It is true that the BioBus’ current engine runs on ecological fuel—fuel that harmless to the planet. It is also true that the bus can attain that fuel—vegetable oil—for free from any restaurant or fast food place. Don’t forget, though, that any oil that is donated to the BioBus is used, dirty oil! All of that dirty oil can’t get poured into the BioBus’ engine straightaway!
No, that oil contains copious amounts of food gunk, bacteria, water, and glycerin (a thick, colorless, and sweet-tasting liquid found in most beauty products) that would ruin any engine. Before using it, Dr. Ben has to separate the refuse from the vegetable oil.
Luckily, the BioBus owner has thought up an answer to this dilemma: a filter system. Said system, when I tried to research it, was a total mystery to me! In fact, Dr. Ben had to send me a diagram of the BioBus’ engine, only for me to stare at it blankly in confusion. Thusly, I asked Dr. Ben to explain to me just how the four-step filtration system works, and here’s how he put it:
“Step 1: When we suck grease out of any dumpster behind a restaurant, there is a strainer that filters large chunks (over 150 micrometers) of matter from the oil before it ever enters the bus.
Step 2: Between the dirty tank and the clean tank, there is a PRIMARY VEG FILTER that separates matter 30 micrometers or more—a marine-grade fuel filter.
Step 3: Between the clean tank and the valve assembly in the engine, the SECONDARY VEG FILTER separates water from the fuel, as well as anything 10 micrometers or larger—another marine-grade fuel filter
Step 4: There is a 10 micrometer water separating diesel fuel filter that is a normal part of the engine, which both the vegetable oil and the regular diesel fuel passes through—called the SECONDARY DIESEL FILTER.
Filters 1, 2, & 3 are ones that we put in, filter 4 is a regular part of the engine.”
His explanation, which was much easier to understand than the diagram was, gave me the impression that each filter is like different level of filtration. The first level is easiest to get through, because the stuff that gets stuck in it is the largest. Then, as the filters progress, more and more refuse is limited by the smaller filters. The vegetable oil at the end of the last filter is then guaranteed to be perfectly suitable for the engine!