One authority, Diesel Technology Forum Executive Director Allen Schaeffer, in the “Bright Future For Diesel In The Natural Gas Revolution” press release, shed some light.
“While the nation’s truckers will ultimately be the ones to answer that question, according to international and U.S. energy and transportation experts, the future of America’s heavy-duty trucking industry is very clear – diesel is going to remain the overwhelmingly dominant growth fuel in transportation for several decades to come.”
Schaeffer, moreover, also in the release declared: “Truckers always want lower fuel costs, but are smart enough to know the lowest cost isn’t always the best choice. Diversification of fuels and technologies is in our future, and we need to approach it based on more transparent facts. But one thing is clear. Virtually every U.S. and international energy and transportation agency has said that diesel will remain the overwhelming transportation energy source beyond 2050.”
Though probably true, this has not prevented a cohort of U.S. and Canadian railroad companies from considering as an alternative Liquefied Natural Gas (LNG).
So, why the renewed, yes, renewed interest in LNG among North American railroad concerns as a potential locomotive fuel? In a word: cost. More specifically, compared to diesel, LNG costs significantly less.
That’s but part of the story. Add to that the derived-liquefied-natural-gas benefits of better fuel economies/reduced operating costs, plus lower emissions levels compared to that which is derived via standard diesel fuels.
Looking at the locomotive emissions side of the equation, consider the following U.S. Environmental Protection Agency (EPA) “Locomotives: Exhaust Emission Standards” data. The emissions of hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM) and carbon monoxide (CO) are considered. Quantified units for all exhaust emissions are expressed in grams per brakehorsepower-hour (g/bhp-hr), with the exception of hydrocarbons whose units are expressed in grams per horsepower-hour (g/hp-hr).
Line-haul locomotive data:
- Tier 0 (1973-1992) – HC (1.00), NOx (9.5), PM (0.22), CO (5.0)
- Tier 1 (1993-2004) – HC (0.55), NOx (7.44), PM (0.22), CO (2.2)
- Tier 2 (2005-2011) – HC (0.30), NOx (5.5), PM (0.10), CO (1.5)
- Tier 3 (2012-2014) – HC (0.30), NOx (5.5), PM (0.10), CO (1.5)
- Tier 4 (2015 +) – HC (0.14), NOx (1.3), PM (0.03), CO (1.5)
Switch locomotive data:
- Tier 0 (1973-2001) – HC (2.10), NOx (11.8), PM (0.26), CO (8.0)
- Tier 1 (2002-2004) – HC (1.20), NOx (11.0), PM (0.26), CO (2.5)
- Tier 2 (2005-2010) – HC (0.60), NOx (8.1), PM (0.13), CO (2.4)
- Tier 3 (2011-2014) – HC (0.60), NOx (5.0), PM (0.10), CO (2.4)
- Tier 4 (2015 +) – HC (0.14), NOx (1.3), PM (0.03), CO (2.4)
As the above data show for both line-haul and switch locomotives the higher the Tier rating, generally speaking, the cleaner the specified exhaust emissions.
All well and good but there is the matter of working through the particulars of using LNG in railway applications; more specifically, the logistics regarding transport of the fuel itself. Ditto for roadway applications.
To liquefy natural gas requires cooling or more accurately refrigeration which means with a cold enough temperature to turn the fuel from a gaseous to a liquid state.
On the railroad, that means the creation of a special container – a holding tank of some sort – to both store and deliver the fuel from container(s)-to-locomotive(s) in order to enable its use. Then there is the matter of the re-fueling infrastructure, all of which will surely mean added upfront costs.
So, for railway locomotives, what will it be: diesel or LNG?
Remember, we are talking about the future, so it is difficult to say.
That said, consider the options: biofuel (from waste vegetable oil or otherwise), diesel, dimethyl ether or DME, ethanol (blended formulations or solutions, such as E85), gasoline, hydrogen (as in hydrogen fuel cells), propane; did I miss anything? It seems the sky’s the limit.
And, speaking of skies and bodies of water, too, there is aviation and watercraft. Will blends be the order of the day?
Making engines cleaner-burning and more fuel-efficient, well, that’s a given.
As for the fuel of choice on the other hand, where America’s transportation future is concerned, this is by no means decided.