Grass Energy: Basics of Production, Processing, and Combustion of Grasses for Energy
Conventionally, most solid biomass heating fuels—woodchips, wood pellets, and cordwood—came from forests and the forest products industry. Over the past 15 years, however, growing crops (both herbaceous and woody) specifically for energy has gained widespread appeal, and perennial grasses such as Switchgrass, Miscanthus, and Reed Canarygrass present exciting new renewable energy options.
Perennial grasses are now being used as a solid fuel in co-fired coal power plants as well as targeted as a choice feedstock for such advanced biofuels as cellulosic ethanol. Despite this focus on generating electricity and producing liquid fuels, perennial grasses can also be pressed into pellets, briquettes, and cubes and used as a heating fuel to replace or complement fuels made from wood fibers. Including a thermal component in the use of solid biomass for energy increases a combustion system’s efficiency more than threefold.
Evolution of Grass Energy
In the late 1800s, grasses were widely used as a heating fuel in the prairie regions of the United States, an area with little forested land. Farmers in these areas relied on harvested straw and prairie grasses, or “prairie coal,” which were often twisted into bundles and burned in simple stoves.
Today, modern solid biomass heating systems are highly engineered, automated, and clean-burning. Like the existing wood pellet market in Europe and the developing market in the United States, grasses may soon be pelleted and delivered in bulk by a special tanker truck, pneumatically blown into storage systems, and automatically fed into the combustion system with no manual labor required.