Introduction To Waste Vegetable Oil (WVO)

Running a diesel vehicle on vegetable oil is a great idea from both an environmental and financial perspective, but there's an even greener option available if instead of using shop-bought, fresh, virgin oil, you use Waste Vegetable Oil (WVO) to fuel your engine.

What is WVO?

Waste Vegetable Oil (WVO) is second hand, already used veg oil that is no longer suitable for its original purpose. It's a waste product produced within the catering industry. Wherever deep frying takes place on a commercial basis, you're likely to find used veg oil, such as pubs, restaurants, hotels, chip shops, etc. Once they've cooked with it a few times, the oil becomes dirty and tainted, so fresh oil is required. The old oil then becomes a waste product - a nuisance.

Waste Veg Oil, from this...

to this...

through proper filtering

Waste Product

From my personal experience, I've found that larger organisations (such as Hotel chains, Brewery Owned Pubs, etc) already have an infrastructure in place to deal with their WVO, so obtaining used veg oil from these places is difficult. However, smaller establishments don't have such infrastructures (independent pubs, local restaurants, family run hotels, etc). For these people WVO is usually something they are keen to get rid of.

Obtaining WVO

In days of old, such companies would have paid people to take away their WVO. With the advent of Biodiesel, etc, it's become more common for WVO to be given away. In fact more commonly it seems that you now have to buy WVO, which is great news for the businesses and bad news for the thrifty green motorist.

Personally I have some suppliers who gladly give me their WVO just to get it out of the way, but for the most part I have to pay for it. The rate varies according to the haggling skills of those involved but again, from my experience, the value is usually somewhere between 20% and 40% of the current price of shop bought virgin oil. The reason it's cheaper than pure oil is because you CANNOT just pour it straight into the tank of your vehicle - it needs cleaning first. Plus it's not all usuable fuel...

Problems With WVO

The problem with WVO is that it's a dirty product. It's full of food particles, fats, water and all manner of nasties. These must be removed from the WVO before it's clean enough to use in your vehicle and the cleaning process is time-consuming. Depending on the quality of the used oil, you can often find that up to 50% of the waste oil collected is unusable as a fuel...

Cleaning / Filtering WVO

Waste Veg Oil (WVO) must be cleaned before it's used (click here for a little story that you may find interesting). It is cleaned by filtering out all of the impurities that are within the oil. Typically there are two main methods:

1. Mechanical Filtration : This tends to involve a number of pumps, storage tanks and filters. Oil is driven through varying filters usually to a finished level of 5 microns.
2. Settling : Here WVO is roughly filtered (usually to around 100 microns) before being left to settle for a few weeks. As the oil settles, the heavy fats and water fall to the bottom of the tank and some light impurities rise to the surface. The cleaner oil is then usually filtered through socks to 5 microns.

My Preference

Personally I favour the Settling Method. This is certainly much less costly than buying several pumps and filter media, but it does take a while.

Into The Tank

Once the WVO has been cleaned, it's ready to use. It may not be the best thing to cook your chips in, but it runs a diesel engine just as well as fresh virgin oil. For me it's a fantastic example of recycling - taking a waste product and making it useful.