Renewable energy sectors can actually save the world from extinction. Today, the entire world is dependent on fossil fuels like oil and coal for their energy consumptions. From using electricity to transport, we depend on fossil fuels. The oil reserves are depleting in the world and that is the single biggest reason for the price hike in oil.
There are several sources of renewable energy like wind, solar power bio fuels and bio mass production, nuclear energy and so on. However, these technologies are in their early stage of development and it takes time to come up with something like electricity, for example. People are so used to 24 hour electricity supply that they will not have it any other way.
Transportation is largely dependent on oil and there is no substitute for it yet. Some of the technologies like ethanol, methanol and hydrogen can take care of short term needs. However, when it comes to bigger transportation needs, one needs oil which is a fossil fuel. Ships and airplanes cannot run on alternative fuel available today. It is too risky and just not viable economically.
However, for everyday consumption there are several alternatives including solar power and wind energy which are being put into use. Scientists believe that alternative energies have to be further developed simply because fossil fuels are not renewable. We may survive using fossil fuels, but future generations to come may suffer a lot. While using energy, we also need to learn to conserve energy and that is why depending on renewable sources of energy makes more sense for the betterment of the environment and as well as humanity.