Clean fuel from dirty garbage ?  

The ABC has a report on biogas harvesting in Los Angeles.

About 45 minutes north of downtown Los Angeles, a machine the size of a small truck flattens tons of food scraps, paper towels and other household rubbish into the side of a growing 90-metre pile. To Waste Management, which operates the landfill, this is more than just a mountain of garbage. Pipes tunnelled deep into the mound extract gas from the rotting waste and send it to a plant that turns it into electricity.

Apart from the huge-wheeled compactor driving over garbage on its surface, it looks like an ordinary hillside. And it doesn't even smell. Yet it produces enough energy to power 2,500 homes in Southern California. Rubbish, trash, whatever you call it, the 1.6 billion tonnes of stuff the world throws away each year - 250 kilograms per person - is being touted as a big potential source of clean energy.

As concerns about climate change escalate and prices on fossil fuels like oil and natural gas soar to record levels, more companies are investing in ways to use methane gas to power homes and vehicles. Around the world, landfills where municipal waste is collected and buried are one of the biggest producers of methane, a gas whose greenhouse effect is 21 times worse than carbon dioxide. If instead that gas is collected and burned to generate electricity, proponents say the resulting emissions of carbon dioxide are less harmful to the environment than the original methane.