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Post by masonite on Jul 29, 2009 9:30:31 GMT -8
MTA is looking golden right now for having an almost all LNG fleet as there is less pollution from these busses, which is great as nothing was worse getting off the bus and then having that diesel plume come at you as the bus went off (also better air quality for Los Angeles). Not to mention this is a domestic source of energy as opposed to oil, which we mostly import.
While oil prices are remaining relatively high and thus diesel prices as well, nat gas has tumbled and I believe it is less than half what was a year ago. This must be saving the MTA a pretty penny, although I realize they have other headwinds on the operations budget to deal with.
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Post by ieko on Jul 29, 2009 11:21:36 GMT -8
They use CNG (compressed) not LNG (liquified). Actually they would've been better off if they could've purchased Diesel-Electric buses because they cost relatively the same but get better fuel economy. CNG buses engines run hotter so they're less reliable, and get less fuel economy than diesel (a little less than a gasoline engine). The range is also heavily reduced, it's about half of what a gasoline powered vehicle can do. Diesel-electric also pollutes less than CNG and there would be no need to invest in CNG fueling facilities at each division. Also maintaining the tanks that store CNG is a real problem because each bus has a lot of them, I believe the NABI 60BRT has 18 tanks, the added weight isn't helpful either.
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vnc
New Member
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Post by vnc on Jul 30, 2009 1:02:21 GMT -8
CNG also drives up the cost for each bus built. Diesel powered cost half the price a CNG Powered vehicle
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Post by masonite on Jul 30, 2009 8:35:43 GMT -8
They use CNG (compressed) not LNG (liquified). Actually they would've been better off if they could've purchased Diesel-Electric buses because they cost relatively the same but get better fuel economy. CNG buses engines run hotter so they're less reliable, and get less fuel economy than diesel (a little less than a gasoline engine). The range is also heavily reduced, it's about half of what a gasoline powered vehicle can do. Diesel-electric also pollutes less than CNG and there would be no need to invest in CNG fueling facilities at each division. Also maintaining the tanks that store CNG is a real problem because each bus has a lot of them, I believe the NABI 60BRT has 18 tanks, the added weight isn't helpful either. Good points. Yes, I confuse LNG and CNG. My point that nat gas is currently very cheap and a domestic source of energy vs. imported oil and more expensive diesel remains. Also, I question the point that diesel electrics are cleaner than nat gas (not saying you aren't right, but I still have my doubts without seeing any conclusive evidence). Particulate pollution has been deemed much more dangerous the last few years as these particles lodge deep inside the lungs causing all sorts of health problems. These particulates come from diesel. I know the diesel engines are much cleaner than they used to be. Also, realize it takes many years for a bus fleet to reflect a system wide standard. Some of the CNG busses are 10 years old. Not sure what diesel-electric was like then. Also, diesel busses may be cheaper than nat gas, but I am not sure diesel-electrics are much cheaper if at all.
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Post by ieko on Jul 30, 2009 10:13:28 GMT -8
The thing is, with CNG the cost looks low but it really isn't because the range of the fuel is less. So the cost is the same because you must refuel twice as much.
Diesel-electric is definitely cleaner than CNG, I've read that several times but of course when I try to find a link I can't haha.
Diesel buses are banned in southern California so its not like they had a choice, but yeah it certainly would've been a good choice if they could've done so.
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Post by bluelineshawn on Jul 30, 2009 11:43:36 GMT -8
I also used to think that natural gas was cleaner, but I looked at some studies that were on-line last year and diesel is just about as clean for particulate emissions (they have filters now) and emits much less carcinogens. The particulate that you're talking about is called "respirable" particulate. It used to be called PM10 (less than 10 microns in size) but recent studies have shown PM2.5 to be the really bad stuff. The new diesel filters do well at reducing that to almost nothing.
Also, natural gas byproducts include things like formaldehyde and acetaldehyde which have much higher cancer risks than anything in diesel. I didn't look at diesel-electric, but if diesel is already better, then I can see where diesel-electric is much better.
Maybe I'll cite some sources later, but the studies are on-line if anyone wants to search for them.
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