What is light energy?
Light energy is the part of the electromagnetic spectrum visible to the human eye. It propagates in the form of waves and particles (photons), and plays a vital role in natural and technological processes, from photosynthesis to electricity generation. Its study and use are key to advancing towards a greener future.
Light energy: much more than light
Light energy production can occur in various ways, both naturally and artificially, involving different physical and chemical processes:
Natural sources
The most powerful natural light energy source is the Sun, produced through nuclear fusion reactions. As you know, this energy is the basis of life on Earth. In addition, other natural phenomena include lightning, bioluminescence (fireflies and certain marine species), and the northern and southern lights.
Artificial sources
Since the invention of fire, humans have sought ways to generate artificial light. Today, the sources are varied and increasingly efficient:
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Incandescent
traditional light bulbs that heat a filament to give light. Due to being inefficient, they are increasingly being replaced by LED lights.
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LED
they are light emitting diodes and they are currently the most advanced and efficient technology. Light is produced when electrons move through a semiconductor. Their low consumption and long service life have made them the standard today.
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Fluorescent
Lamps that use a gas that reacts to electricity.
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Laser
High-current light, produced by stimulated radiation emission.
Physical and chemical processes involved
Light production is based on fundamental principles such as the emission of photons, where the electrons of an atom or molecule release energy in the form of photons when transitioning to a state of less energy. Nuclear reactions, which, like in the Sun, release enormous amounts of energy through the fusion of atomic nuclei. Chemical reactions which produce light without generating heat, and electrical discharges, whereby electricity excites the atoms of a gas to emit light.
Practical applications of light energy
Light energy not only allows us to see, but it is a driver of innovation in multiple sectors.
In renewable energy
The most prominent application is photovoltaic solar energy, which converts sunlight into electricity. Spain is a benchmark; in 2024, photovoltaic solar energy generated 17% of the total electricity of the country, contributing to renewable energy exceeding 50% of national electricity generation for the first time.
In sustainable agriculture
Light is essential for photosynthesis. In modern agriculture, LED lighting is used in greenhouses to optimize crop growth, allowing production at any time of the year and reducing the use of pesticides and water, a key factor for food safety.
In technology, science
From fiber optics that transmits data at the speed of light, to the lasers used in medicine, industry, or scientific research, light energy is a pillar of innovation. Photonics, the science that studies light, is a constantly expanding field.
In our daily lives
Beyond lighting, light energy is present in our device screens, bar codes, traffic lights, and countless applications that facilitate our daily lives.
Impact of light energy on sustainability
The impact of light energy on sustainability is profound, especially when it is harnessed efficiently and in a renewable way. The widespread use of photovoltaic solar energy drastically reduces dependence on fossil fuels. In 2024, CO2 emissions from the Spanish electricity system decreased by 16.8% compared to 2023, thanks to the increase in renewable energy generation, including solar energy.
Furthermore, the efficiency of LED lighting contributes to lower energy consumption. It is estimated that by 2030, the widespread adoption of LED could reduce lighting energy consumption by 40% globally.
Real cases: how light energy is changing the world
Light energy is already transforming our world. In Spain, there are an increasing number of public buildings, apartment complexes, and industrial buildings that have photovoltaic panels on their rooftops. In this way, the self-consumption of electricity is encouraged in each building, allowing for the sharing of surplus energy.
On an urban level, many cities are updating their street lighting with LED technology, achieving significant energy savings. In recent years, London has changed the lighting of its 15 bridges with 22,000 LED lights. And many cities in Spain are also committing to lighting their streets sustainably. For example, the city of Alicante has updated 85% of its street lighting, also with LED lights.
In short, light energy is much more than a resource; it is an integral strategy for sustainability. Its intelligent use, from clean energy production to agricultural optimization and technological innovation, is the inevitable path towards a more prosperous and eco-friendly environment.