That’s a popular misconception. Our local (and quite modern) landfill produces enough methane to run a generator producing a steady 1.6 megawatts of electricity.
There’s more about this here:
http://www.crd.bc.ca/waste/hartland/lfgelectricity.htm
Natural gas replacement from landfill
I'm not sure what the latest figures are, but the projection was $500k per year to the city from sale of the gas