What if the future of farming isn’t bigger, but smaller, slower and powered by solar?
As discussed in our exploration of creating a pathway for alternative farm fuels, there are some specific challenges associated with moving away from diesel in agriculture. Electric powertrains face significant challenges in agricultural vehicles due to energy density limitations.
Lithium batteries are approximately 25 times less energy-dense than diesel fuel. John Deere had a go at developing an electric version of a typical diesel tractor weighing about 9 tonnes, to find that the electric equivalent weighed 18 tonnes. Furthermore, the electric tractor could only operate for about 10 hours at 80% load, compared to the 12+ hours expected from a conventional diesel tractor.
So, if the space required for the battery storage is the key limitation, what about connecting to electric power via cable?
John Deere has also had a go at this, powering a tractor via a cable, and also coming up with a concept to link multiple vehicles together in the field via sub extension cables. While this overcomes the issue of carrying the mass of the batteries, it is impractical from a logistical perspective, as operators would need to navigate the field without tangling or running over high voltage power cables.
Speaking in the webinar, Kit Franklin, Senior Engagement Fellow at Harper Adams University, highlights that it may not be possible to get electrification working for large scale tractors, but perhaps there is another way.
Compact electric tractors
Compact tractors are already leading the way in electrification in some areas of food production. Products available include:
- TAFE has brought to market a 24 horsepower equivalent electric tractor, which is available to buy in the UK.
- Monarch Tractor, a start-up based in California, are selling compact electric tractors internationally, and has recently opened a European headquarters
- Fendt has a 70 horsepower equivalent tractor, which is designed for use in orchards and vineyards
Speaking in the webinar, Kit highlights that these compact tractors typically offer about 5 hours of run time, with an hour required on fast charge. These run times are acceptable for the amenity, horticulture and viticulture sectors, where the tractor could run for 5 hours, charge during a lunch break then be ready for another 5 hours use.
But what about larger scale, field-based agriculture?
Automated farm machinery
Kit explains that the limitations for agriculture can be overcome by not being reliant on having a driver. Without an operator, machines can be smaller and unusual working hours can be adopted.
Small, automated machines can work slowly over a longer period of time, and can offer the following additional benefits:
- Ability to work on ground earlier or later in the season, which may be too wet for conventional sized machinery to travel on
- Greater precision and efficiency of inputs
- Reduction in vehicle mass preventing soil compaction, leading to improved soil structure
- Alignment with a goal to increase farmland biodiversity, as small machines can work efficiently in small fields, allowing new hedges to be established to provide habitat for wildlife.
FarmDroid
An example of automated farm machinery is FarmDroid. This machine provides seeding and weeding, covering a third of a hectare per hour, powered entirely by solar power. It has on board battery storage, which allows it to work circa 20 hours within a 24-hour window on a typical spring day in the UK.
Because it is used for both seeding and weeding, the FarmDroid can open opportunities to grow high value crops, such as lettuces, without the cost of multiple specialist machines and additional work load required for conventional weeding methods.
Kit concludes by making the point that it is possible to reimagine what agricultural machines look like and how they operate. Automation enables the design and development of machines that work using electricity, and even paving the way for energy independence for at least some farm operations.
To find out more, watch the full webinar in the RASE members resources. Not yet a member? Discover how RASE membership could benefit you here.