Agriculture vs aviation: Who wins the battle for biofuel?
HVO fuels are not yet available in sufficient quantities. They are sought after in other sectors, such as aviation and shipping.
The sustainability target to make Europe climate neutral by 2050 includes greenhouse gas emissions from the use of diesel fuel being reduced to zero by 2045 at the latest.
This poses a long-term problem for farmers. Liquid fuels with high-energy density remain irreplaceable in farming for activities with high power requirements and long operating times, such as soil cultivation and harvesting.
Even in the medium power range, gaseous fuels require tank sizes of several cubic metres, while electric drives require huge batteries. There are already fully electric tractors, but large tractors and harvesters still depend on liquid fuels to work for long hours.
Pending technological breakthroughs, if the EU enforces its climate-neutral policies, it looks like there is a big future for alternative liquid fuels. There is a range of such biodiesels available already for modern tractors and agricultural machines, which can be used in tractors without very big changes. Engine adjustments are usually minimal or not necessary at all, and the existing fuel tank volume can be used.
The high-energy density of these also makes long hours of heavy field work possible.
One of these biodiesels went on test recently at the German Agricultural Society (DLG) Test Centre for Technology and Farm Inputs. A Valtra Q 285 tractor was tested under realistic conditions to compare conventional diesel and the bio-based alternative fuel, HVO (hydrotreated vegetable oil). The alternative fuel performed impressively.
No significant differences in power output were found between the two fuels. There was a slightly higher consumption in litres per hour of HVO, due to its lower energy content and density. Fuel consumption with HVO is about 3% to 4% higher than with diesel.
But HVO can lead to better ignition behaviour and efficiency, and the engine starts better at low temperatures.
The test was carried out on the DLG roller test bench, which simulates realistic operating conditions for traction, hydraulic, and PTO power.
The maximum PTO power was determined at various engine speeds, with no significant difference detected between the two fuels.
According to the DLG, HVO thus represents a practical, immediately implementable alternative that can contribute to reducing the carbon footprint of agriculture. This is particularly true for farms that want to improve their carbon footprint without having to invest in new vehicle technology.
"There is hardly a better or faster way to improve the carbon footprint of existing machinery," concluded DLG test engineer Martin Hanstein.
Unfortunately, HVO fuels are not yet available in sufficient quantities. They are sought after in other sectors, such as aviation and shipping, which limits their availability, and existing production facilities are currently unable to meet the demand for HVO.
In addition, the required reduction in emissions and carbon footprints is only positive if HVO is produced in an environmentally friendly way. And this type of production is expensive, which explains why HVO, in Germany, costs about 10 cents per litre more than diesel.
Nevertheless, HVO obtained from waste and residual materials enables emissions to be reduced by up to 90%, although it has almost the same energy density as fossil diesel.
HVO can also be mixed with fossil diesel, in any ratio. Furthermore, existing storage and tank facilities can be used.
Other claims for HVO are it is cleaner and more thorough burning further reducing emissions, so air quality is instantly improved; HVO can be stored for up to 10 years, and it breaks down naturally in soil and water, for reduced environmental risk in the event of a spill.
However, zero-emission technologies like electric and hydrogen may be needed for long-term decarbonisation, because HVO still produces some emissions, even if it reduces carbon output significantly.
According to the German Agricultural Society, if the agricultural sector wants to become independent of fossil diesel, other drive systems such as batteries or fuel cells will be needed in addition to alternative fuels such as HVO and e-fuels.
Small machines such as farm loaders or maintenance tractors will go electric, while large tractors and harvesters will continue to rely on reciprocating engines into the distant future, with the only question being which liquid fuel will be used.
One of the biggest challenges to farm vehicle electrification could be the charging and power storage infrastructure needed by farmers for fast charging, day or night. Interchangeable batteries would be needed.
Could farmers produce their own fuels?
The door is already open to use solar panels for self-sufficient electricity production on the farm. Methane production from a farm's biogas plant could help too.
Now that HVO is proved an ideal replacement for fossil diesel, could it be produced from the farm's own rapeseed crop, bringing independence from suppliers, and hopefully reducing costs?
Unfortunately, there are political and technical hurdles, such as the EU capping use of crop-based biofuels in transport, at 7%.
Other climate action rules are also seen by many in agriculture as flawed, including emissions measurement "at the tailpipe”, without considering the entire life cycle of a machine, from production to recycling.
