So why is pennycress being considered for biofuels?
Pennycress, like most weeds, is quite an unfussy plant and
is happy growing just about anywhere. It doesn’t require
much work, indeed, the weed-like traits of this plant mean
that once the seeds have been sown, no maintenance is
required at all until harvest. Its flat, heart-shaped pods
contain tiny black seeds with 36% oil. This is double the oil
contained in soybeans and very similar to rape/canola, and
is considered to be a high yield. The seeds also contain 32%
protein meal, which is a viable animal feed.
In the form of oil, pennycress has attributes which
make it a strong contender in the biodiesel market. A US
Department of Agriculture (USDA) study published in 2010
expounded the outcome of research into pennycress’ properties. As part of its study, the USDA’s Agricultural Research
Service (ARS) produced a small amount of biodiesel from
pennycress oil and evaluated it. Commenting on the
research, it was said: “All diesel-based oils start to gel when
it’s cold enough. So the cloud point, which is the temperature at which crystals become visible in the fuel, is a crucial
factor in both biodiesel and petrodiesel production. Another
important property is the pour point, the temperature at
which the fuel fails to pour as a result of excessive solidification. The average cloud and pour points for field pennycress
biodiesel were 14°F (– 10°C) and –0.4°F (– 18°C), respectively.
These temperatures were well below the cloud and pour
pennycress: What’s the catch?
Field pennycress (Thlaspi arvense), also known as stinkweed or frenchweed, couldn’t be called new by
any stretch of the imagination and is, in fact, an enthusiastic weed which has been incensing farmers
and land owners for centuries. Part of the Brassicaceae family, related to mustard and canola, the
reason for its oversight is, ironically, the same thing that lies behind its possible success: Pennycress is
not edible, and cannot be used for food production, but grows quickly and easily in reasonably hostile
points of soybean oil-based biodiesel.” These findings indicate
that pennycress-based biodiesel could be used in cold climates.
In addition the researchers observed that: “…field pennycress
methyl ester characteristics, such as acid value, oxidative stability,
cetane number, cold flow properties, viscosity, sulphur content, and
phosphorous content, are all satisfactory under ASTM D6751
(Standard Specification for Biodiesel Fuel Blend Stock (B100) for
Middle Distillate Fuels).”
Significantly, pennycress is not a food crop. Therefore using it to
produce biofuel does not compete with food use, quashing the food
versus fuel debate that has clouded so many potential oilseeds in the
past. The debate is fixed upon the risks of diverting farmland suitable
for producing food to biofuel production.
Also, in March 2015, the US Environmental Protection Agency
(EPA) completed an analysis of the greenhouse gas (GHG) emissions
attributed to the production and transportation of pennycress oil for
biofuel production. The analysis determined that pennycress “is not
expected to have significant indirect land use changes (ILUC).” It is a
winter annual that is sown in the early autumn and harvested in late
spring, meaning it is not in competition with the rotations of soybean
or corn, and can be grown while the fields would otherwise be empty,
as exemplified in Fig. 1.
FIg. 1. Example of soybean, corn, and pennycress rotation.
compiled by the Environmental protection Agency. source:
Excerpted from Fig. 2 in “A life cycle assessment of pennycress
(thlaspi arvense l.)-derived jet fuel and diesel,” biomass and
bioenergy ( http://dx.doi.org/10.1016/j.biombioe.2012.12.040,