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Producing Plant Oil Fuel at the Folkecenter

Written on: Tuesday October 30th, 2007

Plant Oil Processing

The Folkecenter has a demonstration lab which contains all of the equipment to press, filter and test vegetable oil for engine use. As Europe has pioneered the use of vegetable oil for fuel it was realized very quickly here that a vegetable oil standard was going to be needed in order to ensure that oil quality met a certain criteria. The standard that was adopted was the German RK Standard for PPO. You can see after looking at this standard that there is more than meets the eye than just vegetable oil. There is talk right now in Germany about revising this standard to make it more stringent.

The plant oil lab has two, cold seed presses made by Taby in Sweden and one by Bt Combirenser (BTC) made in Denmark. The BTC press that is seen here is simply a screw press with a C flanged mounted motor which presses the seed into oil and seed cake. The BTC has an integrated seed storage and screening device to remove straw pieces, rocks, and any foreign material that is not supposed to be going through the press. At the bottom of the seed storage tank there is an auger that removes the unwanted material for disposal. To the right is a cross section of a typical seed press with all of the components labelled.

As a general rule of thumb cold pressing of seed produces 33% oil and 66% seed cake. This of course can vary depending on the quality of the seed.

The press is capable of pressing 30 kg/hour of seed which yields 10 kg/hour of oil and 20 kg/hr of seed cake. This might not sound like a lot but if this press operates 24/7 it can add up to a lot. The Folkecenter?s main goal was to encourage the wide spread use of these devices on local farms so that farmers could produce their own fuel thus value adding before the farm gate.

So, the oil can be used as fuel but what do we do with the seed cake? Well the smart folks over here figured that one out as well! The seed cake happens to have a high protein content perfect for feeding livestock such as pigs, steers and even fish in aquaculture systems. It can also be spread as fertilizer or burned in a stoker boiler to heat water which I will do a blog on in a week or so.

In order to do a proper economic analysis of this a study evaluating the price of feed, fuel and feed stock seed would have to be completed. Also, as farmers do not pay road tax in Canada their fossil fuel is cheaper and thus their economics will need to take this into account. I currently run my van on waste vegetable oil which I get for free by approaching restaurant owners. The waste oil is of far worse quality than PPO but when you are living on a beer budget you can?t always afford to drink champagne.

Oil Cascade Sedimentation

Once the seed has been crushed it is important to filter out any particles, and if you talk to greasers like Adam Gagnon and the pros here at the Folkecenter they will tell you that the oil should be filtered down to no less than 2 microns. This might sound like an impossible task, but with the right tools and a little bit of leed time most of the particles can be removed with Newton?s best friend, gravity. The Folkecenter uses a cascade filtration system employing four 50 gallon barrels. As the oil travels through each barrel the particles drop out. The Folkecenter recommends that the oil settle for two days in each of the four tanks at 20 degrees C. After the sedimentation period the oil should then be filtered at 20 to 40 degrees C with a commercial diesel filter down to 2 microns. This prevents any last particles from entering the storage tank. While the main objective of this system was to be used locally in Denmark, the simplicity and cost effectiveness of the design meant that they could use this system in developing countries and projects such as the Mali Folkecenter.

The beauty of the Folkecenter processing plant is that it fits into a 6 square meter space which means that you don?t need a lot of real estate or money to set one of these systems up. With a little bit of scrounging around and a couple of phone calls the filtration system could be constructed quite quickly and cost effectively. Additionally the construction of these seed presses are quite simple and could easily be made in Canada or a third world country to create local jobs and supply local fuel and feed on the farm.

With the price of canola increasing every day I am not sure if this fuel is currently more economical than conventional diesel. This would have to be evaluated on a case-by-case basis taking into account many of the factors I mentioned above. But as crude oil becomes ever more expensive it is going to become imperative that farmers implement technologies and systems in their day to day life to become more vertically integrated on the farm.