What do you see when you look up at the sky in the morning? Birds? Clouds? Perhaps the sun? Well, you may see all three, but the sun rises and sets steadily every day. No matter where we are located, we have all seen the sun. The sun is so important that it has been observed by astronomers, scientists, and researchers for generations. At one point, it even spanned a war between churches and astronomers like Galileo, and out of that ordeal, we gained a now widely accepted theory of the sun being the center of our solar system. With a title like that, the sun must undoubtedly be a star! Well, it is physically a star and performs many functions, like providing solar energy and life on earth, which makes it deserving of its star-studded title.
Solar energy and life on earth overview
Solar energy is any energy that comes from the sun.
Solar energy is made by nuclear fusion that occurs in the sun. Nuclear fusion happens when the protons of hydrogen (H) atoms collide rapidly and combine to create a helium (He) atom.
In the fusion process, energy is released because the mass of the resulting helium atom is less than the starting hydrogen atoms.
The sun's core fuses around 620 million metric tons of hydrogen every second and provides the sun, a star, with an endless amount of energy and heat. The temperature is about 4 million degrees Kelvin, or 7 million degrees Fahrenheit.
Light and energy from the sun mostly travel through X-rays, gamma rays, ultraviolet radiation (UV), and infrared. X-rays, gamma rays, and UV light are high-frequency light mainly absorbed by the earth's atmosphere. Almost all the heat we receive on earth is in the form of infrared light.
Between UV and infrared light lies the visible spectrum, which includes all the colors we can see with the naked eye.
Light emitted from the sun is essential to survival as it creates "a greenhouse effect". When we think of the greenhouse effect, we think of global warming, but the greenhouse effect is essentially just heat caused by infrared, UV, and visible light radiated from the sun. The heat from these waves makes the earth warm enough to sustain life.
Around 30% of solar energy on earth is reflected in space, and the rest is absorbed into the earth's surface and atmosphere. The solar energy or radiation heats the earth's surface and, as it rises through the atmosphere, it's trapped by greenhouse gases such as carbon dioxide (\(CO_2\)) and methane (\(CH_4\)).
By trapping radiation greenhouse, gases can be likened to the glass walls of a greenhouse, whereby they sustain life by trapping heat.
Figure 1: Greenhouse effect illustrated. Wikimedia, EPA.
Importance of the sun for life on earth
Now that we understand what solar energy is and how it relates to the sun and life on earth, we can go over how the sun sustains life on earth.
The sun can provide heat that warms the planet through the greenhouse effect. Solar energy can also be used by living organisms such as Plants to synthesize nutrients in the form of glucose. Primary producers or autotrophs can make their food through Photosynthesis and give other organisms energy through consumption.
For example, Plants make their own food, obtaining light energy from the sun, and in turn, organisms like humans consume them for energy. Organisms that need to eat other organisms to gain nutrients are called Heterotrophs, or consumers.
The energy created by photosynthesizing plants from millions of years ago is responsible for forming fossil fuels. Fossil fuels currently provide around 80% of the energy on our planet, making them a crucial source of energy and gas for us. Fossil fuels formed millions of years ago from the remains of plants and Animals. These remains underwent enormous pressures and intense temperatures to create fossil fuels. Fossil fuels include things like natural gas, oil, propane, and kerosene and, unfortunately, are non-renewable, as they take millions of years to form.
The sun also provides us with solar energy, which is a renewable resource.
A renewable resource is a resource that self-replenishes after some time.
Solar energy can be harvested by panels or Cells and converted into usable energy in electricity and heat.
The sun also sustains life by driving our seasons, climate, weather, and ocean currents!
The earth rotating with a tilted axis around the sun provides us with our seasons.
Solar energy warms the air masses causing climate and weather changes.
Ocean currents result from global wind patterns fueled by solar energy.
Figure 2: The sun powers processes likephotosynthesis. Daniela Lin, Study Smarter Originals.
Types of energy life receive from the sun
After understanding the sun's role in sustaining life on earth, we need to go over the types of energy the sun emits in detail.
The sun provides two main types of energy, in the form of light and heat. Generally, we call electromagnetic radiation produced by the sun solar radiation. Solar radiation can be converted into valuable energy, including heat and electricity, that can power our planet. Energy from the sun comes from nuclear fusion or when hydrogen atoms are converted into helium. This process releases energy in the form of electromagnetic waves.
Electromagnetic waves cause charged particles, such as electrons, to move through time and space at around 300,000 kilometers per second, or the speed of light. Electromagnetic waves can be described through waves and frequency.
The longer the wavelength, the lower the frequency; the shorter the wavelength, the higher the frequency.
The electromagnetic spectrum is the range of wavelengths and frequencies to which electromagnetic radiation can extend.
Recall that the sun emits energy mainly through X-rays, UV radiation, and infrared light. Gamma rays are not emitted as the sun produces them but converts them into low photons before they are emitted into space.
Ultraviolet radiation is a type of electromagnetic radiation that makes up about 10% of the total energy emitted from the sun. Its wavelength is shorter than visible light but longer than X-rays. At controlled levels, it's beneficial for humans as it allows for the synthesis of vitamin D, but too much can lead to skin conditions such as sunburn and cancer.
Figure 3: Electromagnetic spectrum illustrated. Wikimedia, NASA.
Advantages of solar energy
Now that we comprehend why solar energy is vital and the types of solar energy, we can go over the advantages of using solar energy.
- Solar energy is a renewable resource that can be replenished or restored within a period of usage. Solar energy will remain an accessible form of energy, unlike fossil fuels, for as long as the sun remains in our sky.
Our sun is projected to die because it is a star, but thankfully not for billions of years.
- Solar energy is diverse, as it can generate electricity and heat. Electricity is generated by solar photovoltaics or semiconducting materials such as silicon. In comparison, thermal solar panels collect energy from the sun and convert it into heat.
Overall, power generated by the sun is more cost-effective and cheaper than fossil fuels.
- Solar energy can provide energy to places without energy grids, power energy satellites in space, and even clean up water.
- Solar energy is also a cleaner form of energy compared to fossil fuels.
When fossil fuels are burned, they release nitrogen oxides into our atmosphere resulting in smog and acid rain. Fossil fuels also release large amounts of carbon dioxide into our air leading to global warming.
Nuclear power in high doses can cause sickness and death in humans and releases radioactive waste. Nuclear energy has an expensive start-up cost, is non-renewable, can impact our environment, and has risks of accidents.
A famous example of a nuclear accident is Chernobyl in Ukraine in 1986.
Negative impacts of solar energy
Bet you are now thinking if solar energy is so great, why are we still using nuclear power and fossil fuels? Well, the amount of solar energy has increased in recent years.
For example, in 2020, the renewable energy growth rate grew by around 45%!
Despite this, there are still pitfalls of harnessing solar energy, which we will discuss in this section.
There are two ways we can harness solar energy, and that's through either photovoltaic solar Cells or solar thermal plants. The location and the amount of land required can differ depending on which one we use.
The estimate for photovoltaic panels is 3.5 to 10 acres per megawatt and around 4 to 16.5 acres per megawatt for thermal ones. Solar facilities also can't share the land with agricultural uses like other forms of energy. Some solutions to this include building commercial-size photovoltaic plants and using contaminated land or other areas where habitat loss is less of a concern.
Water is required for cooling when we manufacture solar energy panels. The amount of water used depends on the design, location, and type of system used. We can use dry-cooling technology to minimize the amount of water utilized, but it leads to lower efficiency rates, significantly above temperatures of 100 degrees Fahrenheit. This is a problem because many regions in the U.S. that need alternative forms of energy the most are in the driest climates.
The chemicals used to produce solar energy plants can also be hazardous.
For instance, hydrochloric and sulfuric acid is used in the semiconductor industry, and photovoltaic plants comprise gallium arsenide. If not recycled properly, it could harm the environment.
Although solar energy is not associated with global warming emissions, manufacturing photovoltaic and thermal panels is. Most problems aren't related to solar energy usage but the material we use to convert energy into electricity and heat. Installation, manufacturing, maintenance, etc., cause an average of 0.07 and 0.18 pounds of carbon dioxide per kilowatt-hour.
Overall, as our technology implementation improves, we should see higher usage of renewable energy, such as solar energy. The sun is an essential star in our lives and provides us with many forms of energy, therefore is studied closely by many scientists and researchers.
Solar Energy and Life on Earth - Key takeaways
- Solar energy is any energy that comes from the sun, an essential star.
- Solar energy is made by nuclear fusion that occurs in the sun. Nuclear fusion happens when collisions occur rapidly and cause the release of energy.
- The sun provides two main types of energy light and heat. Solar radiation can be converted into useful energy, including heat and electricity, that can power our planet.
- Light emitted from the sun is essential to survival as it creates "a greenhouse effect." The greenhouse effect is heat caused by electromagnetic radiation from the sun, which makes the earth warm enough to sustain life.
- Overall, as our technology implementation improves, we should see higher usage of renewable energy, such as solar energy.
References
- Kimberly Dumke, The Power of the Sun, National Geographic, 2022.
- Andrew Turgeon Elizabeth Morse, Solar Energy, National Geographic, 2022.
- British Geological Survey, The greenhouse effect, 2022.
- Climate Science Investigations (CSI), Electromagnetic Radiation, 2013.
- Union of Concerned Scientists, Environmental Impacts of Solar Power, 2013.
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