History:
Two years ago we began researching bio-fuels as an alternate means of funding the GWV. We have found that it is indeed possible to reduce the fuel costs for fueling the GWV’s vehicle by replacing the old gasoline powered Toyota van for a diesel powered vehicle, which could be run off recycled vegetable oils. Additionally, it is a fact of the internal combustion engine that diesel engines get more miles per gallon than do gasoline engines. And, waste oils are available from various sources either by being paid to haul it off and recycle it, or acquiring it for free, or paying considerably less for it than the cost of petroleum fuel.
Using waste oils, such as vegetable oil as a biofuel, begins with a vehicle that can burn diesel fuel and can be modified to run off vegetable oils. Thus, the GWV’s Biofuels project is based upon a recently acquired 1983 Chevy diesel van, which is twice the size of the Toyota van and also has a V-8 engine, yet it gets the same mileage as the Toyota’s 4-cylinder engine. The Chevy van’s V8 diesel engine and automatic transmission with overdrive are in excellent mechanical condition, and with only 175,000 miles on it. Diesel engines are known to get 400,000 miles before overhaul, so this engine is just barely broken in. The body of the van is cosmetically in excellent condition as well. The Chevy van was acquired with the GWV surplus funding for 2006.
Collection of Waste Oils:
Burning recycled oils and vegetable oils begins with collection. In the winter of 2006 we used most of the surplus funding for the GWV from 2005 to acquire a transfer pump, collection tube, 20-mesh (841 microns) pickup screen, collection vacuum hose, output hose, 30-micron fuel filter and quick cam couplings. We assembled the system in the spring, but we did not have a chance to demonstrate collection until July of that year, when we collected about 75 gallons of waste vegetable oil from tallow bins behind restaurants. Altogether about 220 gallons of waste oil was collected in 2006 with our collection equipment.
Pre-Filter Screens:
In the process of collecting waste oils we found the 20-mesh (841 microns) pickup screen was very effective at blocking the large food particles in a tallow bin without clogging nor slowing down the transfer of oil during collection. In speaking to the sales staff at a diesel equipment and fuel business in Blythe California, that just happened to also sell farm equipment, we were informed of a Y-trap, which is a device that is common to agriculture for removing sediments in well water. Y-traps come with a screen in them for that purpose. In July a 1.25” Y-trap with the off-the-shelf 50-mesh (297 microns) screen in it was donated to us. We found the Y-trap was very effective at blocking smaller food particles in the waste oil stream coming from a tallow bin without clogging nor slowing down the transfer of oil during collection.
We have since purchase another Y-trap with an 80-mesh (177 microns) screen in it as a tertiary filter prior to the disposable cartridge filters. We have found this second Y-trap was very effective at blocking even smaller food particles in the waste oil stream coming from a tallow bin without clogging nor slowing down the transfer of oil during collection. We also use it as a second pre-filter just prior to introducing the waste oils to the disposable cartridge filters. The finest Y-trap screen is 120-mesh (120 microns), which we hope to experiment with because the more particulate we can remove with a non-disposable screen will reduce the particulate load on our disposable cartridge filters, which will extend the life of the first disposable cartridge filter.
Processing:
The next crucial step in using waste oils as a fuel is they must be filtered to acceptable levels before introducing them to the fuel system. We determined that since the fuel filter, on a typical diesel automobile, filters particulate down to 10 microns then we designed our recycling equipment to do just that. It so happens that 10-micron filters are not easy to come by, but 5-micron filters are, so our system filters down to 5 microns, which is just half the particle size, and is thus superior to the auto manufacturer’s specification.
The filtering system we chose was an off-the-shelf water filtration system from a hardware store, which uses disposable cartridge filters. We did choose the high volume 10” filers over the more common low volume under-the-sink variety, because waste oils come heavily loaded with sediments. In February of 2007 we successfully demonstrated this process
Processing Chamber:
In filtering waste oil in disposable cartridge filters we discovered that it is no small task forcing viscous waste oils through filters that were designed to filter water. We found that by heating up the oil to the maximum operating temperature of the water filter housing, which was 100 F, we found the waste oil moved more freely. However, the disposable cartridge filters are also designed to operate with city water at line pressure, which is 100 PSI. We found, the transfer pump could only deliver 30 PSI and it could not deliver the pressure for the duration required for filtering a tank full of oil. We looked into various pump solutions, which all cost well over $200 for which we did not have the funding.
Thus we implanted a method that Jeffrey Brooks learned while he worked as a research technician in the petroleum industry in the 80s. The method is simple hydraulics. By applying air pressure above a container of oil that oil can be forced through a system of pipes and filters at its maximum flow rate determined by the viscosity of the oil and the constricting orifices, and friction. The air pressure needed for this operation can be acquired from a small portable compressor capable of delivering 100 PSI at about 2.5 CFM. Due to generous donations a suitable compressor has been acquired.
Pressure chambers are expensive to build, however, a standard water heater has exactly the specifications that are required for this project. They are also inexpensive, as pressure vessels go. We found upon further investigation that for a variety of reasons water heaters in good condition are commonly discarded by hardware stores and commercial plumbing companies, but often for cosmetics only. Thus we acquired a damaged, but serviceable 30-gallon water heater for no cost. In early March of this year we implemented this design and found it exceptional for the inexpensive processing of waste oils for fuel.
Waste Oil as a Fuel:
The next step in using waste oils as a fuel in diesel engines is to solve three basic problems. Waste oils are commonly more viscous than diesel fuel, and solidify at higher temperatures and do not burn is efficiently. The waste oil fuel users have found that heating waste oil up reduces its viscosity, because viscosity is a function of temperature, and thus one need only increase the temperature of waste oil to about 100 F to approximate the viscosity of diesel fuel. However, we have found that as long as the oil is liquid the fuel system will pump it.
Another problem with waste oils is they commonly solidify at 50 to 32 F. Again heating is the solution to solving the freezing temperature, or what is called “pour point” in the industry. The third problem with using waste oils as a fuel is they do not burn as efficiently as diesel fuel; however, waste oils users have again found that heating the oil up prior to injection into the engine will improve the burn efficiency of waste oils.
There are two common solutions to solving the various viscosity and pour point related problems of recycling waste oils as a fuel. The most common solution is to convert the waste oil to bio-diesel. This process requires heating the oil up to 130 F, then mixing in a combination of sodium hydroxide and methanol. Because the chemical reaction requires 20% of the reactant to be alcohol by volume to waste oil, it is thus a costly solution, in addition to be a dangerous one because of using caustic sodium hydroxide. The equipment required to implement this operation is typically quite large and takes days to accomplish due to requiring days for the resultants of the reaction to separate through settlement.
The second most common solution to solving the various viscosity and pour point related problems of recycling waste oils as a fuel is to install a second fuel system in the vehicle and start up with diesel fuel and run the engine on diesel fuel until it comes up to temperature then switch over to the second fuel system which is heated with waste engine heat through conducting the radiator fluid through heat exchangers that are installed throughout the secondary fuel system. One then must shut down the system with diesel fuel or otherwise the injector pump will have solid waste oil in it on a cold morning.
Electrically Pre-heated Fuel System:
The GWV’s design strategy is going to be different. Instead of installing a second fuel tank, which is the more accepted way of converting a vehicle to run on vegetable oil, We are planning on wrapping nichrome wire along the full length of the fuel system and fuel tank, along with a pipe-on-pipe 1/2” copper tube that directs radiator water the full length of the fuel system, including a coil around the bottom of the fuel tank. Then the entire fuel system will be insulated. We are presently collecting discarded ½” copper tubing for that purpose.
The mechanical solution of a second tank, second fuel line, filter and the valves needed to make a 2-tank system work is a lot more complicated and expensive than simply wrapping resistance wire around all of the crucial factory installed parts and simply warming up the whole system with electricity. A role of glass insulated nichrome resistance wire will probably cost about $10, whereas a typical 2-tank system runs about $1,000 to $2,000.
How this system will work is, when the ambient temperature is below the cloud point of whatever recycled oil happens to be in the fuel tank, then the engine and fuel system will be pre-heat with the factory installed block heaters and the additional electrical heating system that will be installed. Once the engine and fuel system are up to temperature, then the engine can be safely started. When the engine is running at operating temperature, then the electrical heating system will be switch off.
For electricity standard household AC line current can be used when it is available, otherwise a small generator could be brought along for that purpose. A 1000-watt generator runs about $350, and we have determined 1000 watts should be sufficient to heat the entire system up 50 degrees above ambient temperatures. Since the GWV is mobile because we do not have the funding for a building we will require a generator for this solution.
In addition to heating the fuel system so that the more viscous recycled oils (that often also solidify at 50 F) will run unimpeded through the fuel system, there is also a need to process recycled oils on-the-go so that waste oil can be turned into fuel. As noted above this system is based upon pushing waste oils through a set of reverse osmosis filters at 100 PSI. This is accomplished by transferring the oil into a pressure vessel that is pressurized to 100 PSI via an air-compressor. Thus the generator will be needed to operate the compressor as well.
A Temporary Solution:
Since the GWV is not well funded we have determined that purchasing a $400 generator could be avoided if we avoid ambient conditions below 32 F (0C), which would necessitate pre-heating the fuel system. However, we would still need 110 Volts AC at about 1000 to 1500 watts to run the 1 HP compressor that drives the waste oil recycling system. This power could be delivered through a sufficiently large capacity inverter that is powered by the 1200 watts delivered by the alternator and momentarily supplemented by the three batteries we have on board.
Last weekend I went to Quartzite in search of a reasonably priced inverter, because Quartzite not only has large swap-meets, but it is a place where many people who live in RVs congregate and they use high capacity generators and inverters. There I found a business that specializes in mobile power systems and solar energy. They had reconditioned 1750-watt inverters for only $135.
An Oil Proof Equipment Bin:
One of the useful items in this system will be a large utility bin to store the 4 hoses, the pump, the two y-traps and the filtering manifold. These items are likely to get pretty messy with oils, so a oil-proof bin that was stored outside of the van would be most useful. A week ago I found a large ice chest in refuse-pile. It looked perfect for the utility bin, so I took it and cleaned it up.
Inexpensive Solar Drum Heater:
While taking a walk 2 month ago I found a contractor bag, which is a large clear plastic garbage bag made of 2-mil plastic. It fits over a drum perfectly and makes an excellent solar drum heater.
