November 21, 2011. The Profi 4135 Natural Power has a natural gas engine along with a total of nine biogas fuel tanks - three on the rear of the cab, two on either side of the engine and four under the bonnet. That is enough to run the tractor for 5-7 hours, but there is also a 15 litre petrol reserve tank.

   The machine is still a concept and there are no plans yet for a release date. However, with nearly 7.000 biogas plants, 650.000ha of crops planted for biogas and 1.000 fuel stations offering CNG/LPG in Germany, this is a machine that has a particular market in mind.

   Finnish maker Valtra has also been working on biogas technology for some years. Its dual-fuel biogas/diesel system is almost ready for sale and a T133 tractor with it was on show at Agritechnica. When running in biogas mode 17% diesel is required to ignite the biogas in the combustion chamber and when you are out of gas it'll just switch over to diesel. Gas tank capacity is 170-litres which equates to between three and five hours work.

   Valtra says that when running on a mix the six cylinder engine is significantly more efficient than when running on straight gas or diesel.