Natural gas is an odourless, combustible, non-renewable, and low-emissions fossil fuel which can be used to power electricity generators and vehicles. The principal component of natural gas is methane (95%). Methane has a half-life of 7 years. [Source: Duke University]
Natural gas is gaseous at room temperature because of its low density, and it can be liquefied by cooling it to -260° F. It can be burned in combustion engine alone to produce electricity or propel vehicles, or it can be both burnt in a combustion engine to produce electricity, and the wasted heat generated can be used to boil water to produce steam, which could then be used to turn an electricity generating steam turbine.
The latter design is called a combined cycle power plant, or NGCC. The efficiency of combined cycle power plants is high because instead of wasting the heat generated by the combustion engine (whether it is a gas turbine or another type of generator) by radiating it into the surrounding air, it can be used to generate even more electricity, effectively increasing electricity production per litre of gas consumed (in other words, increasing efficiency).
- 95% Methane.
- 2% Ethane.
- 1% Carbon Dioxide and Nitrogen.
- <1% Propane.
- Boiling Point Of Natural Gas: -164 °C (Celsius)/327 °F (Fahrenheit).
- Melting Point Of Natural Gas: -182 °C/360 °F.
- Flash Point Of Natural Gas: 221 °C/430 °F.
- Density Of Natural Gas: 0.717 g/L at 20 °C/68 °F.
- Autoignition Temperature: 537 °C/998 °F.
Economic Characteristics of Natural Gas
Average residential price of natural gas per thousand cubic feet: $10.33 USD (2013). Source: U.S. DOE.
Is Natural Gas Sustainable?
If an energy source is sustainable, then it can be relied on for electricity for an extended period of time (such as hundreds of years) and economically, but many sources of energy become very expensive after a while if they are finite.
Natural gas is a finite but cheap resource, and the cost of it will continue to increase as adoption of it as a source of energy increases worldwide (hence demand for it increases and reserves dwindle). According to MIT’s report on the future of natural gas, there is enough natural gas in the world’s recoverable reserves to supply the world with electricity for 160 years at the current rate of consumption.
Many people will look at this and think “that is a long time”, but the problem is that is not how long it will actually last, but if natural gas demand does not increase, and natural gas demand has been increasing significantly, plus reserves are dwindling.
One of the laws of demand and supply is that if supply decreases, and demand does not decrease with it, then the cost of the commodity will increase. This is inevitable, and the cost of natural gas will continue to increase unless demand for it significantly decreases.
As reserves dwindle and demand increases, that 160 year figure decreases very quickly. Also remember that supply isn’t the same thing as reserves, supply is the amount being produced, this can be increased or decreased based on demand, or for whatever reason the suppliers may have.
They may increase supply to keep the prices below a certain level, because demand may decrease too much, or they may decrease supply to increase the price to at least a certain level, depending on the situation. When a commodity’s reserves are small (rare commodity), supply is limited to prevent it from running out too quickly and it becomes very expensive because of that, gold and silver are two examples of this.
I believe that natural gas is an important part of the energy mix and that it should be used in the most efficient way possible, it has to be used sparingly, to back up solar and wind power plants, and in Natural Gas Combined-Cycle (NGCC) power plants, which are actually quite efficient because the waste heat from natural gas generators in such a setup is used to heat a steam generator which turns an electricity generating steam turbine.
Environmental Impact of Natural Gas
Natural gas does pollute the air, but is a low emissions fossil fuel, it emits much less of the pollutants that gasoline powered engines emit including sulfur dioxide, carbon monoxide, soot (almost none), carbon dioxide. Please note than when you read a page such as the DOE one below, please remember that “carbon” refers to carbon dioxide and carbon monoxide (but usually carbon dioxide), carbon itself is not a problem, but people often shorten 'carbon dioxide' to 'carbon' which you should not practice. Also remember that carbon dioxide is not a pollutant. It is not toxic, but excessive amounts of it contribute to global warming.
Transportation of Natural Gas
There are different states in which natural gas is transported, including:
- CNG (Compressed Natural Gas).
- LNG (Liquefied Natural Gas).