Natural Gas May Be Worse for the Planet than Coal

[wtmusic]

"This week the U.S. Congress heard testimony supporting a bill that would push to replace diesel with natural gas in heavy vehicles. It's an attempt to cut oil imports, and at the same time reduce greenhouse gas emissions. Part of the argument is that natural gas is substantially cleaner than diesel, and results in the emission of about 25 percent less greenhouse gas.

But experts are warning that natural gas might not be as clean as it seems.

In fact, using natural gas rather than diesel in vehicles could actually increase climate change, says Robert Howarth, professor of ecology and environmental biology at Cornell University. "You're aggravating global warming more if you switch," he says."

http://www.technologyreview.com/blog/energy/25058/?nlid=2903

Nightshade vs. hemlock? If the debate has come down to which poison is more poisonous, we're screwed.

[iris27]

1. Wouldn't the fact that it's cleaner be part of WHY it would aggravate global warming?

Diesel exhaust contains particulate matter, which, when released into the atmosphere, helps block solar radiation. Not great for the lungs, of course, but keeps the planet just a bit cooler. A vast release of particulate matter from (I think) volcanoes was one of the crazy geo-engineering solutions to global warming that was proposed a while back.

[wtmusic]

2. That's correct, we've been too successful at cleaning up particulates

Bottom line - fossil fuels are a dead end.

[meeshrox]

3. For once, I agree with your post!

It boils down to the efficiency of natural gas and how much more you have to burn to get the equivalent energy from a gallon of diesel, for example...

Natural gas is still a fossil fuel...we need to get off of all fossil fuels as much as practicable.

I like your new sig line, too! :hi:

[Statistical]

4. Something to consider however it is only a starting point.

The author assumes 1.5% leakage rate. Natural gas itself emits less CO2 when burning however methane is substantial contributor to GHG. The author concludes there is very little data on amount of natural gas leakage.

If we assume a 1.5% leakage rate, this would have a greenhouse gas warming potential equal to
14.8 g C of CO2 per million joules of energy. This would be additive to the emissions during combustion
(13.7 g C of CO2 per million joules of energy) and to the emissions associated with obtaining and
transporting the natural gas (very roughly estimated above as 4.5 g C of CO2 per million joules of
energy). Total greenhouse gas emissions from natural gas from hydraulic fracturing may, therefore, be
equivalent to 33 g C of CO2 per million joules of energy. For diesel fuel or gasoline, the total greenhouse
gas emissions are equivalent to approximately 20.3 g C of CO2 per million joules of energy.

If leakage was say 1% then it would be like 28g per MJ and 2% would be even worse at 38g per MJ.

Also the author doesn't account for long distance transportation of oil. The lifecycle CO2 from gasoline will depend on length of transportation. As we use up more and more "local" oil we will need use more and more "long distance" oil and CO2 cost will rise.

Last thing to consider is efficiency of powerplant. ICE are about 15% efficient (tank to wheel). Using a fuel cell instead of internal combustion engine for natural gas could cut CO2 release per mile by half or more.

Internal Combustion Gasoline: 20.3g / 0.15 = 135g per MJ effective work (work at wheels).
Internal Combustion Natural Gas: 33g / 0.15 = 220g per MJ effective work (work at wheels).
Fuel Cell Natural Gas: 33g / 0.40 = 82.5g per MJ effective work (work at wheels).

[NNadir]

5. This is a function of the long atmospheric half-life of methane. However, dimethyl ether

has a very short environmental half-life, on the order of 5 days, in comparison to decades for methane.

I don't support any aspect of the car CULTure, but if we must have cars, dimethyl ether would be the best approach by far, particularly since it is fairly straight forward to adapt it to existing infrastructure.

[Fledermaus]

6. It appears you left something out.

Natural gas does porduce less green house gas than coal.

Howarth's analysis, however, is just a preliminary one. He's already found one major error in his original calculations. "I blew it," he says, by not including the impact of methane leaks from coal mining. (Here's a link to his original, which contains the error; and here's the updated version). But he still says the gap between coal and natural gas is far smaller than generally thought.

http://www.technologyreview.com/blog/energy/25058/?nlid=2903

[joshcryer]

7. The point is, widely used natural gas is no better. It's only worth having as a stop gap.

Going further, using it for cars, is a non-starter and won't help us.