This article aims to present the evolution of the use and production of energy from prehistory to the present time, as well as its probable future evolution towards the use of clean and renewable energy with the abandonment of fossil fuels. From prehistory to the 18th century, the use of renewable energy sources such as wood, wind and hydraulic energy predominated. From the 18th century to the contemporary era, fossil fuels predominated with coal and oil, but their use will probably end in the 21st century to avoid catastrophic global climate change resulting from their use in emitting greenhouse gases responsible for the global warming. With the end of the fossil fuels era will come the era of renewable energy sources when the use of hydroelectric energy, solar energy, wind energy, tidal energy, wave energy, geothermal energy, biomass energy and hydrogen energy will prevail.

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ENERGY REVOLUTIONS THROUGHOUT HISTORY AND ITS FUTURE
EVOLUTION TOWARDS CLEAN AND RENEWABLE ENERGY
Fernando Alcoforado*
This article aims to present the evolution of the use and production of energy from
prehistory to the present time, as well as its probable future evolution towards the use of
clean and renewable energy with the abandonment of fossil fuels. From prehistory to the
18th century, the use of renewable energy sources such as wood, wind and hydraulic
energy predominated. From the 18th century to the contemporary era, fossil fuels
predominated with coal and oil, but their use will probably end in the 21st century to
avoid catastrophic global climate change resulting from their use in emitting greenhouse
gases responsible for the global warming. With the end of the fossil fuels era will come
the era of renewable energy sources when the use of hydroelectric energy, solar energy,
wind energy, tidal energy, wave energy, geothermal energy, biomass energy and
hydrogen energy will prevail.
Use and production of energy from prehistory to the 18th century
Energy is an essential input for human beings and for economic and social development.
It can be argued that the most basic need of human beings is the energy to keep their
bodies functioning. For a long time, in the dawn of humanity, muscle strength was the
main source of energy used by man. At the beginning of human history, the domestication
of animals provided the mechanical energy necessary for transport and agricultural
production, etc. The discovery by human beings that they could control forms of energy
that would be useful to them, such as fire, represented a very important milestone for
humanity to be able to cook their food and heat up with the use of thermal energy. About
7 thousand years BC, in the Neolithic period, the use of fire began. A few millennia ago,
hydropower from rivers and wind were used by humanity based on available science and
technology. Around 12,000 years ago, the Agricultural Revolution marked the beginning
of the use of animal traction, the power of winds and waterfalls in agricultural and
livestock production.
During Antiquity, the use of wind in sailing navigation was essential for colonization and
trade on the shores of the Mediterranean Sea, replacing rowing navigation that used
human muscle strength. During the Roman Empire, from 31 BC to 410 AD, firewood
was widely used for the production of weapons in the process of forging metals. This
caused deforestation of much of Italy and the Iberian Peninsula. At the same time, far
away from there, more specifically in China, great innovations in hydraulic technology
were introduced, through the creation of water lifting devices and irrigation systems.
Since the domain of fire until the advent of the 1st Industrial Revolution in the 18th
century, there has been no great evolution in the way humanity uses energy. Changes in
the global energy matrix, in terms of the diversity of sources and patterns of use, did not
change much over the centuries until the 1st Industrial Revolution.
The use of coal from the 18th century on energy production
Only with the advent of the 1st Industrial Revolution, also called “the age of coal and
iron”, which took place in England in 1786, the use and production of energy assume
fundamental importance in the replacement of men and animals by machines. With the
1st Industrial Revolution and the consequent industrialization process, the need for energy
increased and new primary sources, with greater energy density, were introduced. The
use of coal as an energy source marked the end of the era of renewable energy represented

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by the use of wood and the meager hydraulic and wind farms used since the dawn of
humanity to start the non-renewable energy era, the era of fossil fuels with the use of coal
and the invention of steam engines.
A steam engine has a boiler, which, with the heat from burning fuel, causes the water to
turn into steam, with the purpose of transforming the hot energy that is released by
burning fuel, coal. The adoption of the steam engine was slow, taking a century after
James Watt's patent (1769) was used to transform industrial production and land transport
with the advent of the railroad and its use in long-distance maritime transport with steam
vessels. The replacement of charcoal by coke in iron smelting was one of the "greatest
technical innovations of the modern era, as it ended the unsustainable use of wood in
England and skyrocketed iron production. In addition, coal laid the foundation for the
modern steel industry and paved the way for the advent of the key metal of
industrialization, iron.
The use of oil from the 19th century onwards in energy production
From 1860 onwards, in England, new transformations in the industry emerged. This phase
was called the 2nd Industrial Revolution which became known as the “era of steel and
electricity”. With the 2nd Industrial Revolution, which lasted until the first half of the
20th century, new fuels with greater energy power were needed, with petroleum being
the fuel that brought these properties together. Thus began a new phase in the use of liquid
fuels that continues to this day. Initially, petroleum was used only to obtain kerosene and
lubricating oils. At that time, the gasoline generated during the distillation of oil was
thrown away in rivers or burned. It was sometimes mixed with kerosene to produce a
dangerous explosive. Among the inventions that emerged during the 2nd Industrial
Revolution are the Bessemer process of transforming iron into steel, which allowed the
production of steel on a large scale, the dynamo that allowed the replacement of steam by
electricity and the internal combustion engine that allowed the large-scale use of oil
creating conditions for the use of its derivatives in the automobile and, later, in trucks and
planes.
The use of gasoline as a fuel for motor vehicles only began after the invention of internal
combustion engines and large-scale car production. The automobile became viable with
the invention of the internal combustion engine and the discovery that one could use the
petroleum derivative, gasoline, as fuel, which took place from 1876 onwards. Nikolaus
August Otto, German engineer and inventor, invented it and built the first four-stroke
internal combustion engine and determined the theoretical cycle under which the
combustion engine works, the well-known Otto cycle. Thereafter, the demand for
petroleum products, especially gasoline, rose sharply in industrialized countries. The oil
until then only used to obtain kerosene became a source of obtaining gasoline. A few
decades later, this same trend turned diesel into a fuel used in jeeps and trucks, and fuel
oil that was widely used in industry after World War II.
The use of electricity from the 19th century on energy production
The 2nd Industrial Revolution was the continuation of the process of revolution in
industry, through the improvement of techniques, the creation of machines and new
means of production. Advances in scientific and technological knowledge enabled the use
of electricity and the invention of electrical machines in the 19th century, together with
the introduction of automotive vehicles, which laid the foundation for the introduction of
the modern consumer society, characterized by an energy intensity never seen before in
the history of humanity. It was in 1913 in the United States, with the automobile industry

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as its flagship, that the Second Industrial Revolution was consolidated. With the 2nd
Industrial Revolution, electricity emerged as a combined effort of several engineers and
scientists, starting with Michael Faraday's discovery of electromagnetic induction. This
culminated in the work of Thomas Edison, who not only designed the first light bulb, but
also built an electricity generating plant and a direct current electrical system in 1880 to
power customers in lower Manhattan, New York.
Later, in the last two decades of the nineteenth century, the famous "war of electric
currents" took place between alternating current advocated by Nikola Tesla and George
Westinghouse and direct current advocated by Thomas Edison. The difference between
direct current and alternating current is that, while in direct current, electrons move in
only one direction, alternating current has electrons that change their direction constantly.
If electrons move in only one direction, this current is called continuous. If electrons
change direction constantly, it is alternating current. For the distribution of electricity,
alternating electrical current is significantly more practical than direct current, as it is
much easier to change the electrical voltage into alternating current than the voltage of
direct current.
Based on a work with rotational magnetic fields, Nikola Tesla developed a system for
generating, transmitting and using electrical energy from alternating current. Tesla has
partnered with George Westinghouse to market this system. The "war of electrical
currents" ended up favoring alternating current because it has the advantage of being able
to easily lower or increase its electrical voltage through transformers, and high power
transmission is more economical, as it offers less energy loss. The electrical systems
deployed in the world started to be based on it. Today, alternating current is the norm for
electrical energy systems that produce electricity using conventional and nuclear
hydroelectric and thermoelectric plants, among others.
The use of nuclear energy from the 20th century onwards in the production of
electrical energy
The operation of a nuclear plant in the generation of electricity consists of using the
nuclear reactor (the main part of the plant) to simply boil water whose steam is used by a
thermodynamic cycle to move an alternator and produce electricity. Nuclear energy is
obtained from the fission of the nucleus of the enriched uranium atom, releasing a large
amount of energy. The transformation of nuclear energy into electrical energy can happen
in a controlled manner in a nuclear reactor through the nuclear fission of uranium as the
main civil application of nuclear energy. Electric power was first generated by a nuclear
reactor on September 3, 1948 by the X-10 Graphite Reactor in Oak Ridge, Tennessee,
United States by turning on an electric light. Today, the United States is the country with
the highest number of nuclear power plants, totaling 104, representing 18% of the
country's energy matrix. France is at the top of the countries with the greatest dependence
on this type of energy, using 80% of nuclear energy in its energy matrix.
The main advantage of nuclear energy is that it makes it possible to avoid using fossil
fuels such as oil and coal in the production of electricity, which has come to be defended
even by some ecologists because it does not generate greenhouse gases. These ecologists
advocate a radical shift towards nuclear energy as a way to combat global warming
resulting from the emission of greenhouse gases from fossil fuels, especially oil.
Compared to hydroelectric generation, the use of nuclear energy has the advantage of not
requiring the flooding of large areas for the formation of reservoir lakes, thus avoiding
the loss of natural reserve areas or agricultural land, as well as the removal of entire

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communities in the areas that are flooded. However, nuclear power plants have the
disadvantage related to the final disposal of their waste (atomic waste) that has not been
resolved to date and the impossibility of avoiding accidents such as those that occurred
in Chernobyl in 1986 and in Fukushima in 2011 which, when they occurred, took on
catastrophic dimensions. .
Fossil fuels and global climate change
There is no doubt that human activities on Earth cause changes in the environment in
which we live. Many of these environmental impacts come from the generation, handling
and use of energy with the use of fossil fuels. The main reason for the existence of these
environmental impacts lies in the fact that the world consumption of primary energy from
non-renewable sources (oil, coal, natural gas and nuclear) corresponds to approximately
88% of the total, with only 12% of renewable sources. This huge dependence on non-
renewable energy sources has resulted, in addition to the permanent concern with the
possibility of depletion of these sources, the emission of large amounts of carbon dioxide
(CO2) and other greenhouse gases into the atmosphere that set a record in 2013 having
been on the order of 36.3 billion tons, approximately 3.9 times the amount issued in 1960
(9.3 billion tons).
Everything suggests that, if the current trend in energy consumption is maintained, the
share of fossil fuels (oil, coal and natural gas) in the world energy matrix will reach 80%
in 2030. Oil has a dominant position among the sources of energy used. Oil, coal and
natural gas are, in order, the most used energy sources today in the world's final energy
consumption. The industrialized countries of the OECD (Organization for Economic
Cooperation and Development) are the biggest energy consumers, followed by China,
Russia and other countries in Asia. According to the International Energy Agency, oil and
coal are the main responsible for the emission of CO2 into the atmosphere, whose biggest
emitters are the industrialized countries of the OECD [See article AIE: mundo se
encaminha para futuro energético insustentável (IEA: world moves towards an
unsustainable energy future) published on the website
<http://g1.globo.com/mundo/noticia/2011/11/aie-diz-que-mundo-se-encaminha-para-
futuro-energetico-insustentavel.html>). If the current trend is maintained, it is very likely
that by 2025 the world will be using 75% more energy and that most of it will be supplied
by oil, coal, natural gas and nuclear energy. This is the likely energy scenario for the next
30 years, if the current global energy matrix is maintained.
The International Energy Agency (IEA) warned that "the world will move towards an
unsustainable energy future" if governments do not adopt "urgent measures" to optimize
available resources. For the IEA, by 2035 a global investment of US$ 38 trillion in energy
infrastructure would be needed - two thirds in countries outside the Organization for
Economic Cooperation and Development (OECD) - to meet the growing demand, 90%
to supply emerging countries like China and India. Regardless of the various solutions
that may be adopted to eliminate or mitigate the causes of the greenhouse effect, the most
important action is, without a doubt, the adoption of measures that contribute to the
elimination or reduction of the consumption of fossil fuels in energy production, as well
as for its more efficient use in transport, industry, agriculture and cities (homes and
commerce), given that the use and production of energy are responsible for 57% of the
greenhouse gases emitted by human activity (Lashof, DA & Tirpak, DAorgs. Policy
options for stabilizing global climate, Washington, DC, Environmental Protection
Agency, 1989). In this sense, it is essential to implement a sustainable energy system.

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The future sustainable energy system
In a sustainable energy system, the global energy matrix should only rely on clean energy
sources (hydroelectric, solar, wind, hydrogen, geothermal, tidal, wave and biomass), and
therefore should not rely on the use of fossil fuels (oil, coal and natural gas). Until this
condition is reached, the world energy matrix should go through a transition in which
renewable and non-renewable energy sources coexist, such as the proposal by the
Worldwatch Institute, which advocates halving the world production of oil and 90% of
coal, while renewable energy sources should grow almost 4 times. By the year 2030,
renewable energies should account for 70% of the planet's total energy production. To
optimize the energy resources available on the planet, it is necessary to implement a
sustainable energy system on a global scale. The technologies are already available to
initiate this historic energy transition that will only occur with fundamental changes in
energy policy in the vast majority of countries [ALCOFORADO, Fernando. Energia no
mundo e no Brasil (Energy in the world and in Brazil). Curitiba: Editora CRV, 2015.
Page 31].
According to the Worldwatch Institute, the first step in changing energy policy in the
world is to redirect a large number of government policies in countries so that they are
aimed at achieving the central goals of energy efficiency and reducing the use of fossil
fuels. For example: rewarding the acquisition of efficient motor vehicles and electric
vehicles with reduced taxes on them, encouraging high-capacity mass transport
alternatives on rails such as subways and trams to replace the automobile, implementing
railroads to replace the use of trucks in freight transport, restructure industries to make
use of clean and renewable energies and raise taxes on fossil fuels. A sustainable energy
system will only be possible if, in addition to abandoning fossil fuels, energy efficiency
is also greatly improved. With the sustainable energy system, it is very possible that
natural gas will become, among fossil fuels, the only one of these energy resources to be
used in the future. Nuclear energy will not be an important source of energy in a truly
sustainable energy system. This is largely due to the accidents at Chernobyl in the former
Soviet Union and Fukushima in Japan.
Regardless of the various solutions that may be adopted to eliminate or mitigate the causes
of the greenhouse effect, the most important is undoubtedly the adoption, in the transition
phase, of measures that contribute to the elimination or reduction of the consumption of
fossil fuels in the production of energy, as well as for its more efficient use in transport,
industry, agriculture and cities (homes and commerce), given that the use and production
of energy are responsible for the emission of 57% of the greenhouse gases emitted by the
human activity. In this sense, it is essential to implement a sustainable energy system.
Conclusions
For these reasons, humanity is currently facing the urgent need to replace fossil fuels
(coal, oil and natural gas) with clean energy sources to avoid the catastrophic climate
change that is admitted with the maintenance of the current energy policy, as well how to
adopt energy efficiency or energy saving measures to reduce dependence on fossil fuels.
Clean energy refers to any energy source that does not emit polluting substances. This is
the most basic and succinct definition of clean energy. Its production and consumption
are important for protecting the environment and for improving people's quality of life.
The clean energy sources to be used preferably are (hydroeletric, solar, wind, hydrogen,
geothermal, tidal, wave and biomass). Exceptionally, nuclear energy could be used as a
source of energy, which would have restrictions due to the risks it represents, and natural

6. 6
gas, as it is the fossil fuel that is less aggressive to the environment. Clean energy sources
are already a reality around the world. The future of the energy sector around the world
will necessarily mean the use of clean energy sources. Clean energy is a concrete
alternative to face environmental degradation and the misuse of the planet's natural
resources. The use of clean energy is, without a doubt, the rational way to guarantee the
sustainability of planet Earth for current and future generations.
The transition from the current energy matrix based on fossil fuels to one that
contemplates the adoption of an energy matrix based on clean energy requires the
optimization of energy resources available on the planet, with world oil production being
reduced by half and coal by 90% , while that of renewable energy sources would grow
almost 4 times. Progressively, the world energy matrix would evolve to have in its
composition the predominance of clean and renewable energy.
* Fernando Alcoforado, 81, awarded the medal of Engineering Merit of the CONFEA / CREA System,
member of the Bahia Academy of Education, engineer and doctor in Territorial Planning and Regional
Development by the University of Barcelona, university professor and consultant in the areas of
strategic planning, business planning, regional planning and planning of energy systems, is 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,
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) and A humanidade ameaçada e as estratégias para sua sobrevivência
(Editora Dialética, São Paulo, 2021) .