Natural Gas Fuel Overview Natural gas may be used as a transportation fuel in two forms: compressed natural gas (CNG) and liquefied natural gas (LNG). Fundamentally, the difference between these two forms is energy density - a liquid fuel carries more energy per pound than a gaseous fuel. (Remember that the vehicle doesn't care how the fuel is stored, just that the fuel reaches the engine in the vapor phase). Compressed Natural Gas (CNG) Compressed natural gas (CNG) is pressurized natural gas that is stored in cylinder tanks at pressures up to 3600 pounds per square inch (psi). Usually, CNG is pipeline gas that is compressed at a refueling station and "dried" (to remove water). Many refueling stations have been constructed to compress natural gas for use in NGVs. Currently, CNG is the most common form of natural gas use as a clean alternative fuel, though it is noteworthy that heavy-duty vehicle fuel markets are developing rapidly for liquefied natural gas (LNG). Throughout this website you will find detailed information regarding various aspects of CNG as an alternative fuel, since the vast majority of NGVs in use today operate on CNG. Additional detail regarding LNG is provided below. Also, please check out the section for more information about LNG as an alternative fuel. Liquefied Natural Gas (LNG) - What is it? Liquefied natural gas (LNG) is cooled to a temperature of about -260°F at atmospheric pressure where is condenses to a liquid. LNG weighs less than one-half that of water and is odorless, colorless, non-corrosive, and non-toxic. When vaporized, it burns only in concentrations of 5 to 15 percent when mixed with air. Neither LNG, nor its vapor, can explode in an unconfined environment. Natural Gas Composition Pipeline natural gas is composed primarily of methane (typically, at least 90 percent), but may also contain ethane, propane and heavier hydrocarbons. Small quantities of nitrogen, oxygen, carbon dioxide, sulfur compounds and water may also be found in pipeline natural gas. Pipeline natural gas is refined through a process called liquefaction to make LNG, which removes the oxygen, carbon dioxide, sulfur compounds, and water from the fuel. The process can also be designed to purify the LNG to almost 100 percent methane. Benefits of NGVs Economic Benefits of NGVs Choosing natural gas increases energy security. Fuel Cost is Lower than Gasoline An economic analysis of natural gas as a vehicle fuel depends on many factors, including vehicle application (gasoline or diesel), vehicle size (light-duty, medium-duty,or heavy-duty), fleet size, annual mileage, etc. The extent of the economic benefits will depend on these factors for each fleet or individual user. An equivalent (on an energy content basis) gallon of natural gas currently (October 1998) costs between $0.95 and $1.041 per gasoline gallon equivalent in the southern California region. This is the fully allocated price of natural gas fuel with transportation, compression* and tax costs. These prices will vary by region please consult the Natural Gas Utility NGV Sites reference section for price information for other regions. It is noteworthy that many public fleets are tax exempt, so there is an opportunity for additional savings for these fleets. Also, additional savings are possible if existing fuel station networks are utilized. Convenient and Abundant There is a well-established pipeline infrastructure throughout the country that delivers natural gas to almost every urban area and most suburban areas. This existing infrastructure provides a safe, environmentally benign fuel transportation network for vehicle fuel customers. Only the installation of a fuel compressor station, or in the case of private home use, a home refueling system, is needed to provide natural gas as a vehicle fuel. No costs associated with transportation and delivery of fuel in large tanker trucks are incurred. Also, there are significant avoided economic and environmental costs of underground storage for liquid fuels. More important, natural gas is a domestic resource, so no importation of foreign product is necessary. Increased displacement of petroleum imports could reduce the national trade deficit by reducing our dependency on foreign oil, leading to enhanced energy security for the nation, an important economic benefit for all citizens. Industry experts indicate natural gas supplies will last beyond the 21st century. Currently, there are over 60,000 NGVs operating nationwide. It is estimated that if this were increased to ten million, natural gas consumption would only increase by six percent. In other words, dramatic increase in NGV implementation will not adversely affect conventional uses of natural gas. Price Stability Historically, natural gas prices have exhibited significant price stability as compared to petroleum-derived fuels. This stability is an important benefit of NGV use since more accurate long term cost planning may be conducted and expected savings may be projected. Natural Gas Vehicles and Engines Available Today High performing natural gas engines and vehicles that have been thoroughly tested in field demonstrations are available to the commercial market today. See the NGV Products page for details! NGV safety NGV Cylinder Safety Information This research bulletin from Gas Research Institute (GRI) provides background and guidance on natural gas vehicle (NGV) cylinder inspections Cylinder selection is critically important when designing a natural gas vehicle. Gas Research Institute's (GRI) summary of cylinder technology and design theory provides helpful information for the vehicle designer. This research bulletin from Gas Research Institute (GRI) provides background and guidance on natural gas vehicle (NGV) cylinder inspections. Another important GRI document, which identifies proper practices in the care and handling of NGV compressed gas cylinders. Please call our NGV Product Sales & Services Department : +603-9282 0172 or email us. |
