, Volume 1, Issue 1–2, pp 4–9 | Cite as

Perspectives of the World’s Energy System

  • José GoldembergEmail author
Original Article


The evolution of the energy systems since 1850 is presented as well as the contribution of electricity since 1970. Biomass as the dominant source of energy in 1850 was replaced by coal. Afterwards, petroleum and natural gas became dominant but changes are slow and take many decades. In recent years, the contribution of renewables (particularly electricity from wind and photovoltaics) is growing faster than other sources of energy but their contribution is still relatively small. The geopolitical and environmental consequences of the heavy dependence on fossil fuels are discussed as well as the main solutions being implemented to face these problems: increase of the share of renewables and energy efficiency. It is shown that the measures taken so far fall short of meeting the targets of the Sustainable Development Goals (SDGs) adopted by the United Nations Organization and that additional efforts are needed. The eventual role of carbon capture and storage (CCS) and geoengineering is highlighted.


Evolution of the world energy system The geopolitics of petroleum The role of renewables Energy efficiency The Sustainable Development Goals (SDG7) 

1 Introduction

Energy, food, water, and air are essential ingredients of life. However, unlike food, water and air consumption of which is approximately the same for all human beings—rich and poor—the energy consumption “per capita” can vary considerably between the poor and the rich and from country to country.

Worldwide energy consumption approximately is 1.5 tep1/capita: in the USA, ≈ 7 tep; in India and many other African countries, less than ≈ 0.1 tep. Energy consumption varies widely with GDP2 per capita and patterns of consumption.

With an expanding population, the world’s energy consumption has grown at a rate of ≈ 1.5%/year between 1850 and 1950 and that rate of growth has doubled to approximately 3%/year from 1950 to 2000. In recent years, it has declined to approximately 2%/year (Fig. 1).
Fig. 1

The world’s primary energy consumption (EJ) (1850–2000) (GEA 2012) EJ (exajoules), 108 J

The energy sources have changed considerably since 1850 when biomass was practically the only source of energy available with a small contribution from coal, which increased rapidly and became dominant. Petroleum consumption started to increase in 1900 and became dominant around 1975. After that, the contribution of natural gas rose vigorously. Hydropower, nuclear, biomass, and other renewables made also significant but not spectacular contributions.

The transition of the world’s energy system from biomass to coal, to petroleum, to natural gas, and to nuclear and renewables is due to a combination of technological advances, availability of resources, consumption patterns, and relative cost.

As an example, the consumption of petroleum derivatives increased quickly in the beginning of the twentieth century after the development of the internal combustion engine, which opened the way to the automobile. Liquid fuels proved to be less awkward than coal to transport and use. The discovery of large deposits of petroleum in the USA and the Middle East at low cost of production consolidated petroleum as the dominant fuel of the twentieth century. Today, transportation is almost completely dependent on liquid fuels derived from petroleum (diesel gasoline and kerosene) and represents 23% of the world’s energy consumption. More recently, the contribution of natural gas is increasing steadily while the contribution of petroleum decreases (Fig. 2).
Fig. 2

The composition of the world’s primary energy consumption (1850–2000) (GEA 2012)

Presently, the world’s energy system remains highly dependent on fossil fuels (coal, petroleum, natural gas) which represent 78% of total consumption; biomass contributes 7%, hydroelectricity 6%, nuclear energy 5%, and other renewables (mainly wind and PV) 4% (Fig. 3).
Fig. 3

The world’s energy matrix (BP 2018)

Renewables include wind. PV, biomass, and geothermal; wind represents more than half of the contribution of renewables.

The present energy system is heavily dependent on fossil fuels (85% in primary energy consumption).

The sources of electricity production worldwide (2017) are shown in Fig. 4.
Fig. 4

World electricity production in 2017 (TWh) (BP 2018)

Other renewables include wind, PV, biomass, and geothermal.

Electricity is easy to transport and can be converted into motive power with high efficiency (close to 100%) unlike fossil fuels for which it is necessary go through a thermodynamic cycle, which has the limitations imposed by the 2nd Law of Thermodynamics. Efficiencies higher than 50% are difficult to achieve in the generation of electricity from fossil fuels.

One of the striking features of the evolution of the world’s energy system is the increased importance of electricity, which is growing faster than the total energy growth (Fig. 5).
Fig. 5

Evolution of primary energy electricity (1970–2016) (IEA 2014)

The importance of electricity in the world’s energy consumption could grow even more if electricity use in transportation increased.

The two main drivers of change in the world’s energy system are the geopolitics of petroleum and environmental concerns.

2 The Geopolitics of Petroleum

The geopolitics of petroleum today is determined basically by Saudi Arabia which leads OPEC (Organization of the Petroleum Producer countries), Russia, and the USA. Increasing or decreasing petroleum production in these countries determines its price around the world, which has enormous economic consequences. Among the three main players, Saudi Arabia is the dominant one, not only because it produces approximately 10 million barrels per day (≈ 15% of the world’s total production) but because it has spare capacity to extract and process 2 or 3 additional million barrels per day at very low cost. It is therefore able to set oil prices worldwide and create turbulence in the markets.

If the price of oil is set at a very high level (≈ US100), it benefits Saudi Arabia but encourages other countries to produce petroleum even if it is more expensive which is what happened in the USA where the new “fracking” technology which opened the way to the production of large quantities of petroleum at ≈ US$50/barrel. The same happened to production of petroleum in the PRE-SAL (deep ocean production) area in Brazil and other countries at costs around US$40/barrel. If Saudi Arabia sets the price too low (US$30/barrel) to discourage competition, the lower income could force its government to curtail social programs in the country.

More recently with political turmoil involving other producers such as Iran, Iraq, Libya, and Venezuela, the international cost oil reached a price of US$80/barrel in 2018 after reaching a low value of US$30/barrel.

As the political crisis involving these countries stabilized, their oil production increased, and the cost of oil most likely will decrease and stabilize around US$50/barrel, in the near future.

The oil sector is moving from an age of scarcity in which prices of finite resources could be expected to rise to an age of plenty (Butler 2018).

3 Environmental Drivers of The Energy System

In the last 50 years, concerns on the environmental consequences of the use of fossil fuels at the local level (air pollution) and at the global level (warming due to the increase of the CO2 in the atmosphere) increased very significantly.

Coal and petroleum have impurities such as sulfur oxides and particulates, which are thrown in the air when burned in industrial process and in electricity production as well as when petroleum derivatives such as gasoline or diesel oil are burned in automobiles, trucks, and busses. The problems caused by local pollution (particularly health problems) pressured national governments to tighten local environmental regulations.

CO2 emissions are the unavoidable consequences of burning any fossil fuel and represent approximately 60% of all greenhouse gases emitted in the world.

The problems of global warming—although more controversial—led national governments to an international agreement of which the most recent is the Paris Accord with the objective of avoiding adopt in global temperature raise of more than 2 °C.

There are two main strategies to address such problems:
  • To use energy more efficiently

  • To increase the contribution of renewable energy sources replacing fossil fuels.

These strategies are part of the Sustainable Development Goals (SDG7) adopted by the United Nations with the following targets to achieve.
  • By 2030, double the global rate of improvement in energy efficiency

  • By 2030, increase substantially the share of renewable energy in the global energy mix

Other options to address the temperature increase caused by CO2 (and other greenhouse gases) are being considered such as CCS (carbon capture and storage) and geoengineering but they have not reached yet a mature stage.

4 Energy Efficiency

The energy efficiency is usually measured by the energy intensity I which is rate of energy consumption divided by GDP.
$$ \mathrm{I}=\raisebox{1ex}{$E$}\!\left/ \!\raisebox{-1ex}{$ GDP$}\right. $$
What the data shows is that there are is a strong “decoupling” between GDP growth and primary energy supply; GDP is growing more rapidly than energy consumption. Consequently, the energy intensity is decreasing at 2.2%/year (Fig. 6).
Fig. 6

Trends in underling components of primary energy intensity at a global level, 1990–2015 (World Bank 2018)

The SDGs require a decrease of the intensity of 2.6% per year.

The industrial sector made the most progress toward improved efficiency. Mandatory energy performance regulations are an important instrument in driving reductions in energy intensity as well as modernization. In China, the largest savings come from avoiding coal use in industry, which can in large part be attributed to policies of phasing out older, more inefficient coal-based plants.

Transport remains the highest energy-consuming sector and electric mobility represents a key opportunity to drive reductions in transport energy intensity.

5 Renewables

In the last 50 years, a considerable effort has been made to promote with government incentives, the introduction of “new” renewables in the market, the main ones being wind and PV for electricity production and biofuels for transportation. Biofuel production of ethanol to replace gasoline and biodiesel to replace diesel oil represent only 3% of the petroleum consumption (Fig. 7).
Fig. 7

Global trends in ethanol, biodiesel, and HVO production, 2006–2016 (REN21 2017)

This is an area in which Brazil could play an important role since it could increase its biofuel production (ethanol from sugarcane and biodiesel from soybeans) since there are very favorable conditions for expansion of its present production of these fuels.

The development of “drop-in” biofuels that could be used in aviation replacing kerosene would be extremely important to reduce the growing CO2 emissions resulting from the growth of air transportation in the world already responsible for 5% of the CO2 emissions.

Large investments in renewables for the production of electricity are being made in recent years: 320 billion dollars in 2016 more than investments in electricity produced from fossil fuels and nuclear and their contribution is growing fast but from a very small baseline. In contrast, investments in fossil fuels and nuclear have been made for many years (Fig. 8).
Fig. 8

Global electricity market shares: 1980–2014 (Liebreich 2018)

A large expansion of electrical vehicles would favor the expansion of renewables for electricity generation but battery-driven automobiles would require also a new extensive grid of recharging stations which particularly in a large country is a serious problem.

Electrically driven automobiles using batteries were tried in the beginning of the twentieth century but were abandoned when Otto cycle and diesel engines proved to be more attractive. The basic reason for that is that the energy content of 1 liter (L) of gasoline is approximately 9000 kWh/L while the best batteries available today (based on lithium) store at most 0.3 kWh/L, i.e., 30 times less. Lead acid batteries store only 0.1 kwh/L (Fig. 9).
Fig. 9

Storage capacity of batteries; gasoline 9000 kWh/L; alcohol 5000 kWh/L (Lawson 2018)

What this means is that a 60-L tank reservoir, which is used in most automobiles, would have to be replaced by 1800 L of lithium batteries in order to guarantee the same autonomy (usually 200–300 km). Since electric-run automobiles are more efficient, that number can be reduced but is still very significant. In addition to that, lithium-based batteries are still expensive although their cost is decreasing.

It is clear therefore that battery storage is still very far from reaching a stage in which it could compete with ethanol or gasoline in the transportation area.

The problem remains of producing electricity to charge/recharge the batteries. In countries where renewable sources of electricity are dominant such as Norway, the introduction of electric cars means a strong reduction of the emissions of pollutants and CO2. In larger countries where fossil fuels generated electricity, the introduction of battery-run automobiles will help clean the air in the cities but will not solve the problem of CO2 emissions.

There are presently in the world only 3 million electrically driven automobiles out of the 1 billion in the world including hybrids.

In large countries such as the USA where electricity is produced mainly from fossil fuels (≈ 90%), the introduction of a large share of renewables will not be simple because it will require a major reorganization of the power sector for the following reasons:
  • Wholesale power prices will decline as well as emissions but volatility of electricity costs will increase

  • “Ancillary services” will become more important such as frequency and voltage regulation, demand response, and especially storage

  • One should also realize the immense amounts of storage that will be needed when renewables are absent (evenings for solar and wind fluctuation). As an example, 1 million liters of lithium ion batteries are able to store only 1 MWh. A wind farm with 10 MW operating for 10 h produces 10 MWh. To store this amount of energy during 10 h in which there is no wind, one would need 300,000 L of lithium-ion batteries

  • The costs of the traditional sources of electricity such as coal will be affected negatively

6 Conclusion

To achieve the goals of sustainable development discussed and thus avoid serious environmental problems at the local and global level is not proving to be an easy task.

Recent estimates of the International Energy Agency (Birol 2018) indicate that the present investments in the expansion of the contribution of renewable energy sources fall shortly of what is necessary to avoid an increase of 2 °C to the global average temperature.

It is clear therefore that stronger emphasis on energy efficiency is necessary as well as additional efforts on new technologies such as carbon capture storage (CCS) and eventually geoengineering.


  1. 1.

    Tep, tons of equivalent petroleum

  2. 2.

    GDP, gross domestic product


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Copyright information

© Escola Politécnica - Universidade de São Paulo 2018

Authors and Affiliations

  1. 1.Instituto de Energia e AmbienteUniversity of São PauloCidade UniversitáriaBrazil

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