Learn It: Sources of Energy

It is estimated that at current levels of usage, there is sufficient coal to last for about 300 years – but the world’s gas and oil supplies will run out around the middle of the 21st century. Hence there is a growing urgency in seeking new sources of energy, preferably renewable ones, and in promoting energy conservation.

Many of the world’s pollution problems result from man’s ever increasing demand for energy. The pollution of the air by motor vehicles and industry, the fear of “another Chernobyl” (where a very serious accident occurred in a nuclear power station in 1986), the problem of nuclear reprocessing, and the imminent shortage of the world’s reserves of fossil fuels are all symptoms of our desire for more sources of cheap energy.
 

Energy usage from different sources:

As is clear from this graph, most of the world's energy comes from fossil fuels - oil, coal, peat and natural gas. Because they were formed over millions of years, they cannot be reformed during a lifetime and are said to be non-renewable. 
 

Renewable energy

Renewable sources of energy offer sustainable alternatives to our dependency on fossil fuels, a means of reducing harmful greenhouse emissions and opportunities to reduce our reliance on imported fuels.

Renewable energy from sources such as the wind, the sun, wood, waste and water are abundantly available in Ireland. Several renewable energy technologies are now commercially viable and capable of supplying clean, economical heat and power.

The term “renewable” usually refers to sources of energy that are continually renewable, such as the sun’s rays, wind, rainfall or tides, or those which can be replaced within a short time-span, such as biomass.

Next: Learn It - Forms of Renewable Energy