When oil exists below a certain depth, the heat of the earth breaks the molecules down and it becomes "natural gas" it is not necessarily found (in significant quantities) alongside oil. It is the simplest of the natural fuels, composed mainly of methane (CH4), the most basic hydrocarbon. When it is burned it releases carbon dioxide (CO2), water (H2O) and energy. It contains more energy per weight than any other fossil fuel and produces the least carbon dioxide which makes it very attractive for power companies concerned with climate change. Because there is more gas than oil, there has been a huge rush in recent years to build gas-powered power stations. New techniques such as combined-cycle power stations have been introduced. Unlike coal and oil stations which have to produce steam to turn turbines, gas can be used to directly turn the turbines. The exhaust heat is then captured and reused to produce steam for further power production. This technology can increase the efficiency of a fossil fuel from about 40% average to 80%. Gas has many uses besides heating, cooking and power generation. Motor vehicles can be converted to run on it and it has long been used to create nitrogen fertilisers using a procedure called "The Haber-Bosch process" It is also the primary means of creating hydrogen at the moment. Gas production differs in several ways from oil. Being self-pressurised, it flows more easily which means that production is usually held at a plateau of about 80% of natural output for long periods. The problem then is that the production drops off rapidly, often with little warning. That is why the gas production profile is often referred to as a cliff rather than a peak.

Carbon Monoxide:
A build up of Carbon monoxide, or “CO” for short, happens when an appliance that burns fuel isn't working correctly, It can also happen if a vehicle is left running inside a garage or confined space. If an appliance is burning correctly it mixes its gas with oxygen to produce harmless carbon dioxide and water vapor, but if the fuel doesn't get enough oxygen, or if equipment parts are broken, worn or cracked, carbon monoxide can develop creating a deadly environment.
A common mistake is trying to keep warm using the cooker burners when the heating fails, the flames on the hob and people in the room soon burn up the available oxygen and eventually causing the production of CO. Carbon Monoxide Kills and should be avoided at all times.