NEWS
High octane mix
Lotus research engine could lead to improved biofuel efficiency
CARS could run on biofuels more
efficiently with a new research
engine being developed by Lotus
Engineering.
The sports car manufacturer is
teaming up with Queen’s University
Belfast and Jaguar Cars to develop
a single cylinder engine prototype
specially designed to run on sustainable
bioethanol, synthetic
methanol and petrol mixtures.
The engine, which is planned to
be unveiled in January 2009, will
use a variable-compression ratio
system and a two-stroke operating
cycle with direct fuel injection.
The research programme, called
OMNIVORE, is sponsored by
DEFRA and the DoE NI (Department
of the Environment, Northern
Ireland) through the Renewable
Materials LINK Programme.
There are a small number of
cars with flex-fuel engines on the
market, including the Peugeot 307
1.6 BioFlex and Citroën C4 1.6
BioFlex. But the drawback is that
currently they get fewer miles to the
gallon running on biofuels. Lotus
engineers hope the OMNIVORE
engine will not require drivers to
choose between efficiency and
more sustainable fuel.
Engines designed specifically
for alcohol-based fuels usually perform
well, but designing an engine
that can handle multiple fuels presents
many challenges.
Numbers add up for hydrogen
THE MUCH-TOUTED hydrogen economy depends on improving
ways to create the element swiftly and affordably. Now scientists at
Sheffield University have used mathematical models to show how
bacteria could be pressed into service to achieve that goal.
Like all living creatures, bacteria sustain themselves through their
metabolism, a huge sequence of chemical reactions that transform
nutrients into energy and waste.
Using mathematical computer models, the Sheffield team has
mapped the metabolism of a type of bacteria called Nostoc. This
fixes nitrogen and, in doing so, releases hydrogen that can then
potentially be used as fuel.
Fixing nitrogen is an energy intensive process and it was not
entirely clear how the bacterium produces the energy it needs to
perform. The system has been used to map out how this happens.
Until now, scientists have had difficulties identifying bacteria
16
The Exige 270E demonstrator runs on any mixture of petrol, ethanol and methanol
Typically, the best performing
engines have high compression
ratios, which makes them more
prone to engine knocking — an
erratic form of combustion that
occurs when multiple flames spontaneously
generate throughout the
combustion chamber. The phenomenon
is the result of excessive
heat and pressure in the combustion
chamber that causes the
air/fuel mixture to autoignite.
The multiple flames will collide
and create shockwaves that
produce a sharp metallic pinging or
‘knocking’ noise in the engine.
Prolonged knocking can cause
extreme damage.
Petrol is unsuitable for engines
with high-compression ratios, but
alcohol-based fuels work well
because they have a higher-octane
level — which is a measure of
resistance to knocking. The higher
the octane number, the better the
fuel is able to resist knocking.
Lotus engineers have taken this
into account and is designing a
flex-fuel engine with a variable
compression ratio system that can
metabolic pathways. The bacterial metabolism is a huge network of
chemical reactions, and even the most sophisticated techniques can
only measure a small fraction of its activity.
‘The research uncovered a previously unknown link between the
energy machinery of the Nostoc bacterium and its core nitrogen
metabolism,’ said Dr Guido Sanguinetti, from the university’s
Department of Computer Science, who led the study.
‘Further investigation of this pathway might lead to
understanding and improvement of the hydrogen production
mechanism of these bacteria. The research is yet another small step
towards sustainable fuels.’
The next step will be further investigation into hydrogen
production, as well as constructing more mathematical models
capable of integrating various sources of biological data.
Max Glaskin
be scaled back to a lower compression
when running on regular
petrol or a blend of petrol and bio
alcohol.
The OMNIVORE programme
complements the recently unveiled
Lotus research on the complex
combustion process involved in
running on mixtures of alcohol fuels
and petrol.
At this year’s Geneva Motor
Show the company unveiled the
Exige 270E Tri-fuel a 270bhp
flex-fuel car capable of running on
petrol, ethanol and methanol.
Mike Kimberley, chief executive
of Lotus, said the company’s engineers
are not only working on
developing more efficient vehicles
but also all aspects of future fuels
and for alternative powertrains that
will accommodate alcohol fuels as
they enter the market.
‘Alcohols possess superior
combustion characteristics to
petrol which allows greater optimisation,’
he added. ‘Taking full
advantage of the benefits of
sustainable bio alcohols will ensure
a greater percentage of vehicle
miles will be travelled using renewable
fuels.’
Kimberley said he was delighted
with DEFRA’s investment that will
help take forward research, development
and the demonstration of
the technology.
Siobhan Wagner
the EnGIneeR 18–31 AUGUST 2008
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