Tank Choice Affects Alt-Fuel Efficiency
The advantages of propane autogas tanks, include the ability to get them in a number of shapes, including toroidial, which doesn't compromise cargo space. Photo: Worthington Industries
While today’s lower cost of traditional fuels may have shrunk the market for alt-fuel vehicles, they can still make economic sense for light-duty fleets.
One of the often-overlooked aspects to choosing the most efficient alt-fuel system is the choice of fuel tank, according to Chris Hanners, product manager for alternative fuels for Worthington Industries.
Worthington supplies both propane autogas and compressed natural gas (CNG) tanks for light-duty vehicles.
CNG tanks tend to be lighter, but are restricted to a cylindrical shape. Photo: Worthington Industries.
CNG tanks come in two types: Type III, which has an aluminum inner liner, and Type IV, which has a bladder made of plastic. The tanks are then wrapped in carbon fiber. Worthington supplies Type III tanks, which Hanners said has several advantages.
“It has superior fast fill capabilities, 25% more storage capacity because you can fill it 100%, and, thus, better range,” he said. “It also has no filling restrictions.”
One of the added benefits of choosing a Type III tank — no matter the manufacturer — is that the added capacity may mean that a fleet may need fewer tanks to get the same range. This also decreases vehicle weight, increasing fuel efficiency. The cylindrical design of CNG tanks means that light-duty sedan and truck fleets that choose to use CNG may have to accept a loss of cargo capacity. In sedans, the tanks are often mounted in the trunk space, and in light-duty trucks in the bed. Truck fleets can counteract this loss of space by spec'ing a longer bed length, but this could add costs to the vehicle.
If a fleet decides on propane autogas, it will have the option of choosing from a number of shapes, including toroidal, which can fit in the spare tire void in a sedan trunk or under the bed of a light-duty pickup.
“Because the tank can fit in the spare tire space, you still have 100% of your trunk cargo space,” Hanners observed. “On the commercial side, you’ll have 100% of a light-duty truck bed or van cargo space.”
All propane autogas tanks are made of steel, thus add weight to the vehicle. Hanners said that Worthington has solved this issue by using lighter-weight steel, which cuts the weight of the tanks by about 30%.