Once diesel fuel was touted across parts of the world as a readily
available solution to increase fuel economy.
Diesel engines were praised as heavy-duty, hardworking, fuel-sipping
engines that were great for some of the hardest jobs and heaviest
machinery — hauling, clawing through the dirt and driving long distances.
Their reputation as efficient and long-lasting engines made them a popular
choice across Europe, one of the world's largest car markets.
They were supported by government incentives and embraced by major
automakers. For a while, it looked like diesel engines could be one of the
best available technologies for reaching ambitious fuel economy targets.
Then the case for diesel seemed to crash.
Cities where diesels were common struggled with extremely high levels of
air pollution. Global health authorities determined diesel fuel to be
carcinogenic. In 2015, German automaker Volkswagen, one of the world's
largest car companies, shook the industry when executives admitted the
company had cheated on diesel emissions tests.
Executives were fired and jailed.
Volkswagen was on the hook for billions in fines and payouts, and some
wondered whether the scandal spelled the beginning of the end for diesel
engines themselves.
At the same time, hybrid and electric vehicles increasingly became, for
many, the best new hope for providing low emission or even emission free
transportation and equipment.
But diesel advocates say diesel is not done yet.
It is still widely used in heavy machinery and commercial applications.
Companies are developing new technology, such as pollution filtering
systems and renewable biofuels that could keep diesel relevant and widely
used for years to come, even as solutions for reducing toxic emissions.
Within the truck markey, the diesel is a huge player as far as, you know,
the amount of vehicles that we produce with diesel, certainly in heavy
duty. And there's a constant desire for more capability.
The diesel engine was named for its creator, Rudolf Diesel, a Paris-born
son of Bavarian immigrants.
Diesel was an engineer who worked on refrigeration technology during the
day. But in his spare time, nursed ideas for an engine more efficient than
the typical designs of his time.
He designed an engine that worked in a manner similar to conventional
internal combustion engines, but with a few crucial differences.
In an internal combustion engine, diesel or otherwise, fuel and air
combined inside a cylinder chamber where they combust.
The explosion pushes a piston, which turns a crank shaft and ultimately
turns the wheels that move a vehicle.
In a typical gasoline engine, a spark plug ignites the fuel and air
mixture inside the cylinder.
But Rudolf Diesel determined that no spark was necessary.
His design simply compressed the air in the cylinder to the point that the
air was so hot it would cause the fuel to combust.
As soon as it was injected into the cylinder.
Diesel's basic design innovations are still seen in diesel engines today.
The design of the diesel engine gives it some of the advantages so
appreciated by fans.
Diesel engines tend to get better fuel economy than gasoline engines,
sometimes much better.
And they can also deliver a great deal of power to the wheels at low
speeds, making them excellent for heavy machinery and vehicles that need
to haul, whether that be freight trucks, construction equipment or trains.
Diesel fuel is also different from gasoline, and it is more energy dense,
meaning more energy can be extracted from diesel than can be extracted
from the same amount of gas.
Diesels get about, on an average basis, about 30 percent more energy
efficient than a comparable gasoline vehicle.
So that comes from two things.
The fuel itself has more energy potential in it, and then the engine burns
that fuel more efficiently. So those two things together make diesel the
most energy efficient internal combustion engine.
Over time, their fuel saving potential made them highly desirable choices
in countries where governments were trying to reduce carbon emissions.
Lower carbon dioxide emissions were one of the reasons the European Union
began pushing the fuel in the 1990s.
Around the time climate change became a serious global issue and countries
began signing on to major global carbon reduction agreements, such as
1997's Kyoto Protocol.
For a long time through most of the 90s and into the 2000s and a lot of
countries in Europe, diesel was the majority, represented the majority of
light vehicle sales.
In some markets like in Italy it got as high as 90 percent
of the market was diesel engines.
And Germany and France was also very popular.
But that, in North America, diesel never really caught on quite as
much, except during periods where we tended to have very high fuel prices.
However, diesel engines do have their drawbacks.
Whereas diesels are good with low end torque, it is easier to get higher
horsepower in a gasoline engine.
That is why diesel engines are typically found on large trucks and heavy
machinery, but seldom found on sports cars or race cars.
There have been other drawbacks that eventually gave diesels a bad
reputation they are still battling today.
Overall, diesel engines produce less CO2 than gasoline burning engines,
helped by the fact that they burn less fuel.
However, they produce higher concentrations of other hazardous pollutants,
especially nitrogen oxides and very tiny particles, commonly referred to
as PM 2.5.
The European countries that embraced diesel considered it a tradeoff.
Sacrificing some losses in air quality for gains in CO2 reduction.
Many European countries put tax advantages in place to encourage diesel
engine adoption. These incentives sent diesel car sales skyrocketing
throughout Europe. But over time, cities such as Paris showed signs of
dangerously high pollution.
European emissions standards have restricted pollutants such as nitrogen
oxide since at least the 2000s.
But for years, laboratory tests were easy to exploit.
As the European Environment Agency noted in a 2019 report.
In 2012, the World Health Organization said it considered diesel exhaust
carcinogenic. Several studies over the years have shown harmful levels of
nitrogen oxides and other pollutants in European cities, often high above
legally allowed limits.
Perhaps the biggest hit to diesel's reputation was the cheating scandal
that rocked Volkswagen and other automakers beginning in 2015.
The German carmaker, one of the largest in the world, had been heavily
invested in diesel fuel and marketed for its fuel economy benefits.
But starting in 2015, revelations began to surface that the company had
installed software in cars designed to manipulate emissions test results.
These defeat devices were able to recognize when a car was being lab
tested, as opposed to being driven in real world conditions and thus
calibrate the engine to cheat the test by temporarily producing emissions
low enough to comply with regulations.
Once on the road, the cars outfitted with these devices were often
releasing pollutants that far exceeded legal limits.
Volkswagen has had to pay roughly 35 billion dollars since 2015 and
penalties, fines, settlements and other payouts.
The scandal seems to have marked a turning point in Europe's history with
diesel. Following the Volkswagen scandal, diesel sales did drop off
dramatically in Europe, even though it was still more cost effective to
drive a diesel engine there.
It has dropped significantly.
Our own stats, globally, between 2016 and 2018,
while overall vehicle sales and electric vehicle sales increased globally
by about one percent.
Diesel sales dropped by about nine percent globally in that same
timeframe. Of course, in Europe, where diesel was most popular, it dropped
off the most. In 2015, diesel's share of new passenger cars in Europe was
about 51 percent.
By 2018, that share had fallen to 36 percent.
That is the lowest share of total new car registrations since 2001,
according to industry data firm JATO Dynamics.
Association with the high profile VW scandal hurt diesel's reputation.
But perhaps even worse was the talk among European politicians of banning
internal combustion cars entirely, including diesel, from major cities.
The UK said in 2020 it plans to ban the sale of both new diesel and new
gasoline cars by 2035.
France has also plan to end the sale of internal combustion cars by 2040.
Automakers such as Volvo and Nissan have said they plan to either reduce
their share of diesel vehicles or phase them out entirely.
In the wake of the scandal, VW made a pretty sharp turn toward
electrification. The company said in December 2019 it planned to produce
one million electric cars by 2023, sooner than the 2025 target it had
previously set. Of course, there is hardly an automaker in the world that
isn't moving into electric vehicles.
That poses some real competition for diesel engines, even larger vehicles
such as buses and delivery trucks can run well on electric and hybrid
power trains. Encroaching on territory diesel once had pretty much to
itself. Vehicles that operate in a local area like trash trucks, buses are
increasingly shifting towards electric power trains.
Local authorities are buying a lot more electric buses because they're
cleaner, quieter or more efficient, cheaper to operate.
Companies like Amazon that operate huge fleets of delivery vehicles says
those FedEx and UPS and Amazon vans that deliver all its packages to you,
those are traditionally been powered by diesel engines.
But, you know, that's starting to change now.
Amazon invested $800 million last year in an EV startup called Rivian.
And UPS and FedEx are doing...
they're also buying a lot more electric vans.
So for local operations where those vans are coming back to a depot at
night, it's easy to plug those in and charge them overnight.
Not a big deal. For now, diesel is still everywhere.
Most of the farm equipment in the United States runs on it.
It is still very common in heavy construction, mining, shipping and marine
transport and much of public transit.
Though companies such as Tesla are venturing into electric long-haul
trucks, diesel is still the powertrain of choice for that sector.
The last place where you'll likely see diesel is in those long-haul trucks
where it's still a challenge.
You need so much battery in those things to go electric with those.
You know, they're driving, you know, thousands of miles across the
continent, that it's gonna be a while before those get electrified.
But, you know, the emissions, the diesel emissions are less of a problem
with those because they tend to be out more out in rural areas when you're
driving across the country.
Whereas, you know, the diesel emissions aren't...where they are a bigger
problem is in urban areas.
So the urban local delivery vehicles — they're going electric.
The long-haul stuff is going to go stay diesel for a while yet, but
probably by the late 2020s, we'll start seeing those going electric as
well. Diesel advocates say it is too soon to count the fuel out and there
may be further opportunities for growth.
Companies are developing technology that can reduce the emission of the
harmful pollutants that have run diesel into trouble before.
All diesels sold in the United States is ultra-low sulfur diesel, which is
a form of the fuel that contains a tiny fraction of the sulfur contained
in older forms. This fuel allows diesel vehicles to be fitted with new
pollution, reducing devices.
Today we know that operating on the nation's roads that about 43 percent of
all commercial vehicles registered and operating are the newest generation
of diesel. So that means they have the full suite of particulate control
and advanced selective catalytic reduction systems, diesel exhaust fluid,
et cetera, that enable them to achieve near zero emissions.
Companies are also investing in renewable biofuels, which are refined from
crops or organic waste.
Many diesel engines can now use a blend of 20 percent renewable fuel and
80 percent petroleum based diesel, commonly called biodiesel, but known
more technically as B20.
Some are going even further and using entirely renewable fuels and diesel
engines. The city of San Francisco converted its fleet of municipal
vehicles to totally renewable diesel fuel.
The advanced renewable biofuels, like biodiesel, enabled the carbon
footprint to be reduced from a diesel engine by anywhere from additional
20, up to as much as 80 percent, if you're using the most refined and
advanced processing of those biodiesel feedstocks.
Diesel also appears to have crept back into a few key segments that are
especially popular among American consumers and profitable for American
automakers: pickup trucks and sport utility vehicles.
Diesels provide greater efficiency, greater range.
And a light duty diesel, you can drive from going Duluth to Dallas on one
tank of fuel, compared to gas — 35 miles per gallon on the highway.
And if you look at the torque curve, the torque curve is a very low R.P.M.
In 2019, all three U.S.
automakers had, for the first time in years, at least one diesel, full
size, half-ton pickup truck in their lineups.
Diesel engines are also options on mid-sized pickups such as the Chevrolet
Colorado. And General Motors is offering diesel engines on its Chevrolet
Suburban and Tahoe sport utilities.
Those pickup trucks and some great options for those that really like
off-roading and Jeep.
The Wrangler and the Gladiator both have diesel engine options in those
vehicles. So we get a lot of grunt for those folks that really do true
off-roading activity.
Diesel's low end torque is really a kind of thing that that that segment
really likes. So I think there's great opportunities for diesel in the
light vehicle segment in these bigger vehicles and these performance
veterans. Much of the auto industry is betting that the future is
electric. But the bridge to fully electric cars, trucks, trains and
construction equipment could be a long one.
The diesel industry is betting consumers and governments will want
effective solutions they can deploy along the way.