Going Diesel - Good or Bad?
Conventional wisdom tells us that U.S. drivers will not switch to diesel power. That wisdom comes in part from the disastrous attempts to produce domestic diesel-engined cars during the fuel crisis of the 1970s.
The same conventional wisdom also would have us believe the other reason U.S. drivers will not switch to diesel is because they perceive diesel vehicles as slow, noisy, smelly, and smoky. In both cases, reality is quite different.
Now in the 21st century, diesel power is an entirely new matter. Not only are modern light diesel engines quiet and smooth, they can operate on biodiesel fuel made in part from natural materials, thereby not contributing to greenhouse gas formation.
Of course, the other major impetus in the thrust towards diesel power comes from the fact that diesel engines are roughly 40-percent more efficient in their use of fuel than spark-ignition engines. That is one of the reasons Europeans and Asians, whose daily fuel costs $5-$7 per gallon, are such large diesel users.
Diesel vs. Hybrid
In the U.S., gasoline-electric hybrid power has sparked the imagination of the public. The hybrid is ideal for high-density city driving. In stop-and-go traffic, a hybrid runs most of the time on its electric motor, keeping fuel consumption down. But take that same hybrid vehicle out on the interstate, and it runs on the gasoline engine, burning fuel almost as fast as a conventional vehicle.
So why hasn’t everyone simply switched over to diesels? There are several reasons. First, conventional diesel engines available through the 1990s were considered old technology — noisy and smoky. Though they burned less fuel, the clatter — and worse — the choking smoke, limited their popularity. Just take a look at any construction site and see dozers and graders belching clouds of black smoke.
Plus, as air quality requirements became stricter, diesels were dropped by the few companies providing them for passenger cars. Since pollution requirements for heavier vehicles were less strict, they continued to be offered in heavy pickups and other vehicles.
The revolution in diesel power came around the turn of the 21st century, with the development of the common-rail injection system and electronic injectors, rather than the old system of an injection pump that mechanically supplied the injector for each cylinder individually. The much higher injection pressures possible with the new system allow better atomization of the fuel, which correspondingly allows it to burn cleaner.
Technologies improving diesel performance include Bluetec and TDI. Bluetec refers to a suite of emissions technologies that focus on reducing particulates and nitrogen oxide output to help diesels meet the most stringent California regulations and thus be saleable in all 50 states.
TDI technology includes common rail permanently pressurized fuel injection. This allows multiple injections of fuel for each power stroke of the engine, tailored precisely for the most efficient combustion that also minimizes vibrations and noise. Regenerating particulate filters and other exhaust after-treatment are integral with TDI engines’ smooth, quiet, and powerful operation.
The Biodiesel Revolution
The second revolution, at about the same time, comes from the development of biodiesel fuel. Since diesel engines as a rule are not finicky about what they burn, substituting vegetable oil for mineral oil has many benefits. Biodiesel significantly reduces overall greenhouse gas emissions, including particulates, from diesel vehicles.
In addition to its environmental benefits, biodiesel reduces dependence on oil, especially imported oil, and supports the U.S. agricultural economy.
According to the Environmental Protection Agency (EPA), if the U.S. had a light-duty fleet that was one-third diesel, the country would reduce its oil consumption by up to 1.4 million barrels of oil per day. That is equivalent to the amount of oil the U.S. imports daily from Saudi Arabia.
Biodiesel is rated by the percentage of vegetable versus mineral oil. Thus, B-5 biodiesel is 5-percent vegetable oil. B-20 is 20-percent vegetable oil. Again according to the EPA, if B-5 (5-percent biodiesel blended in conventional diesel fuel) were used in all diesel fuel for onroad use in the U.S., it would reduce fuel consumption by 1.85 billion gallons, the amount of fuel produced from all oil imports from Iraq.
Today, most diesel vehicles available in the U.S. are certified to run on B-5, which is available at pumps in some areas. What manufacturers are working on is certifying vehicles to run on B-20, a much cleaner fuel.
To expand the use of biodiesel, Chrysler announced that, beginning with the 2007 model-year, it will approve and endorse the use of B-20 in diesel-powered Dodge Ram trucks by government, military, and commercial fleet customers.
The company is also working with the biodiesel industry, other OEMs, suppliers, nonprofit organizations, and federal and state governments to develop national quality standards for B-20.
According to Loren Beard, Chrysler’s senior manager – fuels, “Diesel will be good for America, and biodiesel makes diesel better. Emissions of particulates — an important issue in congested urban areas — can be reduced more than 80 percent with modern, clean diesel engines running on biodiesel.”
Bluetec is now the standard name for clean diesel technology, driven by a cooperative agreement between several manufacturers, designed to identify diesel technologies that meet 50-state clean diesel requirements for the U.S. market..