Bioenergy Crops

Firewood is a great example of, and probably the earliest example of, bioenergy.  Photo courtesy of Joseph O'Brien, USDA Forest Service, Bugwood.org.

What exactly is "bioenergy?" Bioenergy is defined as renewable energy derived from biological sources. That sounds a little exotic, but people have been using bioenergy since we learned to use fire.

Bioenergy can be as simple as firewood or as complex as oils refined from wood waste and burned in diesel engines. Bioenergy touches our day-to-day lives in many ways that we don't even recognize. Here are some examples:

• Many people use fire places or wood-burning stoves to provide some or all of the heat for their homes. They are using bioenergy.
• Most of the gasoline available in Arkansas is blended with ethanol. Most of that ethanol is derived from plant materials, so it is a bioenergy.
• Pellet stoves are becoming more common in Arkansas. Pellet stoves burn wood or corn stover compressed into pellets. This is a bioenergy.
• Biodiesel is becoming more common on farms in Arkansas. Tractors, harvesters, irrigation pumps, and trucks can all run on biodiesel. The foods we eat are grown, in part, using bioenergy.
• Bioenergy has been used within the forest products industry for several decades. Most paper mills burn wood waste, often with other materials, to generate electricity to run the mill. The paper upon which we print is produce, in part, using bioenergy.

Research is underway by the Arkansas Forest Resources Center and many universities to find ways to use forest products and logging residue as a raw material for bioenergy. Some of the problems that must be solved to make bioenergy commercially viable include how and where to grow it, how to harvest and transport it economically, and how to process it into a usable energy source.

Several crops can be grown as bioenergy crops.

Cottonwood and switchgrass are currently being investigated by the Arkansas Forest Resources Center. Cottonwood is a fast-growing tree native to the moist well-drained soils of eastern Arkansas. It can be grown on a short rotation as a source of fuel wood. Cottonwood is a good choice as a woody bioenergy crop on some sites because it grows quickly and, since it is a hardwood, it will resprout vigorously after harvest. Cottonwood will tolerate several rounds of harvesting before it must be replanted.

Switchgrass is also being tested as a bioenergy crop.

Switchgrass is a native perennial warm season bunchgrass that, once established, grows quickly and can be harvested every year. It grows to approximately 8 feet tall and will grow well even grow well even under droughty conditions and high temperatures. Switchgrass has the advantages of being a long-lived perennial grass that is tolerant of infertile soils.