How Energy from the Sun Drives the Earth

The Sun produces massive amounts of energy by a process called nuclear fusion where Hydrogen atoms are combined to form Helium atoms. This energy is emitted to space in the form of electromagnetic radiation. After 8 minutes of journey, a portion of it arrives on Earth with an estimated energy density over a 1000 Watts per square meter. About 30% of this energy is reflected back to space. The rest of it powers up the planet as we know it.


On Earth, energy arrives in the form of electromagnetic waves including Infra-red (IR), visible light and Ultraviolet (UV). We refer to it as “sunlight”. The following list is a composition of the main forms of energies produced from solar energy and stored on Earth.




1. Thermal Energy
Infra-red waves from sunlight builds up heat unevenly on terrains and oceans. This results in winds. Winds affect weather and climate patterns. We harvest Wind energy to do mechanical work (by Windmills) and to produce electricity.

Heat powers the Water Cycle; water in the oceans is evaporated to form clouds. They move along with the winds to condense and precipitate as rain. This provides fresh water on land making it habitable for life. We harvest its potential energy as hydropower to generate hydroelectricity.

Clouds also happen to generate static electricity which results in lightning and thunder. This promises a potential energy source to tap into in the future.



2. Electrochemical Energy
Energy from sunlight is stored in chemical molecules through a process called photosynthesis by plants, algae, etc. (referred to as autotrophs). This chemical energy is exchanged from plants to herbivores and then to carnivorous animals and so on. This flow of energy within the ecosystems is called the food cycle.


Some of the biological matter built up is used as fuel (biomass) to produce electricity. We use Coal, Petroleum oil, Natural gases for energy. All of those fossil fuels are biological matter that was trapped within the Earth thousands of years ago.

Photosynthesis is a vital function for maintaining a favourable atmospheric composition for life. It uses up CO₂ and produces O₂. This prevents excessive greenhouse effect while providing Oxygen to animals for respiration.



3. Photoelectric Energy
We harvest electricity directly from sunlight by the use of photovoltaic cells. These are commonly known as solar panels.
Alternatively sunlight is concentrated to produce steam/vapour to operate turbines which produces electricity. This is known as “Concentrated Solar Power”.



Energy from the sun is the main source of energy for Earth’s normal functioning. It is the main source of thermal energy for surface of the Earth, for Climate, for Water Cycle and Photosynthesis. In fact, most of the renewable and non-renewable sources of energy we use are directly or indirectly derived or stored from solar energy. Tidal, Geothermal and Nuclear energies are the main ones that are independent from the energy from sun.