Technology
reference — a gasoline engine is only about 35% efficient.
These gains have come from high-pressure common rail fuel
injection systems, turbo-charging, and the introduction of
computing power to control precisely the combustion and the
after-treatment management systems.
Is fuel efficiency important?
A question I get asked often, is whether increasing fuel efficiency
is customers’ number one demand? The answer is yes, without a
doubt. Good fuel efficiency is the most important element, but
customers also require good engine performance and durability.
Then it has to be durable and meet emissions requirements —
and these are sometimes in competition with one another.
Are engines also becoming more powerful? There is an
upwards trend: customers are moving larger loads and that
requires greater power. The Volvo Group’s largest output is
now 1 000hp. But compared to passenger cars, all heavy-duty
applications are still (relatively) underpowered.
There have been accusations that diesel engines are not
environmentally friendly. However, making diesel engines very
clean is possible and that is something that the heavy-duty
industry has made greater progress on than the light-duty sector
has. Part of the reason for this is that the efficiency demanded by
customers in the heavy-duty sector is much higher.
Can we increase efficiency while at the same time
lowering emissions? It has been a challenge to refine the
thermodynamic process to compensate for the burden of
having added the SCR after-treatment system. But now we are
Diesel engines remain the most effective means to power heavy-duty
vehicles that deliver ore to the crusher.
back on track to increase efficiency step by step while at the same
time aiming for zero emissions. What we need to understand is
how much further can we go in our pursuit of zero emissions. It all
depends on how we define emissions. If you propel the engine with
fuel that has no carbon and couple it with an efficient combustion
process that creates no soot, then zero emissions are possible.
We have been working on using methane and DME (dimethyl
ether) as clean alternatives to diesel. This is not a new idea; in 1900
the diesel engine was successfully run on peanut oil. The problem
isn’t with the technology of making the clean fuels work, but rather
their availability. But if the supply issue of renewable fuels can be
solved, then it is possible for diesel engines to run 100% CO 2 free.
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But, of course, there is a theory that clean fuels also have their own
environmental challenges. Bio-fuel production shouldn’t compete
with food production — but there are other fuels where this isn’t a
problem. Electro-fuels (e-fuels) use solar or wind power to ‘crack’
water and combine it with CO 2 from methane — and these fuels
feature quite a high efficiency — up to 80% claimed. This could be
an interesting complement to electrification.
Improving efficiencies
From an efficiency point of view, the engine doesn’t care if the
fuel molecule comes from a fossil or a renewable source. So, with
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