Thursday, October 31, 2013

Good Background on CNG in U.S.

The New York Times earlier this week published a good article about the adoption of CNG for passenger vehicles in the U.S. that makes a few points that I have not heard emphasized yet.  The article doesn't have any particular scoop, but it gives a good "state of the union" of where we stand on natural gas and passenger cars.

I found most interesting the discussion of the engineering challenges of optimizing natural gas in a gasoline/natgas dual fuel engine, which most mainstream carmakers are starting to offer as a way of dipping their toes in CNG.  Natural gas is inherently disadvantaged in these types of engines because natgas has a lower energy density than gasoline.  The trade-off, however, is that natural gas has a much higher octane rating of 130, compared to low 90s and below for most conventional gasoline.  The higher octane allows car engines to run with higher cylinder pressure, which provides greater power and offsets the energy density issue.  Unfortunately, none of these dual fuel engines are optimized for natural gas and therefore run less efficiently on natgas than a dedicated natgas engine.  Ultimately, a cost effective and efficient home fueling solution will be the single greatest impetus for automakers to bring dedicated CNG models to the U.S.

But while CNG for passenger cars would be great for the natural gas industry, it is trucking and commercial fleet vehicles that are more of the holy grail.  Not only would these LNG vehicles use more natural gas than passenger cars, but moving the proverbial needle towards adoption in this market is considerably easier because companies that are able to buy vehicles in large scale purchases often can create a fueling infrastructure to support these vehicles.

But beyond the cost benefits to owning a natural gas vehicle are the environmental benefits, most notably the reduction in particulate air pollution (not just carbon emissions), a topic I find under-discussed.  Everyone wants to talk about carbon, but that's just a piece of the larger puzzle in my book.

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