FAQ
Is there a publically accessible CNG Filling Station located close to or on a regular route pattern that my fleet drives?
There are several websites that are regularly updated with publically accessible CNG filling station locations and the current sale price of the fuel. Visit www.altfuelprices.com or www.cngprices.com/station_map.php.
What is a GGE and DGE, why is this significant?
GGE = Gasoline Gallon Equivalent
DGE= Diesel Gallon Equivalent
Natural gas is measured in standard cubic feet (scf) while gasoline and diesel are measured in liquid gallon units. Natural Gas is converted to either GGE or DGE units of measurement for several reasons, one of which is to equalize the energy density of the natural gas to either gasoline or diesel. Industry standards vary but on average 1 gasoline gallon is equivalent to 125 scf of natural gas while 1 gallon of diesel fuel is equivalent to 137 scf of natural gas. When natural gas’ energy density is equalized with that of gasoline or diesel the end user should expect similar fuel efficiency and power from their CNG vehicle.
Do I have sufficient Natural Gas service at my proposed site to support a CNG filling station?
Cobey recommends contacting your local Natural Gas utility as a first step to a successful station design. Your utility will calculate the available line pressure range throughout the year and determine if the pipeline will appropriately handle the additional capacity demand of a CNG filling station. This information is required by Cobey Energy to properly size your filling station equipment.
For how many vehicles should I size my CNG station for?
Cobey Energy recommends sizing your CNG station for your predicted demand over the course of the next (3) three years. Typical fleets phase their vehicle replacements over a period of time. Sizing your station for three years of anticipated use will assure the system is not grossly oversized and therefore underutilized; it also assures your equipment is not undersized causing you to upgrade your equipment sizing on a regular basis. Economies of scale in sizing your compressor typically favor larger compressor when calculating cost per GGE or DGE.
What are the typical site electrical requirements?
Due to the size and electrical loading requirements of CNG filling station equipment typical electrical service requirements are 480V/3PH/60 Hz for the compressor and gas dryer. 120V/1PH/60Hz service is also required to operate the compressor control panel and the CNG dispenser. Other electric service requirements can be accommodated as required by the site layout and utility availability.
What pressure does the compressor compress the natural gas to?
For CNG applications it is common to compress natural gas to 4,500 psi. The greater the pressure of the gas the more volume that is able to be stored for fast fill or buffer fill scenarios. Also, compressing the gas to 4,500 psi and storing it in your ASME pressure vessels allows the gas to be transferred to the vehicle being filled by means of the kinetic energy stored in the gas and pressure pushing the volume from storage to the dispenser. Greater pressures than 4,500 psi are achievable but add additional cost tends to outweigh the benefits.
If the Natural Gas in a pipeline is dry, why do I need a gas dryer on my system?
Although pipeline quality natural gas is considered dry it is still allowed to contain up to 7# of H2O/MMBTU. All CNG compressor systems operate ideally with gas that is dried to an acceptable level of .5# of H2O/MMBTU. As Natural Gas is compressed from pipeline pressure to 4,500 psi moisture is simultaneously squeezed out of the gas stream, much like wringing a wet towel. The moisture will cause degradation of your compressor, ASME storage vessels and dispenser. There is also potential that moisture may carry over to the vehicle you fill, causing future maintenance issues.
Can my Cobey Energy CNG filling station be easily expanded for future demand?
Yes, All of Cobey’s primary components: Gas Dryer, compressor, ASME storage and dispenser are modular and can easily be added to for future site/fleet expansion projects.
What other costs are associated with operating my own CNG filling station?
Industry experts recommend when calculating the cost to operate and maintain your CNG filling station system to account for the following:
- Electrical costs approximately = $.10 per GGE
- Maintenance Costs approximately = $.30 - $.40 per GGE
Is there funding available to help offset the costs of installing a CNG filling station?
Cobey Energy recommends contacting your local Clean Cities Coalition coordinator to learn more about potential state incentives and U.S. Department of Energy grant programs. Visit Clean Cities website to locate your appropriate coordinator. http://www.afdc.energy.gov/cleancities/coalitions/coalition_contacts.php
Cobey Inc is a global designer and manufacturer of customized modular lubrication-compression-conditioning packages for the oil & gas, power gen and air separation industries. Products include lube oil consoles, dry gas seal panels, high speed reciprocating compressors, water injection skids, rundown tanks and rotating equipment packages. Systems can be designed to customer specifications, industry and applicable ISO/API standards.
