Home' Australasian BioTechnology : Vol 26 No 3 Contents Australasian BioTechnology | Volume 26 | Number 3
at AusBiotech’s International BioFest
What do you think of when you see grass?
A cow? Football? Grass-type Pokémon?
Nowadays, it is also possible to relate grass to
a jet or, more precisely, jet fuel.
Fossil fuels are made from carbon compounds that
originate from plants and animals that died millions
of years ago. When dead organisms are buried, they
decompose in the absence of oxygen. Depending
on the time and conditions, such as the temperature
and pressure at which they are decomposed, different
fossil fuels (for instance petroleum, natural gas and
coal) can be formed. The formation of fossil fuel takes
millions of years, which is also why they get the name
‘fossil’; however, this process can be assimilated and
accelerated under controlled engineering conditions.
Currently, the fuels that we are using in our transport
are refined from fossil fuels. As fossil fuels are
not infinite, and as global warming is increasing
greenhouse gases (such as carbon dioxide) in the
atmosphere, there is an urgent need to turn to
renewable energy and resources. This is where the
biorefinery approach comes in.
‘Biorefinery’ is a conceptual model for future biofuel
production, where both fuels and high-value co-product
materials are produced. It attempts to apply the
conventional petroleum refining methods to biomass,
incorporating biological processes. A biorefinery
can get its feed from dedicated crops, either from
agriculture or from forestry.
Getting dedicated crops from agriculture to feed
biorefinery, however, is a contentious issue because
it is seemingly in conflict with the demands of food
production as the world population is expanding
exponentially. Thus, waste biomass can be used as an
Plants like grass are rich in cellulose, and if you
break down the cellulose, you can utilise its sugar.
Some bacteria are able to consume these sugars
and convert them to other compounds such as lactic
acid, a three-carbon compound that can often be
found in your muscles, as well as in yoghurt and dairy
products. Other bacteria can make caproic acid, a
six-carbon oily compound found in goat milk fat.
While it would take too long to form fuels through
microbial processes alone, electrochemistry can be
applied to assist the process.
Electrochemistry is not unfamiliar in everyday life; it
involves a reduction and oxidation reaction between
materials—for example, in the rusting of iron. When
iron comes into contact with oxygen and water, iron
is oxidised into iron
oxide, which we see
as rust, while the
oxygen is reduced to
water. By applying
caproic acid can be
reduced to decane,
a 10-carbon, energy-
dense, liquid hydrocarbon
fuel commonly used in
Our research makes use of these natural microbial
actions, and adds spices of an engineering approach
to achieve a process that would otherwise take years
to accomplish. We aim to produce hydrocarbon fuel
directly from grass. First, we feed grass to bacteria
to obtain lactic and caproic acids, and then we apply
electrochemistry to convert these microbial oils into fuel.
The next phase is a feasibility study and upscaling of
the process. While industrial plants that convert grass
into methane gas (which is similar to natural gas for
energy generation) have already existed, it is also of
prime interest to produce liquid biofuels that are more
compatible with combustion engines.
With minimal nutrient requirements, grass can grow
almost anywhere, except in the coldest region of the
Arctic and Antarctica. If it is left unattended, grass will
grow and wilt, decompose by bacteria into carbon
dioxide, and finally be absorbed again by new grass,
forming a cycle. Here, we intercept the cycle and
produce a useful product, while still keeping the cycle
closed, and without introducing more carbon dioxide
into the system. In this way, we can reduce the reliance
on fossil fuels and hence curb the emission of carbon
dioxide into the atmosphere.
As grass normally grows by spreading across a great
area instead of being packed into a small space, one
of the biggest challenges is the efficient harvesting and
collection of grass. Apart from that, as fragile-looking
as grass is, in reality it is a tenacious organism, both in
terms of vitality and structure.
Considerable energy investment is required to break
down the biomass to improve its biodegradability.
This increases the process cost and optimisation
required to attain a prospective economic outlook. But
considering the sheer volume of grass worldwide, it is
very worthwhile to investigate how its potential can be
Way Khor will be speaking at the 17th
International Biotechnology Symposium
Way C. Khor
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