(merging info from WVO, minor tweaks to the text to integrate)
(removed category:technology (depricated category from wikigreen))
Line 48: Line 48:
*[[Wikipedia:Waste vegetable oil]]
*[[Wikipedia:Waste vegetable oil]]


[[Category: Technology]]
[[Category:Biofuel]]
[[Category:Biofuel]]

Revision as of 06:06, 1 September 2008

Waste vegetable oil (WVO), is used cooking oil that is often discarded by restaurants and businesses that deep-fry a lot of food. It can be used to fuel diesel vehicles and for a variety of other purposes.

SVO is more expensive than W fuel, and the ethics of burning food for transportation must be questioned. But after it's been used to cook food, waste vegetable oil can still be used as fuel! Restaurants typically pay "recycling" companies to take away their waste oil, which is then used in animal food or cosmetics. This is not closed-end recycling, and is non-sustainable.

While not at first obvious, using WVO as a fuel is actually closed-end recycling, since the CO2 that is emitted is sucked up by the next year's oil crops.

WVO must be "cleaned" before using. This can be as simple as days to weeks of gravity settling, or it might be pumped through filters. Using cleanable, reusable filters eliminate the waste of replaceable filters.

Because WVO is gleaned from a wide variety of sources, it's energy content and pollution is impossible to characterize accurately, but it should be similar to SVO.

In vehicles

Diesel vehicles can be converted to run on vegetable oil. However, vegetable oil is thicker than diesel fuel and may not burn efficiently in the engine, leaving burnt residue in the engine that will eventually break it. Vegetable oil is thinner and less viscous when it is hot. In order for vegetable oil to burn efficiently, it must be hot when it enters the fuel injectors. Conversions employ various strategies to ensure this.

A drawback of running a vehicle on vegetable oil is that they may have trouble in cold weather. Even regular diesel vehicles have trouble starting when it is very cold, and vegetable oil is thicker than diesel. Vehicles employ various methods to heat up the oil, and vehicles used in cold climates can add extra heaters. One type of heater is called a "hot fox" which can be installed for example in the trunk; it heats up the oil before it gets to the front of the vehicle, where there is another heater that finishes the job before the fuel reaches the fuel injectors.

Another option is to turn waste vegetable oil into biodiesel. It must still be filtered for particles, but there is no need to convert the vehicle or add another tank if you are using biodiesel: you can just put it in your regular tank and drive. Biodiesel works like regular diesel. There are directions for making biodiesel here.

Filtration

Particles (e.g. of food that was cooked in the oil) and water in the WVO will damage the engine—particles will create buildup in the engine, and water in the fuel can destroy the engine. Repairs to the engine can cost more than the price of the vehicle. Therefore WVO must be filtered and water must be removed before it can be used as fuel. Some people allow the oil to stand (e.g. in barrels) for about a week to allow water to separate from the oil; it can then be drained off through a spout at the bottom of the barrel. Standing also allows particles to separate out from the oil and drift to the bottom of the barrel; this is a first step in filtration. One method is to install two drains on the barrel: one that drains from the bottom, to drain off water and particles, and another higher up, to drain off (hopefully) clean oil. That way, clean oil can be drained off without disturbing it and mixing the contaminants back in.

The barrels must be left alone while the oil is standing—jostling will mix some of the water and particles back into the oil.

After standing, the oil is filtered, first through a large filter and then through filters with progressively smaller holes in order to get out small particles that would collect in the engine and damage it. The oil can be filtered multiple times.

The oil can also be heated to boil off water. One way to test whether standing has gotten rid of the water is to heat up frying pan on the stove until it is very hot and a drop of water skitters in the pan, then take a cup of the oil after it has been stood and pour it into the pan—if it boils and spurts and makes a fuss, there is still water in it.

So-called "straight vegetable oil" (SVO), store-bought oil, can be used instead of WVO at greater expense but with less filtration and purification hassle.

Acquisition

Some restaurants have to pay to have their grease hauled off, and they may be willing to let you take it away for them. Sometimes you'll be required to take all or nothing. Some restaurants are willing to put used oil back into the containers it came in, which makes it convenient for hauling away. Oil is discarded into barrels or large, rectangular grease traps usually located behind the restaurant, often near the dumpsters or the back door of the kitchen.

See also: Negotiating For Waste Vegetable Oil

Determining whether oil is good to use

Grease from restaurants that fry red meat is not good to use in a vehicle—it is thick and will form solids, reducing flow and creating clogging. Asian and Mexican restaurants and vegetarian restaurants are better sources because they're frequently frying vegetable products. Chicken is also ok. A way to test whether oil is of good quality is to dip a piece of cardboard into it and watch it drip off—is it smooth and runny? Or is it thick and clumpy?

It is important to check to see whether water has gotten into the oil—if the containers were not closed, water may have gotten in.

Rancid oil cannot be used for fuel.

Portions (cc) S.E.E.D.S. under Creative Commons

See Also

Links

Cookies help us deliver our services. By using our services, you agree to our use of cookies.