What is Natural Gas?
Natural gas is a mixture of hydrocarbons, primarily methane, which is a relatively nonreactive hydrocarbon. Natural gas delivered through the pipeline also contains hydrocarbons ethane and propane as well as other gases (i.e., nitrogen, helium, carbon dioxide, hydrogen sulfide, and water vapor). Natural gas can be produced from gas wells or as a result of crude oil production. Because of the gaseous nature of natural gas, it must be stored on-board a vehicle in either a compressed gaseous state (CNG) or a in a liquefied state (LNG). End users for natural gas include all economic sectors: residential, commercial, industrial, and transportation.
How is Natural Gas Made?
Most natural gas used in the U.S. is produced domestically. Most natural gas is drawn from wells or extracted in conjunction with crude oil production. Natural gas can also be mined from subsurface porous rock reservoirs through extraction processes, such as hydraulic fracturing. Processing is required to separate the gas from petroleum liquids and to remove contaminants. In addition, natural gas (methane) can also come from decaying organic materials, such as waste from plants, landfill gas and water/sewage, and livestock.
First, the gas is separated from free liquids, such as crude oil, hydrocarbon condensate, water, and entrained solids. The separated gas is further processed to meet specified requirements. For example, natural gas for transmission companies must generally meet certain pipeline quality specifications with respect to water content, hydrocarbon dew point, heating value, and hydrogen-sulfide content.
A dehydration plant controls water content; a gas processing plant removes certain hydrocarbon components to hydrocarbon dew point specifications; and a gas sweetening plant removes hydrogen sulfide and other sulfur compounds.
Natural Gas Fuel Market
Natural gas is distributed throughout the United States in extensive pipeline systems that extend from the wellhead to the end user. Every continental state has access to natural gas through pipelines. The pipeline system consists of long-distance transmission systems, followed by local distribution systems.
Natural gas vehicles can easily be fueled at public stations or on-site refueling can be built. Individual home compressors use a slow-fill system for overnight refueling. A small compressor would usually be located in a home’s garage area and would be connected directly to the natural gas supply in the house. In heavy-duty applications, the cost of a high capacity fast-fill private or public station ranges from $200,000 to as much as $3 million.
The future holds great potential for natural gas because it can potentially be used in fuel cell vehicles to make hydrogen. Researchers have found that fuel cell vehicles using hydrogen produced from natural gas could present an attractive solution for cutting greenhouse gas emissions.
What are the Benefits of Natural Gas?
The difference in tailpipe emissions between conventional and natural gas vehicles has narrowed because more stringent emissions regulations have been applied to conventional vehicles and modern emissions controls have been deployed. In light duty applications, the emissions from natural gas vehicles are similar to conventional gasoline vehicles with modern emissions controls. However, CNG vehicles do see a reduction of 50% in evaporative volatile organic compounds and a 10% reduction in carbon monoxide. Currently the primary applications for compressed natural gas vehicles are heavy haulers, public transit bus fleets, and waste hauling trucks, however, there are effective vehicle options ranging as small as compact passenger vehicles.
CNG Vehicle Fueling Animation
Use this interactive animation to learn more about how the outside temperature and fill speeds affect the final fill volume in compressed natural gas vehicle tanks. Learn more about filling CNG vehicle tanks.
Clean Cities Natural Gas Working Group
Virginia Clean Cities conducts bi-monthly working group webinar calls with interested fleets, fuel providers, and other groups from around Virginia to discuss natural gas. If you are interested in joining the CNG Working Group, please contact us! Below is the presentation from the last working group call:
Hank Brown, TFC Recycling (PowerPoint by Stephe Yborra, NGVAmerica)
Arlington County CNG: Virginia Clean Cities awarded Arlington County Public Schools with State Energy Program Special Projects funding to purchase OEM compressed natural gas school buses.
Charlottesville CNG School Bus Project: Funding for Charlottesville Public Schools to purchase 2 CNG school buses was provided by Virginia Clean Cities through a State Energy Program Special Projects award. Funding also allowed for the purchase of a time-fill CNG refueling system manufactured by Fuelmaker which has the capability of refueling four buses simultaneously.
National Airport CNG Transit Bus Project: Virginia Clean Cities provided Ronald Reagan National Airport funding to help defray the incremental cost of purchasing CNG transit buses and purchase the CNG station from Washington Gas on Clark Street in Northern Virginia.
Natural Gas Toolkit
Virginia Clean Cities worked with the East Tennessee Clean Cities Coalition to create the Natural Gas Toolkit http://www.ngtoolkit.net. This toolkit allows you to find and utilize two primary numbers, the fuel price difference and your vehicle cost difference, to calculate a simple payback period. Perhaps more importantly, it helps you get basic pieces of information in one place to prepare for potential funding opportunities in the future. What you need to know is that this is just a starting point for looking at natural gas for your fleet. Clean Cities coalitions, NGVAmerica, and other resources are out there to help you find the other numbers you need, so use the resources page to find those as you need them.