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Wednesday, July 16, 2014

CNG Pickup Experience - Not ready for prime time!
Articles thanks to Bruce Smith and Links provided:

First CNG Pickup Experience: Chevy Silverado 2500 Bi-Fuel

First Impressions Driving A 2015 Bi-Fuel CNG 2500 Silverado HD

May, 2014  There’s this big push to get us to embrace clean energy by opting for propane- and CNG-powered pickups over diesel and gas. 
I’m all for helping the environment and am not afraid to give alternative fuels a look. 
So I’ve been eager to test both propane and CNG. I was impressed by the Roush-converted propane-powered F-250 I ran back in March. You’d never know it was propane by the way it performed over all. 
I was elated last week when I got my hands on a 2015 Chevy Silverado bi-fuel 2500HDCrew Cab 4×4 with the factory CNG package. 
But after spending a few days with it, I don’t think you can sell me on making the CNG switch just yet. 
Here’s the skinny: The CNG fuel tank takes up about 1/3 of the bed, it only holds about 17 GGE(gasoline gallon equivalent), and there’s a significant drop in both power and fuel economy compared to running the 6.0L GM V-8 on gas.

[RELATED: The Truth About CNG Tank Capacity]

It appears my test truck is averaging around 11mpg on CNG driving on the open road, while the V8 on gas is getting close to 14. (I haven’t done the final numbers.)
I paid $2.22 to fill up the CNG tank at a Clean Energy station 65 miles away in New Orleans while gas was selling for $3.23. 
Yes, 65 miles to go get CNG. There’s not a single fueling station anywhere along the Alabama and Mississippi I-10 corridor.
So much for the improved CNG fueling infrastructure.
2015 Chevy Silverado 2500HD bi-fuel with 6.0L CNG package.
2015 Chevy Silverado 2500HD bi-fuel with 6.0L CNG package.
On the track, the truck is a full two seconds slower accelerating to 60mph on CNG than it is on gas because the engine loses 60hp. 
Hook up a trailer and the CNG power difference will be be even more significant.
Quite honestly, I expected better performance.
CNG has about 20 percent the energy (BTU) per gallon compared to E-10 unleaded, so some power and fuel economy loss is expected.
But when the price of CNG is only 30 percent less than gas, there’s not much benefit to running it.
After you pay the $9,000 or so price for the option package the ROI may never be realized by trade-in or resale time unless you own multiple trucks and put in your own CNG fueling point.
(A $60,000 initial expense, but then you can get CNG for about $1.75 GGE.)  
So far my preliminary evaluation in this instance is:  Propane 1, CNG none. Sorry Chevy.

CNG Fuel Tank Capacity: Not What You Think

The other day  I was testing a CNG-powered bi-fuel pickup and was stumped when the truck’s “empty” 17 GGE CNG tank would only hold 12 gallons. 
After discussions with both CNG tank suppliers and CNG automotive pickup engine builders, I found out the stated size on a CNG tank isn’t the capacity that’s actually useable by the vehicle. 
CNG, a gas, is under 3,600psi when it goes into the fuel tank and around 3,400psi headed upstream to the engine.
That lower pressure has to be maintained in order to supply the truck’s fuel delivery system, which is separate from the truck’s gasoline fuel system if bi-fuel.
When the CNG volume decreases, so does tank pressure. When tank pressure reaches a certain point, CNG delivery ceases.
In most instances, according to both CNG tank suppliers and CNG pickup builders, that’s somewhere between 12-13 GGE on a 17 GGE fuel tank. 
On the truck I was testing the useable CNG capacity was only 12 GGE, not the 17 as listed on the brochure and spec sheets.
Keep that in mind when you are figuring the CNG range of a vehicle.

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