Since ancient times, human beings have used the resources provided by the Earth to survive and produce energy. Some energy resources have a longer renewal time than others. The resources used to produce energy are classified into two broad categories: renewable and non-renewable sources. There are three main differences between these two types of sources:
- availability and renewal time;
- cost of production and transportation;
- impact on the environment and people’s health.
Renewable resources, whether they are material or energy, are natural resources which, due to natural characteristics or due to the production of man, are renewed over time (at a higher, or equal, renewal rate than the rate of consumption/use) and can be considered inexhaustible, or may be available for use by humans almost indefinitely. A renewable resource is also said to be “sustainable” if its rate of regeneration is equal to or higher than the rate of use.
As renewable resources are also an energy source, there is a wide range of different types of renewable energy sources such as wind, solar, hydropower, geothermal, biomass, and biofuels. Wind and hydroelectric power are the direct results of differential heating of the Earth’s surface which leads to air moving about (wind) and precipitation forming as the air is lifted. Solar energy is the direct conversion of sunlight using panels or collectors. Biomass energy is stored sunlight contained in plants. Other renewable energies that do not depend on sunlight are geothermal energy, which is a result of radioactive decay in the crust combined with the original heat of accreting the Earth, and tidal energy, which is a conversion of gravitational energy. It is useful to highlight how the forms of energy present on our planet (except nuclear energy, geothermal energy, and tidal energy) almost all originate from solar radiation, in fact:
- without the Sun there would be no wind, which is caused by the irregular heating of air masses, and with it wind energy;
- biomass energy can be considered chemically stored solar energy, through the process of chlorophyll photosynthesis;
- hydroelectric energy, which uses waterfalls, would not exist without the water cycle from evaporation to rain, triggered by the Sun;
- fossil fuels (coal, oil, and natural gas) derive from the sun’s energy stored in the biomass millions of years ago through the process of chlorophyll photosynthesis.
As we have said, renewable energy sources have indisputable advantages. Above all, the absence of polluting emissions and their inexhaustibility. The use of energy from renewable sources does not affect, therefore, the availability in the future. Renewable energies offer advantages for the environment and human health. In contrast to fossil fuels, which release CO2 emissions into the atmosphere and accelerate global warming, renewables are sustainable and allow for clean electricity production. The fact that they come from readily available and inexhaustible sources allows renewable energy to reduce dependence on foreign suppliers and to develop the domestic economy.
Renewable energy does not emit pollutants and does not present the problem of waste to be disposed of. In addition, it is economical, creates jobs and allows for the combined use of multiple energy sources. In fact, renewables can be used in synergy with each other. Renewable energy sources include:
- Solar energy
- Wind energy
- Geothermal energy
- Biomass energy
- Ocean energy
Solar energy represents the most known, widespread and efficient renewable source in Italy. It allows the production of electricity starting from the sun’s rays and, to transform solar energy into electricity, it uses photovoltaic or solar power plants.
- Photovoltaic systems use silicon panels to transform solar radiation into electricity. Photovoltaic systems can be installed on the roofs of condominiums or detached houses. Among their major advantages there is undoubtedly the savings in the bill, which combines perfectly with tax incentives for installation.
- Solar systems are connected to a storage tank that heats water, replacing the boiler or water heater.
- Concentrating solar power is a system based on the use of mirrors that channel heat into boilers capable of starting a thermoelectric plant.
- Passive solar, finally, exploits the sun’s rays in a natural way through the construction of buildings capable of passing a greater amount of radiation.
Wind energy is the energy that is generated by exploiting the wind. Using wind blades, the kinetic force of the wind is used to produce mechanical energy, from which electricity is then generated. Wind energy is therefore the energy produced by wind currents and can be considered a form of energy derived from solar energy. The formation of winds, in fact, is linked to factors such as the Earth’s rotation and atmospheric temperature.
The transformation of energy occurs through turbines and wind blades, in a system that resembles windmills.
In order to ensure the efficiency of the system, as well as a good quality of the same, it is essential to place the blades in large areas and particularly windy. In fact, the ideal solution is to install the blades near seas and oceans.
Geothermal energy is that which exploits the natural heat of the Earth, released by the processes of nuclear decay of radioactive elements present within the nucleus, the mantle and the earth’s crust, such as potassium and uranium. This heat is subsequently converted into electricity by geothermal power plants. The flow of steam coming from underground makes a turbine move and this mechanical energy is transformed into electricity by an alternator. It is, therefore, a mechanism that can only work thanks to high temperatures.
Hydropower is produced by the movement of water. This form of energy was once used to run mills. Today, the kinetic energy produced by waterfalls, rivers, waves and tides is converted into electricity using turbines. The energy is produced by hydroelectric power plants: these are usually built in the mountains, close to water courses. In this way it is easier to exploit the combination of kinetic energy and the force of gravity. Among the constructions that allow to maximize this system there are dams: these ensure the channeling of water resources in specific basins. For these plants, it is possible to use power plants with accumulation or flowing water systems.
Biomass energy is generated from waste produced by man and, therefore, cannot be considered inexhaustible. This energy is produced from fuels or organic substances and industrial and agricultural waste through combustion processes. It is derived from plants and animals and allows the production of heat and electricity, as well as liquid fuels. Energy derived from biomass is mainly used by transportation companies, to power vehicles, and by manufacturing industries.
Renewable energy also includes the so-called ocean energy, which must be distinguished from hydroelectric power. This, in fact, uses the movement of currents and tides, or the motion of the waves, to produce electricity. It should be remembered that the oceans are also able to produce thermal energy from the heating of the water caused by solar radiation. Marine energy works in every way like wind energy: it is recovered through technologies that use blades or turbines set in motion.
The need to produce more and more renewable energy and to get away from traditional sources is a need shared by all countries. According to the latest data, green energy contributes to more than a third of the world’s total electricity production. Renewable also rhymes with sustainable and it is precisely in that direction that the economy, necessarily circular, of the future must look.
A non-renewable resource is a natural resource that is used up faster than it can be made by nature. It cannot be produced, grown, or generated on a scale which can sustain how quickly it is being consumed. Once it is used up, there is no more available for the future.
Fossil fuels (such as coal, petroleum, and natural gas), types of nuclear power (uranium), and certain examples. Resources such as timber (when harvested sustainably) or metals (which can be recycled) are considered renewable resources. Non-renewable resources are also called exhaustible resources.
Non-renewable energies, or more properly non-renewable energy sources, also simply called non-renewable sources, are energy sources that have been generated in nature in the order of millions of years in the case of fossil fuels, or before the formation of the planet Earth in the case of fissile materials (uranium and plutonium), as opposed to renewable energies, which are naturally replenished in a relatively short period of time; for this reason, once they are finished, non-renewable sources will not be available again on the human scale of time.
Most non-renewable energy resources are concentrated in a limited number of areas on Earth, which can lead to geopolitical and military issues, unlike renewable resources, which are primarily distributed over large geographic areas. Reducing the use of non-renewable sources, implementing renewable energy, and increasing energy efficiency results in climate change mitigation and subsequent economic benefits.
Since the early 1900s, mankind has consumed more primary energy from non-renewable sources (fossil fuels) than from renewable sources (at that time wood, animal energy, hydraulic and wind power) because fossil fuels, at equal weight, were able to produce greater amounts of energy than wood, in addition to the fact that deforestation had become unsustainable. Through the industrial revolutions, these energy sources have allowed the improvement of human living conditions.
Currently, non-renewable resources are technologically preferred because, once extracted, they are easy to transport, have a high energy density, and produce energy when needed with technologically simple and proven facilities, which has resulted in the consolidation of fossil industries at the center of the world economic system; However, the use of these sources brings with it some environmental problems such as the emission of greenhouse gases for fossil fuels or the disposal of radioactive waste for nuclear fission; for these and other reasons, the environmental impact associated with the fossil fuel cycle is generally greater than that of renewable energy sources.