The natural gas industry in the United States has been growing by leaps and bounds over the past six years due to new technology in extraction and billions of dollars in investment by energy companies. Natural gas has been used in heating homes for more than 75 years and natural gas is now being considered as energy for transportation. A few different popular fuels are known as “natural gas” and it is important to know the difference between the fuels.
The most widely used fuel for heating homes is methane, known by many as “natural gas.”
Methane is one of the most abundant organic compounds on Earth that can be found in natural gas fields, landfills, coal mines and even farms that produce livestock. Methane is gathered and transported by pipeline as a gas to its final location where it is burned for heat or to generate electricity. Methane has a wide distribution network to millions of buildings in the United States. Methane in its typical gaseous state does not work for transportation because a constant flow of methane at low pressure is needed to operate furnaces and turbines at their most efficient level.
Methane in a liquid or high-pressure gas state can make sense for transportation. The liquid form of methane is known as liquefied natural gas, or LNG, and the high-pressure form of methane is known as compressed natural gas, or CNG. Each has unique characteristics.
LNG is methane under pressure and stored in a refrigerated tank that keeps the methane at about -240 Degrees C. For comparison, the coldest temperature ever recorded on earth was -82.8 Degrees C. LNG can require a tremendous amount of energy to maintain its liquid state and is hindered by a very narrow distribution channel. However, methane in its liquid state has about the same amount of energy as ethanol, yet is cheaper to distribute than ethanol.
CNG is methane under extreme pressure stored in a tank that fits in a vehicle. CNG is stored at about 3600 PSI at the same temperature as its surroundings. The pressure will change with its use and surrounding temperature, so maintaining a constant pressure is key in using CNG.
Another type of natural gas that is widely used is propane, both in its liquid and gas form.
Propane in its liquid form, known as LP, as been used for years to power indoor lifting equipment like forklifts and other large machinery, like Zambonis and city buses. LP is injected into engines and ignited similar to gasoline. The intake for the fuel line is at the bottom of the storage container to ensure only liquid is delivered to the engine. There is already a wide distribution network to support propane delivery since businesses already use LP tanks for their equipment. However, propane is a by-product of petroleum refinery and supply cannot be easily adjusted based on demand. Once it is produced, propane is stored in large salt caverns where is it distributed by pipeline to other areas.
Liquid propane gas, LPG, is not used in transportation but as a fuel for cooking. LPG is the same propane hydrocarbon, but rather than igniting the injected propone, LPG pressure is regulated with a nozzle to maintain a steady flame. LPG is almost identical to LP, but rather than delivering the fuel as a liquid, it is delivered as a gas.
Renewegy is currently working on up-fitting on-highway engines to burn natural gas. The process involves recalibrating the engine settings, replacing the fuel injectors, changing the harnessing on the engine among other vehicle changes like replacing the tanks. Since natural gas energy prices are about half that of gasoline, companies are able to take advantage of lower fuel prices while using a cleaner-burning, American source of energy.