Barley as Biofuel

article image
courtesy Peggy Greb/ARS
Chemical engineer Akwasi Boateng, right, and mechanical engineer Neil Goldberg, center, adjust pyrolysis process conditions while chemist Charles Mullen, left, loads reactor with bioenergy feedstock.

The benefits of
using barley for bioenergy production don’t stop at the gas pump, according to
U.S. Department of Agriculture studies. 

Scientists with
USDA’sAgricultural Research Service
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
the grain-to-ethanol conversion. 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 at the ARS Eastern Regional Research Center at
Wyndmoor, Pennsylvania, 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 No. 2 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 in No. 2 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.

Farmers in the Mid-Atlantic states and the Southeast could cash in on
the production of winter barley cover crops while continuing to raise corn and
other food crops in the summer. Growing winter barley for biofuel production
would also help reduce soil erosion and nitrogen leaching, a major concern for
farmers in the Chesapeake Bay watershed.

Results from
this work were published in Energy & Fuels.

Read more about
this research in the November/December 2010 issue of Agricultural Research
magazine, available online.