Surplus biomass from the production of flax shives, and
generated from Brassica carinata, a yellow-flowered plant
related to those which engulf fields in spring, can be used to
produce bioethanol. This has been suggested by two studies carried
out by Spanish and Dutch researchers and published in the journal
Renewable and Sustainable Energy Reviews.
"These studies evaluate, from an environmental point of view,
the production of bioethanol from two, as yet unexploited sources
of biomass: agricultural residue from flax (for the production of
paper fibres for animal bedding), and Brassica carinata
crops (herbaceous plant with yellow flowers, similar to those which
carpet the countryside in spring)", Sara
González-García, researcher of the Bioprocesses and
Environmental Engineering Group of the University of Santiago de
Compostela (USC), explains to SINC.
González-García, along with other researchers from
USC, the Autonomous University of Barcelona and the University of
Leiden (Holland), has confirmed that if bioethanol is produced from
these two types of biomass "both CO2 emissions and
fossil fuel consumption will be reduced, meeting two of the
objectives established by the European Union to promote
biofuels".
These works have analysed the environmental load associated with
the different stages of the process: the harvesting of flax or
Brassica; the production of ethanol (through enzymatic
hydrolysis followed by fermentation and distillation); mixing it
with petrol (in varying proportions); and its use in passenger
automobiles.
The results of both studies, published in the journal Renewable
and Sustainable Energy Reviews, show that the use of ethanol-based
fuels can help to mitigate climate change (by reducing greenhouse
gases).
However, these fuels also "contribute to acidification,
eutrophication, the formation of photochemical oxidants and
toxicity (for people and the environment)". According to the
experts, these negative effects could be lessened with the use of
high-yield crops, as well as through optimisation of agricultural
activity and better use of fertilisers.
Which is better: flax or Brassica?
The studies developed by the researchers reveal that flax (which
is richer in cellulose) can produce up to 0.3 kg of ethanol for
every kg of dry biomass, compared with 0.25kg/kg of
Brassica. However, when the whole production cycle is
analysed, the yellow-flowered plant offers a greater production of
biomass per hectare and has a lesser environmental impact.
The biofuel produced from these two plants is "second generation
bioethanol", which is obtained from forest or agricultural
residues, or from herbaceous crops, and does not enter into direct
competition with agricultural crops intended for animal or human
consumption.
The European Union and the International Monetary Fund are
promoting the development of these types of biofuels. Spain is the
third largest producer of bioethanol in Europe, after France and
Germany, although its use still only represents 0.4% of total
energy consumption.
SOURCE