DIESEL ISN’T DIRTY. Say what?
Diesel is, officially, a clean technology.
Diesel is a technology undergoing continuous improvement. And clean diesel or ULSD (ultra-low sulfur diesel) is the new generation of diesel technology. At 97 percent less sulfur, this new diesel fuel has been the standard for both on-highway and off-highway diesel engines nationwide since 2007. By cutting sulfur levels in diesel fuel by 97 percent, benefits were immediately measurable — 10 percent lower soot emissions from all diesel vehicles and equipment using the fuel (both old and new). (Reducing the sulfur content of diesel fuel is similar to removing lead from gasoline during the 1970s.)
Cleaner diesel fuel (97% less sulfur) laid the foundation for the development and introduction of a new generation of advanced engines and emission control devices to achieve strict “near zero” emissions standards. With proven energy efficiency, diesel is positioned as a key technology for growing economies to achieve cleaner air, lower greenhouse gas emissions and a sustainable environment around the world.
Why is diesel technology so fuel efficient?
Diesel, a petroleum-based fuel, is the world’s most efficient internal combustion engine. With the highest energy density among transportation fuels, it provides more power and fuel efficiency than alternatives such as gasoline, compressed natural gas or liquefied natural gas.
Fuel combustion is the primary difference between gasoline and diesel engines. Gasoline engines ignite fuel with spark plugs, whereas diesels ignite fuel with compression. Inside the engine, the combustion of air and fuel takes place under the pressure and heat created by compressing the air-fuel mixture so intensely that it combusts spontaneously, releasing the explosive energy needed to turn the wheels on a vehicle, fire pistons into motion and create useful mechanical energy.
New advanced technologies such as electronic controls, common rail fuel injection, variable injection timing, improved combustion chamber configuration and turbo charging have made diesel engines cleaner, quieter and more powerful than ever before.
Advanced diesel engine designs and emission control technologies were developed to meet strict tailpipe emissions standards for new commercial vehicles manufactured in 2007 and the stricter standard established for 2010. Thanks to the clean diesel systems found on newer diesel commercial vehicles, it takes about 60 of today’s trucks to generate the same level of emissions as just one truck manufactured in 1988. EPA and National Highway Traffic Safety Administration (NHTSA) established a national program to reduce greenhouse gas (GHG) emissions and establish new fuel efficiency standards for commercial vehicles that will increase their fuel efficiency by up to about 40 percent when fully implemented in 2027. Clean diesel is the preferred power train to achieve these goals.
Phase 1 of those standards are now implemented beginning with model year 2014 and EPA and NHTSA announced proposed rules for the second phase of fuel economy and GHG reduction from the heavy-duty fleet that would apply beginning in 2021 through 2027 to further reduce carbon emissions.
Innovating manufacturers have employed numerous methods to meet emission standards using a variety of after treatment technologies and advanced engine systems that do not involve the use of additional emissions control technology, particularly in the off-road sector.
Introduction of ULSD fuels for both on- and off-road applications is a central part of the clean diesel system designed to meet tough emissions standards. With the introduction of lower sulfur diesel fuel came the ability to use a number of exhaust after treatment options such as diesel particulate filters (DPF), exhaust gas recirculation (EGR), diesel oxidation catalysts (DOC), and selective catalyst reduction (SCR) with the use of diesel exhaust fluid (DEF) that can be sensitive to the sulfur levels in the fuel.
Construction and Agriculture
Next on the horizon for clean diesel is off-road equipment.
In 2014, new engines that power off-road equipment including construction and/or agricultural equipment are required to meet the similarly strict Tier 4 standards. These requirements kicked in starting in 2015 for much larger engines that power locomotives, marine vessels and other impressively large applications.
Diesel Cars, Pickup Trucks and SUVs
The US already has one of the strictest standard sets in the world regarding clean air requirements for automobiles and light trucks — including diesel models, which are held to the same strict standard as gasoline, hybrid and other competing technologies.
While introducing new clean diesel is an accomplishment in and of itself, the industry is not stopping there. Beginning in 2017, a tougher Tier 3 emissions standard will replace the Tier 2 standard for newly manufactured passenger vehicles. Thanks to over a decade of innovation, clean diesel technology has been developed and deployed to meet these strict Tier 2 passenger vehicle emissions standards. According to the National Academy of Sciences, these same technologies will be capable of meeting the stricter Tier 3 standards scheduled to phase in beginning in 2017.
Looking beyond the VW headlines, diesel is poised to regain momentum in the passenger market space and clean diesel is one of the clear pathways to meet the 52.5 mpg corporate fuel economy mandates looming in 2025.
Alkane Truck Company thanks the Clean Diesel Forum (www.dieselforum.org) for the content of this article.