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Commonly Asked Questions about Compressed Natural Gas (CNG) for vehicles

What is CNG? – Compressed natural gas (CNG) is just like the natural gas you use to heat your home, but it is under a lot of pressure so it remains clear and non-corrosive. This fuel can be used in special vehicles, in place of gasoline or diesel. Although vehicles can use natural gas as either a liquid or a gas, most vehicles use the gaseous form. CNG is typically stored in a tank at a pressure of 3,000 to 3,600 pounds per square inch. Natural gas is sold in units of gasoline or diesel gallon equivalents based on the energy content of a gallon of gasoline or diesel fuel.

Why choose CNG? – Using CNG on high-mileage fleets—such as buses and taxis—that are centrally fueled or operate within a limited area can provide several advantages. Typically, the advantages of natural gas include its availability, widespread distribution infrastructure, low cost compared with gasoline and diesel, and environmentally friendly, or clean-burning properties. Natural gas vehicles show an average reduction in ozone-forming emissions of 80 percent compared to gasoline vehicles.

How is natural gas produced? - Most natural gas comes from three types of wells: natural gas-and-condensate wells, oil wells, and coal bed methane wells. Well-extracted natural gas requires a cleanup process before it can be used in vehicles or residences. This natural gas is then delivered to special CNG filling stations through traditional or existing pipelines and utility infrastructure. At the filling station, it is compressed and transformed into CNG.

Where does natural gas come from? – Nearly all (more than 99 percent) of the natural gas used in the United States comes from North American sources.

How is natural gas delivered to transportation customers in Iowa, Minnesota, and Wisconsin? - The natural gas used in the Midwest is transported by pipeline to gate stations. Alliant Energy takes the gas from the gate stations and distributes it to customers through its pipelines. Most CNG vehicle fueling stations are owned and operated by private companies and local governments. These fueling stations then take the natural gas and compress it to create CNG.

Where is CNG fuel available in Iowa, Minnesota, and Wisconsin? – The number and location of CNG fueling stations varies by state. To find a location near you, go to the U.S. Department of Energy Station Locator.

How is CNG stored? - CNG is stored in tanks at smaller fueling locations and on vehicles.

Is natural gas safe? – Natural gas is safe, and CNG-powered vehicles must follow the same safety guidelines of other vehicles. Natural gas is flammable only when the mixtures or air and natural gas are within 5 to 15 percent natural gas. When the mixture is less than 5 percent natural gas, it doesn't burn. When the mixture is more than 15 percent natural gas, there is not enough oxygen to allow it to burn. Because natural gas is lighter than air, it quickly dissipates when released from tanks.

How do CNG vehicles perform? – CNG vehicles are very comparable to traditional gas or diesel power vehicles in terms of performance. Power, acceleration, and cruising speed are all comparable among the different fuel options. However, the driving range of CNG vehicles is generally less because of the different energy density of natural gas versus gasoline and diesel. Less energy can be stored in the same size tank as the more energy-dense gasoline or diesel fuels. Extra natural gas storage tanks can help increase range for larger vehicles.

How much do CNG vehicles cost? - Light-duty CNG vehicles cost $5,000 to $7,000 more than comparable gasoline vehicles, and heavy-duty CNG vehicles cost more than their counterparts by $30,000 or more. The price depends on the fuel-tank capacity and whether the vehicle is produced by an OEM or converted to run on natural gas. However, government incentives are available to offset CNG vehicle costs. For more information, visit the Alternative Fuels and Advanced Vehicles Data Center (AFDC) Incentives and Laws section at afdc.energy.gov. Due in part to the high octane rating and clean-burning properties of natural gas, some fleets have reduced maintenance and operating costs for CNG vehicles compared with conventional vehicles. - Information from the U.S. Department of Energy

What vehicles use natural gas? - CNG vehicles have many applications, like taxi cabs, and also in medium-duty trucks like UPS delivery vans and postal vehicles. CNG is also used in more heavy-duty vehicles like buses and street sweepers.

Are there any home refueling options for CNG? There are a few options for consumers on the market that they can install at their own home. With this device, CNG vehicle owners can refuel their vehicles overnight in their own home – if they already have natural gas service. Because natural gas is delivered to homes under very low pressure, refueling CNG vehicles takes time. You can also read this article from Consumer Reports on the advantages and disadvantages of using CNG at home.

How much does CNG cost? – In June, 2012, prices of a therm of CNG ranged from $1.29 to $2.29 for pumps in Iowa, Minnesota, and Wisconsin. You can go here to find current prices. A therm of natural gas is comparable, but has a little bit less energy content than a gallon of diesel or gasoline.

What are the environmental benefits of CNG?
• Heavy-duty CNG vehicles met 2010 EPA emissions standards in 2007, making them six times cleaner than 2007 diesel engines in terms of smog-forming hydrocarbon and nitrogen oxide (NOx) emissions.
• Light-duty CNG vehicles emit up to 90 percent less NOx and 98 percent less hydrocarbon than gasoline-powered cars.
• CNG vehicles greenhouse gas emissions are about 20 percent lower overall than those of gasoline-powered cars and heavy-duty diesel vehicles.
• The variety of CNG vehicles on the market means they can reduce pollution and greenhouse gas emissions generated by most vehicle sources, from commuter traffic to delivery trucks and refuse haulers.
(Information from California Natural Gas Vehicle Coalition - cngvc.org\why-ngvs\air-and-climate.php)

What do I need to know if I want to build a CNG station? There are three important pieces of information you will need to know before contacting Alliant Energy to learn about gas availability for a CNG refueling station.
• What pressure do you need natural gas delivered at?
• Where do you want to place the refueling station? You can provide multiple options.
• What will be your daily and hourly CFM need?

Additional Information

• To learn more, call Alliant Energy’s Distributed Resources Hotline at 1-800-972-5325.
• Download this information sheet from the U.S. Department of Energy.
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