I know biogas digesters exist, but I am unfamiliar with the economics of such systems. It seems like a better way to deal with the methane than flaring it off, but cheap natural gas in the US might make it uneconomical to do so. I’d be curious if anyone has any insight into that.
People have looked at microturbines to burn landfill gas. It's not something one could just put into a natural gas pipeline as it's about 1/2 CO2. Even in microturbines it requires cleanup because of cosmetics. In a landfill, cosmetics decay to produce volatile organosilicon compounds, and when these burn they deposit silicon dioxide slag on turbine components.