What is Renewable Energy?

Authors Avatar

Renewable Energy

What is Renewable Energy?

Renewable energy means it comes from a source that's constantly renewed - the wind keeps blowing, the sun keeps shining, and the Earth keeps heating underground rocks. This energy will be around for as long as the Earth is, so we don't have to worry about running out of it. And renewable energy sources are also usually less pollutant.

There are seven sources of renewable energy:

  • Solar Energy
  • Biomass
  • Wind Energy
  • Wave Energy
  • Hydro-electric Energy
  • Tidal Energy
  • Geothermal Energy

Solar Energy

Solar energy is energy taken from the sun’s rays. The amount of energy that falls from the sun each day can reach the amount of energy used in total around the world per year. The sun’s rays have a low energy density so large panels and collecting devices must be used to gather the energy and convert it into electricity.

Solar heating
Have you ever sat in a car that was closed up on a sunny day? Did you notice how hot it was in the car? This warmth is just one example of solar heating. We can use the sun to heat other things, including our homes. Today, more than 200,000 houses in the United States have been designed to use features that take advantage of the sun's energy. These homes often use passive solar designs, which do not normally require pumps, fans, or other mechanical equipment to store and distribute the sun's energy.

A challenge with solar heating is keeping the heat inside the house. One way to do this is to use special windows that reflect the heat back into the house. Another aspect of solar heating is that the house absorbs heat even during hot weather, when the last thing you need is more heat! So, passive solar homes need to be designed to let the heat in during cold months and block the sun in the hot months.  

Solar water heating
The sun also can heat water for bathing and laundry. Most solar water-heating systems have two main parts: the solar collector and the storage tank. The collector heats the water, which then flows to the storage tank. The water stays in the storage tank until it is needed for something, say a shower or to run the dishwasher.

A common collector is called a flat-plate collector, and is usually mounted on the roof. This collector is a rectangular box with a transparent cover that faces the sun. Small tubes run through the box, carrying the water or other fluid such as antifreeze to be heated. The tubes are mounted on a metal absorber plate, which is painted black to absorb the sun's heat. The back and sides of the box are insulated to hold in the heat. Heat builds up in the collector, and as the fluid passes through the tubes, it heats up.

While a solar water-heating system can work well, it can't heat water when the sun isn't shining—and we all know it can be cloudy for days at a time! For that reason, homes also have a conventional backup system that uses fossil fuels.

Join now!

Biomass

When you burn a log in your fireplace or in a campfire, you are using biomass energy. Because plants and trees depend on sunlight to grow, biomass energy is a form of stored solar energy. Although wood is the largest source of biomass energy, we also use corn, sugarcane wastes, and other farming byproducts.

There are three ways to use biomass. It can be burned to produce heat and electricity, changed to a gas-like fuel such as methane, or changed to a liquid fuel. Liquid fuels, also called biofuels, include two forms of alcohol: ethanol and ...

This is a preview of the whole essay