Energy security is a term that refers to the availability of natural resources for energy consumption in a given period of time (short or long-term period in order to estimate future energy security).
Energy security is one of the main prerequisites for future economic growth. Our economy is traditionally based on fossil fuels (oil, coal and natural gas). This leads to conclusion that the adequate supply of fossil fuels is still the only thing that guarantees future energy security.
The transition to renewable energy could change this but all current estimates say that our economy will continue its dependence on fossil fuels till at least the end of the century. Under this scenario fossil fuels will continue to determine the destiny of future global energy security.
The role of renewable energy in improving energy security is still not negligent because more renewable energy coming from domestic renewable energy sources means less need for fossil fuels and expensive foreign fuel import.
The bigger share of renewable energy sources in country's energy mix also means improved energy independence. Energy independence and energy security are two closely connected terms, basically in most cases improved energy security means also improved energy independence (lesser reliance on expensive foreign fuel import).
There are many different threats to energy security, for instance political turmoils in rich oil producing countries, the rise of new economic giants (China and India that present heavy competition over energy sources), natural disasters and accidents, etc.
Also, energy security doesn't refer just to the amount of energy resources that are at disposal to certain country but also to a security of energy supply (adequate distribution network).
Energy plays key role in the national security of any given country because without energy there's no economy, and without economy there's no progress of society in general.
Major oil exporters today play key role in global energy security. Many powerful countries are looking for long-term solutions to increase energy security by reducing dependence on foreign oil import. This has not only resulted in the growth of domestic renewable energy resources but also in different measures aimed to improve energy efficiency and energy conservation.