"I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that."

Thomas Edison (1931)

On The World Counts website, the observation of one of the many featured meters can stop us from moving further. This meter indicates the number of terajoules (one terajoule is equivalent to one billion joules) used, in real-time, in the world. This meter, much like our revolving world, does not stop. The annual global energy consumption is estimated at around 580 million terajoules or about 13.865 million tons equivalent to oil. It’s hard to think about these measurement units, right?

Putting this in another way: the annual global energy consumption corresponds to the energy released by Hiroshima’s atomic bomb…every four seconds.

Nearly 85% of the energy we use comes from fossil fuels. Oil is the largest source of energy, followed by coal and natural gas. The increase in global energy consumption is being fed, largely, by coal and gas, which release egregious amounts of carbon dioxide (CO2) into the atmosphere, worsening the greenhouse effect and the consequential climate changes. (Again, we suggest taking a look at the meter, which indicates, in real-time, how many tons of CO2 are released into the atmosphere).

In 2019, around 43,1 billion tons of CO2 were released into the atmosphere, as a result of human activities. It was a historic record. These emissions would be able to shape a gigantic “CO2 cube”, with 30 km on each side.

Renewable energy sources. The Magnificent 5

Nearly 83% of the energy we use comes from non-renewable sources such as oil, coal, and natural gas, which are impossible to recharge. Renewable energy sources are natural resources, capable of regenerating in a short period and in a sustainable way. These sources, considered clean and eco-friendly, also represent a thriving sector, one that has been creating jobs, expanding access to energy in developing countries, and helping with energy-cost reduction.

All of these factors have contributed to true growth in renewable energies in the last few years, where eolic and solar energy established new records of electricity production.

Biomass

Biomass is the organic matter from plant or animal sources, that may be used in a solid, liquid, or gas state. Solid biomass has, as a prime source, agriculture products and waste (including plant and animal substances), forest residue, and biodegradable components of industrial and urban waste.

The liquid is found in a series of liquid biofuels with the potential to be utilized, such as biodiesel, drawn from rapeseed or sunflower oil: ethanol, made with the fermentation of carbohydrates (sugar, starch, cellulose), and methanol. The gas biomass is found in farming industry waste, from agribusinesses and the urban environment, as well as municipal solid waste and landfills (MSW).

Biomass is used directly as fuel or through energy production from processes such as pyrolysis, gasification, combustion, or co-combustion. Among the advantages are the low cost in the acquirement, the low polluting character, the non-issuing of carbon dioxide (according to the natural cycle of neutral carbon), and is less corrosive to the types of equipment (heating boilers, ovens, etc.).

Wind

Over the last two thousand years, human beings have taken advantage of wind power, whether to move sailing boats, grind cereal or draw water from wells. Nowadays, wind, one of the cleanest sources in the world, represent one of the primary sources of electricity production. Generally, the windfarms are established in locations where the annual average speed of the wind exceeds 6 m/s, usually in mountainous and off the coast.

Since James Blyth (1839-1906), the first engineer of eolic energy in the world, a lot has changed. The modern wind turbines, which can reach up to 90 meters high, are very complex, having around 8000 pieces assembled.

Geothermal

Geothermal energy is obtained by heat generated from the Earth’s core. The Romans were pioneers in using this heat source, in the buildings they designed; besides having built community baths in thermal fountains, in Italy, a country that gave birth to the first thermal power plant, back in 1904.

This type of energy may be used in thermal power plants, through a wind turbine whose propeller blades are moved by the steam of the water produced by the Earth’s core heat. This rotation motion is transmitted to the axis of generators, producing electricity. In Portugal, in the Autonomous Region of Azores, electricity production units are resorting to geothermal energy.

Geothermal energy is also used as a heat source for greenhouses or heat pumps, hot springs or industries, and the heating and cooling of buildings. In contrast to solar and wind energy, geothermal energy is always available but presents an unpleasant feature: the foul smell of rotten eggs, very characteristic of hydrogen sulfide being released.

Hydro

There are records, in Greece, from two thousand years ago, of the use of water power to spin windmills and grind cereal. Hydroelectric energy, generated from water motion, is one of the largest, cleanest, and cheapest energy sources, used by over 60 countries all over the world, being able to respond to half of the worldwide electricity needs.

China is the largest manufacturer of hydroelectricity and has the largest hydroelectric power plant in the world, located in the Three Gorges Dam. Nearly 71% of the renewable electricity generated by Earth comes from water energy.

In Pico Island, Azores, there is a power plant with 400 kW, the first in the world to produce electricity from the waves in a regular way.

Solar

In less than 80 minutes, the sun provides the same energy amount the world needs for a year. This means that, during a year, the sun could feed the world, in terms of energy needs, almost 7000 times. We’re not capable, obviously, at the moment to recover all of this potential energy, but if we could, 2% would be more than enough.

In 1839, Alexandre Edmond Becquerel found a photovoltaic effect, that is nothing more than the ability to create an electric current from the sun's rays. Russell Ohl invented the first cell for solar panels in 1941, having the first commercial panel released by Bell Laboratories, in 1954. It was because of this invention, by using photovoltaic solar panels and thermal solar panels, that it became possible to produce energy, resorting to the sun.

More democratic energy?

The production of renewable energy in developing countries has surpassed the ability generated by fossil fuels. Factoring in, we have the constant growth of electricity needs, the implementation of innovative energetic policies, large investments, and low cost of technology, which have assured, for the first time, in 2017, that developing countries would occupy a prominent place in the production of renewable energy.

According to the Renewables Global Status Report, of the REN21 network, which foresees the evolution of renewable energies, all over the world, developing countries have sustained the majority of the investments placed in renewable energies in 2019, reaching 54% of the global total, surpassing the developed countries margin, for the fifth year in a row. Brazil has come forward as being the primary growth engine of renewable energies in Latin America.

The drastic fall in the development cost of the technologies associated with the production of renewable energy, in the last years, has allowed the developing countries to increase their production capacity.

In 2020, a report made by Bloomberg New Energy Finance (BNEF) explained that developing countries had produced cleaner energy than the capacity of energy production generated by fossil fuels, for the second year in a row. In that same year, Brazil was placed second, globally, among the clean energy producers (with 84,1%). Portugal occupied the 8th position, with nearly 60% of the energy originating from renewable sources. The data can be found in Global Energy Statistical Yearbook (Enerdata).

A salty solution

Through Project Malta (that has recently turned into Malta Inc. company) developed by the X department of the Alphabet company (Google owner), it has been discovered that salt - more precisely molten salt - can, possibly, become the solution to store renewable energy at a large scale.

The underlying idea is the storage of energy in the form of heat, in high-temperature molten salt, being conditioned after, in the cold, dipped in a low-density liquid for days, or weeks, until it’s necessary for use. For the development of this project, the resources are accessible and cheap materials, like salt, steel, antifreeze, and air.