Renewable energy is considered today the future in terms of energy production on the planet because the fossil fuels used today on a large scale for energy production are no longer a viable solution for the green society that will follow.

Renewable energy is booming today due to the increased interest in clean technologies, and due to the innovations in the sector that are bringing down the costs.

The renewable energy sources known today can be divided into two different categories:

1. Renewable energy sources that have no impact on the environment;

2. Renewable energy sources that have some impact on the environment.

Renewable energy sources that have no impact on the environment

We can include here clean sources of power such as: solar energy, water and hydrogen.

1. Solar energy

The power of the Sun is the main source of clean energy in the Solar system and also on our planet, which means that we need to increase the generation capacity for solar energy on planet Earth in order to replace the dirty fossil fuels.

The sunlight is used today in two different forms.

The Sun is used to generate clean electricity and to heat water or another agent.

The sunlight is also used to naturally heat and illuminate the rooms in a house, which will drastically lower the energy bills of the building.

The house needs to be built from natural materials (preferably wood) and must have a certain position in relation to the Sun (to allow sunlight to enter the rooms), and also needs to be well insulated (to keep the warm air inside the house during the winter and also the cold, ventilated air inside the building during the summer).

To produce electricity (clean power), we are using solar panels filled with solar cells that are converting the sunlight into clean electricity through the photovoltaic effect.

The sunlight is also used to concentrate heat using a large number of large mirrors that are pointed towards the top of a tower located in the center of the solar thermal power plant.

In the top of the tower there is a reservoir of molten salt or another agent that due to the extreme heat concentrated by the mirrors, starts boiling and produces steam that is used to spin a turbine and generate clean electricity using generators.

Electricity produced by solar cells or by the spinning turbine of a solar thermal power plant is considered clean electricity because is produced without affecting the environment or releasing harmful emissions into the atmosphere.

2. Water

Water is a great renewable resource on Earth because it sustains life on the planet and can also be used to generate clean electricity.

To generate clean electricity using the kinetic power of the water we have hydroelectric power plants, tidal power plants and devices (buoys) that are harvesting the kinetic power of the waves.

From these sources of clean electricity involving the use of water, only wave energy and tidal power have little to no impact on the environment.

Tidal energy is produced using the tides on planet Earth, which are generated daily by the gravitational forces of the Sun, Moon and our planet combined that are moving the water in our oceans.

To generate clean electricity, we are placing an underwater turbine where the tides are strong enough to spin the turbine and produce power.

The spinning underwater turbine is not harming sea life because it features a large hole in the middle of the turbine, which is used by marine life as a passing corridor to escape the rotating turbine.

Wave energy relies on buoys installed in areas of the water where the waves are high and steady enough to generate electricity.

Working on the surface of the water, the buoys are not affecting sea life.

3. Hydrogen

Hydrogen is considered the simplest element in existence today because is a gas that is lighter than air and is very abundant on our planet and in the universe.

As a source of renewable energy, hydrogen is the fuel with the highest energy content by weight, and has the lowest energy content by volume among all common fuels.

Hydrogen is also considered a secondary source of energy with high efficiency that releases no harmful emissions while burning.

Today, hydrogen is used for transportation (as fuel) for heating, and as a source of clean electricity in areas where electricity provided by the grid is not an option.

Many people consider today that hydrogen is a dangerous fuel because is highly flammable, but they forget the fact that hydrogen is dangerous only mixed with air, and even if we get a leak, hydrogen being so light, it will rise up into the atmosphere very fast.

We have a different case if there is a gasoline leak, which accumulates under the car and can ignite and destroy the entire vehicle in just a couple of minutes.

Hydrogen was and is still used as fuel for the rockets in the space missions, and also to power electrical systems using hydrogen fuel cells.

Lately, hydrogen has become a fuel for green vehicles, which are using hydrogen like any other fuel, but with higher efficiency and no harmful emissions into the atmosphere.

Hydrogen can also be used as nuclear fuel for the nuclear fusion reaction that can generate unlimited amounts of clean electricity and as byproducts only water and heat (no harmful nuclear waste).

How is hydrogen produced today?

Hydrogen cannot be found on planet Earth in gaseous form, but can be found in different compounds.

The most common methods used to extract hydrogen are steam reforming, electrolysis and water splitting.

Steam reforming represents the least expensive method for hydrogen production, and is mostly used in the industry where hydrogen is separated from methane.

Electrolysis is another method used to produce pure hydrogen and involves passing an electric current through water that will separate the liquid into its basic elements that are hydrogen and oxygen.

Hydrogen will be collected at the negatively charged cathode while oxygen will gather at the positive anode.

There are other methods used to produce hydrogen such as biomass gasification and photoelectrolysis.

Gasification represents the thermochemical conversion of an organic material (a certain type of biomass) into a valuable gaseous product such as hydrogen.

Photoelectrolysis or simply water splitting is a process that occurs in a photoelectrochemical cell that uses light as an energy source and produces dihydrogen, which is used as a fuel.

Scientists have discovered that a certain type of bacteria (cyanobacteria) and the green algae can be used to split water and produce hydrogen under certain conditions.

In the future, hydrogen can slowly replace the dirty fossil fuels used in our vehicles, and can generate unlimited amounts of clean electricity using the nuclear fusion reaction.

Renewable energy sources that have some impact on the environment.

We can include here clean sources of power such as: wind energy, water and biomass.

1. Wind energy

Wind represents a great source of clean energy on our planet, but the technology used today to turn the kinetic power of the wind into clean electricity can kill birds and bats that can be hit by the blades of the rotating turbines.

Horizontal wind turbines (horizontal axis wind turbines), which are widely spread today, both on land (onshore) and on the sea (offshore), have made many victims among the bird and bat population in their area.

Of course that the number of birds killed by horizontal axis wind turbines is way smaller than the number of birds killed by windows every year (birds get crushed by windows often because they do not differ from the surrounding environment being transparent).

However, there is a new technology on the market (vertical axis wind turbines) that has no impact on wildlife and is no longer affecting birds and bats.

Another advantage of the new technology used to generate wind power is represented by the fact that vertical wind turbines are more practical (require less space), more silent compared to the regular wind turbines (horizontal axis wind turbines), and start working in low speed winds.

Due to these qualities, vertical axis wind turbines are becoming more popular among home users that are installing them in the yard or even on the terrace of the house or flat.

These mobile vertical axis wind turbines are lowering the energy bills and are protecting the homeowners from power outages.

2. Water

Water appears again in the list because is a source of both, renewable energy that has no impact on the environment, and also a source of renewable energy that has some impact on the environment.

Hydroelectric energy or simply hydropower, is the most developed renewable energy source on the planet today because it has the highest share among all renewables in the energy mix of many developed and developing countries.

Today, mankind produces hydroelectric energy using three different types of power plants.

1. Hydroelectric power plants that rely on a large dam that is used to hold a large volume of water;

2. Run-of-the-river hydroelectric power plants that produce energy using the kinetic power of a stream or river;

3. Pumped storage hydroelectric power plants that pump water from a reservoir located at lower altitude to a reservoir located at a higher altitude to keep the water there when the demand for electricity in the grid is low.
When the demand for electricity in the gird increases, water from the above reservoir is released to generate electricity.

All these types of hydroelectric power plants rely on powerful underwater turbines that spin under the action of the falling or fast moving water.

The problem could appear when fishes and other creatures living in the water get caught by the spinning turbines.

The construction of the dam for the hydroelectric power plant can damage the ecosystem in the area and lead to land loss.

Stored water can also be lost through evaporation, and if the area is not cleaned of trees before filling the dam with water, a large amount of methane will be released after a few months due to the presence of rotting trees and vegetation (methane is a dangerous greenhouse gas).

3. Biomass

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

When burned, the biomass that consists of wood, agricultural waste and energy crops releases harmful emissions into the atmosphere.

Biomass is actually the only renewable energy source known today that releases harmful emissions into the atmosphere when is burned to generate electricity and heat.

However, the amount of harmful emissions produced when burning biomass is much lower and less dangerous than the emissions produced when burning coal, oil or natural gas.

Conclusion

There are several types of renewable energy sources available today on the planet, some are 100% clean, others are affecting the environment in some way (wildlife and underwater life), while others are releasing harmful emissions into the atmosphere while burning.

I’m sure that the future development of the technology will reduce the impact of the renewable energy on the environment, and will slowly make the switch to a global economy that relies mostly on renewable energy.