Moving from fossil fuels to renewable energy

Simone Bruckner, managing director of resistor manufacturer Cressall, explains the steps that need to be taken to help farmers around the world make a shift from fossil fuels to renewable energy.

Moving from fossil fuels to renewable energy
The electrification of the on-road automotive sector is well documented. But off-road applications can also benefit from electrification, and this includes agricultural equipment.
Photo: Supplied
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With governments around the world becoming more concerned with emissions targets, farmers are trying to reduce their carbon footprints.

The 2021 Farm Practices Survey, conducted in the UK, indicated that 67% of farmers in the region consider recognising greenhouse gases to be either fairly or very important when taking decisions about their land, crops and livestock. One method of reducing emissions is to electrify equipment that traditionally runs on fossil fuels, such as tractors.

A necessary change
Modern agriculture depends on a fleet of heavy-duty vehicles, from bakkies and small utility vehicles to massive tractors and combines that can weigh several tons, plus attachments. This machinery is commonly powered by diesel engines, mostly due to their higher torque and dependability. And here is where an electrification challenge may lie.

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The electric sceptics of the agriculture industry claim that the largest problem with electrifying tractors and other heavy vehicles is that battery-powered options don’t have the energy density of a diesel model required to do long, hard work in the land. As load affects battery life, pulling a piece of heavy equipment would drain power fast.

Battery technology, therefore, needs to be developed in order to withstand the heavy loads of agricultural vehicles and supply a lasting and reliable source of power.

Some manufacturers have produced compact, swappable batteries to extend the length of operation. Another option, developed by John Deere in 2019, features a long power cable that’s only available for farmers who are able to produce their own electricity via the use of solar panels, manure digesters or windmills.

Regenerative braking
Attempts to electrify farming vehicles are well underway. The work is being done, and it won’t be too long before electrification becomes more accessible. In addition to the battery itself, manufacturers must consider the other components that make electrifying possible.

Resistors will play a role in electrification by support regenerative braking. In regenerative braking, excess kinetic energy is used to recharge an electric vehicle (EV) battery. This can be done because the electric motor in an EV can run in two directions: in one direction, using the electrical energy, to drive the wheels and move the vehicle, and in the other, using the excess kinetic energy to recharge the battery.

When the driver lifts a foot off the accelerator pedal and steps on the brake, the motor resists the vehicle’s motion, ‘swapping direction’, and begins putting energy back into the battery. As a result, regenerative braking uses the EV’s motor as a generator to convert lost kinetic energy into stored energy in the battery.

Other technologies
Regenerative braking can support the ongoing dilemma of electric tractor battery range. However, to work effectively, other technologies are needed to make the process safe and effective.

If the vehicle’s battery is already full or there’s a failure, regenerative braking cannot take place as the excess energy has nowhere to go and must be dispelled safely. If not dissipated, it won’t be possible to slow down the vehicle, resulting in braking failure. To make electrifying agriculture safe, resistors are used to collect excess energy and dissipate it safely.

While electrifying on-road vehicles has become well recognised, the same attention must be paid to other areas of the automotive industry. The agriculture sector is beginning to wake up to the prospects of decarbonising, and positive steps are being taken towards electrification.

To make it happen, agricultural vehicle manufacturers need to consider the technology that can make agricultural EVs more efficient, and safer.