UCS report highlights bioenergy potential of agriculture residues

By Erin Voegele | July 21, 2014

The Union of Concerned Scientists has published an analysis that estimates how much biomass the U.S. could sustainably use while balancing certain energy and environmental tradeoffs. Overall, the report forecasts the U.S. could tap into nearly 680 million tons of biomass annually by 2030, which is enough to produce more than 10 billion gallons of ethanol or 166 billion kWh of electricity, which equates to approximately 4 percent of U.S. power consumption in 2010. Of that volume, the report notes the U.S. agricultural industry could provide up to 155 million tons of crop residues and 60 million tons of manure annually by 2030 for use as feedstock to produce fuels and power. According to the report, 10 states could produce approximately two-thirds of that volume of crops residue and manure.

The report notes that non-food components of crops, such as stocks, husks and cobs, account for about half of the total biomass of U.S.-grown crops. While residue materials play an important role in protecting soil from erosion and loss of soil carbon, the report indicates that farmers can sustainably remove a portion of those materials. Regarding manure, the report stresses that livestock raised in large confined animal feeding operations “produce nearly unmanageable concentrations of manure,” which regulatory pollutes water supplies in many areas of the country. Farmers, however, can use anaerobic digesters to convert manure into biogas, which can be used to produce heat, power, or renewable natural gas.

According to the UCS, Iowa, Illinois, Nebraska, Minnesota, Arkansas, Texas, California, Indiana, South Dakota and North Carolina can provide approximately two-thirds of the projected 155 million tons of crop residues and 60 million tons of manure forecasted to be available annually by 2030.

Iowa leads the nation in expected crop residue production. The report forecasts that approximately 31 million tons of agricultural residues will be available within the state by 2030. The biofuels industry is already developing biorefineries in Iowa to convert those residues into cellulosic ethanol. “Corn stover from Iowa farms could yield 1 billion additional gallons of ethanol each year in 2030—an expansion of more than 25 percent—without the use of one extra kernel of corn,” said the UCS in the report. Iowa also leads the nation in pork production, which provides manure for use in biogas production.

The analysis published by the UCS also highlights the biomass potential of Arkansas, which leads the nation in rice production, ranks second in poultry, and third in cotton production. With an estimated 10.3 million tons of agricultural residues expected to be available in 2030, the UCS reports the state is poised to become a leader in bioenergy production.

In Texas, the UCS forecasts 9.8 million tons of agricultural residues will be available annually by 2030, with cattle manure, field residue, and cotton gin byproducts highlighted as significant bioenergy opportunities. Residues from rice fields and rice hulls and sugarcane bagasse are also identified as potential bioenergy feedstocks in the state.

The UCS also highlights California in the report, noting that the state has the seventh highest potential to provide agricultural coproducts for bioenergy production in the nation. The estimated 9.2 million tons of agricultural residues expected to be available in the state in 2030 include manure from milk production, residues from vineyards and orchard prunings, and rice straw.

A full copy of the report is available on the USC website.