Alcohol may be known as the demon drink but a growing number of
people are billing alcohol-to-jet (ATJ) fuel as having the potential to
save the aviation industry from its dependence on fossil fuel. As with
any movement, though, there are staunch and vociferous critics who doubt
the reality of such claims.
Those in favour of ATJ fuels point to the wide availability of
feedstocks - principally sugarcane - that can be fermented and distilled
into ethanol and subsequently converted into jet fuel. This, say
proponents, means it has a much better chance of being scaled up to
commercially viable quantities once certificated than other alternative
fuels that have already received the ASTM International stamp of
approval.
Critics, however, argue that the amount of energy needed to convert
these feed-stocks into the end-product cancels out the environmental
benefits of burning ATJ fuels when the whole life cycle is taken into
account. Opponents also doubt claims that the cost of ATJ fuels can be
reduced to compare with the cost of kerosene any time in the near
future.
HEAVYWEIGHT SUPPORT
Despite such criticism, airlines such as Virgin Atlantic and Qatar
Airways have thrown their weight behind companies developing ATJ fuels,
as has the US Department of Defense, which is in the process of
trialling ATJ fuels produced by global chemicals company
Gevo.
Each company developing ATJ fuels adopts a slightly different process
or feedstock, but they are all unified in their belief ATJ fuels will be
approved for commercial use by certificating body ASTM International
within two years and, following that, can be rapidly scaled up.
One such company is California-based
Byogy Renewables,
which claims to have produced the world's first 100% replacement for
kerosene by bolting on its own back-end process to an ethanol plant to
convert the ethanol into jet fuel via catalytic synthesis. "We've
invented a process that converts alcohol to jet fuel. Most companies
take the alcohol to someone else to turn into jet fuel," says Byogy
chief executive Kevin Weiss. "This is a 100% replacement jet fuel from
the most abundant feedstock in the world - sugar."
But the abundance of sugarcane as a feedstock is questioned by
Stephen Bowers, a Germany-based specialist in evaluating feedstocks for
petrochemical production. "Is sugar viable as a feedstock? In my
opinion, no. The lowest cost of sugar production will come from cane
sugar grown in a tropical climate [such as] Brazil," says Bowers.
"Global sugarcane production is close to two billion metric tonnes
and Brazil is about 650-700 million tonnes per annum. In theory, Brazil
could produce about 55 million tonnes of ethanol if all the sugarcane
was processed into ethanol. On a global scale, sugarcane could produce
150 million tonnes of ethanol. Global jet fuel demand is something like
200 million tonnes and rising," Bowers adds.
Weiss believes the key advantage ATJ fuels have over fuels derived
from hydroprocessed esters and fatty acids (HEFA) - which were
certificated for commercial use by ASTM International on 1 July 2011 and
have since been used to partially power commercial flights by a number
of airlines - is that they do not have to be blended with kerosene
because they already contain aromatics.
"HEFA fuels require massive hydroprocessing - the fuel has to be
taken to an oil refinery. We're completely different - the fuel is made
at our site and is ready for distribution at a fraction of the cost," he
says. Weiss is hopeful ASTM certification for ATJ fuels can be achieved
by the end of 2013 or the middle of 2014. "It's not a matter of if ATJ
will get approved, it's a matter of when."
Qatar Airways has signed an agreement with Byogy to use its fuel once
certificated. The selection of ATJ fuel and Byogy followed a year-long
feasibility study by Qatar Airways "to see what kind of technologies are
out there and what feedstocks are available locally and globally, and
to find out if biofuels for aviation are feasible", says the airline's
senior manager of corporate responsibility, environment and fuel
optimisation, Chris Schroeder.
The feasibility study led Qatar Airways to believe "ATJ is probably
going to be the frontrunner when it comes to biofuel for aviation", says
Schroeder. "We engaged with Byogy 18 months ago and we threw our weight
behind them. We wanted to push for ATJ with aromatics because we're
looking in future to possibly blend it with GTL [gas-to-liquid fuel],
which contains no aromatics."
In 2009, Qatar Airways operated a commercial flight between London
Gatwick and Doha using an Airbus A340-600 with all four Rolls-Royce
Trent 500 engines powered by a 50:50 blend of GTL and Jet A1 kerosene.
The airline has teamed up with Qatar Petroleum and Shell, which have
built a GTL plant in the gulf state. Schroeder says the carrier has
received a "very, very promising" sample of ATJ fuel from Byogy. "We
have signed an off-take agreement with them whereby whatever fuel they
produce, once certified, we'll take it for the next couple of years. So
with that, they can go into the venture capital market and raise
capital."
Schroeder believes ATJ will be "the mainstay" of alternative fuels
for aviation because "the feedstock is there in large quantities and
certification is nearly there". However, he admits the industry is "in
its infancy" and it will be a long time before ATJ can be scaled up to
such a level it makes a significant impact on aviation's carbon
footprint.
GRAVE RESERVATIONS
"It will be at least another decade and even then it will not be
close to 5% or 8% of jet fuel because aviation is growing and this
[growth] will slow everything down," says Schroeder.
Bowers has "grave reservations" about Byogy's claims, accusing the
company of "pinning their technology to some magic breakthrough in
cellulosic ethanol technology to somehow bring the price down to
economic levels". While Schroeder says that "on paper the figures look
good" and the price of Byogy's fuel "is relatively close to what we're
paying for jet fuel", he admits that "until we really go into
production, we don't know".
Read More @
Source: Flight Global
