The development of biogas tractors has been based on the needs of users, who expect them to operate exactly the same in all tasks, in all conditions and with all equipment whether they are run on diesel or biogas. Essentially, the operator should not notice which fuel is being used. Other key principles include maintaining a high level of efficiency, optimising the use of biogas and controlling emissions. For tractor owners, using biogas as a fuel can also mean significant savings in fuel costs.
Dual fuel tractors can be run on diesel alone or on a mix of diesel and biogas, in which case a small amount of diesel is required for combustion. In order to run on biogas alone, the engine would require spark plugs, in which case it could not be run on diesel alone.
Whereas Valtra’s first biogas tractors ran on a fixed mixture of 83 percent biogas and 17 percent diesel, the new models alter the ratio dynamically according to the driving conditions. For example, after cold starting the engine, it can run completely on diesel, whereas after hard use it can run on up to 90 percent biogas.
Developed in Sweden and Germany
Valtra’s biogas models have been developed in cooperation with the Swedish government financed MEKA project and a project sponsored by the state of Bavaria in Germany. One of the objectives of the Swedish project has been to obtain measurement data that could be used for Swedish and possibly EU legislation, as registering biogas tractors currently still requires special approval due to the lack of legislation.
Dual fuel tractors have also been received well in Russia, where Valtra was awarded the silver medal at the AgroSalon exhibition in Moscow last year. The alternative fuel used in Russia is not biogas, however, but natural gas.
Recent development work has focused on increasing series production and managing emissions. Biogas tractors are essentially environmentally friendly, since they run on a renewable fuel. However, work continues on reducing the nitrogen oxide, particulate and especially methane emissions of biogas tractors. Since some methane does not combust in biogas engines, intelligent engine management systems and various catalytic converters have been developed to combat this problem.
In order to facilitate series production and spare parts service for biogas tractors, all the components have been standardised and documented. For example, the fuel tanks and their frames are delivered to the assembly location as a single package, the exhaust pipe has been redesigned especially for biogas tractors, and the methane catalytic converter has been converted to fit the shell of a traditional DOC catalytic converter.