When bio diesel is mixed with regular fossil fuel diesel the result is given as a B number, therefore a five per cent mixture is called B5 and a 20 per cent mixture is called B20. Bio diesel in a 100 per cent mixture can have as much as an eight per cent reduction in heat value. Therefore the common mixture of B20 would have a 2.5 per cent reduction in heat value. Here is one problem: if a diesel engine were 100 per cent efficient then at a B20 mixture you could be down only 2.5 per cent in power. But a diesel engine is, at best, 35 per cent efficient with about 65 per cent of the heat energy of the fuel leaving the engine as waste heat from the exhaust and cooling system. That means a B20 mix would cause a reduction of power closer to seven or eight per cent. While its hard to say if this could cause a worn engine to fail a pump test, I would want to conduct my yearly pump test with 100 per cent No. 2 diesel (you do a yearly pump test right?). Remember No. 1 diesel is the lighter, less powerful winter fuel.
|Students at Lakeland College crush canola.
PHOTOS COURTESY DON HENRY
As many of you haven been following the progress of the ultra low sulfur levels in diesel fuel you will be happy to know that bio diesel contains no sulfur, unless the bio diesel is made from oil that was used to deep fry onion rings.
In fact, bio diesel has a lubrication property at the B2 level that more than compensates for the loss of lubrication of the fuel injectors that we, in the past, got from the higher sulfur fuel.
Another drawback to bio diesel is that it does biodegrade over time. This could be a problem for some rural department or departments that have units that have been put into reserve or second-line service. Fuel will begin to degrade in the fuel tanks of both the engine and the fuel storage.
Bio diesel is a very good cleaner and solvent; any contamination that has settled out on the bottom of the fuel tanks of older units will be put into suspension. That’s a nice way to say that if you’re lucky, the fuel filters will become plugged. That’s also why most bio diesel will not be put into the refinery pipelines but will be tank mixed just before delivery.
|Dynamotor testing of bio diesel fuels by Rob Baron at Lakeland College.
There is a standard to keep people from producing sub-standard fuels; its the ASTM 6751 fuel test. It costs about $1,500 to conduct a full test at a certified lab but don’t even think about getting fuel that does not meet this test. Demand proof of the test before you buy.
The process of taking oils and fats and refining them to bio diesel is not really complicated but needs to be done and done correctly. No matter what you may have heard or seen on a television newscast you can not pour used French fry oil directly into your diesel fuel tank and expect it to work for any length of time. My college here in Vermilion has been making bio diesel for many years.
| Bio diesel lab at Lakeland College.
In conclusion, is bio diesel for the fire service? I would have to say no; the risks do not outweigh the benefits for a service that uses such a small amount of fuel. Let’s burn it in our garbage trucks, city snow removal and bus fleet but at this time I cannot in good conscience recommend it for the fire service. If you are forced to use a bio diesel mix use only a B5 and be prepared for the replacement of fuel filters on older in service units.
BIO DIESEL PRIMER
Don Henry teaches in the Automotive Service Technician and Heavy Equipment Technician programs at Lakeland College in Vermilion, Alta., where he has been a faculty member for more than 17 years. He has co-developed and delivers Canada’s only post-secondary level fire-apparatus maintenance program and has completed a textbook on fire apparatus.