Natural Gas Vehicles, Part II

So at the end of my post on natural gas vehicles I asked the question, 'if there is a cheaper, cleaner source of fuel here - why all the dirty buses?' Needless to say, I've been bugging many of my Colombian friends about it as well. Well, word got round to a chemical engineer and I got some more information to share.

One specific question I had involved why Transmilenio wasn't developed with natural gas powered buses as the foundation. Her reply was that natural gas does not work as well for large vehicles for the same reasons that they use diesel instead of gasoline (that is higher energy per unit of volume, more torque, greater efficiency.)

So natural gas powered buses are not a feasible alternative and neither are expensive and short-lived exhaust filters, then what?

Apparently the easiest and most effective reform would involve eliminating low-grade diesel from Colombia's fuel inventory. Diesel fuel in Colombia contains 10 to 100 times more sulfur than the diesel used in the U.S. and Europe, known as 'Ultra-Low Sulfur Diesel (ULSD).' Sulfur acts as the nucleus for particulate matter, attracting other pollutants to form big gross balls of nastiness.

Wow! That seems like a straight-forward and achievable policy goal. Undoubtedly, ULSD is likely much more expensive than the dirty stuff. However, if you frame the analysis in terms of cost-savings via chronic disease prevention I would guess that it's a pretty good deal and worthy of government subsidy. Especially here, high in the Andes, particulate matter can cause all kinds of public health problems.

I'm not sure if an analysis has been done on this or not. But I'm going to find out!