The benefits of using barley for bioenergy production do not stop at the petrol pump, according to US Department of Agriculture (USDA) studies.
Scientists with USDA’s Agricultural Research Service (ARS) have found that barley grain can be used to produce ethanol, and the leftover byproducts-barley straw, hulls, and dried distillers grains (DDGS)-can be used to produce an energy-rich oil called bio-oil. The bio-oil could then be used either for transportation fuels or for producing heat and power needed for both industrial and domestic purposes. ARS is USDA’s principal intramural scientific research agency, and these results support the USDA priority of developing new sources of bioenergy.
The barley work was conducted by several scientists, including chemical engineer and pyrolysis team leader Akwasi Boateng, chemist Charles Mullen, mechanical engineer Neil Goldberg, chemist Robert Moreau and research leader Kevin Hicks. The researchers produced bio-oil from all three barley byproducts using a technology called ‘fast pyrolysis’, an intense burst of heat delivered in the absence of oxygen.
In the lab, a kilogram of barley straw and hulls yielded about half a kilogram of bio-oil with an energy content of about half that of standard diesel fuel oil. The energy content of bio-oil made from barley DDGS, including DDGS contaminated with mycotoxins, which can’t be used to supplement livestock feed, was even higher, about two-thirds of the level diesel fuel oil. However, the bio-oil was more viscous and had a shorter shelf life than bio-oils produced from straw or hulls.
The process also created a solid byproduct called ‘biochar’ that might improve the water-holding capacity and nutrient content of soils. Amending soils with biochar can sequester carbon in the soil for thousands of years.
The pyrolysis dimension to the ARS research could have a direct usage in Ireland, as the technology has long been mooted as a treatment option for poultry litter. There is currently deep concern about the transport of litter throughout the island of Ireland and the health risks this poses to poultry enterprises. Litter can also be a potential source of botulism in cattle, when spread on grassland!