Are "clean diesels" ready to join good hybrids as a clean vehicle option?

Patricia Monahan, Senior Vehicles Analyst for UCS here.  I work primarily on diesel issues, and car manufacturers are racing to produce diesel cars that can meet new tailpipe standards coming into full effect in 2009. Honda, Mercedes-Benz, DaimlerChrysler and VW are all planning on selling diesel cars, touting their 20 to 30 percent superior fuel economy over comparable gasoline models. That could be good for consumers who want vehicles that travel further on a gallon of fuel and have lower greenhouse gas emissions.

But it's important to do the right math when it comes to diesel fuel. A gallon of diesel fuel takes more oil to produce and it produces more greenhouse gases than a gallon of reformulated gasoline (with ethanol). This means you should cut the diesel fuel economy by as much as 15% when comparing it to a gasoline model.

We're also not sure how the first generation of so-called "clean diesels" are going to perform on the road. Diesel cars don't have sophisticated pollution monitors-—like gasoline vehicles do— to catch systems when they fail.  So long-term use and emissions impact is still very much up in the air. In all, there are reasons to be both excited, and wary, about the new diesel cars we'll soon be seeing on the market.

Posted by: Patricia

Comments

[altfuels]

By "diesel cars don't have sophisticated pollution monitors," do you mean they aren't required to have On-Board Diagnostics (OBD)? Yikes--that's a pretty whopping loophole. Also, in California (where I live), diesel vehicles don't have to get biennial smog checks because the smog-check procedures don't work properly except on ordinary spark-ignition vehicles (gasoline, ethanol, propane, natural gas). Of course, they don't work on hybrids, either, so hybrids also get a free pass letting them off the smog check treadmill (as contrasted with pure electric vehicles, which aren't smog-checked simply because they have no tailpipe to sniff!).

[Jeff Chase]

Thanks for your good works Patricia. UCS has long claimed that it takes more oil to make diesel, but is that a choice of refinery configuration, or is it fundamental? I have not heard it anywhere else, and I was not convinced by the 2003 (2004?) UCS report.

UCS and others (Becker of Sierra Club) set up a false choice of diesel vs. hybrid. These are complementary technologies. Why not a diesel hybrid? We need both, and biofuels besides. There is no silver bullet for our energy/climate challenge.

My family has two Jetta TDIs that we run on B100 biodiesel available in our area. They are climate-neutral, perform better than hybrids on the highway, and there are no batteries to fail or replace. If we could buy a diesel hybrid we would, but if the market makes us choose, then so be it: hybrids are better for city drivers, but we will keep our diesels.

[Marv Moskwa]

Marv Moskwa here, President of One Merchant Inc.

I represent a company that owns the exclusive global marketing rights to an Internal Combustion Engine that is designed to withstand the high pressures necessary to achieve stoichiometric conditions. That is, enough oxygen to burn all of the fuel in the combustion chamber. It is a pressure ignited engine that burns almost any fuel.

• Has only one cylinder (can be more)
• No engine head
• Can develop 900 horsepower per liter
• 3 to 4 times more efficient
• Pollution free even with diesel fuel
• Pressure ignited which means no ignition system
• 1/16th the size of a standard engine, about 35 parts

The head of DARPA stated, “This engine design is to engine technology as the computer chip was to the computer.” This engine can be used for any application: generating electricity, pumping gases or fuels, and any transportation application. This design is such that for every action there an opposite action and therefore no external torsion. With no unburned fuel exhausted, it is pollution free. Requires no special fuel or alternative fuels. There are so few parts it can be manufactured at about 1/3 the cost of existing engines. Because of its size it can be used for Hybrid vehicles requiring only a starting battery with direct connections to motors on the wheels, hence no drive train transmission Its 80% efficiency is achieved across the entire power demand. That is, the oxygen to fuel ratio is constant throughout the operation of a vehicle to maintain both the efficiency and zero emissions. Being a two stroke engine, the intake air is used to expel the last of the exhaust. This called “total intake – total exhaust.” The design is well patented and there is no competition. This is truly the engine for now.

I would like to see if we can get funding to bring this technology to market, and would appreciate any assistance available.

[Justin]

It takes LESS oil to make a gallon of Diesel than it does to make a gallon of Gasoline.

The only way the converse holds true is if you recrack diesel fuel to make more gasoline...
As imple distillation of crude oil yeilds 35% diesel, 10% gasoline. Only thru recracking and combining thru catalysts has the US refining technology been able to reverse the distilation curves to get 30% gasoline, and 15% diesel from the same volume.

This means in effect to get the extra 20% gasoline you've expended far more energy in the process than your gaining from the conversion. Energy input (cracking, and reformation), and left with less energy per gallon of gasoline.

[Bob Waggoner]

Patricia,

I have heard from several places that a small amount (maybe 10%) biodiesel added to petroleum based diesel fuel cleans up the exhaust. What have you seen on this?

Bob

[perryj43]

I own a 1986 Mercedes Benz 300 SDL, a 6 cylinder diesel car. I currently use b-11 in it and have never experienced any negative impact. In fact, the cleansing properties of Biodiesel are well known and help the mechanical function and manitenance on the car.

By using a higher blend of bio (preferably 75% or greater) you can also get close to or exceed current EPA standardsfortailpipe emissions. Using B 100 would qualify you for this standards in all 50 states. You have to be cautious using b-100 in cold climates as you will have a coagulation problem in the winter without a heated tank.

As for performance---the new generation of diesels do not resemble their predecessors in any way. The MB 320 CDI gets similar or better performance than a similar gas powered car, gets up to 35 MPG highway and MB diesels sre well known to last 300,000 miles or more with basic maintenance.

Europeans are well aware of this advantage as diesels are far more common there due to the cost of fuel. The BMW 535D is one of the most popular sports sedans there and gets similar performance to the gas 5 series---but gets 35MPG highway.

The benefits of diesels are many and that is why car manufacturers are scrambling to market them, except US manufacturers of course, who have no current plans for diesel cars except for suv's and pickups. Obviously, they are waiting for BMW, Honda, Toyota, and Mercedes to succeed first before they enter the market and get rolled under because they were too late.

[Mike Tieman]

www.omnivalves.com ...... say they have the answer.

If you can idle a diesel motor at 200 RPM and then keep it under 1000 rpm while driving around in town, that sounds like a great breakthrough.

And with truckers never turning off their engines, well at 200 rpm that will really decrease emissions? These omnivalves look like they will really make a differance!

[August Uhl]

You mention that it takes more oil to produce a gallon of diesel fuel. But doesn't the diesel produced contain more energy per unit than gas. You say to reduce mpg by 15 % for diesels, but they typically get 30& or more better fuel economy. People are considering diesels vs hybrids not just for the high fuel economy, but also for the potential to burn various blends of biodiesel up to B100 (then how much oil is used?) Then of course there will be the ultimate next step of the diesel hybrid.

[Shannon]

I have been in that situation, my suv consume to much and i think i spend too much on it. then i have discovered http://www.suvandtruckparts.com . I have change some parts and save so much. thanks guys!

By the way, nice site.