What Is Renewable Energy?

 

Renewable energy is energy from a resource that is naturally replenished.  It is regarded as being essentially inexhaustible.  Examples of such resources include: sunlight, wind, rain, tides, and geothermal heat.  In contrast, fossil fuel resources are finite and will eventually run out, becoming too expensive or too environmentally damaging to retrieve.

 

Although renewables can be categorised into several different forms, the Sun actually plays a major role in the generation of most of these resources.  For example, solar radiation directly provides solar energy (discussed below) but the Sun’s heat also drives the winds (utilised by wind turbines) and causes water to evaporate, which in turn produces precipitation resulting in rivers and lakes whose energy can be captured using hydro power.  Sunlight helps plants to grow and produce biomass which can be used to generate electricity, fuels, and chemicals.

 

Of course other sources play a role too: geothermal energy utilises the internal heat of the Earth; the gravitational pull of the Moon and Sun affect the ocean’s tides; ocean energy is driven by wind systems, tidal cycles, and heating from the Sun.

 

Here we look at a few examples of renewable energy.

 

 

Solar Energy

 

The Sun is approximately 150 million kilometres away from the Earth, and is continuously releasing vast amounts of energy every second.  In fact, so much energy is released that even just the small percentage of the Sun’s energy that strikes the Earth is considerably more than mankind’s energy requirements.  In just one minute enough energy reaches the Earth to meet our demands for a whole year; the challenge is to harness that energy properly.  Several unique methods already used include:

 

Photovoltaic Systems: Directly producing electricity from sunlight.

 

Solar Hot Water: Using solar energy to heat water.

 

Solar Electricity: Using the Sun's heat to produce electricity.

 

Passive Solar Heating and Daylighting: Using solar energy to heat and light buildings.

 

Solar Process Space Heating and Cooling: Industrial and commercial uses of the sun's heat.

 

 

Wind Power

 

Wind power is the conversion of wind energy into a useful form of energy.  When thinking about wind power our first thought will likely be that of a wind turbine or windmill.  Wind turbines are used to turn generators and directly produce electricity whereas windmills are used for mechanical power.  Windmills have been around since the middle ages where they were used to grind corn, hence the term “windmill”, but wind power was actually used long before that: 4,000 years ago wind power was used to pump water for irrigating crops, and sails have been used to propel ships for even longer.  Wind is an abundant free energy source that will never run out and so it only makes sense that we utilise it where and when appropriate.  

 : :  Renewable Energy