What Are Renewable and Non-renewable Energies?

Renewable energies are those that come from natural, inexhaustible sources that either have a large amount of energy or can regenerate naturally. However, these energy sources must meet their renewal periods in order to truly function as unlimited energy sources.

This type of energy was considered alternative energy in the 1970s. However, it is currently more expensive than conventional energy. Another disadvantage is that the use of these energy sources requires very large areas of land, so the possibility of having these large areas at one's disposal is not always guaranteed. In addition, renewable energy projects often face challenges such as environmental regulations and community opposition, which can delay or even halt projects.

At this point, however, one detail should be noted. The fact that they are renewable energy sources does not mean that they are not harmful to the environment. Therefore, renewable energy sources are divided into environmentally harmful and non-polluting or clean energy sources.

Among the non-polluting or clean sources we find the following:

• Hydroelectric power
• Solar energy
• Tidal energy
• Wave energy
• Wind energy

On the other hand, polluting renewable energies are those that come from biomass or organic matter. These can be used directly as fuel by burning or can be used once converted into bioethanol or biodiesel. Since they are polluting energies, their problem is the same as that of most nonrenewable energies, their combustion produces carbon dioxide. It should be noted that advancements in technology are aiming to make biomass energy more sustainable, such as by improving the efficiency of conversion processes and using waste materials as feedstock.

Now that we know what renewable energy is, let us take a closer look at these forms of energy and their impact on the environment.

• Wind energy: we have been using wind energy for hundreds of years. Old-fashioned windmills have evolved into turbines as tall as buildings. Wind energy turns the blades of a turbine that feeds an electric generator and produces electricity, and is one of the cheapest sources of energy. Wind farms can be situated both onshore and offshore, with offshore installations often benefiting from stronger and more consistent wind patterns. However, they can also pose challenges such as potential impacts on marine life and shipping routes.
  
  
• Geothermal energy: uses accessible thermal energy from the earth's interior. Heat is extracted from geothermal reservoirs by drilling or other means. Once at the surface, fluids at different temperatures can be used to generate electricity. This technology for generating electricity from hydrothermal reservoirs is mature and reliable, and could even play a role in the future. Geothermal energy is particularly advantageous in regions with volcanic activity, where the earth’s heat is more accessible.
  
  
• Solar energy: for thousands of years, people have used solar energy to grow crops, keep warm, and dry food. Solar cells, or photovoltaic (PV) cells, are made of silicon or other materials that convert sunlight directly into electricity. Generally, solar panels have little impact on the environment beyond the manufacturing process as long as they are placed responsibly. Recent innovations in solar technology, such as solar roof tiles and transparent solar panels, offer new possibilities for integrating solar energy into everyday life.
  
  
• Hydroelectric or hydraulic energy: by turning the turbine blades of a generator, hydropower converts the power of water-typically fast-flowing water in a large river or rapidly falling water from a high point-into electricity. However, this type of power generation often has an impact on the environment. Some divert and reduce natural water flows, limiting access for animals and people who rely on these rivers. Despite these challenges, hydroelectric power remains one of the most stable and reliable sources of renewable energy.
  
  
• Osmotic energy: it is obtained from the difference between the salt concentration in river water and in seawater. It is particularly useful in regions where rivers are very large, as a greater amount of energy is generated. The only waste produced is brackish water. Research and development in osmotic power are focusing on improving the efficiency and scalability of this technology.
  
  
• Tidal energy: is still in the developmental stage, but the ocean will always be dominated by the moon's gravity, making harnessing its energy an attractive option. Tidal barriers, which function like dams and are built in ocean bays or lagoons, are one way to harness tidal energy, but they can be harmful to wildlife. Another method involves underwater turbines that are less intrusive and can be placed in strong tidal currents.
  
  
• Biomass: is organic material that comes from plants and animals, such as grains, wood waste, and trees. When biomass is burned, the chemical energy is released in the form of heat and can generate electricity with a steam turbine. Scientists have recently found that many forms of biomass, especially those from forests, produce higher carbon emissions than fossil fuels. Not to mention the negative impact on biodiversity. Efforts are underway to develop sustainable biomass practices that mitigate these environmental impacts.

Non-renewable energies are, as already mentioned, conventional forms of energy whose resources are limited, i.e. they do not regenerate like renewable energies.

All of these energy sources are produced by burning fossil fuels, which produce large amounts of greenhouse gasses when burned. These gasses are now one of the main causes of climate change, as their quantity in the atmosphere is increasing very rapidly. In addition to contributing to climate change, the extraction and use of fossil fuels can have severe environmental impacts, including habitat destruction, oil spills, and air and water pollution.

Within this type of non-renewable energy, we can find two main groups:

Fossil fuels

Fossil fuels, such as oil (in liquid form), coal (solid), and natural gas (gaseous). These fossil fuels come from biomass that was created millions of years ago and converted into the aforementioned fuels under suitable pressure and temperature conditions. There are three types of fossil fuels which can all be used for energy provision:

• Petroleum: petroleum is an organic compound consisting of a mixture of water-insoluble hydrocarbons, formed from the conversion of organic material that has accumulated in the form of sediments. It is a versatile energy source used not only for fuel but also as a raw material in the production of plastics, chemicals, and other products.
  
  
• Coal: coal is a sedimentary rock, also of organic origin, formed from plant remains that decompose and accumulate in marshy areas. Despite its declining use in many parts of the world due to environmental concerns, coal remains a significant energy source in many developing countries.
  
  
• Natural gas: it is formed from a mixture of natural gases, mainly methane, that have decomposed over millions of years as a result of intense heat and high pressure. Natural gas is often considered a "bridge fuel" due to its lower carbon emissions compared to other fossil fuels, but concerns remain about methane leaks during extraction and transportation.

The nuclear energy

Nuclear energy is the energy released by the reaction in the fission of heavy atomic nuclei. This is also called nuclear fission. This process produces large amounts of heat, which is used to generate pressurized steam that can be used to produce mechanical energy to run electricity generators.

Nuclear energy has the advantage of producing very small amounts of gasses that cause the so-called greenhouse effect. However, a major environmental problem associated with nuclear energy is the generation of radioactive waste such as uranium mill tailings, spent reactor fuel, and other radioactive waste. These materials can remain radioactive and hazardous to human health for thousands of years. Moreover, the high costs and risks associated with nuclear power plant construction and operation remain significant barriers to its widespread adoption.

To conclude this article, we now summarize all the information presented in the previous sections.

As we have already said, renewable energies are those that come from almost unlimited natural sources, but they need some time to renew themselves. There are environmentally friendly or clean renewable energies and environmentally harmful renewable energies.

Clean renewable energy includes wind energy, solar energy, hydroelectric energy, geothermal energy, tidal energy, wave energy or blue energy. As polluting renewable energies, we have highlighted those whose source is biomass or organic matter. Their problem is that when they are burned, as with conventional energies, carbon dioxide emissions are released into the atmosphere. Efforts to develop cleaner biomass technologies and practices are ongoing, with the goal of reducing the environmental impact of this energy source.

On the other hand, what we have said about non-renewable energies is that, unlike renewable energies, they are obtained from resources that are limited and do not have the capacity to regenerate. Usually, these energies are obtained mainly by burning fossil fuels such as oil, coal or natural gas. The burning of these materials contributes to current climate change by emitting a large amount of greenhouse gasses. In addition, the extraction and transportation of these fuels can cause environmental damage, such as habitat destruction and pollution.

There is another group of non-renewable energies, namely nuclear energy. Nuclear energy comes from nuclear fission, a process in which the nucleus of atoms decays to later release energy that is used in thermonuclear power plants to generate electricity. The major disadvantage of nuclear energy is that it takes a very long time for nuclear waste to disappear and lose its radioactivity. Moreover, the potential for catastrophic accidents, although rare, can have severe consequences for human health and the environment.

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