CNG & DGEs

I've been looking for info to determine the size in terms of methane mass contained in the smaller sized carbon-fiber composite tanks used for CNG vehicles.

There are several examples of these smaller tanks exploding, rupturing, catching fire, turning into a blowtorch, etc., but none I can find of the larger tanks rupturing. 

They seem to be rated in DGEs, Diesel Gallon Equivalent. 

Here is a nice explanation, and a price chart. 

http://www.nat-g.com/why-cng/cng-units-explained/

It says if methane is $3/MCF, then the cost of a DGE of CNG is $0.44, not including operational costs of compression, capital depreciation, profit, etc.

I took a rough guess at their operational costs (excluding profit), including labor and capital depreciation, and came up with between $.65 to $.90 added per MCF as a "CNG midstream cost". 

(One thing I forgot to add was per-mile fuel costs -- I'll work on adding this).

Spot price at Liedy Hub is now about $2.70. Add the CNG midstream costs and it's $3.35 to $3.60/MCF. Plug that in to the table above and we get under $.60 per DGE. 

Diesel in Binghamton is $2.60 - $2.85/gal. So CNG represents a saving for vehicle fleets of $2/DGE! 

Quite substantial. CNG fuel costs are about 1/6th the cost of diesel. 

That creates a great push towards CNG vehicles.

The problems are that CNG is not as ubiquitous as diesel, and also CNG trucks lack the torque of diesel. Not ideal for heavy loads or where there are steep hills. So limited applications. 

--

--
May you, and all beings
be happy and free from suffering :)
-- ancient Buddhist Prayer (Metta)