Energy Security can be defined as the uninterrupted availability of energy sources at an affordable price. It is how energy is utilized in order for it to be available,affordable and able to sustain the lives of the population of a country.
Nigeria is the largest oil producer in Africa due to the reason that it is naturally blessed with crude oil . Oil production is very important in Nigeria because it is one of the major sources of the country's revenue.  The fluctuation of Nigeria's oil production is due to illegal bunkering. Illegal bunkering can be defined as the theft of crude oil and its derivatives without the permission of the government of a country.This causes economic instability as majority of the government's income is from oil production.
Another one of Nigeria's natural resources is coal. Coal is a sedimentary deposit composed predominantly of carbon that is readily combustible. Coal is mined in different sates in Nigeria and is used for different purposes such as power generation, cement production , coal exportation and so on.  Land and water pollution, poor infrastructure and lack of funds are major problems why the production of coal is not maximized to produce maximum benefit.
 Liquid Natural Gas (LNG) is a natural gas that has been cooled changing it from a gas to a liquid. Nigeria is the world's fourth leading exporter of liquid natural gas (LNG), its company NLNG (Nigeria LNG Limited) was incorporated to harness Nigeria's vast gas resources for export. This has in turn increased the income and revenue for the Nigerian government thereby improving the standard of living for its inhabitants. Lack of oil and gas fields and lack of new drilling are reasons for reduced export of LNG and lower revenue for the Nigerian government.
SOLUTIONS
1. Building of oil refineries in oil-rich regions in the country.
2. Government should provide funds to aid the production of coal.
3. Building and maintaining of good infrastructure.
4. Government should provide modernized equipment and materials needed for mining and drilling of crude oil and its derivatives.
5. There should be heavy penalties for those who pollute the environment with their own wastes (personal or industrial).
6. Oil-rich regions should be heavily guarded so as to prevent illegal bunkering. There should be heavy penalties for those who break the law and involve themselves in illegal bunkering.

References : https://www.iea.org/topics/energy-security , https://oilprice.com/