Petroleum fueled diesel engines emit SOX, NOX, and particularly nasty particulates. Among the worst are small particles called "PM-2" (size measured in testing equipment using "Particulate Matter, Method 2", meaning particles with average diameter of 2 micrometers or less). These diesel-emitted particles are hazardous because, once breathed in, the human lung is unable to eject the small particles from diesel engines as efficiently (cough cough) as it would eject larger particles that originate from other natural and manmade sources.
But it is not just the particles per se that are of concern: Oil-based diesel results in poly-aromatic hydrocarbons (PAH's) condensing on the co-emitted particles, exposing the lung to irritating and potentially carcinogenic effects of the PAH's.
Biodiesel fuel has been reported to have a lower particulate emitting characteristic than petroleum diesel. No information was found on the difference between particulate emissions from pure veggy burning cars to refined biodiesel burning ones. Jury is out on that one: comments appreciated.
One might also expect less PAH's (of the hazardous type emitted from petro-based diesels) to be present and condensing on biodiesel emitted particles. Blends of petro and bio-diesels will of course be "in between" on the PAH spectrum.
A critical positive advantage of all biodiesel is that it has has very low, or virtually no sulfur. Getting the sulfur out of petroleum is feasible, but expensive. Blending biodiesel fuel with regular diesel offers a "cut" in average sulfur acid gas emissions per mile; but, it's only part way there. Burning neat biodiesel is always going be better with SOX. This is an important positive because SOX results in sulfuric acid aerosols that acidify natural waterways, corrode buildings and things, and cause lung disease. Until all petroleum diesel has sulfur removed, biodiesel has a health and environmental leg up. Its a net positive and will remain so for years.
Just as with petroleum diesel engines, and with gasoline fueled engines, pure biodiesel fueled engines now on the road will emit NOX, perhaps even more NOX than the other types, depending on the engine design. NOX is an acid forming gas bad for the environment and human health. Fortunately, this drawback will disappear in biodiesel-capable engines made in 2007 and after (see press release that follows).
To tackle the diesel engine's NOX emissions, regardless of fuel, engine designs needed to be modified, altering such things as compression temperature, fuel injection rates, and exhaust gas recycle rates. New, low NOX forming diesel engines are on the road now, testing such design changes. Besides reducing NOX, the improved engines are more fuel efficient and have reduced releases of stinky diesel exhaust smells. See the press release excerpt at the end of this post for details on how the redesigns and testing are planned.
Diesel emitted particulates can be a serious issue for any kind of diesel fuel. The agreed to solution by US diesel engine makers is to filter the particulate matter out with on-board equipment. As stated above, this equipment has been designed and is now being field tested for the deadline date of 2007 in the US. Because engine makers go after world markets, perhaps we'll be lucky to see an impact that benefits all biodiesel and petroleum diesel users.
In Europe, diesel cars are a big part of the fleet (up to half in many countries), they're everywhere, and very dirty indeed. Because diesel engines can last far longer than internal combustion engines (good for the environment from life cycle perspective), lowering the emissions in Europe is a real challenge, assuming you don't want to throw away those vehicles or replace the engines immediately. The sensible fix for European diesel cars is to retrofit the existing engines that have plenty of design life left with pollution controls and create incentives that get cleaner and more efficient ones on the market as soon as possible. There seems to be progress along these lines.
TreeHugger has learned that in Germany, a diesel particle filter...some of the smaller engines claim to meet the particle standards without filter...will be needed soon; and, if a new car design is offered without the option of particle filter, the car magazines give negative reviews. There is also, in Germany, serious discussion of a tax-credits for retrofitting existing cars with particle filters and a tax-break for new cars that come with one.
Engine designs and materials vary widely depending on country of sale; and so it is important to keep in mind that not all diesel engines are certified by the manufacturer to use biodiesel. There is a risk that biodiesel use in engines not so certified could plug injection ports or damage rubber hoses, and gaskets. If TreeHuggers promote biodiesel and it's adopted, uncritically, by people hoping to do the "right thing", then indvertantly causing damage, guess who will be blamed in the mainstream media? TreeHuggers of course.
TreeHugger has also learned that it may be illegal in Britain to put pure homemade biodiesel in existing cars because it is considered tax evasion and they have patrols scanning exhausts for traces of emitted the vegetable oil particles. Comments appreciated from anyone who knows more about this.
In the US, diesel powered cars are only a trivial part of the domestic fleet; and, therefore, anything biodiesel powered you might do is going to have a trivial impact on overall public health in the next few years. Trucks, buses and trains are logically the first targets for engine and fuel improvements. Once they have better engines, or at least retrofitted particle filters, biodiesel fuel can help lower emissions further.
Biodiesel shares a vulnerability with ethanol, in that it relies on energy intensive agriculture that, ironically, is based largely on diesel engines. Depending on the feedstock biodiesel source, the net energy balance for biodiesel could be negative, neutral, or positive. Caution: biodiesel burning engines outperform ICE engines in overall fuel efficiency. They have to be compared based on an analysis that takes that efficiency advantage and the lowered sulfur emissions into account. This is something that may or may not play well as a media sound byte. Take all comparisons, therefore, with a grain of salt until you learn how the efficiency differences were normalized.
Press Release from Diesel Engine Manufacturers follows.
Diesel Engine Manufacturers Will Begin Landmark Emissions Testing Program to Help
Assure Cleaner Air
June 6, 2005 12:00am
CHICAGO--(BUSINESS WIRE)--June 3, 2005--The Engine Manufacturers Association (EMA) today announced a landmark emissions testing program for heavy-duty diesel vehicles that will help assure lower emissions and cleaner air throughout the United States.
EMA's members, together with the U. S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB), will implement an in-use testing program to provide information on how systems installed on the nation's new trucks and buses perform to control emissions.
"The voluntary agreement to develop, conduct, and fund a new in-use testing program demonstrates the continued strong commitment of diesel engine manufacturers to produce heavy-duty engine systems that reduce emissions and improve air quality in our cities and states," stated Jed Mandel, EMA President. "Together with the cleaner engines scheduled for introduction with the 2007 model year, the in-use testing program announced today will help assure that high emissions levels from diesel trucks and buses are truly a thing of the past. Clean diesel technology is here today and will provide real in-use emissions reductions."
Beginning with a pilot program for model year 2005 and 2006 trucks and buses, heavy-duty engine manufacturers will measure exhaust emissions on selected vehicles to determine how the emissions control system is working and to assure that emissions meet all applicable EPA and California standards.
The collected data will verify whether the emissions levels required when the engine is new remain at those levels for the useful life of the engine. The agreement also includes a jointly funded research program to simultaneously develop the procedures needed for accurate in-use emission measurements. Based on the results of the pilot program, the in-use testing program will become a regulatory requirement for model year 2007 and later engines and vehicles.
"This landmark agreement among EMA, EPA, and CARB to finalize an in-use testing program is the result of cooperation with focused attention on the end result of cleaner air," continued Mandel. "Each of the parties worked long and hard to address the technical issues and to develop an effective solution. We are pleased with the end result and the fact that EMA and its members were able to work with both agencies to develop and implement a practical and workable program."
The in-use testing program announced today was developed as a means to demonstrate compliance to EPA's and CARB's Not-To-Exceed (NTE) emissions requirements. The NTE standards impose strict controls over heavy-duty engines by establishing emissions limits throughout the range of an engine's operating conditions, rather than the traditional set of discrete compliance points. By measuring emissions under real-world conditions, the in-use testing program will provide a means for manufacturers to verify compliance with NTE standards.
In summing up the importance of today's announcement, Mandel concluded, "The agreement on an in-use testing program with EPA and CARB is truly a milestone for heavy-duty diesel engine manufacturers and cleaner air because it moves emissions testing from the laboratory into real-world operating conditions. The program not only will verify that the near-zero emissions levels measured under laboratory certification conditions are being achieved on our streets and highways, but also will provide valuable feedback to engine manufacturers on any need to further improve and enhance emissions control systems. The clear winners here are our communities and our citizens who will benefit from cleaner air as a result of this program."
The Engine Manufacturers Association is a trade association representing worldwide manufacturers of internal combustion engines used in applications such as trucks and buses, farm and construction equipment, locomotives, marine vessels, and lawn, garden and utility equipment. EMA works with government and industry stakeholders to help the nation achieve its goals of cleaner fuels, more efficient engines and cleaner air.
CONTACT: The Engine Manufacturers Association Joe Suchecki, 312-827-8734 KEYWORD: ILLINOISINDUSTRY KEYWORD: AUTOMOTIVE ENVIRONMENTSOURCE: The Engine Manufacturers Association
Business Wire -- 06/06/05
Copyright ©2005 Business Wire
by: Mike and John.
Tip-o-the hat to "Deep-Biodiesel" for tutoring us in European ways.