The current status and future of natural gas-powered heavy vehicles
Heavy vehicles may be assuming a greater importance in the world not only because of increasing commerce but for, perhaps, a commonly unforeseen reason: the need for greater mass transit. At present (2011), there are a billion passenger cars on the road, and that number is projected to go much higher, especially in China and India, as those economies develop further .
There are two practical limitations facing this expansion: traffic congestion, the inability of the planet to support everyone having a personal vehicle, and peak oil . If people expect to be transported by means other than walking or animals, and if personal occupancy vehicles are not available, then mass transit is about the only option, and that means heavy vehicles, such as trains, busses, and trucks.
The vast number of heavy vehicles, such as trains, busses, earth moving machinery, and large trucks use number two diesel fuel, though methanol is replacing it . While less polluting than gasoline , it nevertheless is environmentally contaminating. There is controversy about how much natural gas can alleviate the problem for cars and whether it is practical, but there seems to be less of a debate about large vehicles. By converting large vehicles, there could be a savings not only of energy but a reduction of contaminants in the atmosphere, including greenhouse gasses. Of course, natural gas does emit carbon dioxide as a greenhouse gas, and this must be figured into the overall air pollution equation . Natural gas produces 20% of the U.S. carbon dioxide emissions . It may questionable whether it is practical to have an all out campaign to have small cars run on natural gas, especially when it is considered that a more immediate reduction of fossil fuel and air pollution use may be had by targeting those vehicles that use the most of it, i.e., large vehicles. For example, what would be the cost of converting a locomotive or bus to natural gas compared to the numerous
cars it would supplant? The limitations set for smaller vehicles in terms of the capacity to carry fuel tanks, for example, are not as much of a problem for trains and busses. Especially for trains, the cryogenic apparatus required for LNG can be carried more readily. About the only major question is that of economics. Each category of heavy vehicle illustrates a strong reason for using natural gas.
References (Subject is indicated by URL – accessed 18 September 2011)
plain.pdf&embedded=true&chrome=true , and
impact/, as examples