Tuesday, March 01, 2005

Making the best of garbage gas

A new method of harvesting methane from trash dumps could yield a significant amount of methane gas. Methane is extracted from landfills by sinking pipes or wells into the landfill and sucking the gas out. But if the surroundings are not airtight, sucking out methane also sucks in air. This is not only difficult to separate from the methane; it also means methane production slows down. "You don't want oxygen in there because that would prevent anaerobic digestion," says Popov. In addition, oxygen reacts with methane, further diminishing the supply. As a result the only landfill sites suitable for methane extraction are those that are large and deep enough to restrict the entry of air.

But Viktor Popov at the Wessex Institute of Technology, in Southampton, UK, says simple modifications to existing landfills will make it possible to extract methane from any site. Popov's solution is to cover landfills with a membrane that prevents air contaminating the methane. The membrane consists of three layers: a middle permeable layer sandwiched between two relatively impermeable layers, which would probably be made of clay.

It is estimated that Europe alone has the potential to generate as much as 94 billion cubic meters of methane each year, which by comaprison represents about 5% of all the natural gas produced in the U.S. each year.

This is yet another part of the puzzle. There is no one solution to decline oil and gas production, but there are many little solutions that just might patch together to fill the gap.


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