There are a wide variety of energy resources available on planet Earth today, some of them being used by mankind to generate electricity and heat, while others requiring serious technological advancements to become a great source of clean power for us.

Energy Resources – Definition

Energy represents the capacity to do work and can be found in all the life processes that are taking place on the planet.

The energy resources can produce heat, power life processes, move objects, or generate electricity.

All the energy resources available on the planet can be divided into energy resources that pollute the environment and energy resources that can be considered clean, because they release no harmful emissions into the atmosphere.

Energy Resources that Pollute the Environment

The energy resources used today on a large scale for energy and heat production on the planet are represented by non-renewable energy resources also known as fossil fuels.

We can include here energy resources such as coal, oil, natural gas and nuclear energy.

1. Coal

Coal is a black or dark-brown combustible rock that consists primarily of carbon and was formed millions of years ago from the dead plants and trees that were compressed by the intense pressure and heat in the underground rock.

Coal can be classified into four main types after their carbon and heat content.

1. Lignite (25% to 35% carbon).
2. Sub-bituminous (35% to 45% carbon).
3. Bituminous (45% to 86% carbon).
4. Anthracite (86% to 97% carbon).

Coal is extracted using underground or surface mining depending on the geology of the coal deposit and the distance from the surface.

Coal is still used today to generate heat (for heating and cooking in some countries) and also for electricity production because is one of the cheapest sources of energy.

The problem with coal is generated by the massive amount of harmful emissions released while burning coal for heat or electricity production.

Coal is actually the cheapest, but also the most polluting energy resource on the planet today, and this is the reason why the use of coal will be slowly phased-out, and replaced with cleaner power resources.

2. Oil

Oil known as crude oil or petroleum is a thick and black liquid that primarily consists of carbon and hydrogen.

The oil thickness depends very much on the concentration of hydrocarbon molecules in its composition, and contains besides carbon and hydrogen, significant traces of sulfur, nitrogen and oxygen.

The oil deposits available today have been formed millions of years ago when the dead marine organisms have been sunk to the bottom of the ocean and were buried under deposits of sedimentary rock.

Due to the intense heat and pressure in the underground rock, the marine organisms have been turned into oil over a period of millions of years.

Oil deposits are located today in underground geological formations called reservoirs.

When such a reservoir (onshore or offshore) is detected, oil will be extracted by drilling a well.

Once recovered from the underground rock, oil is transported through pipelines, with large ships (oil tankers), via rail or on the road using trucks, it will be moved to refineries where will undergo a complex refining process that will create petroleum products such as fuels (gasoline, diesel and jet fuel), asphalt and many others.

Oil is primarily used today in the transportation sector and to create synthetic products such as plastics and petrochemical products.

Oil is a fossil fuel that releases harmful emissions into the atmosphere while burning, and this is the reason why oil and coal will be slowly replaced by cleaner sources of energy such as natural gas and renewables.

3. Natural gas

Natural gas is considered today the cleanest fossil fuel and has a good chance to become in the near future, the main low-carbon energy source that will successfully replace coal and oil as main sources of power used on the planet.

Natural gas reserves have been formed millions of years ago when dead marine organisms have been sunk to the bottom of the oceans and were buried under deposits of sedimentary rock.

Under the action of intense heat and pressure, the dead marine organisms have been turned into natural gas over a period of millions of years.

Exactly like oil, we can find natural gas deposits today in the underground rock (onshore and offshore) called reservoirs.

Natural gas reserves are categorized into dry or wet reserves.

Dry gas is the natural gas that contains mostly methane (CH₄), while wet gas contains besides methane, 1ethane, propane, pentane, butane etc.

These are called natural gas liquids or shortly NGLS, and are used to create conventional plastics, refrigerants and others.

Conventional natural gas reserves are extracted by drilling wells, while the unconventional reserves of natural gas such as shale gas, tight gas, sour gas and coal bed methane require specific extraction techniques (hydraulic fracturing or simply fracking).

When natural gas is extracted alongside oil, it is called associated gas.

In the past, associated gas was considered waste and was burned on-site as a waste gas.

However, today is captured and used as natural gas.

Once extracted from the reservoir, natural gas is sent through pipelines (gathering lines) to the processing plants where the different hydrocarbons and fluids will be separated from the pure natural gas.

The processed natural gas will become ‘pipeline quality’ dry natural gas and will become ready for transportation.

Processing natural gas involves four main steps that are required to remove the various impurities:

1. Oil and condensate removal
2. Water removal
3. Separation of natural gas liquids.
4. Sulfur and carbon dioxide removal.

Natural gas will then be transported through pipelines called feeders to distribution centers or it will be stored into underground reservoirs for later use.

Natural gas is a fossil fuel, but because it releases a small amount of harmful emissions into the atmosphere while burning, it is the perfect candidate to be used both as electricity and heat source, but also as fuel, and replace the dirty coal and oil for a cleaner environment.

4. Nuclear energy

Nuclear energy is the power held in the nucleus of an atom and can be harvested using two different nuclear reactions like nuclear fission and nuclear fusion.

Nuclear fission produces energy by splitting atoms, which releases heat and energy that can be used to produce electricity.

The most common fuel used in the nuclear fission reaction here on the planet is uranium, but also other elements such as plutonium and thorium.

Today, mankind uses only the nuclear fission reaction in its nuclear power plants because the other nuclear reaction (fusion) seems to be too advanced compared to the today’s technology.

Nuclear fission produces clean electricity, but the nuclear waste resulted after the nuclear fission reaction that takes place in the nuclear reactors, it is hard, dangerous and very expensive to dispose.

The nuclear waste, which is very dangerous for any living being is the reason why nuclear fission will be replaced by nuclear fusion in a not so distant future.

Using hydrogen (a very abundant element on Earth and in the universe) as nuclear fuel in the nuclear fusion reaction will produce only heat and clean electricity, and as waste only water, which is perfect for us.

The nuclear reaction that takes place in the Sun every second, is the nuclear fusion reaction of the hydrogen, which is turned into helium, releasing heat, light and a tremendous amount of clean energy and radiation.

Mankind has already made significant steps towards mastering the nuclear fusion reaction, but there is plenty of work to do to make nuclear fusion commercially viable.

Energy Resources that Are Considered Clean

The energy resources considered clean today are represented by the renewable resources.

We can include here renewable resources such as solar, wind, water, gravity, the internal heat of the planet and biomass.

1. Solar energy

Solar energy or the power of the Sun, represents today the greatest source of renewable and clean electricity on the planet.

We are using the sunlight to heat and illuminate rooms (in a passive house, which will generate low energy bills), to heat water or to generate clean electricity by using large mirrors pointed toward the top of a tower where an agent (usually molten salt) is heated at high temperatures to produce steam and spin a turbine (solar thermal) or with the help of solar panels covered with solar cells (solar PV systems).

The technology used today to harvest the power of the Sun is not very efficient (most solar cells are made of silicon and have an efficiency between 13% and 21%), and this the reason why we need to develop a new type of solar technology that can turn into clean electricity a way larger amount of the sunlight.

Solar power is a clean and renewable energy resource and has a great future ahead.

2. Wind power

The wind is another great energy resource that can be used to navigate with boats and ships, and also to generate clean electricity.

Wind is produced by the Sun by heating the different layers of the atmosphere in an uneven way.

The warm layer of air will move up, while the colder layer of air will move down, and this is the wind created by the Sun.

To generate clean electricity, mankind uses very tall wind turbines installed onshore and offshore in areas without natural obstacles, where the wind is steady throughout the year.

Today, wind energy is becoming more popular among home users because small size vertical axis wind turbines have become affordable and they are also silent and friendly with wildlife.

Wind power is a great renewable and clean energy resource that will become a main source of green power for mankind in the future.

3. Water

Water is a very complex resource on the planet because it sustains life and is also a great energy resource.

The kinetic power of the falling or fast moving water (streams) is used to generate clean electricity in hydroelectric power plants.

The kinetic power of the waves is also used to generate clean electricity.

Because water is a renewable resource on the planet, we can say that until we have water on Earth, we also have a great energy source at our disposal.

The power of the water (hydropower) is another clean and renewable resource that will continue to be used by mankind in the future.

4. Gravity

Gravity is a pretty constant force on our planet, but in terms of energy generation, is the source of tidal power.

Tidal energy or the power of the tides is a great energy resource produced by the combined gravitational forces of the Sun, Moon, and Earth, acting upon the water in our oceans.

Tidal power is a form of hydropower that converts the energy present in the natural rise and fall of the tides into clean electricity.

Tidal power plants can only be found along coastlines because only there we can find two high tides and two low tides daily.

With the current technology used to harvest tidal energy, the differences in water levels must be at least five meters high to produce electricity.

Tidal energy can be produced today using tidal barrages, tidal fences and tidal turbines.

Because ocean water is 832 times more dense than the air, the underwater turbines used to harvest tidal energy are more robust.

Modern tidal turbines contain a hole in the center of the turbine, which can be used by marine life as an escape corridor from the rotating turbine.

The technology used to harvest tidal power needs to evolve because the difference in height of 5 meters between the low and high tide required today is not available on the entire planet.

In many coastal areas of the planet, the difference in height between the high and the low tide is much smaller, and technology must evolve to turn these places (which are the most frequent) into sources of tidal energy.

Tidal power is a clean and renewable energy resource that along with the other renewables has a great future ahead.

5. Geothermal energy

Geothermal energy or the internal heat of our planet is a great energy resource that can be used for residential heating and cooling and also to generate clean electricity.

Geothermal power is produced by the hot nucleus of our planet (also called the inner Sun because is hotter than the surface of the Sun) and reaches the surface under the form of hot steam and water.

In many countries of the planet (Iceland is one of them) the geothermal resource is so powerful that it provides free warm water for all households.

It is also a great source of residential heating during the winter and cooling during the summer.

The steam produced by the very hot water coming from the underground is also used to spin a turbine that will generate clean electricity using a generator.

Being a continuous and clean energy resource, geothermal power represents an energy source of the future.

6. Biomass

Biomass consists mostly of wood waste, agricultural waste, energy crops, human and animal organic waste, trash etc.

Biomass is the only renewable energy resource (trees regrow) that releases harmful emissions into the atmosphere while burning.

However, the level of emissions released by the burning wood are less harmful compared with the level of emissions released by the burning fossil fuels.

Because wood and the agricultural waste, energy crops, trash and the human and animal organic waste are all produced daily, we can say that biomass energy is a great low-carbon energy resource because it turns the trash, the plant waste and organic waste into electricity.

As long as we live on the planet, the trash and the waste materials produced by us will represent a continuous source of low carbon energy for mankind.

Final conclusion

Fossil resources no longer represent a viable energy solution for the future, and this is the reason why we need to work hard and develop the advanced technology required by the renewable resources of energy because the future must be clean and free of pollution.