Methane is a much more powerful greenhouse gas than carbon dioxide. According to Wikipedia, methane has 21x more warming potential than CO2. On the good side, Methane is relatively short-lived. Many human activities produce methane, dairy cattle and rubbish landfills among them. Should capturing methane from sources like landfills and cows, and flaring it, provide CO2 credits, given how bad ass methane is as a greenhouse gas? According to Kyoto, yes. In fact, according to the Wall Street Journal it's happening in some locations like Brazil. Kyoto specifically allows for other gases that are more potent greenhouse agents to be sold proportional as CO2 credits.
One ton of methane that is simply captured and flared will produce 2.75 tons of CO2. So then given the 21:1 ratio, we should expect to get 18.25 tons of CO2 credits for doing this. Given that one ton of CO2 is currently worth US$35 in the European Union, the value of flaring a ton of methane is US$640.
So, how much is a ton of methane worth if we capture and distribute it? I.e. how much more profit is there to be made by storing it rather than simply burning it. In North America, methane goes for more than $10.00 / MBtu. That works out to one cent per cubic foot, or US$4.88 / m3. At 0.101 MPa and 295 K methane has a density of 0.65524 kg/m3. So how much is methane worth? $7450 / ton, or an order of magnitude more than the Kyoto credit.
Obviously, much depends on the economics, but it would appear that there's much more value in capturing and selling the methane gas produced from various biological decomposition processes than simply flaring the gas off. The order of magnitude increase in price would hopefully offset the cost of purifying and storing the methane, although I don't really know. Unfortunately, few places in the world pay as much for natural gas as the USA and Canada. In South America, for example, the value of methane is comparable to the value derived in flaring it. That's probably why we see them simply burning it in Brazil for profit.
I used a program called ALLPROPS -- developed by researchers at the University of Idaho -- to find the density of methane at my given conditions. I would like to share it with my readers. It can normally be found here:
Unfortunately, the site is down. I do not feel comfortable posting a link to it since the program explicitly states not to redistribute it.