Contractors and farmers alike are being forced to run on white diesel for certain types of jobs, including gritting and construction work.

This has rocketed running costs but there’s a chance that biodiesel can be used to combat this rise.

The question is:

Will a tractor engine perform as well running on biodiesel as it would on mineral-based fuels?

Biofuels are making the news headlines on a national and international basis with increasing frequency.

Even American President George Bush recently acknowledged the relevance of green fuels for the future.

Many people are already well informed on the subject of biodiesel and despite manufactures not honouring warranties for vehicles run solely on 100% biodiesel – people are bucking the trend and taking the risk.

For many people the cost benefit of running on biofuel can be offset against the limited risk of potential engine damage – especially where older vehicles are involved.

Students at Harper Adams University College have conducted research into the effects of running a tractor on biodiesel.

Within the engineering department, tests have been set up with what was once a Fiatagri G170 prototype tractor, running it on various blends of biodiesel.

Variations from 5% biodiesel mixed with standard mineral diesel to 100% biodiesel have been used.

In an extreme test the college has tried running the unit on 100% unprocessed vegetable oil.

Measuring the tractor’s pto output and fuel use enables the students to determine the effect of biodiesel on engine power, torque and fuel consumption.

“Plotting the power and torque curves of the engine running on both normal diesel and on biofuel allows us to compare the two fuel sources and highlight any differences,” says Mr White.

Running the tractor engine on a range of blends, the trials found that the engine typically looses between 5% and 10% of its power and torque with biodiesel.

“One disadvantage is that the calorific value of biodiesel – the amount of heat generated by a given mass of fuel when it is burned – is lower than normal diesel produced from crude oil,” he adds.

“This lower calorific value also has an effect on fuel consumption of the engine and we typically see a rise here of about 3%.”

As to how long will it be until we see farmers and contractors running tractors on biodiesel remains to be seen.

“The problem is that typically manufacturers only honour warranties for a 5% blend of biofuel,” points out Mr White.

“Outside these parameters it is down to whether the individual is willing to take a calculated risk and perhaps run an older machine on blends containing greater percentages of biodiesel.”

In this coming term a final year student at the college will be doing further research into biodiesel, primarily looking at the effect of mixing additives with biodiesel to improve the performance characteristics of the fuel.

With certain research already under way elsewhere looking at the effects of adding such things as algae to fuel to change its properties, the college plans to look at adding agricultural by-products to fuel and studying the effects.

fwmachinery@rbi.co.uk