Waste Vegetable Oil or (WVO)
There is a lot of information about vegetable oil and how it is made, its use from the time it is processed to the time it is considered as a waste product. Usually the point it becomes a waste product is when it leaves the fryer. But is that the end of its serviceable life some say no there is an increasing interest to use this waste oil as fuel, biodiesel and biofuel.
How is waste vegetable oil or (WVO) made into fuel? First of all, this needs to be done at room temperature at about 70 degrees Farenheit – add some sodium hydroxide (lye), methanol (heet), and vegetable oil. Adding these three ingredients together in correct quantities and mix them until they are completely blended. At this point, you let the mixture settle and it will separate into layers where the bottom layer will be the glycerin and the top layer the biodiesel.
The process mentioned above was with pure oil, but what about the oil and grease from fryers and grills, what should be done when you have old oil or isn’t very clean? Well at the start of the process you need to filter the oil there are many ways to do this Bag filters are the easiest, cheapest and slowest processing tool that you have other than strait settling to process WVO . Oil will run through a 100 micron filter bag at 2-5 gallons per minute however, if the oil is dirty or just creamy the flow rate will deteriorate rapidly . Pre-heating oil helps as does larger/longer filter bags. You can use filter bags after settling, but the best advise is to use the centrifuge to get more precision process.
Cartridge WVO filters, tee strainers ECT, should be used only with heated oil or heating of the filter. Waxy precipitates in cool oil quickly clog cartridge filters and no amount of pressure will resolve this issue. Reserve cartridge filters for final polishing/filtering at transfer into the vehicle or very low volume/emergency use. Any mechanical cartridge filter will require an amount of pressure to work, finding an appropriate pump, plumbing and pressure relief system can be difficult and large spills are possible.
Another way is to use what I call “Forced Settling” WVO centrifuges can clean WVO to sub micron levels as well as removing heavier liquid contaminants such as water. If you are looking at having to deal with hundreds of gallons or more, a centrifuge is your only solution.
You probably don’t stop to think about it, but all fuels have a shelf life that depends on their chemical composition and storage conditions. The chemical stability of biodiesel depends on the oil from which it was derived. Biodiesel from oils that naturally contain the antioxidant tocopherol or vitamin E (e.g., rapeseed oil) remain usable longer than biodiesel from other types of vegetable oils. Stability is noticeably diminished after 10 days and the fuel may be unusable after 2 months. Temperature also affects fuel stability in that excessive temperatures may denature the fuel.
