Tractors“The multi-fuel tractor provides farmers with more flex­i­bility in these uncer­tain times”

Mr Remmele, what are the greatest chal­lenges when it comes to devel­oping a tractor that runs on different fuels?

The goal of our project was to develop a tractor capable of working with biodiesel, rape­seed oil, and diesel. These fuels differ very signif­i­cantly, in terms of their chem­ical and phys­ical prop­er­ties. It is there­fore impor­tant that the fuels – or rather their mixing ratios – are clearly iden­ti­fied. This is the only way to avoid over- or under-perfor­mance. Of course, in addi­tion to this, the emis­sion limit values must be complied with under all oper­ating condi­tions. And then there are the prac­tical require­ments: They must be able to cold start and fuel consump­tion has to be right.

What had to be modi­fied, to meet these require­ments?

First, there is the low-pres­sure fuel system for rape­seed oil, which has a signif­i­cantly higher viscosity at lower temper­a­tures, compared to diesel and biodiesel. The focus, however, was on modi­fying the engine control system: It has to store different char­ac­ter­istic diagrams for the different fuels or their mixtures. This is the only way to achieve perfor­mance and emis­sion limits.

How does the tractor reli­ably recog­nise the fuels?

We chose a two-sided approach to achieve this: On the one hand, John Deere worked on detecting fuel with sensors already installed on the tractor. Our job was to then create a working solu­tion, using sensors that are readily avail­able on the market. All systems must work reli­ably, both at low temper­a­tures and at very high temper­a­tures. To test this out, we exam­ined several metrics, like viscosity, density, and conduc­tivity, and devel­oped suit­able models for them.

How does testing of such a new system work in prac­tice?

We first examine a new machine on our tractor test stand. There, we take power from the power take-off (PTO) shaft. We also use an auto­mated accel­er­ator pedal adjuster. Thanks to this combi­na­tion, we can request various speed-load cycles from the engine, from our control room. This we do with stan­dard­ised cycles, which are required by law, to take measure­ments on the engine test bench. We can then use this to deter­mine fuel consump­tion, perfor­mance curves, and emis­sions.

After 600 to 1,000 hours of oper­a­tion, we then bring it back to our tractor test bench and measure how the fuel consump­tion, perfor­mance and, where applic­able, emis­sions have changed.

Dr Edgar Remmele

After this incoming inspec­tion, the machine goes into prac­tical field testing at our state test fields. The tractor performs all sorts of work that occurs throughout the year, like any other machine. After 600 to 1,000 hours of oper­a­tion, we then bring it back to our tractor test bench and measure how the fuel consump­tion, perfor­mance and, where applic­able, emis­sions have changed.

However, the legis­la­tors are already thinking ahead, in terms of Stage V Emis­sion Stan­dards, and want to know the emis­sions coming from machines in the field. That’s why we equipped ourselves with a portable emis­sion measure­ment system (PEMS) several years ago, to be able to measure the Real Driving Emis­sion (RDE) under actual oper­a­tions.

In your opinion, what poten­tial do multi-fuel solu­tions offer to agri­cul­ture?

Agri­cul­ture has been tasked with reducing green­house gas emis­sions, for example through the Climate Protec­tion Act in Germany. Many green­house gas emis­sions in agri­cul­ture come from biogenic processes, which can hardly be reduced: Methane emis­sions from moor­land and animal husbandry, or nitrous oxide emis­sions from nitrogen fertiliser.

On the other hand, what can easily be reduced are the so-called energy-related emis­sions, and two-thirds of these come from fuel use. And here I see the chance for biofuels to quickly make a signif­i­cant contri­bu­tion to reducing green­house gases in the agri­cul­ture sector.

The great charm of the multi-fuel solu­tion is that it gives the farmer freedom of choice. In this way, they can counter high fuel price fluc­tu­a­tions by switching back and forth between different fuels – depending on which are currently avail­able or least expen­sive.

Will biofuels create compe­ti­tion for land that is currently used for food produc­tion?

The most impor­tant message, from my point of view, is: There’s nothing on the table without some­thing in the fuel tank. After all, we need fuel to produce food. I don’t really see any compe­ti­tion for land, either, because we produce a by-product, like rape­meal cake, when processing oilseeds, for example. This valu­able protein feed can, for example, replace soya imports from South America if it were to be produced locally. In this way, we kill two birds with one stone.

What I want to empha­sise: At the moment, almost all vegetable oil-based fuels go to the trans­port sector, and not to agri­cul­ture. We operate our cars with 7% biodiesel content. And we will not need biofuels for them in future, because the private trans­port segment is on its way to elec­tri­fi­ca­tion. The quan­ti­ties of biodiesel which will be released in the long term, due to no longer being used in the passenger car sector, would be enough to supply agri­cul­ture.