From the July 2008 Issue of Biomass Magazine
Grass: It???s Not Just for Grazing
We know cows like it???and by eating certain varieties, they give
more milk. So do these grasses??? higher sugar content also mean
greater ethanol output?
By Susan Aldridge
Grass is everywhere???on golf courses, football fields, parks, in
your garden and, of course, wherever cows are content.
Could we use it for transport fuel?
That idea is under consideration in several places around the
world, including Wales???and in Wales, cows in fact may be a guide
for researchers studying cellulosic ethanol.
Steve Kelly, a molecular biologist at Swansea University in Wales,
is one scientist working on a process that may eventually let
motorists tank up on ???grassohol??? from the very meadows past
which they drive on their next holiday.
Kelly???s is a two-step process, using high-sugar, low-lignin,
highly digestible variants of ryegrass. These grasses were
developed at the Institute of Grassland and Environmental Research
at Aberystwyth University in Wales through conventional
crossbreeding techniques, particularly with the AberDart and
AberMagic varieties (see sidebar on page 33).
Researchers have deliberately avoided the laboratory techniques of
genetic modification, which directly alter the genetic makeup of
the plants, because it is controversial in Europe. Among the
concerns is that genetically modified (GM) crops will spread into
the natural ecosystem. Grass is wind-pollinated, and the
scientists don???t want to risk gene transfer to non-GM plants.
The first step for Kelly and colleagues is processing the grass to
extract a water-soluble ???juice??? that contains fructans
(fructose oligomers and polymers). Kelly???s team has cloned genes
for enzymes that can hydrolyze these fructans. They insert the
fructans into the fermenting yeast to optimize the process.
The second step is fermenting the relatively dry, stable
lignocellulose fraction residue. This involves use of enzymes that
can break down the plant cell walls.
Iain Donnison, leader of the bioenergy and biorenewables program
at the Aber Bio Centre at Aberystwyth University and one of
Kelly???s main collaborators, says preliminary calculations
suggest ryegrass could be as good as or better than wheat or sugar
beets as a source of ethanol.
Swansea???s Kelly is well-schooled. He studied molecular biology
with Nobel Prize winner Sir Paul Nurse, who shared the 2001 prize
for work on key regulators of the cell cycle. That positions Kelly
to push forward a genomic approach in meeting the challenges of
producing ethanol from biomass.
Wales, on England???s west, is famous for its grassy landscapes.
No surprise, it is trying to build its biofuels involvement in
part on all that grass. The Welsh government is funding a planned
Centre of Excellence in Biorefining at the universities of
Aberystwyth, Bangor and Swansea, with additional funding from the
In a region where mining once drove the economy but has since
diminished in importance, the purpose of the centre is to provide
research and guidance for businesses to create new employment and
preserve existing jobs. Backers seek commercial partners as well.
???This,??? says Kelly hopefully, ???is a good time to invest in
this area of science.???
He pushes ahead with his work on ryegrass to establish a better
understanding of the grasses and the key microbes associated with
Ryegrass represents an important prospective source of biomass
because it is present on two-thirds of agricultural land in the
U.K. At the same time, EU efforts to reform agricultural subsidies
encourage farmers to decrease the number of animals grazing on
their land. ???So, farmers are wondering what they can do with
this excess of grass.??? Donnison says.
Cows Like It
Grass stands out from other prospective perennial feedstocks for
its high soluble carbohydrate (sugar) content. Indeed, IGER has
bred ryegrasses from varieties such as AberDart and AberMagic to
select for this high-sugar content, originally because cattle
grazing on high-sugar grasses gave a higher milk and meat yield.
Now it appears that the same grasses can also provide a high
potential ethanol yield.
Donnison???s team is scaling up. ???We believe ethanol from grass
could be comparable in yield to wheat and beets,??? Donnison says,
???and the key advantage is that it could be low-input, as it is a
perennial crop. If it is grown with clover, which fixes nitrogen,
then not much fertilizer is needed.???
The work tracks research published earlier this year showing the
economic feasibility of producing ethanol from switchgrass.
Researchers at the USDA and the University of Nebraska-Lincoln
carried out field trials on 10 plots of 15 acres to 20 acres each
on marginal cropland on 10 farms in the U.S. Midwest. Measuring
inputs, biomass yield, estimated ethanol output, greenhouse gas
emissions and net energy, researchers found that switchgrass
produced more than six times the renewable energy compared with
nonrenewable energy consumed. Researchers also calculated that
emissions of greenhouse gases from switchgrass ethanol would be 94
percent lower than regular gasoline.
Meanwhile, back in the U.K., Richard Dinsdale of the University of
Glamorgan in Pontypridd, Wales, has found another use for grass.
Collaborating with IGER researchers, Dinsdale is working at
Using anaerobic organisms???mainly Clostridium cultures???to
produce hydrogen and methane, Dinsdale and colleagues are now
working on a variety of techniques to improve hydrogen yield from
Biogas can include both methane and hydrogen, depending on the
nature of the fermentation process. It can be piped off,
compressed and used as a transportation fuel.
Dinsdale???s figures suggest that, as a transport fuel, biogas can
produce three times more mileage than either ethanol or biodiesel
per unit of land. He and his colleagues are currently building two
pilot plants to establish key engineering parameters and seeking
funding to extend the work beyond 2009.
Biogas is already used in Germany, Austria, Sweden and Italy???but
not yet much in the U.K. or the United States. Dinsdale believes
biogas ought to have a big future as a transportation fuel in the
U.K. However, existing liquid-fuel infrastructure inhibits its
In any case, researchers say that 30 acres can fuel a London bus
for a year. If true, evidently the cows knew it first.
Susan Aldridge is a London-based freelance writer and editor
specializing in biotechnology, medicine, health and chemistry.