-The Bus-
The BioTour Bus is a 1989 International Blue Bird school bus is powered by waste vegetable oil, biodiesel, and solar (photovoltaic) panels for electricity.
Over 100 years ago, Rudolph diesel designed the diesel engine to run on a variety of fuels, including vegetable oil. After a century of abundant cheap petroleum, the diesel engine has been modified to run on a the less viscous petrodiesel. In order to run a modern diesel engine on vegetable oil, the viscosity of the vegetable oil must be lowered, or in other words the vegetable oil must be thinned.
There are two ways to lower the viscosity of vegetable oil:
1) Convert vegetable oil into biodiesel by chemical reaction
2) Heat the vegetable oil.
Warming up. The bus starts on biodiesel/petrodiesel from a smaller separate fuel tank. Biodiesel is chemically altered vegetable oil, produced by separating and removing the thick glycerol molecule, through a process called “transesterification,” resulting in a thinner vegetable oil based fuel that can be used in any unmodified diesel engine.
As the bus runs on biodiesel, the engine temperature increases. As the temperature increases, the engine coolant (radiator fluid) absorbs some of the heat, keeping the engine from overheating. When the radiator fluid reaches 170 degrees, the vegetable oil conversion system automatically switches fuel tanks from the biodiesel starter tank 
to the main fuel tank filled with waste vegetable oil (WVO).
Hot Thin Vegetable Oil. The bus utilizes excess heat stored in the radiator fluid to lower the viscosity of the vegetable oil. Just like cooking with vegetable oil in a pan, when the oil gets hot, it gets thin. The first heating occurs as the hot radiator fluid travels from through hoses to plastic tubing inside the vegetable oil tank. The vegetable oil is then drawn from the heated tank through an aluminum fuel link encased in a larger hose containing hot radiator fluid. Just before reaching the injection system and the engine, the vegetable oil passes through two heated cleanable metal screen filters and a large main heat exchanger and another final fuel filter. The main heat exchanger also uses hot radiator fluid that passes on one side of metal plates with the vegetable oil passing on the opposite side.
How hot? The optimal temperature to develop the proper viscosity of vegetable oil is above 160F. It's best to stay above 160F to prevent damaging fuel pumps, injectors or cylinders. T he BioTour Bus has a digital temperature gage displays the fuel temperature on the dashboard.
Purging. Before shutting down the engine, the bus is again switched to biodiesel/petrodiesel, purging the vegetable oil from the engine and fuel lines. If the engine were to cool without purging there would be a risk of vegetable oil coagulating in the engine, causing sticking, potential damage over time, and difficulty restarting.
Filling Up “Give me your grease!”
It's a greasy job filling up on vegetable oil. When we begin to run low, we find a local restaurant, throw on some jumpsuits and suck the grease from dumpsters full of restaurant fryer grease (always asking permission first). This is the same oil used to cook french fries and egg rolls across the country. The best grease is usually from Asian food or vegetarian restaurants.
After getting the okay from the restaurant management, we first test the oil to make sure it is non-hydrogenated (no trans fat), does not contain significant amounts of water, is not overused/burnt, is not too old and decomposing, and is not too dirty and filled with animal fat. For us, it isn't an exact science for doing this on the road. We take a piece of cardboard, dip it into the grease, and take a look. If it looks translucent and golden, if it is not watery, if it doesn’t smell bad, if it doesn’t contain too much animal fat and nasty junk to filter, then it is good fuel.
Once we have identified some good grease, we throw a hose with a coarse filter atached ot the end inside the waste oil dumpster. We switch on a pump until we fill the three 50 gallon metal barrells mounted underneath in the rear of the bus. A valve system allows us to transfer vegetable oil from the dumpster to the storage barrels, between the storage barrels, and from the heated storage barrel (which also cycles radiator fluid with plastic tubes) through filters into main tank.
How far does that take the bus on one fill up? When the three storage barrels and the main vegetable oil fuel tank are full, the bus is holding approximately 200 gallons of fuel. If we were to run these tanks dry, at approximately 8-11 miles per gallon, the bus can go approximately 1600-2000 miles before another fill up.
Solar Electricity – Photovoltaic Array
Mounted on the roof of the bus are four 33 watt photovoltaic panels. (Sunflower Solar). The panels are wired into a charge controller (that measures the electrical current from the panels and the charge of the batteries) which is wired into an electrical breaker box. The breaker box also is wired to battry bank that stores the electricity. In addition, the original truck batteries and alternator are connected to the breaker box which charges the batteries as we drive on vegetable oil. Finally, a 5000 watt inverter is wired into the breaker box, converting 12 volt DC (direct current) electricity to 120 volt AC (alternating current). This provides electricity to power standard electronic devices such as laptop computers, cell phones, cameras, and our onboard audio.
Interior Design
The bus continues to evolve inside, outside, and underneath as each tour progresses. We have recently revamped the living quarters and installed new hardwood flooring made from renewable fast-growing bamboo.
See slideshow above for interior photos.
