Advantages and Disadvantages of Green Hydrogen

Written by Levi Naldi do Espirito Santo and Ana Beatriz Pereira Santos in March 2023

Green Hydrogen (H2V) is one of the main emerging alternatives with sustainable characteristics and the potential to replace fossil fuels in various sectors of the economy. It is produced through the electrolysis of water, an intensive process in electrical energy from solar and wind sources. Therefore, it is possible to obtain a fuel that does not emit greenhouse gases both in the production and use processes, unlike fossil fuels, which are responsible for a large part of these emissions.

Green Hydrogen can be flexibly used in a variety of applications, such as in the light and heavy vehicle transport sectors; energy generation and storage and in industrial segments.

Currently, the world faces a growing need for clean and renewable energy sources to combat climate change and meet the growing demand for energy. H2V has the potential to play an important role in this transition, and this moment is considered the most opportune to invest in its production and use.

It is important to mention that the Green Hydrogen production process is different from the processes that have been mostly carried out so far by the industry for the production of hydrogen, as these use fossil sources, such as natural gas and coal, which emit greenhouse gases in their production process.

In this sense, it is important to compare the entire hydrogen value chain in order to have an assessment of the advantages and disadvantages of the different types of technologies for the production and use of this energy vector.

Production

Global hydrogen demand reached 94 million tons (Mt) in 2021, showing a 5% increase on demand from the previous year, mainly driven by the recovery of activity in the chemical and refining sector. In addition, hydrogen demand surpassed its historical maximum of 91Mt reached in 2019. But most of this demand was met by hydrogen produced from fossil fuels, with harmful effects on the environment (IEA, 2022).

Currently the production of hydrogen, mostly used in the chemical and petrochemical sectors, is responsible for more than 900Mt of CO2 emissions (eg Gray Hydrogen and Black Hydrogen). Comparing to the H2V, which has zero emissions of CO₂ in its production, it is noted that one of the first steps would be to suggest an alternative for these sectors to use clean hydrogen.

H2V production technology has been evolving, but it still faces the barrier of technological maturity and scale gains. In Figure 1, it is noted that when compared to other production processes, Green Hydrogen has similar efficiency to Gray Hydrogen [1][3].

Figure 1: Comparison of efficiency between technologies for obtaining hydrogen

Source: Loss of integrity of hydrogen technologies: A critical review, 2021

Investments in new R&D projects aimed at the evolution of Green Hydrogen production technology is one of the solutions to overcome the barrier of technological maturity. In this sense, according to data from (IEA, 2022), public funding for R&D in hydrogen had its greatest annual increase in 2021, with an increase of 35% compared to 2020. Hydrogen technologies received about 5% of the total budget of R&D for clean energy technologies and European countries were the main contributors to this increase.

Comparing production costs, Green Hydrogen still has a very high value compared to gray, for example. In addition to the already mentioned factors of technological maturity and lack of scale gains, which affect the CAPEX share of production, this high pricing is also associated with the availability of generation from renewable sources and acceptance by industries. However, as shown in Figure 2, in the medium term, taxation on CO emissions₂ and advances in production technology, place Green Hydrogen in a more economically advantageous position in terms of production cost.

Figure 2: Cost comparison between Green Hydrogen x Gray Hydrogen

Source: Rethink Energy, 2022

Taking into account the current production efficiency of hydrogen types, we can say that Green is still not as scalable as Gray. But the advantage of contributing immensely to decarbonization, considering that both can be used for the same final uses, denotes the importance of developing Green Hydrogen technologies as quickly as possible. Emphasizing the importance of this new form/source of energy to mitigate climate change and its effects.

Storage/Transportation

Hydrogen can be stored and transported using tanks loaded by trucks, however, in addition to being a dangerous procedure, as it is a highly volatile and flammable product, it has a very low efficiency when compared to the transport of other energy sources. This happens because hydrogen has a very low specific volumetric energy density. For example, to transport the energy equivalent of 10 liters of diesel, present in a truck, 11 trucks of 300 kg of compressed H2 are needed.

Therefore, among other factors, it is interesting that there is renewable hydrogen production close to the place of use. However, it is feasible to say that it would be difficult to disseminate this type of model for most end uses. Thus, some alternatives to storage in tanks are presented, namely: liquefaction, dilution in natural gas and addition to ammonia.

The option of storing and transporting hydrogen in its liquid form is not very efficient because it is a relatively complex technique and can generate high installation costs, in addition to requiring additional processes to liquefy the hydrogen. However, it is still a field of study that has the potential for significant improvements in the technologies used, which may increase the efficiency of this form of storage and reduce the costs of the process.

Another option for transporting hydrogen is by gas pipelines, within which the indication is the construction of a new and exclusive structure for H2, as is being implemented, still in the initial phase, in the USA, Germany, Holland, France and Belgium. However, this is an alternative considered to be costly, so it is suggested to make the transport of hydrogen feasible by reusing the existing network for transporting natural gas. In its initial study phase, it can be stated that the mixture of hydrogen with natural gas is safe, and the concentration of each substance depends on the application, with a concentration of 10% hydrogen in the total volume being considered safe, as shown in Figure 3.

Figure 3. Admissible tolerance of some gas infrastructure components

Source: IRENA. Elaboration Gas Energy

The aggregation of hydrogen to ammonia is seen as another viable option, as it is capable of preserving large volumes of energy for a long time, which makes this form of transport an interesting alternative for long distances, in addition to the already existing consolidated infrastructure for this type of transport.

Use

One of the main applications of hydrogen would be in the mobility sector, where it has been used as fuel since the beginning of the 6th century in various means of transport, such as cars, airships and spacecraft. Currently, hydrogen fuel cells (FVECs) can be used in cars, trucks, and buses to power electric motors, providing an alternative to fossil fuels. However, in road transport, battery electric vehicles are still more efficient and developed than FCEVs. On the other hand, it is possible to notice the accelerated deployment of FCEVs, mainly in heavy trucks. In addition, it is a versatile source of energy and can be used for industrial purposes and energy storage. [XNUMX]

In industry one of the main applications of hydrogen would be in the production of ammonia, methanol and other chemical products. In this scenario, by using green hydrogen these industries can significantly reduce their carbon emissions. This use presents relatively low technical challenges when compared to replacing fuels, as it does not change the process that is already carried out, only the source of production of the hydrogen used.

Another use of green hydrogen is energy storage. This is possible because hydrogen can be easily compressed and stored and thus be used to store excess renewable energy generated during periods of low demand. Stored energy can be used to supplement energy production during periods of high demand, reducing the need for fossil fuel-based energy sources, which currently play this role.

Advantages of the H2 Verde over other types:

1. It does not emit greenhouse gases during its production or use, unlike fossil fuels.
2. It can be produced from renewable energy sources, through water electrolysis using solar or wind energy.
3. It can be used flexibly in a variety of applications including energy transmission, generation and storage.
4. It can be used in vehicles powered by hydrogen, such as trains, ships and planes, eliminating emissions of atmospheric pollutants in transport.
5. It can be used in fuel cells to generate electricity and be stored for future use.
6. It can be used as a raw material for the chemical, petrochemical and pharmaceutical, cement and steel industries, replacing fossil fuels and reducing greenhouse gas emissions.

Disadvantages of the H2 Green:

The following are disadvantages of green hydrogen when compared to other energy sources.

1. It still has a high production cost when compared with other energy sources, mainly due to the low technological maturity involved in its production.
2. For its use as a substitute for fossil fuels, such as gasoline or diesel, the automobile industry would need to adapt to using hydrogen, in addition to having other options, such as the electric car, which could be used as an alternative.
3. The low density of hydrogen, whether in the liquid or gaseous state, also results in a low energy density. Evidencing that hydrogen, in its pure form, is not a good means of transporting energy.

Challenges

In addition to the disadvantages listed above, there are also challenges in the implementation of Green Hydrogen that are not necessarily linked to a comparison between energy sources, namely:

1. The current infrastructure for storing and distributing hydrogen is limited.
2. The production of Green Hydrogen requires renewable electrical energy sources, which are still less available in some regions of the world.
3. There are still technical challenges to increasing the efficiency of hydrogen production and storage.
4. Society still fears the use of hydrogen due to its association with nuclear bombs and explosions.
5. Green hydrogen production is not yet scalable enough to meet the world's energy demand.

6 reasons why now is the time to invest in Green Hydrogen:

1. The growing need for clean, renewable energy sources to combat climate change and meet growing global energy demand.
2. Green Hydrogen has the potential to play an important role in the transition to a low carbon economy as a substitute for fossil fuels.
3. Green Hydrogen production technology has developed significantly in recent years, with prospects of becoming more accessible and economically viable.
4. Growing pressure from governments and society to reduce greenhouse gas emissions and meet climate targets.
5. The need for flexible and scalable energy sources to meet energy demand, especially for energy transport and storage applications.
6. Growing demand for clean and efficient transport solutions due to increased awareness of the importance of sustainability and public health.

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[3] USTOLIN, Federico. Loss of integrity of hydrogen technologies: A critical review. International Journal of Hydrogen Energy, vl 45, 10.1016 June 2021. Available at: https://www.sciencedirect.com/science/article/pii/S0360319920321583?ref=pdf_download&fr=RR-2&rr=7b648398ff7ca5d3

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[9] IBERDOLA. Green hydrogen: an alternative to reduce emissions and take care of our planet. Available at: https://www.iberdrola.com/sustentabilidade/hidrogenio-verde