Agricultural producers may soon hit a trifecta – the ability to clean up the environment, reduce dependence on fossil fuel, and create a new source of income.
Agricultural Research Service (ARS) scientists are helping farmers and ranchers convert farm and ranch leftovers and waste to sources of bioenergy (oil and gas), and high-value by-products.
The researchers are testing a mobile thermo-catalytic system that brings refining to the farm, by employing pyrolysis to create crude bio-oil and bio-char. Pyrolysis uses heat in a no-oxygen environment to rapidly decompose organic material.
According to Charles Mullen, research chemist at ARS’ Eastern Regional Research Center (ERRC), slow pyrolysis has been around for centuries as the traditional way to make charcoal. ERRC’s research has focused on speeding up the process by increasing the temperature to about 1,000 degrees Fahrenheit.
The research team developed the Combustion Reduction Integrated Pyrolysis System (CRIPS) mobile pyrolysis system, which travels to farms and converts feedstocks to bio-oil. The research unit can run “off-the-grid” and process low-value crop leftovers like grasses grown on marginal-quality lands, forest residues, and animal manure.
CRIPS breaks down about 80% of the plant material into vapors, 50-60% of which condense into bio-oil. The 20% of biomass that does not vaporize becomes bio-char. The vapors that do not condense are combustible gas. Burning this gas and some of the bio-char provides enough energy to power the process.
Mullen said that fast pyrolysis is a possible first step to making fuels that are exactly like those produced from petroleum, such as gasoline, diesel, and jet fuel.
The CRIPS system can produce bio-oil that can be upgraded, with a final output of about 40 gallons of gasoline-quality fuel per 1,000 pounds of dry farm waste.
“In addition to producing fuel-grade chemicals, we have also developed methods that purify potential chemical products from the bio-oil,” Mullen said. An especially promising product is bio-coke, a biobased carbon solid that could be a higher quality replacement for petroleum-coke, a material that is used in the production of aluminum, steel, and other materials.
"Essentially, what we are really trying to do is exactly what nature does, turn biomass into hydrocarbon fuels,” Mullen said. “We are just trying to speed up the process.”
USDA will stimulate innovation so that American agriculture can achieve the shared goal of increasing U.S. agricultural production by 40 percent while cutting the environmental footprint of U.S. agriculture in half by 2050.