Here at Franciscan Lines / San Francisco Sightseeing, when we are asked whether we provide "green" transportation, the first question that comes up is "Do we use bio-diesel?". While bio-diesel has become a very chic buzz word in recent years, few actually understand that there are numerous ways to drive these big buses around and still be mindful of the environmental impacts without using bio-diesel.
In looking forward to the changes in California’s emissions standards, our company chose the "eco-friendly" path of treating the exhaust of the diesel engine as opposed to using a new fuel (bio-diesel) that, in itself, creates problems.
While bio-diesel may help reduce our dependence on foreign oil, it is difficult, if not impossible in some cases, to verify whether or not bio-diesel is actually being utilized by an operator that claims to use a bio fuel. Bio-diesel is literally a blend of a bio-renewable resource AND diesel fuel in a ratio of bio to fuel; this ratio can be anywhere from 5% bio all the way to 100% bio.
Typically, due to the restrictions put in place by the engine manufacturers in order to protect the integrity of their engine warranties, the most popular blend ratio of the renewable resource (corn or soy oil) is 5% bio blended with 95% volume of regular diesel fuel (currently the California standard ULSD- Ultra Low Sulfur Diesel). This is referred to as a "B5" bio-diesel mix. All things considered, a B5 bio-diesel blend is fairly insignificant, but fits with the craze of being "green" by claiming to use bio-diesel. With our location having quite a few new buses, we would most likely tend to lean toward the B5 in order to satisfy our engine warranties.
While a large company such as ours uses a bulk fuel purchasing program, with a 12,000 gallon fuel storage tank on site, our fuel must be compatible with all of our diesel vehicles and having a mix of newer and older model coaches, a universal fuel is a must.
In the production of bio-diesel, it has been found that the side effects of producing this new fuel include increased food prices, food shortages on the internationally market (due to the diversion on the marketplace of food crops to fuel), as well as increased water consumption due to the amount of water resources required to grow the bio material (corn or soy beans). Going "green" certainly does have its costs!
In addition to these side effects, the exhaust output of a bio-diesel powered engine creates an increased level of NOx (oxides of nitrogen), which is one of the key components in smog. In addition to NOx, a standard diesel engine emits levels of particulate matter (black soot- unburned diesel fuel) referred to as PM. While a high level of bio-diesel reduces PM levels, a 5% blend has a minimal effect.
Here at Franciscan Lines / San Francisco Sightseeing, in looking forward to the changes in California’s emissions standards, our company chose the 'eco-friendly' path of treating the exhaust of the diesel engine as opposed to using a new fuel that, in itself, creates problems. The program we started in early 2008, in conjunction with the Bay Area Air Quality Management District (BAAQMD) involves the installation of a component called a diesel particulate filter (DPF).
At the time we wrote this information, we have completed installation on 17 of our coaches under the first phase of the program. These filters (manufactured by Cleaire Industries, in Hayward, CA) treat the diesel exhaust gases and reduce the fine particulate matter (the soot emitted by diesel engines — referred to as PM) by 85%; the filters also reduce NOx by 25%. This system produces an overall reduction in diesel emissions that is only surpassed by the new engine emission standards that apply to all diesel engines manufactured after January of 2007.
Overall, the DPF system surpasses any "green" benefit gained by using bio-diesel, even at a high blend ratio, in that bio-diesel use INCREASES NOx emissions, which, in turn, creates smog; and while there are minimal reductions in PM, they are nowhere near the 85% reduction in PM resulting from the installation of the DPF’s.
As in life, nothing is free. As good as the DPF program is in reducing emissions, there are side effects to it as well. The drop in fuel economy for a DPF equipped engine can be in the area of 3-5%. The trade off with the DPF program is a somewhat larger carbon footprint for a much lower volume of harmful emissions being put into the atmosphere.
All things considered, we believe that this path of "treating the exhaust" that we have chosen far exceeds any benefit of using a bio-diesel fuel. It is the technology that has been integrated into the 2007 engines, and will continue to be utilized with the 2010 engine technology. Looking at the end results, it is overall a much "greener" engine technology than the bio-diesel marketing tag line.