This November at the Agritechnica Show in Hanover, Germany, Fendt will be the first tractor manufacturer to introduce a tractor that is able to run on raw rapeseed oil without first having modifications done to the ex-works specification. It is the Fendt 820 Vario Greentec. The new engine, which was developed together with the engine manufacturer Deutz, is comprised of a 340ℓ vegetable oil tank, a considerably smaller 80ℓ diesel tank and sophisticated valve technology. How it works The engine is started with diesel fuel and needs a short time to warm up because vegetable oil has a different viscosity to diesel fuel and different flash points.
Both of these properties of oil have a decisive influence on their combustion. The viscosity of vegetable oil is strongly dependent on temperature. The Greentec engine switches automatically to vegetable oil operation once the oil has been heated to 70ºC. The heating is done by a cooling water heat exchanger or when the engine power output is at 25%, of the maximum load, for more than 30 seconds. When these parameters aren’t stable, the system automatically switches back to diesel operation. The vegetable oil branch is then flushed with diesel, which takes a few seconds.
Flushing with diesel prevents the vegetable oil from being pushed back in the injection system and getting into the diesel tank which would then dilute the diesel. Before switching the engine off, the driver must switch over to diesel operation manually. He will only have to do this if the automatic function has not already done so. The driver can monitor which fuel is being used through a special indicator on the Varioterminal display in the tractor cab. The Greentec tractor has undergone comprehensive testing and the Fendt manufacturer’s guarantee is the same as for conventional diesel-operated vehicles. Significant operating cost benefits Tractor owners with long memories will remember the days when many of the earliest tractors operated on a two-tank system.
They used petrol to start up and power paraffin – tractor vaporising oil (TVO) – when the engine temperature was high enough. The biggest operating cost in many farming businesses is fuel. With the use of homegrown vegetable oil these costs can be significantly reduced. The fuel itself could be manufactured regionally, or even on the farm, bringing a saving on fuel transportation. A dditionally, farmers can use the byproducts of vegetable oil production – oil and press cake – as high-grade protein stock feed. O rganic fuels offer a wide range of benefits. It should, however, be kept in mind that a renewable energy source, such as vegetable oil, is a living raw material and requires a special awareness of its properties, particularly with regard to strict quality control and the correct storage. – Joe Spencer For more information on Fendt tractors and the new engine e-mail [email protected]. |fw