While it has been a challenge convincing passenger-car customers that electric battery power is a viable alternative to conventional fossil fuels, in the construction, agriculture, and mining industries, electrification is an even steeper uphill battle, according to Dr. James Jeffs, Senior Technology Analyst at IDTechEx. If machines run out of battery energy, operators soon start losing money.

The author of IDTechEx’s new report, “Battery Markets in Construction, Agriculture and Mining Machines 2024-2034,” looked at a total of 15 machine types across construction, agriculture, and mining, evaluating the needs of each and matching them up against ten existing and emerging battery technologies.

Jeffs writes that machines require a diverse range of battery solutions to cater to their individual needs. This is especially true of agriculture machines like tractors. It is likely underappreciated just how unique a challenge the electrification of tractors presents.

Among the electrification activity of major agriculture OEMs, the report looked at key electric examples of sub-compact tractors such as the Solis SV26, compact tractors like the Rigitrac SKE 40 Electric, and utility tractors such as the Case IH Farmall 75C Electric. Other electric agriculture tractors Futurride has covered recently include a relatively broad size range, from the relatively large T4 Electric Power from New Holland Agriculture and startups the medium-power prototype by Seederal and the “world’s first” fully electric, driver-optional, smart tractor MK-V from Monarch Tractor.

Considering how and when tractors get used, the three key challenges for electrification. They can be summarized as needing high installed energy capacity to deal with the intensive workload; having limited space and constrained conditions for the battery installation; and needing very quick recharges to minimize downtime in peak season.

The first challenge is that their use case is incredibly energy-intensive. For the most part, the purpose of a tractor is to drag machinery through a field. Plowing a field creates lots of resistance, so it requires lots of energy. If a field has soft mud, the tractor will lose energy due to the tires slipping.

As an example of how much energy tractors consume, a 14-t (15.4-ton) tractor would typically use an engine with around 300 hp (224 kW) and is expected to burn around 50 L/h in fuel. In comparison, a 14-t excavator in the construction industry would typically use an engine with 120 hp (29 kW) and expect to burn around 10-12 L/h.

Both machines have hard and similar workloads; the tractor could be pulling a plow through the mud while the excavator is removing large quantities of material with its bucket. The key difference is that the excavator is at its peak load only momentarily as it breaks through the ground. The rest of the time is spent raising the bucket above the ground, twisting, dumping the load, then repositioning. The tractor is working at a constant near-peak capacity. From a battery standpoint, this means that the tractor needs substantially more storage to give the same run time.

The second challenge for electrifying tractors is chassis-related. While large construction machines have large chassis to incorporate the battery, tractor chassis are more compact, even for large 14-t examples.

Large excavators can handle the weight of the battery, with many already having concrete ballasts for balance. Excessive weight could be an issue for tractors, especially when operating in wet mud. Tractors are more sensitive to the location of the weight, preferring an even distribution across the wheels for the best stability.

The third challenge with electrifying tractors is their uptime. Again, this is an area where tractors are particularly unusual. Construction and mining machines tend to be in almost constant use, but many tractors see very seasonal work. They could sit dormant for large portions of the year, but come harvesting time on a large farm, they could be running 24/7 for days at a time.

In some ways, this is both a blessing and a curse. High uptime in peak season means that the battery needs to be capable of rapid charging to minimize downtime. This is typically tough on batteries, as regular fast charging can degrade their cycle life.

The blessing is that sporadic usage means fewer cycles are needed over a vehicle’s lifetime. Many tractors have life expectancies of around 2000-5000 h, whereas large excavators might operate more than 10,000 h over their life span. A shorter life expectancy, with fewer cycles required, opens up battery options to more cutting-edge and emerging technologies.

The dominant lithium-ion battery technologies used in the automotive industry are NMC (Nickel Manganese Cobalt) and LFP (Lithium Iron Phosphate). NMC offers good energy density, but typically recharges slower compared to LFP. LFP has compromised energy density but is cheaper and can be recharged more quickly. Both have plenty of cycle life for agricultural applications, but IDTechEx suggests that other emerging options with higher energy density could offer a better fit.

Solid-state and silicon-anode batteries are two emerging technologies that might work well in tractors. Both offer improvements in energy density compared to NMC and LFP, making it easier to put more kWh of battery capacity onto tractors. They have good to high recharging performance, minimized downtime, and offer the equivalent or higher safety than LFP and NMC. Unfortunately, both technologies are very new, still in the early stages of commercialization, and therefore are very expensive.

Electrification is an expensive endeavor, with the battery being the costliest factor and creating the bulk of the price premium associated with electric alternatives. IDTechEx says that batteries as large as 1000 kWh have been proposed for electric tractors.

Using NMC or LFP technologies in a battery pack would cost in the region of $300,000, and with solid-state and silicon-anode technologies this could be doubled or even tripled. The battery would likely exceed the cost of a regular diesel tractor of the same size. Even with a tractor burning in the region of $30,000 worth of fuel each year, it is unlikely that the extra cost of a solid-state or silicon-anode battery could be recuperated.

Solid-state and silicon-anode batteries make a good fit for agricultural machines from an engineering perspective, but unfortunately, they don’t quite make the business case, for now. The IDTechEx report forecasts that they will have a small market share of battery demand for agricultural vehicles once they are more mature, and demand will still be dominated by NMC and LFP, even in 2034.