Gas from sewage and landfill (biogas) has already been exploited in some areas. In 2004 it provided 129.3 GW (up 690% from 1990 levels), and was the UK's leading renewable energy source, representing 39.4% of all renewable energy produced (including hydro).
Other biofuels can provide a close-to-carbon-neutral energy source, if locally grown. In South America and Asia, the production of biofuels for export has in some cases resulted in significant ecological damage, including the clearing of rainforest. In 2004 biofuels provided 105.9 GWh, 38% of it wood. This represented an increase of 500% from 1990.
Other biofuels can provide a close-to-carbon-neutral energy source, if locally grown. In South America and Asia, the production of biofuels for export has in some cases resulted in significant ecological damage, including the clearing of rainforest. In 2004 biofuels provided 105.9 GWh, 38% of it wood. This represented an increase of 500% from 1990.