This article aims to present how hydrogen can be used as one of the energy sources of the future and collaborate in the elimination or reduction of greenhouse gas emissions, contributing effectively to the fight against global climate change, which tends to be catastrophic. The International Energy Agency (IEA) assured in a report dated 2019 that hydrogen is an energy of the future. Hydrogen appears to be a real alternative because it does not emit CO2 when associated with a fuel cell. It is important to note that hydrogen is also a renewable energy source that was discovered several centuries ago. There is gray hydrogen, produced from fossil fuels. When this production comes from natural gas and there is carbon capture and storage, we have blue hydrogen. Green hydrogen is that made from the electrolysis of water. However, the initial energy to carry out this process needs to come from renewable sources (hydroelectricity, solar energy, wind energy and biomass) so that the hydrogen obtained qualifies as green hydrogen. Thus, its production takes place without carbon emissions. Although the best-known use of hydrogen is probably in motor vehicles, there are many other possible uses such as generating power for buildings, it can also provide heat, it can be used in aircraft, as an emergency generator system and on a hydrogen-powered cruise ship. It is also possible for hydrogen to power service vehicles such as forklifts and trucks, as well as buses and trains.

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HYDROGEN AS A SOLUTION TO REPLACE FOSSIL FUEL AND AVOID THE
EMISSION OF GREENHOUSE GASES
Fernando Alcoforado*
This article aims to present how hydrogen can be used as one of the energy sources of the
future and contribute to the elimination of greenhouse gas emissions, contributing
effectively to the fight against global climate change, which tends to be catastrophic. The
International Energy Agency (IEA) assured in a report dated 2019 that hydrogen is an
energy of the future. Hydrogen appears to be a real alternative because it does not emit
CO2 when combined with a fuel cell. It is important to note that hydrogen is also a
renewable energy source that was discovered several centuries ago. Why does hydrogen
become a relevant and possible alternative today? To answer this question, the articles
L'hydrogène, énergie du futur? (Hydrogen, energy of the future?), available on the
website <https://www.sirenergies.com/article/hydrogene-energie-du-futur/> and Saiba
como o hidrogênio se transforma em combustível (Find out how hydrogen turns into fuel),
available on the website <https://www.alemdaenergia.engie.com.br/saiba-como-o-
hidrogenio-se-transforma-em-combustivel/>.
The article L'hydrogène, énergie du futur? (Hydrogen, energy of the future?) shows the
reasons why hydrogen is an important source of energy for the future, which are presented
in the following paragraphs::
When talking about alternatives to fossil fuels, hydrogen often appears, a chemical
element that makes up approximately 75% of the Universe. Located mainly in stars and
giant planets, it is a considerable source of energy. The first experiments related to
hydrogen were observed at the beginning of the 19th century, in particular with the
electrolysis of water and later with the development of fuel cells. It is still interesting to
note that this fuel has only recently resurfaced. In fact, it is the energy transition policy
underway in several countries around the world that this energy source has come to be
considered as an alternative to replacing fossil fuels. From a molecular point of view, H20
is present throughout our planet. As a reminder, water is one atom of oxygen and two
atoms of hydrogen (H2O). It is exceptional to note that H2O represents almost 90% of
the atoms (in number) present on our planet. Almost 10% of the mass of the human body
is made up of hydrogen.
It should be noted that hydrogen is not an energy, but an energy vector. In other words, it
allows transport or storage of previously produced primary energy. The energetic power
of hydrogen is also very significant. A hydrogen molecule releases approximately three
times more energy than its gasoline equivalent. When associated with a fuel cell, this
energy does not emit CO2. Water is the only waste product in a fuel cell. Hydrogen is a
vector that is not present in a pure state in nature. It is therefore necessary to mobilize
energy to extract it, transport it and transform it. It is certainly much less polluting than
other alternatives. The climate emergency favors the emergence of renewable energy
(solar, wind and biomass). By definition, these means of production are intermittent. They
only produce when conditions allow. There is a process involving hydrogen that allows
you to overcome this problem:
• 1st step: through the electrolysis process it is possible to create hydrogen from water. In
fact, water is made up of hydrogen and oxygen (H2O) molecules. Using an electric
current it is possible to separate these molecules and thus store hydrogen.

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• 2nd step: Once the gas is stored, there are multiple uses. In the context of storage, it is
possible to produce electricity from hydrogen through a fuel cell.
One of the most important climate issues is the transport sector. In fact, today most
transport runs on fossil fuels. The transport sector represents around 33% of greenhouse
gas emissions in Brazil, 30% in France and 20% worldwide. Transporting goods and
people consumes a lot of energy. Transporting goods and people consumes a lot of
energy. One of the solutions envisaged to decarbonize this sector is, therefore, hydrogen.
One can imagine hydrogen-powered vehicles. The combustion of this gas produces only
water, this property makes it a serious candidate as a fuel of the future. The vehicles'
engines would be powered by hydrogen. There is the possibility of installing a fuel cell
to equip the vehicles. Many manufacturers are interested in the possibility of installing a
battery that supplies the car with electricity. In this scenario, hydrogen solves the problem
of the autonomy of electric vehicles. The efficiency of hydrogen in a fuel cell is almost
50% (which is exceptional). From a technical point of view, it is the opposite of
electrolysis. This is a mixture of air and hydrogen. Inside the battery, the hydrogen energy
is then converted into electrical energy. There are numerous applications for hydrogen,
such as the decarbonization of industry, electricity storage, road, sea or air transport,
among others.
Figure 1- Fuel cell (Hydrogen battery)
Source: https://www.sirenergies.com/article/hydrogene-energie-du-futur/
There are several ways to produce hydrogen. Some of them consume fossil fuels. Even if
future hydrogen use only releases water, initial production could be problematic. Today,
most of the initial production of electricity or hydrogen (depending on the process chosen)
is of fossil origin. The energy transition must allow us to reduce our CO2 emissions,
which is why we must prioritize a renewable energy source (hydraulic, solar, wind and
biomass). This is why we distinguish several “types” of hydrogen: 1) green hydrogen
which is manufactured by electrolysis, with the initial production of electricity from
renewable sources; and, 2) gray hydrogen which is produced by chemical processes

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involving fossil fuels. Green hydrogen is of greatest interest because it is the fuel that
helps our societies decarbonize in the face of the climate emergency.
The development of the hydrogen sector requires heavy investments throughout the
production chain, whether it be production, transport or even storage.
Figure 2- Production, Conversion, Storage and Uses of Hydrogen (H2)
Source: https://www.sirenergies.com/article/hydrogene-energie-du-futur/
It is absolutely necessary to reduce the costs of fuel cells or even electrolyzers. This is the
sine qua non for the large-scale emergence of this technology. It is estimated that around
20 billion Euros of investment will be needed per year to reach a critical size in 10 years.
This amount may seem high, but it is currently more than 30 times lower than the funds
allocated to oil investments. To allow hydrogen to adequately fulfill its role, it would
therefore be necessary to increase the share of carbon-free electricity in the global energy
mix.
The article Saiba como o hidrogênio se transforma em combustível (Find out how
hydrogen turns into fuel) shows the reasons why hydrogen is an important energy source
of the future, which are presented in the following paragraphs:
Hydrogen as a fuel is seen as an important part of a carbon-neutral future. Nevertheless,
its transformation from gas to fuel requires a large amount of energy. Therefore, it is
important to pay attention to the source of this energy so that the final product is the so-
called green hydrogen. The most abundant element in the Universe, one of the ways to
produce it is through a thermal process. In this case, the steam generally reacts with a
hydrocarbon-type fuel, producing hydrogen. There are several fuels that can be used,
ranging from diesel to natural gas and biogas, for example. In this type of generation,
there are carbon emissions. Nevertheless, it is also possible to produce it through
electrolysis. In this case, two electrodes (a type of metal bar) connected to a power source
are inserted into a container with water. The bars have different polarities, and the energy
passing through them separates the hydrogen in the water. This process requires a lot of
energy, because its energy efficiency is around 80%. Which means that, to generate 80
kilowatts/kilo, 100 kWh of electricity would be needed. In this type of production, it is

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possible for carbon emissions to be zero. However, this depends on the source of the
electricity used.
To run engines, hydrogen needs to pass through a fuel cell. In the fuel cell, the process is
the opposite of what happens in electrolysis that produces hydrogen. Just like in
electrolysis, there are two electrodes, one positive and one negative. The negative
electrode is powered by hydrogen, while the positive electrode receives air. In the
negative, a substance separates hydrogen molecules into protons and electrons. While the
electrons leave the electrode and generate a flow of electricity, the protons move towards
the electrode with air. There, these protons mix with oxygen and, in the opposite direction
to electrolysis, generate water and heat. This is how this type of fuel generates energy
without combustion and producing only water vapor. Fuel cells can have a variety of uses,
from transportation to a backup power supply system. Its uses include powering buildings
and even a submarine.
Hydrogen as a fuel can be of different “colors”. These classify it according to the energy
source used to produce the hydrogen fuel. There is gray hydrogen, produced from fossil
fuels. When this production comes from natural gas and there is carbon capture and
storage, we have blue hydrogen. Green hydrogen is that made from electrolysis. However,
the initial energy to carry out this process needs to come from renewable sources
(hydroelectricity, solar energy, wind energy and biomass) for the fuel to fit into this
category. Thus, its production takes place without carbon emissions. That is why experts
see this type of fuel as key to a carbon-neutral world. Although the most well known use
of hydrogen is probably in motor vehicles, there are many other possible uses. Fuel cells
can serve as fixed power generation units for buildings. In some cases, they can also
provide heat. Fuel cells are seen as potential power sources for aircraft. It is possible, for
example, to use them as an emergency generator system. Furthermore, they can serve as
an auxiliary power unit for the plane as a whole. Hydrogen can provide the energy for the
vessel's propulsion. Nevertheless, this use is still in the early stages of testing and
development. However, its use as an onboard energy source is already more advanced.
There is a Norwegian project that aims to create a hydrogen-powered cruise ship. It is
also possible for hydrogen to power service vehicles such as forklifts and trucks, as well
as buses and trains.
From the above, the viability of hydrogen as an energy source capable of replacing fossil
fuels and contributing to the fight against climate change by reducing greenhouse gas
emissions is demonstrated.
* Fernando Alcoforado, awarded the medal of Engineering Merit of the CONFEA / CREA System, member
of the Bahia Academy of Education, of the SBPC- Brazilian Society for the Progress of Science and of
IPB- Polytechnic Institute of Bahia, engineer from the UFBA Polytechnic School and doctor in Territorial
Planning and Regional Development from the University of Barcelona, college professor (Engineering,
Economy and Administration) and consultant in the areas of strategic planning, business planning, regional
planning, urban planning and energy systems, was Advisor to the Vice President of Engineering and
Technology at LIGHT S.A. Electric power distribution company from Rio de Janeiro, Strategic Planning
Coordinator of CEPED- Bahia Research and Development Center, Undersecretary of Energy of the State
of Bahia, Secretary of Planning of Salvador, is the author of the books Globalização (Editora Nobel, São
Paulo, 1997), De Collor a FHC- O Brasil e a Nova (Des)ordem Mundial (Editora Nobel, São Paulo, 1998),
Um Projeto para o Brasil (Editora Nobel, São Paulo, 2000), Os condicionantes do desenvolvimento do
Estado da Bahia (Tese de doutorado. Universidade de
Barcelona,http://www.tesisenred.net/handle/10803/1944, 2003), Globalização e Desenvolvimento (Editora
Nobel, São Paulo, 2006), Bahia- Desenvolvimento do Século XVI ao Século XX e Objetivos Estratégicos
na Era Contemporânea (EGBA, Salvador, 2008), The Necessary Conditions of the Economic and Social
Development- The Case of the State of Bahia (VDM Verlag Dr. Müller Aktiengesellschaft & Co. KG,

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Saarbrücken, Germany, 2010), Aquecimento Global e Catástrofe Planetária (Viena- Editora e Gráfica,
Santa Cruz do Rio Pardo, São Paulo, 2010), Amazônia Sustentável- Para o progresso do Brasil e combate
ao aquecimento global (Viena- Editora e Gráfica, Santa Cruz do Rio Pardo, São Paulo, 2011), Os Fatores
Condicionantes do Desenvolvimento Econômico e Social (Editora CRV, Curitiba, 2012), Energia no
Mundo e no Brasil- Energia e Mudança Climática Catastrófica no Século XXI (Editora CRV, Curitiba,
2015), As Grandes Revoluções Científicas, Econômicas e Sociais que Mudaram o Mundo (Editora CRV,
Curitiba, 2016), A Invenção de um novo Brasil (Editora CRV, Curitiba, 2017), Esquerda x Direita e a sua
convergência (Associação Baiana de Imprensa, Salvador, 2018), Como inventar o futuro para mudar o
mundo (Editora CRV, Curitiba, 2019), A humanidade ameaçada e as estratégias para sua sobrevivência
(Editora Dialética, São Paulo, 2021), A escalada da ciência e da tecnologia e sua contribuição ao progresso
e à sobrevivência da humanidade (Editora CRV, Curitiba, 2022), a chapter in the book Flood Handbook
(CRC Press, Boca Raton, Florida United States, 2022), How to protect human beings from threats to their
existence and avoid the extinction of humanity (Generis Publishing, Europe, Republic of Moldova,
Chișinău, 2023) and A revolução da educação necessária ao Brasil na era contemporânea (Editora CRV,
Curitiba, 2023).