Is methane the big danger?
The world politicians efforts on combatting global warming is concentrating on reducing carbon dioxide (CO2) emissions.
But is that really so important compared to methane (CH4)?
The 'relative greenhouse effect' of methane is estimated at about 17 times that of carbon dioxide. In cold climate, the ratio may be as high as 40 times that of CO2. But it is true that the emissions of carbon dioxide still are much greater than those of methane. So the 'historic' global warming effect that we have seen might be caused largely by carbon dioxide.
However, the emissions of methane are increasing on a much faster rate than those of carbon dioxide. It is no doubt that global warming in the future more and more will be associated with methane.
In addition, the use of methane-containing fuels is even advocated by environmental interests. The methane in the atmosphere come from a variety of sources, among those most important are agriculture, garbage dump sites, exploration of natural gas fields, pipelines for natural gas, leakages from gas depots or gas filling stations, emissions from end use of natural gas or biogas in household, industry or vehicles.
The fact is that natural gas as well as 'biogas' contain 95-98% methane. Environmental organisations use to promote the use of 'biogas' as an alternative to fossil fuels. However, the CH4 emissions must be taken into consideration. 'Biogas' is often produced from garbage or harvested grass that is anaerobically treated. If not biogas was produced, some methane would anyhow be produced from the dump site but the majority of the coal-containing compounds would be transformed into other hydrocarbons or just carbon with time. So there is a considerable net emission of methane (and also carbon dioxide) if biogas is produced and used in vehicles. Still worse is of course the use of natural gas in vehicles and other applications.
The use of natural gas - or biogas - in vehicles is usually associated with significant emissions of methane due to that engines are tuned in to reduce emissions of nitrogen oxides which otherwise would be a problem for gas-powered vehicles. This is especially true for cold starts and during city traffic conditions.
A recent Swedish study published by the Environmental Protection Agency in Sweden gives the following emission parameters for biogas- and diesel-powered vehicles (Framtida mojligheter med nya drivmedel, Naturvardsverket 2004):
Diesel; CO2: 3,500 mg/MJ (emissions from tailpipe incl. production of fuel)
Biogas; CH4: 640 mg/MJ (emissions from tailpipe incl. production and storage of fuel)
In this study, the biogas-powered vehicle contributes 3-6 times more to the immediate greenhouse effect by its methane emissions than the diesel vehicle by its CO2 emissions considering that the relative effect of methane is 17-40 times that of CO2.
However, methane is more short-lived in the atmosphere. But still, biogas vehicles seem to contribute more to global warming than diesel vehicles. The methane emissions from diesel vehicles are very low; in this study only 2 mg/MJ (1/300 of the biogas vehicle).
This is thus a contradiction - that environmental organisations call for the use of gas-powered vehicles when methane emissions might become the most significant global warming problem in the future.
If we cannot control the methane buildup in the atmosphere there might be more severe effects as methane is released from 'frozen' deposits at sea bottom when the water warms up. The resulting greenhouse effect might be much worse than what we are now discussing - there might be an increase in global temperatures of 20-30 degrees C which in fact has happened historically, last time during Eocene period som 55 million years ago when the North Pole had a climate with temperatures about +20 degrees C and of course no ice.
So try to stop the methane emissions before it is too late. Use cheap power from nuclear energy instead of natural gas or biogas wherever feasible. Use electric vehicles in cities with zero emissions instead of experimenting with gas-powered vehicles.
Bo Persson
But is that really so important compared to methane (CH4)?
The 'relative greenhouse effect' of methane is estimated at about 17 times that of carbon dioxide. In cold climate, the ratio may be as high as 40 times that of CO2. But it is true that the emissions of carbon dioxide still are much greater than those of methane. So the 'historic' global warming effect that we have seen might be caused largely by carbon dioxide.
However, the emissions of methane are increasing on a much faster rate than those of carbon dioxide. It is no doubt that global warming in the future more and more will be associated with methane.
In addition, the use of methane-containing fuels is even advocated by environmental interests. The methane in the atmosphere come from a variety of sources, among those most important are agriculture, garbage dump sites, exploration of natural gas fields, pipelines for natural gas, leakages from gas depots or gas filling stations, emissions from end use of natural gas or biogas in household, industry or vehicles.
The fact is that natural gas as well as 'biogas' contain 95-98% methane. Environmental organisations use to promote the use of 'biogas' as an alternative to fossil fuels. However, the CH4 emissions must be taken into consideration. 'Biogas' is often produced from garbage or harvested grass that is anaerobically treated. If not biogas was produced, some methane would anyhow be produced from the dump site but the majority of the coal-containing compounds would be transformed into other hydrocarbons or just carbon with time. So there is a considerable net emission of methane (and also carbon dioxide) if biogas is produced and used in vehicles. Still worse is of course the use of natural gas in vehicles and other applications.
The use of natural gas - or biogas - in vehicles is usually associated with significant emissions of methane due to that engines are tuned in to reduce emissions of nitrogen oxides which otherwise would be a problem for gas-powered vehicles. This is especially true for cold starts and during city traffic conditions.
A recent Swedish study published by the Environmental Protection Agency in Sweden gives the following emission parameters for biogas- and diesel-powered vehicles (Framtida mojligheter med nya drivmedel, Naturvardsverket 2004):
Diesel; CO2: 3,500 mg/MJ (emissions from tailpipe incl. production of fuel)
Biogas; CH4: 640 mg/MJ (emissions from tailpipe incl. production and storage of fuel)
In this study, the biogas-powered vehicle contributes 3-6 times more to the immediate greenhouse effect by its methane emissions than the diesel vehicle by its CO2 emissions considering that the relative effect of methane is 17-40 times that of CO2.
However, methane is more short-lived in the atmosphere. But still, biogas vehicles seem to contribute more to global warming than diesel vehicles. The methane emissions from diesel vehicles are very low; in this study only 2 mg/MJ (1/300 of the biogas vehicle).
This is thus a contradiction - that environmental organisations call for the use of gas-powered vehicles when methane emissions might become the most significant global warming problem in the future.
If we cannot control the methane buildup in the atmosphere there might be more severe effects as methane is released from 'frozen' deposits at sea bottom when the water warms up. The resulting greenhouse effect might be much worse than what we are now discussing - there might be an increase in global temperatures of 20-30 degrees C which in fact has happened historically, last time during Eocene period som 55 million years ago when the North Pole had a climate with temperatures about +20 degrees C and of course no ice.
So try to stop the methane emissions before it is too late. Use cheap power from nuclear energy instead of natural gas or biogas wherever feasible. Use electric vehicles in cities with zero emissions instead of experimenting with gas-powered vehicles.
Bo Persson
posted by LH at
12:24 PM
1 Comments:
CO2 is .934% of the atmosphere. In contrast, methane is only .00002 percent of the atmosphere. Methane is 60 times as effective as a greenhouse gas as carbon dioxide.
.00002 x 60 isn't greater than .934.
Even though it sounds absurd, cows passing gas is one of the biggest methane releasers. As human populations have increased, so has the demand for meat. The only things cows do all day is graze. When they graze, not only do they eat up green plants that could be taking carbon out of the atmosphere, but also it makes them pass gas. What is flatulence made of? Methane.
Thoughts on Global Warming
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Simmons, at 1:11 PM
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