Renewable energy increasingly receives importance in research and development in most of the countries around the world, nowadays. Renewable energy is an energy that can be sourced from a non-depleting source and usually non-pollutant unlike fossil fuel energy sources.
Examples of such renewable energy sources are:
On the other hand, non renewable sources or fossil fuels are:
The answer is very simple. Because it is renewable such that it will not deplete for even a very long duration of time that we are using it, unlike fossil fuels, like oil, that will soon deplete once we already consumed the oil in oil reserves and sources around the globe. There is a projection that on year 2020, the world has already consumed almost half of the oil in the world assuming no further discoveries of oil deposits has progressed.