The UCS says that trees and grasses are best suited for biomass use, even though corn is the main ingredient today. They also estimate that using biomass to produce electricity will someday soon return ten units of energy for every one used to produce the juice.
The UCS has an entire section on clean energy technologies, including solar, wind, geothermal and hydroelectric. If you – or someone you're trying to explain these energy types to – are unclear on some of the basics, these pages will make things much easier to comprehend. The simple explanation they use to describe biomass, for example, is to think of it as a "natural battery for storing solar energy".
[Source: Union of Concerned Scientists]