Why Fleet Operators Should Be Proactive About CNG Fuel Tank Specification


Fleet operators continue to consider compressed natural gas (CNG) as an alternative to gasoline and diesel for a variety of reasons, including lower fuel costs and reduced emissions. But fleet operators who take an active role in the fuel system specification process of their new CNG-dedicated vehicles can gain maximized driving range, increased safety, improved total cost of ownership and reliable performance over thousands of miles of driving.

The key for fleet operators is knowing the right questions to pose to a vehicle dealer or fuel system provider before specification.

The Case for Being Proactive
A CNG vehicle starts with an engine that has been configured to operate on the pressurized gas. The CNG fuel system is separate from the engine and comprises several components, including hose assemblies, tubing, electrical, hardware, the fuel management module, regulators, the cabinet and fuel tanks.

The fuel tank is arguably the most important of those components; a fleet vehicle won’t move an inch without fuel. But the type of fuel tank – particularly its size and construction – is typically not high on the priority list for fleet operators, who usually leave individual component decisions to their prospective dealer or fuel system provider. Those parties, in turn, will specify a CNG system and its individual components based on vehicle application while staying price competitive.

But that’s where a fleet operator needs to be proactive. There are different fuel tank types available, each offering a range of sizes, price points and advantages. Since fleet operators have a choice, they should examine their options and advocate for the tanks that make the most sense for their operation.

Tank Questions to Ask
So, what questions should a fleet operator ask a dealer or fuel system provider regarding fuel tanks during the specification process? Consider the following a starter list:

What type of CNG fuel tanks will you specify?

CNG fuel tanks are designed to store the pressurized gas at 3,600 psi, and there are different technologies designed to do that. Options include Type III tanks, which feature a carbon-fiber outer shell with an inner aluminum liner that all but eliminates gas permeation (i.e., gas dissipation through the liner), and Type IV tanks, which have that same carbon-fiber outer shell along with an inner plastic liner that can expand and contract. Factors to consider when choosing between the two technologies include things like vehicle weight, which is directly influenced by tank weight, and the fleet’s need for fast filling, the quick-fueling process that typically takes less than an hour. (Note that this is different than time filling, which typically takes place over several hours.)

How will you validate the CNG driving range claims?

This question comes down to accountability. If a dealer or fuel system provider makes a claim about the anticipated driving range of a CNG vehicle, fleet operators should ask for validation in the form of referrals, examples and math. For example, some dealers may refer to rated DGE (or diesel gallon equivalency), which is based on the water volume of the CNG fuel tank at 100% fill efficiency. But remember, CNG is a gas, so a fleet operator’s counter question should be focused on what the usable DGE is, which provides a more accurate prediction of eventual driving range.

How will the product be supported?

Whether a dealer or fuel system provider specifies Type III or Type IV CNG fuel tanks, it’s important to know how a fleet operator will be supported in the event that mandatory inspections uncover unusual wear. That includes support not only from the dealer or fuel system provider, but also from the fuel tank manufacturer. What is the manufacturer’s longevity and its ability to support the long-term use of the tank, including technical expertise and customer service?

Transitioning Your Fleet
Those aren’t the only questions a fleet operator should ask. How fuel tanks can help manage a fleet’s costs should also be paramount, especially how a CNG fuel tank contributes to a fleet’s total cost of ownership. Questions about durability should also be addressed, because an important part of the cost equation for fleet operators is liability avoidance.

Factors such as fuel costs, fueling infrastructure and overall maintenance are crucial when considering a CNG fleet. But it’s also important to review fuel system component details. Fuel tank choice alone will impact long-term vehicle performance, including safety, return on investment and reliability.

Wayne Powers is alternative fuels general manager at Worthington Industries, an Ohio-based diversified metals manufacturing company whose product offerings include alternative fuel systems.

Notify of
Inline Feedbacks
View all comments