Crop residue for energy
If we use plant biomass for energy, where will it come from?
Plant biomass is being strongly considered to replace coal and petroleum for the generation of electricity, heat and steam for residential, commercial, industrial and institutional facilities. Due to the strong commodity prices available today, the conversion of cropland into a dedicated energy crop is not likely, unless prices level off. Agricultural biomass will most likely come from crop residues such as corn stover or wheat straw. The supply of this biomass is abundant from the crops of corn and wheat.
Michigan Agriculture Statistics data indicates the acreage of wheat grown in Michigan in 2009 as 620,000 acres. A “rule of thumb” yield for harvestable wheat straw per acre is about 2,000 pounds or 620,000 tons of wheat straw produced annually. Likewise, corn acreage is quoted as 2,350,000 acres in 2009. A rule of thumb yield for corn stover per acre is about 8,000 pounds or 9.4 million tons of corn stover in Michigan. Of course, this total crop residue is not available for energy use since some of it is used for livestock bedding and feed. Additionally, many farmers have agronomic (crop productivity) and environmental concerns about removing residue. These considerations include nutrient removal, organic matter removal and soil erosion protection, all of which impact long term productivity and sustainability of the soil.
Economics will also be important in the development of this industry. The comparison of biomass cost to other energy costs and the ability of crop producers to offset the loss of the benefits of residue will be significant in making the decision to grow bioenergy crops. As with most industries, economic benefit will be instrumental in determining the adoption of new practices.
Michigan farmers produce significant amounts of crop residue each year as a result of optimizing grain yield while practicing environmental stewardship. Additional research on the agronomics and economics of crop residue removal need to be conducted in order to help farmers weigh the opportunities and risks.