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July 05, 2007

Climate control alternative: Sequestering Methane

One of the most widely publicized ideas for offsetting climate change is to sequester carbon dioxide. The US Department of energy estimates the following costs:

Using present technology, estimates of sequestration costs are in the range of $100 to $300/ton of carbon emissions avoided. The goal of the program is to reduce the cost of carbon sequestration to $10 or less per net ton of carbon emissions avoided by 2015.


Assuming $10-100/ton: Sequestering 1 billion tons of carbon dioxide would cost $10 to 100 billion per year.

Methane represents 18% of the total annual greenhouse gas effects Methane has 25 times the global warming effect as an equivalent amount of carbon dioxide

Sequestering 40 million tons of Methane would be the equivalent of sequesterint 1 billion tons fo carbon dioxide.

The sources of methane and the natural sinks for methane are described at this link.


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From wikipedia sources and sinks for methane emissions

We are adding +20 million tons per year of methane.

Slightly over half of the total emission is due to human activity.

Living plants (e.g. forests) have recently been identified as a potentially important source of methane. A 2006 paper calculated emissions of 62–236 Tg a-1, and "this newly identified source may have important implications". However the authors stress "our findings are preliminary with regard to the methane emission strength". These findings have been called into question in a 2007 paper which found "there is no evidence for substantial aerobic methane emission by terrestrial plants, maximally 0.3% of the previously published values".

Long term atmospheric measurements of methane by NOAA show that the build up of methane has slowed dramatically over the last decade, after nearly tripling since pre-industrial times. It is thought that this reduction is due to reduced industrial emissions and drought in wetland areas.


Recent experiments suggest that forming methane hydrates is fairly easy

Here is more information on methane hydrate

Open the Future discusses that each cow produces 110 kg of methane in manure each year

Oil rigs can pump oil up from under a mile of ocean. If we used a reverse of this method a pipeline and ocean oil can be used to send Methane to the bottom of the ocean. Deep ocean oil platforms cost about $100-500 million Oil platforms can move 50,000 barrels of oil per day and 2 million cubic meters of gas. About ten barrels make up one ton. About 2.3 million tons of methane could be sent down one oil platform each year. Twenty oil platforms would be needed to sequester 40 million tons of methane. This would cost between 2 to 10 billion dollars. This is less than the low cost target for carbon dioxide capture.

Methane can be more easily captured in the form of livestock manure and bird poop. Some of the useful fertilizer can get extracted, but we could take methane and convert it into methane hydrate by pumping it onto the ocean floor. Methane hydrate is stable on the ocean floor now. 40 to 200 million tons of methane could be diverted from the generation sources we have now. We could go into a net negative for methane of 20 to 180 million tons. It would be a simple way to start curbing greenhouse gas effects and offset global warming and climate change.

3 comments:

Anonymous said...

If you can sequester methane, you can surely sell it as natural gas, and burn it. Wouldn't that make a lot more sense economically?

bw said...

Yes, methane can be used as fuel, however that would release the methane into the atmosphere. The point of sequestering is to remove/reduce the green house gas from the atmosphere so that we can stop the heating of the atmosphere

al fin said...

Actually, burning methane yields CO2 and H20 into the atmosphere, which presumably would represent a far lower greenhouse effect than CH4. On balance, the greenhouse effect is lowered.

Greenhouse contribution to climate is vastly overstated, however, by current models--which are due for serious revision. Humans affect climate significantly, but most of that effect is from non-greenhouse causes.

Consider it a scandal that the greenhouse bandwagon has garnered as many billions of dollars in support as it has, while presenting itself as the "only game in town" to policymakers and the public.