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Diesel: Gasoline’s Dirty Cousin?
Or the Little Engine that Keeps American Power Reliable
By: Michael D. Mankowski
How is Diesel Different from Gasoline?(1)
• Diesel is a petroleum-based fuel with a higher energy content than gasoline.– contains about 30% more energy per gallon as
compared to gasoline.
• Diesel is a safer fuel than gasoline or other alternatives.– less flammable and explosive than gasoline due to
lower combustibility.
How is Diesel Different from Gasoline?(2)
• Diesel is Cheaper than Gasoline– Current Cost of a Gallon of Gasoline and Diesel
• Gasoline = $1.78
• Diesel = $1.65
How a Diesel Engine Works
Compression Instead of Spark
• Diesel engines ignite fuel with compression – The piston stroke in a diesel engine results in
a compression of the fuel air mixture so intense that it combusts spontaneously.
• Gasoline engines ignite fuel with spark plugs
• Gasoline engines inject fuel during the intake stroke, Diesel during the Compression Stroke.
Three Ways of Injecting Fuel
1. Crankshaft Driven Fuel Pump
2. Common-rail Fuel Injection
3. Unit Injection
Crankshaft Driven Fuel Pump
A fuel distribution pump geared to the crankshaft to sends a pulse of pressurized fuel down a dedicated pipe to each cylinder at a predetermined point in the compression stroke.
Common-rail Fuel Injection(1)
• Uses a pump to deliver pressurized fuel to all the injectors and than relies on electronically controlled valves at each injector to open as needed.
• Used on most modern Diesel Engines
Common-rail Fuel Injection(1)
Unit Injection
• Delivers low-pressure fuel to each cylinder and relies on the injector to generate its own pressure mechanically.
• Most heavy-duty diesels use unit injectors, which can be equipped with an electronic control valve to regulate the amount and timing of the injection.
Misconceptions About Diesel
• It’s Dirty
• It Causes a lot of Pollution
• It has Limited Uses
Benefits of Diesel
• A well maintained diesel engine usually emits lower levels of carbon monoxide, hydrocarbons and carbon dioxide than gasoline engines.
• Better fuel economy,
• Increased durability for longer engine life.
Problems with “Old” Diesel Technologies
• High Sulfur Content of Fuel
• High NOx Emissions
• High Particulate Matter Emissions– The “Black Smoke” everyone sees
• Noisy Engines
Sulfur Content
• Diesel fuel available in the U.S. currently contains from 340 ppm of sulfur to 140 ppm in California.
• European Standards are much lower– As low as 10 ppm in Germany and Sweden
NOx Emissions
• High cylinder pressure and temperature with excessive air is the recipe for making NOx
• Because of excess air in diesel engines, current catalytic can’t scrub out NOx
Particulate Matter
• Unburned fuel in the compression ignition process becomes soot, a pervasive form of particulate matter.
Clean Diesel
• Clean diesel is an evolutionary systems-based process that combines advancements in diesel engines, cleaner burning fuels and emissions control system, all working and optimized together.
What Makes Diesel Clean?
• The Three Pillars of Clean Diesel Technology:– cleaner-burning fuels– state-of-the-art engines– effective emissions-control systems
Cleaner Burning Fuels
• The newest in diesel fuels is called Ultra-low Sulfur Diesel (ULSD)– Ultra-low sulfur diesel fuel is a specially refined diesel
fuel that has dramatically lower sulfur content than regular diesel and can be used in any diesel engine just like regular diesel fuel.
• Today, the sulfur content of ULSD ranges from 15 to 30 parts per million. Regular diesel has a maximum of 500 parts per million of sulfur.
How Does ULSD Help?
• Reduces sulfate emissions
• Allows the use of particulate traps and catalytic converters
• Lowers engine maintenance costs
• Easy to convert to– No retrofitting required
• Only costs a few cents more
State of the Art Engines
• New Engine Technologies– Electronic Controls– Common-rail Fuel Injection– Variable Injection Timing– Improved Combustion Chamber Configuration– Turbocharging
New Pollution Controls
• Particulate Traps
• Oxidation Catalysts
So What does all of this Have to do with Reliability?
• Better diesel technology means greater efficiency
• Efficient diesel technology is required in order to comply with upcoming environmental legislation
• America wouldn’t be able to function without diesel
Diesel is an Integral Part of America
• Diesel is used in many different industries – Transportation
– Shipping
– Agriculture
– Mining
– Energy Production
– Safety
– Homeland Security
– Defense
Electrical System
• Almost all of these industries play a part in making sure that the electrical system in the U.S. stays intact
• Power plants can’t produce power without fuel, and most of that fuel is produced and move by diesel
• Diesel also plays an integral part in providing power when disaster strikes, or the major electrical systems fail
How Diesel Effects Reliability
• Backup Generators• Equipment• Transportation• Shipping
Backup Generators(1)
• Many Sources use Diesel Generators for Backup power– Hospitals– Nuclear Plants– Public Utilities– Food Storage
Backup Generators(2)
• Diesel generators kick on within seconds, providing immediate, full strength power when it is needed most
Equipment
• Most of the nonroad equipment used in the United States is powered by Diesel– Snow plows– Mining Machinery– U.S. Military Vehicles– Emergency Response Vehicles
Public Transportation
• In 1998, 95% of the nation’s full-sized transit buses were powered by diesel
• Close to 60% of America’s elementary and secondary schools used diesel to power the buses that take children to school everyday
Shipping
• 94% of all goods shipped in the U.S. are shipped using diesel power
• Diesel dominates the trucking, railroad, boat and barge industries
Legal Framework for Diesel
• Legislation heavily influences the use of diesel
• Upcoming legislation could eliminate diesel use if it weren’t for ongoing technological development and improvement
New Engines
• Engine manufacturers have been subject to nationwide, federally-enforceable air pollution standards under the Clean Air Act since 1970
• In 1970, the CAA mandated 90% reductions for levels of carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (N0x) in light-duty vehicles by 1976.
• In 1977, further amendments to the CAA mandated a 90% reduction in CO and HC for heavy-duty vehicles by 1984, and a 75% reduction in NOx by 1985.
New Engines (2)
• In 1990, further amendments to the CAA were established and EPA recently enacted regulations that will reduce NOx and non-methane hydrocarbons (NMHC) emissions from heavy-duty diesel engines by over 50% from 1998 levels.
• These standards dramatically reduced the amount of emissions form diesel engines, but tougher standards are on the way.
Regulation of New Engines and Fuels (1)
• In 2001, EPA created a new rule:– Control of Air Pollution From New
Motor Vehicles: Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements
• This rule controls both new diesel engines and the sulfur content of diesel fuels
Regulation of New Engines and Fuels (2)
• New Standards for Particulate Matter and NOx
– 90% reduction of current standard for PM– 95% reduction for NOx
• 97 % reduction of Sulfur content • It sets new standards that will go into effect
in model year 2007 for the trucks and mid 2006 for the fuel
Durability and Maintenance
• EPA’s 1997 rulemaking for enhanced emission standards for heavy-duty diesels included several provisions to enhance durability requirements for emissions performance. – Increased useful life mileage from 290,000 to 435,000.
– Enhanced Inspection and Maintenance requirements.
– Enhanced emissions defect and performance warranties.
Regulation of Existing Engines
• In 1994, EPA established a stringent three-tiered emissions reduction scheme that subjects all non-road engines - regardless of size -- to progressively more stringent emission standards and will radically reduce emissions from non-road engines by more than 70% in many cases.
• Tier 2 and Tier 3 standards, which include large diesel engines, were made more stringent in 1998
• NOx and Particulate Matter emission standards were reduced up to 2/3rds for some applications
Conclusion(1)
• Diesel should continue to be developed because it is important to most of the industries in the U.S.
• Much progress has been made in making diesel a more efficient and clean fuel choice.
• Most of the problems associated with diesel in decades passed have been eliminated or reduced
• The diesel engines of today are cleaner, more efficient, and more powerful than the ones built even ten years ago