1. Toxic and Flammable: Leaks of natural gas are tremendously dangerous. Such leaks may cause explosions or fire. When inhaled, the gas is highly toxic. The main danger is that it is odorless and leaks cannot be detected unless some odorant has been added to the gas. It is for this reason that LPG (residentially used gas) is suffused with odorants, that in the event of a leak, detection is easy and appropriate actions can be taken. In the case of an underground leak, we are helpless as odorant becomes weaker and the gas leak goes undetected.
2. Damage to Environment: Burning of natural gas also releases carbon dioxide, carbon monoxide and other carbon compounds which are greenhouse gases that cause global warming and climate change. Even though it is cleaner than oil or coal as far as its by products are concerned, leakage of natural gas can be have serious consequences as methane is more toxic than carbon dioxide.
3. Complex Processing: For use as fuel, except for methane, all other constituents of natural gas have to be extracted. Processing results in many byproducts: hydrocarbons (propane, ethane etc.), sulfur, water, helium, nitrogen, and carbon dioxide.
4. Non-Renewable: Like all fossil fuels, natural gas though found in abundance is non-renewable and hence likely to be exhausted at some point of time. It is not a long term solution to our energy problems.
5. Expensive Installation: The infrastructure for natural gas production and distribution is fairly expensive. This includes separate plumbing systems and specialized tanks.
6. Inefficiency in Transportation: Natural gas when used as a fuel in vehicles provides less mileage than gasoline.
In spite of disadvantages, the entire process of producing, transporting and making use of natural gas provides an energy efficiency which is best among all fossil fuels. It proves to be less harmful to environment when it comes to pollution. It may not last forever but as of today it is the most popular energy source.