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The American Environmental
Protection Agency (EPA)
has established new reg-
ulations governing diesel
engine emissions for off-road equip-
ment like construction and farm
machinery. The target is a 90% reduc-
tion in sulfur, oxides of nitrogen, and
particulates (a fancy name for soot) by
the year 2014.
This means new diesel engines will
cost more to build and more to buy.
But they should also be more fuel-effi-
cient, more durable and less polluting.
The brawny diesel engine has
been the workhorse of the industrial
world for decades. "No other power
system has the power, durability,
fuel efficiency and reliability of the
diesel," says Bill Buff, spokesman
for the Diesel Technology Forum in
Washington, D.C. "It's unmatched
for its ability to work consistently
and efficiently."
This combination of features puts
diesels into semi-trailers, railroad
locomotives and the engine rooms of
many large ships. It's also the ideal
engine for farm machinery such as
tractors and combines.Although they're already
cleaner-burning than in earlier
times, the sheer number of these
engines now working in the U.S. led
the EPA to set stringent new emis-
sion regulations to be phased in over
time and in 4 stages or tiers. The
Canadian government is moving in
the same direction.
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"The U.S. has the tightest emission
standards in the world as far as we
know and most engine manufacturers
treat Canada and the U.S. as virtually
one market," notes Malcom McHattie,
chief of regulatory development for
Environment Canada.
First step in making diesel engines
burn cleaner is to tweak the fuel. Sulfur
content will be lowered from a current
high of 3,500 parts per million (p pm) to
a projected 15 p pm by 2014.
"Getting sulfur out of fuel is inher-
ently good because it also enables the
use of advanced emissions control
technology like particulate filters and
oxidation catalysts which are sulfur
sensitive," says Alan Schaeffer with
the Diesel Technology Forum. "Sul-
fur is emitted as sulfur dioxide, which
leads to acid rain and also
contributes to fine parti-
cle levels."
Low-sulfur fuel still
works in older engines
and may even improve
their life expectancy. The
fuel will cost more but
should reduce acid
buildup in engine oil.
Acid pits engine parts.
Another emission reduc-
tion strategy is to burn fuel
more completely. The better
the burn, the cleaner the
exhaust. Engine designers
are looking at ways to
improve combustion. One way is by
adjusting exhaust valve timing to
manage cylinder temperature.
"Maintaining optimum tempera-
tures for the lowest possible emissions
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is challenging because you have to do
it under conditions ranging from full
load to idle," Schaeffer said. "Variable
valve actuation and precise fuel injec-
tion and spray patterns are examples
of technology being tested in the
search for ways to cut emissions."
The last piece of the puzzle is the
exhaust system and the devices that
control emissions after combustion.
A low-sulfur fuel allows more effec-
tive particulate filters and other
advanced emission controls that are
sulfur sensitive. These new technolo-
gies will cost more.
" Anybody who buys a diesel
engine is buying essentially the same
engine as they would in the U.S.," says
McHattie. "But tougher emission stan-
dards will raise the cost on both sides
of the border. A rough estimate of the
increase is between 0.5% and 3%."
The U.S. has been introducing its
new emission standards in stages com-
monly referred to as tiers. The last
stage, tier 4, has been finalized and is
set to come into force in 2008.
"Our plan for Canada is to have
regulations in place such that we can
also bring in tier 4 by 2008," McHat-
tie says. "But it's not written into pre-
sent regulations."
All diesel engines will ultimately
have to conform to tier 4 standards but
this applies only to those built after
2008. As it stands, nothing built before
then should require retrofit to tier 4
standards. And these older engines
should still be able to run effectively
on the new low-sulfur fuel. CG
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