In most cases, wastes like rice straw, almond hulls, and the oversize outer leaves of iceberg lettuce will have to be pretreated before being used as a bioenergy resource. The garbage, known as "municipal solid waste," or "MSW," would also be pretreated.
The garbage would be processed in a jumbo-size autoclave, a device which acts something like a giant pressure cooker to convert the MSW into grey, lightweight clumps. The pretreated agricultural wastes and autoclaved MSW would then be transferred to a biofermenter. Yeasts and enzymes would be added to make ethanol.
Scientists are determining the best ways to use just water and heat, instead of hazardous chemicals, to pretreat the farm wastes, thus keeping the biorefining process environmentally friendly. Besides producing biofuels, the biorefinery would also reduce the volume at landfills and minimize the need for new ones.