Was passing by bus park last night; the city runs buses on CNG. First start looking at kids and thinking about diapers, then realized it is methane leaks from buses/fill up stations. Burning NG creates less CO2 but what about real life CH4 emissions? CH4 is 70 times more potent green gas, and it escapes alot faster then petroleum products.
NO cars are good for the environment. The only question is how BAD are they for the environment. That said, a natural gas vehicle should NOT be releasing detectable levels of Methane. Nor should the filling station. Complain to the relevant authorities.
The nose KNOWS, or does it? Keep in mind the purpose of the nat gas odorant is that it can be smelled at ultra-low concentrations. When it comes to risk communication, smell is a problem because people equate odor with pollution and harmful substamces. So the bus park probably has its work cut out to stop even the smallest leaks if it wants to be accepted by the community. I hope the terminal is working to stop the smells, which may not be easy.
I believe methane is only 23 times more potent than CO2 and not 70 times. But pretty potent indeed. You can see some landfills that are creating methane doing "flares" to burn the extra methane that isn't being used so that it doesn't get released into the atmosphere.
Problem with NG is all the leakage from the pipelines. Those are also usually not accounted for when they publish well to wheel emissions, unlike transmission losses. And we aren't even talking about terrible unregulated pollution that fracking causes. Bush made sure the drillers don't need to report on what they use to force the fracking. ps : 2005 Energy Policy Act prohibited the regulation of fracturing under the Safe Drinking Water Act. http://www.propublica.org/article/former-bush-epa-official-says-fracking-exemption-went-too-far
it is really depends if it is calculated over period of 25 or 100 years. It is ~x90 if calculated over 5 year.. as I recall [ame=http://en.wikipedia.org/wiki/Methane]Methane - Wikipedia, the free encyclopedia[/ame]
P.S.- ...are you sure it was not diapers? I can say that's pretty bad now that we have some Gen-II little ones running around
Regulations are more likely to be the reason. Landfills were generally just vented before the 90s (for safety purposes), with the exception of some in California and Washington. The majority of landfills today are also only vented. Collection/destruction is only required >100Mg methane generation/year.
This is 'missing the forest for the trees'. Yes, methane is worse than CO2 for global warming, there are leaks, and the fracking issue was not handled with the public good in mind. But what would be fueling those buses instead of CNG? Diesel. Many oil wells just flare of their methane, and some of that likely leaks. Along with all the local and global issues of its use.
