Renewable energy: definition and types

Renewable energy sources are those derived from natural resources that regenerate in a consistent manner through natural cycles. Discover what they are.

Renewable sources of energy refer to all forms of energy that come from the natural world and have the ability to regenerate at the end of their cycle. Renewable energy sources and the production of energy from them significantly depend on meteorological and climatic conditions. Sun, wind, and water do not provide a constant source of energy, which makes managing production a complex task. For this reason, it can be beneficial to use software for the design of renewable energy systems, with which you can perform dynamic calculations based on reliable climate data and easily process the financial simulation of any system (such as photovoltaic systems and solar panels).

What is Renewable Energy?

Renewable sources of energy are energy sources that harness natural resources sustainably, do not pollute the environment, and do not deplete over time as they can regenerate through natural cycles. Renewable energies have gained importance lately, emerging as a clear choice for the future of energy supply. They offer an opportunity to obtain clean and affordable energy with a significant positive impact on sustainability and energy efficiency. The adoption of sustainable building models, such as passive houses, allows the combination of energy sustainability with the construction of highly energy-efficient buildings.

Types of Renewable Energy

The main sources of renewable energy are:

• Solar energy;
• Wind energy;
• Geothermal energy;
• Biomass energy;
• Hydropower;
• Marine energy.

Solar energy

One of the most well-known and efficient sources of renewable energy is solar energy. This energy source is widely utilized through the installation of solar or photovoltaic systems. These systems consist of panels that capture the radiant energy of the sun and convert it into electricity. This energy can be used for heating spaces, heating water, lighting, and even powering industrial cooling systems. Photovoltaic systems are known for their versatility and ease of installation. They can be placed on the roofs of condominiums or private residences, allowing for a wide range of applications.
In addition to traditional solar panels, solar energy can be harnessed through concentration systems, which use mirrors to direct solar heat to boilers, thus enabling the operation of thermoelectric systems. Another approach is passive solar, which relies on the design and construction of buildings with specific features to maximize solar radiation absorption.

Wind energy

Wind energy is a well-known and widely spread form of energy that harnesses the kinetic energy of the wind and air currents through the installation of wind turbines and wind blades. These blades, once set in motion by the wind, generate mechanical energy, which is then converted into electrical energy. The evolution of this technology is significant, starting from the picturesque windmills of the past to modern wind turbines, which are much more efficient and aerodynamic. Today, these installations can be integrated into the public energy grid, enabling large-scale energy production.
Wind energy facilities can be used both publicly and privately. However, to ensure efficiency, it is essential to install the blades in wide and open areas where the winds are constant and strong. Ideal areas may include coastal zones near seas or oceans, as well as mountainous regions. It is important to note that in the absence of wind, wind energy installations cannot generate energy, which has led to considering hybrid solutions, such as integration with photovoltaic systems to ensure continuous energy production.

Geothermal energy

The production of electrical energy from renewable sources includes geothermal energy, a method that harnesses the Earth’s internal heat through the principles of geothermics. This process is based on the planet’s geothermal gradient, which is the temperature variation with depth, primarily caused by the energy produced by the decay of radioactive elements present beneath the Earth’s surface (potassium, thorium, and uranium).
Geothermal power plants and geothermal systems capture the heat trapped in aquifers or hot rocks beneath the Earth’s surface. This heat is then used to drive special turbines that generate mechanical energy. Subsequently, an alternator converts this mechanical energy into electricity, which can be distributed and used on a large scale. Low-enthalpy geothermal systems focus on shallower geothermal resources, such as hot water aquifers. This form of geothermal energy is particularly suitable for heating residential and commercial buildings and can also support various industrial processes. Geothermal energy represents a significant contribution to the diversification of sustainable energy supply and the reduction of carbon emissions.

Biomass energy

Energy obtained from biomass is the result of the combustion of organic substances such as trees, plants, animals, agricultural or industrial residues, and urban waste. An example of this category is firewood, which, although depletable, is considered a renewable resource due to the ability to replant trees. However, following stringent ecological regulatory guidelines, the use of biomass for energy production is now primarily limited to agricultural byproducts rather than exclusive crops. Nonetheless, biomass plays a valuable role in transitioning to more sustainable energy sources and contributes to reducing greenhouse gas emissions.

Hydropower

Hydropower is one of the oldest forms of renewable energy production and harnesses the kinetic energy generated by water flow, converting it into electrical energy. This process involves hydropower plants equipped with storage facilities, including dams.

Marine energy

Marine energy harnesses the movement of currents, tides, and marine waves to generate electrical energy. The functioning of this energy source is similar to that of wind energy, involving blades or turbines set in motion by the movement of water masses, generating mechanical energy that is subsequently converted into electrical energy. Additionally, oceans have the capacity to produce thermal energy due to solar irradiation, which heats the water.

Advantages and disadvantages of Renewable Energy

The use of renewable energy sources comes with numerous advantages that clearly highlight why these energy forms are gaining increasing relevance.
Some of the main advantages include:

• Absence of polluting emissions: Renewable sources, unlike fossil fuels, do not produce polluting emissions or greenhouse gases that contribute to climate change;
• Inexhaustibility and constant availability: Renewable sources are continually available in the future, ensuring continuous energy supply;
• Absence of waste disposal issues: Unlike non-renewable energy sources that generate radioactive or toxic waste, renewable sources do not pose the problem of hazardous waste disposal;
• Economic benefits: Investments in these technologies can lead to significant long-term cost savings;
• Energy efficiency: Different renewable sources can be combined and integrated synergistically to enhance overall energy efficiency.

However, it is important to recognize that there are also some disadvantages to using renewable sources, including:

• Space requirements: Some types of installations, such as large-scale photovoltaic systems, require extensive land;
• Initial costs and maintenance: Renewable energy installations require significant initial investments for installation and maintenance;
• Environmental impact: Some renewable energy projects, such as hydropower dams, can cause alterations to natural habitats and impact local wildlife;
• Workforce retraining: Transitioning to renewable sources requires skill retraining for energy sector workers.

Renewable vs. Non-Renewable Energy: Differences

Unlike renewable energies, non-renewable energy sources are depletable, meaning their use leads to a progressive reduction in available natural resources. For example, the use of oil, natural gas, and coal for purposes like heating or electricity production requires the extraction of raw materials and results in the gradual depletion of available reserves.
A fundamental aspect to consider is the environmental impact. While renewable sources generate minimal greenhouse gas emissions and have limited impacts on natural ecosystems, non-renewable sources, especially fossil-based ones, produce substantial greenhouse gas emissions and cause significant air, soil, and water pollution. The extraction, production, and transportation of these resources contribute to environmental disruption.

The main non-renewable energy sources include:

• Oil;
• Natural gas;
• Coal.