Big landfill near me has stacks flaring it off every time I've been there. I kinda doubt there's enough to make it commercially viable.
I worked at a landfill that harvested its methane through a network of pipes and processed it through big engines turning the methane to electricity. They sold the electricity to a local city that provided it to their residents at rates better than the state’s biggest power company. There’s big money in that business. The technology works.