>Keith, how does biodiesel compare to CNG, from an emissions standpoint? >Has anyone projected, say, the 10-year emissions ROI (return on >investment) in converting a diesel to CNG, and compared that to the ROI >for running biodiesel unmodified? > >Thanks >Dan
Dan, you'll find a lot of info and resources if you prowl around the Journey to Forever Biofuels section a bit, and in the list archives, both reffed at the bottom of each message. These below might help - biodiesel emissions are easy to find. CNG is not completely safe and environment-friendly. Its GG emissions are the same as or worse than other fossil fuels. A Harvard study found it may generate more ultrafine particles than petro-diesel, of less than 0.1 micron, which are more harmful than fine particles. The study also found that it increases emissions, of C02, and of methane, which "is approximately 20 times more potent as a greenhouse gas than CO2". Harvard press release: http://www.hsph.harvard.edu/press/releases/press1102000.html Complete copy of the report (PDF, 205 KB): http://www.hsph.harvard.edu/Organizations/hcra/diesel/diesel.pdf http://www.dieselforum.org/news/apr_19_2002.html Diesel Technology Forum -- News Releases CA Study Defies Conventional Thinking About "Clean" Fuels: Diesel Tops Natural Gas As Cleaner http://www.arb.ca.gov/newsrel/nr041802.htm News Release: 2002-04-18 -- Diesel and CNG Bus Emissions http://www.greendieseltechnology.com/news24.html International¨ Green Diesel Technologyª Vehicles Clean Diesels Less A Cancer Threat Than CNG: More Proof. ( by Jack Peckham, Diesel Fuel News, September 11, 2000) http://www.greendieseltechnology.com/news72.html International¨ Green Diesel Technologyª Vehicles Toxicologist 'Appalled' At Ignoring CNG Risk Diesel Fuel News, April 16, 2001 By: Jack Peckham http://www.washtimes.com/metro/20020424-70254664.htm Study gives edge to clean-diesel buses By Brian DeBose THE WASHINGTON TIMES April 24, 2002 http://www.teriin.org/features/art93.htm A hasty decision, clean diesel is a better bet A hasty decision, clean diesel is a better bet R K Pachauri The Hindustan Times, 8 April 2001 [Dead link] CNG and Clean Diesel Fueled Vehicles An Economic Comparison The South Coast Air Quality Management District staff has proposed banning new diesel fueled vehicles and replacing them with vehicles using compressed natural gas (CNG) or other alternative fueled vehicles. Low sulfur diesel fuel, coupled with after-treatment ("Clean Diesel"), provides comparable particulate emissions to compressed natural gas (CNG) vehicles. However, clean diesel and after-treatment can achieve this beneficial emission performance much more cost-effectively than CNG. Lower Operating and Maintenance Costs for Clean Diesel Compared With CNG * The US Government Accounting Office recently reported that operating and maintenance costs - in addition to large up-front investments - are higher for CNG buses. Despite "great strides by engine manufacturers," the report states, "CNG buses' engine and fuel system[s] will likely remain less reliable than these components in diesel buses for the foreseeable future." Clean Diesel More Cost-Effective than CNG in Reducing Air Pollution Significantly higher expenses for CNG vehicles and infrastructure were also found in a February 2000 study by Sierra Research. This study determined that the cost-effectiveness ratio (i.e., the cost per ton of emissions removed) was 4 to 11 times lower for clean diesel as compared to CNG. Even the South Coast Air Quality Management District's own assessment acknowledges higher costs for the use of CNG fleets. * In a study commissioned by the California Transit Association, high costs to purchase and operate CNG buses were also reported: a. Replacing all diesel buses with CNG would cost $627.5 million more than fleet replacement with clean diesel; b. Infrastructure costs are estimated at about $4 million for fueling and $500,000 for maintenance modifications for every 200 CNG vehicles purchased; c. Prorated, infrastructure costs add approximately $22,500 to the purchase price of every CNG bus; d. Fleet replacement with clean diesel would allow transit operators statewide to purchase a total of 2,324 more transit buses over 11 years than if CNG replacement were required. * According to a recent Los Angeles County MTA report on fuel strategies, the cost to operate relatively new CNG buses was approximately 40% higher than the cost to operate 1988 diesel buses. Even the more optimistic projections for future operating cost comparisons between new diesel and new CNG buses still showed a 29% higher cost per mile to operate CNG buses. Clean Diesel Vehicles Found to be More Reliable * According to the same Los Angeles County MTA report on fuel strategies, the number of engine and fuel system road calls on the CNG buses was 40% higher than for the older diesel buses. Real World Impact of CNG Conversion * Slower turnover of fleet vehicles; * Widespread use of non-CA vehicles in the state; * Impact on employers and wages of fleet personnel - including migration of vehicles (drivers and maintenance workers out of state) and higher costs, with possible ramifications on wages for those remaining in-state. Copies of this economic white paper in its entirety are available upon request. South Coast Clean Air Partnership á 528 Arizona Ave., #209 á Santa Monica, CA 90401 á (310) 576-1341 á Fax: (310) 576-0968 (5/8/00*) e-mail: [EMAIL PROTECTED] © 2000 Western States Petroleum Association - All Rights Reserved ------------------------ Yahoo! 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