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Solar Energy: The Most Abundant Energy Source on Earth
That big orange ball up in the sky isn’t just there for looks. Besides warming us, helping everything grow, and keeping the sunglass industry in business, the sun is also the greatest source of untapped energy for our planet.
And there’s so much of it, every day! All the energy the entire world needs for a full year strikes the earth’s surface in just an hour and a half. Just 90 minutes for the whole year! Plus, the energy itself is free!
Solar Energy Production
So, how do the sun’s rays become useable electrical energy to charge your cell phone or, ironically, cool your home? It’s actually quite simple. If you’ve ever seen a solar panel up close, maybe you’ve noticed that it’s made up of grids of photovoltaic cells, commonly called PV cells or just solar cells.
When the sun's rays strike the solar panel, energy from the sunlight is absorbed by the PV cells in the panel. That energy creates electrical charges that move in response to an internal electrical field in the cell. This is what causes the electricity to flow.
Basically, every place on Earth receives some sunlight over the year, but the amount that reaches each place can vary, or isn’t produced when the energy is actually needed. Some areas don’t receive the same amount of solar radiation or the sun’s rays can be blocked by weather patterns, or even dust and haze.
For example, peak power usage during the summer is in afternoons and evenings, when less solar energy is being generated. At the same time, more energy is needed at this point to cool homes, cook dinner, and run appliances. That’s why solar energy needs to be stored for use when needed, just as other sources of energy have been stored throughout the ages, but in a variety of innovative ways.
Interestingly, there are seven diverse methods of storing solar energy, each with its own advantages and special applications.
Pumped-Storage Hydropower — Having been used for nearly a century, electrical energy is used to pump water up into a reservoir when demand is low, then the water is released to flow when needed, turning a turbine to generate electricity when demand is high.
Electrochemical Storage — Similar to batteries in laptops and mobile phones, electricity is fed into a battery, causing a chemical reaction that stores the energy. While lithium-ion is the most common, others include lead-acid, sodium, and nickel-based batteries
Thermal Energy Storage — A fluid, such as water or molten salt, is used to store heat which is then stored in an insulated tank until the energy is needed. The energy can be used directly for heating or cooling, or can be used to generate electricity. This type of storage is useful in concentrating solar power (CSP) plants where sunlight is focused onto a receiver to heat the fluid.
Flywheel Storage — Although they quickly provide power, flywheels don’t store a whole lot of energy. Expanding energy makes the wheel turn faster and that energy can be extracted by attaching the wheel to an electrical generator, which slows down the wheel due to electromagnetism, producing energy.
Compressed Air Storage — A compressor system pumps large tanks or caves full of pressurized air that can be released to drive a turbine that produces electricity. The released air is part of the natural gas power cycle to produce electricity.
Solar Fuels — Solar power can be used to create new fuels that can be burned or consumed to provide energy, effectively storing the solar energy in the chemical bonds. There are a number of naturally occurring elements that are being combined to produce electricity or heat homes.
Virtual Storage — Energy can be stored by heating or cooling a building before the energy is needed, then the building stores the thermal energy so more electricity isn’t used later during the peak. The building basically acts as a thermos by storing the cool or warm air.
Pros & Cons
With so many ways to harvest and store solar power, you might be wondering if there’s any downside to using it. Like everything in life, there are pros and cons—check out the list below.
Pro - Reduced Electricity Bills — Over 20 years, the average household can save anywhere from $10,000 to $30,000 on their utility bills.
Con - High Initial Cost — Initial costs for equipment, panels and installation could be more than $20,000.
Pro - Energy Independence — Installing solar panels reduces your dependence on fossil fuels.
Con - Weather Dependence — Climates with an abundance of cloudy days and long winters produce less solar power.
Pro - Reduced Carbon Footprint — Installing solar panels can reduce carbon footprint by more than 3,000 pounds annually per household.
Con - Inability to Move — Most solar panel systems can’t be removed and taken if you sell your house.
Pro - Longevity — Most solar panel systems last 20 years and the technology continues to improve.
Con - Limitations — While popular in many areas, solar companies offer services by region so some might not find local services. Also, there’s a real concern over recycling the heavy metals in solar panels once their lifespan has expired (about 25 years).
Pro - Government Support — Taxpayers could potentially deduct up to 30% of the installation costs.
Con - Limited Space — Inner cities and buildings with limited space might not have the roof capacity for a system.
While solar energy is a vital part of providing the electrical energy needs of the world, some of the factors above keep it out of reach for some sectors of the population. If you’re interested in learning more about if your home is suitable for solar panels or how much you will need to invest, you can read this U.S. Department of Energy’s Homeowner’s Guide to Going Solar.
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