TodayApril 17, 2022

Diesels vs. hybrids

The times they are changing

Hybrids are all the rage in the United States and they are great for reducing our dependence on oil, but only if they’re driven the way they’re meant to, in city traffic under around 25 mph. City buses are actually the best hybrid around; 13,000 hybrid buses equal about 500,000 hybrid cars in gas savings. Very few people argue that gas prices will be coming down, so it stands to reason that people will continue to demand more hybrids.

It will be interesting to see what happens when hybrids are 10-15 percent of the market. Will the Federal government still give a tax incentive after 2006? Will state governments continue to let the one car that idles the cleanest, while burning the least amount of gas in traffic congestion, drive free in the HOV lane while the 3/4 ton pickups wait in line? How will all those Nickel Metal Hydride batteries be recycled and when will they be eclipsed by the Lithium-Ion battery?

Is there any other way to reduce our dependence on oil while waiting for hydrogen? In a Los Angeles Auto show speech, Dr. Bernd Pischestsrieder, chairman of the Board of Management for Volkswagen, said: “the best way to do this is to diversify our fuel sources while reducing the emissions.” The diversification he was talking about would be by using diesel, alternative and regenerative energies.

Diesel is widely used in Europe. Nearly 25 percent of all fuel used for transportation of cars in Germany is diesel. 50 percent of all Volkswagen sales in Canada are diesel and 70 percent of all Jetta wagons in the United States are diesel. Diesel is obtained through the partial distillation of crude oil. Diesel fuel often contains higher quantities of mineral compounds and sulfur. For example, in most Europe diesel has on average 15ppm (parts per million) of sulfur, while in the United States diesel has 500ppm.

In 14 months, starting on October 15, 2006, oil companies are supposed to bring their diesel sulfur levels down to 15ppm. According to the Environmental Protection Agency (EPA), the oil companies are “kicking and screaming” about reducing sulfur content in the United States, even though they do it for Europe. EPA is holding fast to the reduction, but have sweetened the pot by allowing a 45 day transition period through the pipelines to average 15ppm. The EPA has agreed to give fuel refiners incentives to increase the production of ultra-low-sulfur diesel ahead of schedule so that pipeline companies and fuel retailers can test their distribution systems.

Bio-fuels and synthetic liquids are a part of Volkswagen’s strategy to broaden the energy sources for vehicles. Bio-diesel is already popular in Europe, and Volkswagen is working with Archer Daniels Midland to introduce Soya Methyl Ester (SME), or soybean oil. RME or rapeseed methyl ester is the technical name for biodiesel made from rapeseed, or canola, oil, which is used in Europe. Through the process of transesterification, the large, branched triacylglycerol molecules of the oil feedstock are altered to become smaller, unbranched methyl ester molecules, which are comparable in size to the components of classic diesel fuel.

In March of 05, Volkswagen announced that five percent of SME was acceptable in their cars. SME and RME offer enhanced lubricity and cetane, plus similar horsepower and torque when compared to petroleum diesel. Because plant-based feedstock crops absorb CO2 as they grow, the lifecycle of biodiesel fuel can be up to 85% CO2 neutral. SME contains oxygen which reduces particulate matters in the emissions when blended with conventional diesel, but it has to be in concentrations of 10-20 percent. According to Stuart Johnson, Volkswagen is in its initial phase of a research program with ADM to use 10-20 percent of SME in their diesel vehicles. This presents a true reduction in emissions and energy savings.

Large quantities of the world’s gas reserves are to be found in parts of the world where there is relatively little demand for them. Another process Volkswagen is excited by is gas to liquid (GTL). Its where gas is synthesized to form high-quality environmentally friendly diesel fuel. Volkswagen and Shell tested GTL on a fleet of their Volkswagen Bora TDI engine cars and it produced 50 percent fewer particle emissions and 20 percent Nitrox Oxide (NOX) emissions than conventional diesel -with the same engine. The method such as “Shell Middle Distillates Synthesis” (SMDS), a modern form of Fischer-Tropsch synthesis. This process is used to make high-quality ecologically acceptable diesel fuel (“SynFuel”), as well as other products.

Using SMDS in a Volkswagen Bora TDI engine, 50 percent fewer particle emissions and 20 percent fewer NOx emissions than with conventional diesel fuel were measured.

Biomass to liquid (BTL) is another synthetic fuel. BTL is basically planting life that is processed into a liquid synthetic fuel that can be blended with diesel fuel. Known as sun fuels, BTLs are CO2 neutral and their properties are similar to GTL fuels.

All of these fuels and new engines will have to meet Tier 2 Bin 5, a part of EPAs new Tier 2 emissions program being phased in through 2009. Tier 2 bin 5 represents the average level of emissions performance that each auto manufacturer’s fleet will have to achieve. Bin 5 also is equivalent to the emissions level that all vehicles must achieve under the California LEV 2 standards enforced in 5 states at present. In each of those five states, diesel vehicles are not sold, in part because the diesel fuel itself is so dirty. In effect, cars to be sold in 50 states must meet at least the tier 2 bin 5 limits. The Tier 2 program works in concert with new rules for sulfur levels in gasoline and diesel fuel.

The Tier 2 program represents several “firsts”:

For the first time;

SUVs, pickups, vans, and even the largest personal passenger vehicles are subject to the same national emission standards as cars;
vehicles and the fuels they use are treated as a system, so the cleaner vehicles will have the low-sulfur gasoline they need to run their cleanest;
new emission standards apply to all light vehicles, regardless of whether they run on gasoline, diesel fuel, or alternative fuels. People say that hybrids are the bridge to hydrogen fuel cell vehicles because we will incorporate some of the same technologies in the fuel cell vehicles that are in hybrids.

The same will happen with renewable fuels.

According to Pischetsrieder, on a well to wheel basis, these technologies can dramatically reduce CO2 emissions without requiring major changes to the way a driver wants to drive. They can utilize existing vehicles with existing diesel engines and these technologies are fully compatible with longer-term possibilities like hydrogen fuel cells.

These processes can reduce emissions right away and our dependence on foreign oil, giving technologies like hydrogen the time they need to mature.

Gasoline hybrids work well in the stop and go traffic because they harness energy by braking. Diesel gets as good gas mileage as many of the hybrids, imagine combining diesel into a hybrid. According to Automotive News, Mercedes-Benz will show a diesel-electric hybrid version of it’s new S-class, a luxury sedan, at the Frankfurt auto show in September. Mercedes will also show a CLK roadster with a hybrid powertrain that includes an integrated starter-generator.

Johannes Reifenrath, Mercedes-Benz, will only say that “Mercedes-Benz is constantly working on various powertrain concepts. For Mercedes-Benz, the hybrid technology is an important element within the strategy for alternative drives. At the International Auto Show in Frankfurt, we are going to present under the title “Clean Power” various drive concepts that provide high comfort and superb handling while at the same time cutting emissions and fuel consumption.”

If this is the same S-Class that was quietly on display at the 2005 Detroit Auto Show in January, the drivetrain in the new Mercedes-Benz S-Class “Hybrid” develops a maximum output of 340 horsepower “ a new record for cars with hybrid drive systems. The V8 CDI diesel engine develops 260 horsepower and 560 Nm of torque.

The two electric motors have a combined output of 70 horsepower. Thanks to the second electric motor, the diesel can be started at any time without transition, independently of driving mode. The electric motors are powered by a 1.9 kWh nickel-metal hydride battery in the trunk of the S-Class vehicle. Energy is recovered during braking, and the V8 diesel engine recharges the battery while the vehicle is in motion. According to Prof. Herbert Kohler, Head of the Vehicle Body and Drive Systems Directorate at DaimlerChrysler AG. “Fuel consumption amounts to 34 miles per gallon, or about seven liters per 100 kilometers.”

Since Europe has seen a growth in diesel engines they have seen a reduction in CO2 by almost 25 percent.

Lou Ann Hammond

Lou Ann Hammond is the CEO of Carlist and Driving the Nation. She is the co-host of Real Wheels Washington Post carchat every Friday morning and is the Automotive, energy correspondent for The John Batchelor Show and a Contributor to Automotive Electronics magazine headquartered in Korea. Hammond is a founding member of the Women's World Car of the Year #WWCOTY, and board member of the Women in Automotive.

Leave a Reply

Your email address will not be published.