydrogen is obtained based on different sources of origin and their production chain.
On the one hand, we have the black or brown hydrogen, which is produced from coal gasification. In this case, it is highly polluting, so there should be no incentive for its use. Coal gasification has been used for heating and lighting in cities in Europe and North America. Although at the moment, this method has other applications, its use is tending to be reduced because of the large environmental impact due to the generation of large amounts of carbon associated with it.
Currently, the grey hydrogen is the most widely used, accounting for almost 90% of the world production. It is generally obtained from natural gas or oil. It can be obtained in large quantities through the process of steam methane reform (SMR) by heat treating of the gas and mixing it with steam. Although it is less polluting than the brown hydrogen it contributes decisively to increasing the CO2, as for every kilo of grey hydrogen, 9,3 kilos of CO2 are emitted. It should be borne in mind that during the production process, there are indirect emissions, including methane. It should be remembered that, according to specialists, the methane favours the formation of the ozone in the lower layers of the atmosphere which has an impact on health. It can cause irritation of the respiratory tract and impaired lung function, as well as being 23 times more harmful than CO2 on the greenhouse effect.
If, on the other hand, the carbon generated is captured and stored underground (CSS), we are in the presence of the so-called blue hydrogen. While this contributes to the decarbonisation policy, this technology is not fully efficient as between 10% and 20 % of the emissions cannot be captured. In addition, as with grey hydrogen, there are methane emissions.
Continuing with the different processes, the pink hydrogen, as well as the green one, is based on the process of electrolysis of water. However, in this case, only electricity from a nuclear power plant is used. Nuclear energy provides an almost constant flow of energy, making it a continuous and reliable process in terms of time availability, as opposed to electrolysers using sources such as solar or wind, which are variable as they depend on weather conditions.
A less common alternative, which still requires further development of the technology for obtaining hydrogen, is the one that results from the generation through molten metal pyrolisis, fuelled by natural gas. In this case,it is called turquoise hydrogen. During this process, the natural gas passes through a molten metal, releasing hydrogen and solid carbon, avoiding in this way the CO2 emissions. This process is simpler than the reforming of natural gas used to obtain the so-called grey or blue hydrogen.
We then come to green hydrogen which has become popular in recent times and has marked an interesting path for countries that have renewable sources at their disposal, as in the case of Argentina . Hydrogen is produced by the electrolysis process, which is driven by renewable energies ,such as solar or wind, making it a clean fuel, considered as zero emissions.
This technology is available and developed so as to be implemented at industrial level. It is worth mentioning the project that was signed at the beginning of this year, which will allow the development and construction of a green Hydrogen production plant in the province of Río Negro. Argentina has a great opportunity in this case, due to the abundance of wind and solar resources in different areas of the country.
Lately, there has been reference to a process to obtain hydrogen with environmental advantages. This is the so-called golden hydrogen. It would be a technology with negative emissions. In other words, it would have a positive environmental impact. News from the Comillas Pontifical University (Spain) claim that the hydrogen obtained from biomethane reformed with water vapour and CO2 capture could be considered as decarbonised. It is a complement to electrolysis which, although it has a limited potential, would be able to remove up to 9 kg of CO2 from the environment for each kilo of hydrogen produced at comparable or even lower prices than the current electrolysis.
Taking into account this variety and the prospects raised, we must bear in mind that hydrogen is not a magic wand for a final transfer to a sustainable energy supply, but it will make significant contributions to the energy transition.
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