Renewable energy resources are those energy resources that are going to last forever because they are replenished quickly. Some examples of such resources are solar energy, wind energy, geothermal energy, biofuels, wave energy, tidal energy, etc. One of the biggest advantages of such resources is that they are (practically) unlimited in quantity and more importantly, do not generate carbon dioxide (except for biofuels) which cause the greenhouse effect and global warming. Fossil fuels' shortage of supply and their contribution to global climate change are big worries and renewable energy sources have provided a good alternative. One of the biggest disadvantages of renewable energy sources is that many of them (such as solar and wind energy) are location-specific and the existing infrastructure is not designed for them, thus necessitating modifications in the infrastructure. Many of these sources generate energy intermittently (say during windy hours or sunshine hours, etc.) and require batteries for energy storage. The fact that their efficiency is low is another disadvantage.
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