SPECIAL FEATURE ELECTRIC CHAINSAWS

Silence in the woods:

The advent of electric chainsaws

Story: Dr Stephan Hoffmann, researcher at NIBIO in Norway, and Professor Rien Visser, head of the Forest Engineering programme at the University of Canterbury.

FOR MANY PEOPLE, THE ROMANCE OF FOREST WORK IS THE

sound of a two-stroke engine. While the concept of a chainsaw was first used 200 years ago in medicine to cut bone, portable gasoline-driven chainsaws for cutting wood became commercially available from the 1930s. This is considered a milestone in forestry that improved efficiency and reduced labour effort. The bulky twoman chainsaws of the early days are not comparable to modern standards; numerous improvements in a short period made the chainsaw the logger’s first choice.

Today with technical features such as chain break, quick start, vibration damping, even electronic fuel injection, chainsaws have progressed to compact, hi-tech machines. Even with our focus on mechanising all aspects of operations, chainsaws remain relevant in professional operations e.g. for large dimensional trees or cut blocks of small scale, where mechanised operations are not efficient.

Source: FNR Forestry 2019.

Despite continuing technical improvements to reduce hazards, the compact and powerful combustion engine remains the heart of a chainsaw. While Hand-Arm Syndromes are significantly reduced by anti-vibration systems, they cannot be fully eliminated due to the piston movements in the engine. The use of alkylate fuels has reduced the toxicity of exhaust fumes, but fuel emissions cannot be eliminated from a combustion engine. And despite romanticising the chainsaw’s sound, hearing damage due to noise strain over the entire work day is still an issue.

Electric power tools have the potential to reduce, and in terms of exhaust fumes, even completely avoid these hazards. Interestingly, the first chainsaws pioneered by Andreas Stihl were electric driven, but energy supply and compact construction issues gave precedence to two-stroke petrol engines in forestry. The recently increased power range and improved battery capacities has raised the interest of forestry professionals, creating a general market opportunity for the next generation of cordless chainsaws.

New developments are being brought to market targeting professional users, for example the Stihl MSA 220 C-B, with powerful 36 V lithium-ion batteries and a chain speed of 24 m/s. First field trials in Germany are evaluating this as a potential alternative to the conventional MS 201 C-M, a professional grade thinning saw with a displacement of 35.2 cc and 2.4 hp. Both saws are comparable in their operational capacity for early, pre-commercial thinnings, with the battery load and tankful lasting about the same time intervals. General handling of the saws is similar, since both have

Above: The uprising of electric power? Stihl’s MSA 220 C-B cordless saw (front) competing with the combustion model MS 201 C-M (back). Image: M. Huber. Left: Power supply is the biggest challenge off the grid in the forest.

the woods:

an operational weight close to 5 kg, excluding guide bar and chain. Besides the general occupational health advantages of the electric saw, another asset is the direct start and availability of the full power range, making cold start issues and related wear a thing of the past.

In terms of cost, there is already not much of a premium for electric powered saws. For example, the Stihl 241 C-M (42.6 cc and 3.0 hp), costs about 15% less than the electric MSA 220 C-B saw (with AP 300 S battery, AL 300 charger and spare battery). Electricity is cheap compared to fuel, especially compared to alkylate fuels, but obviously under our current operating practices, not as convenient.

Extensive trials are currently underway in Europe to ascertain, not only an economic comparison, but to also establish the ergonomic benefits for saw operators. First results were good and feedback from experienced loggers in the trial positive. Thus, the loggers were excited to hear about the release of STIHL’s new battery power saw, the larger MSA 300, promising a chain speed up to 30 m/s and a bar length of 18 inches.

The non-fossil fuel energy revolution in forestry has had a slow start, with power supply being the biggest challenge off the grid in the forest. There are still a few steps before manufacturers can present a competitive electric model for large felling saws. Higher capacity batteries and smart concepts for recharge and exchangeability between pieces of equipment are crucial developments. However, the potential of electric motorised hand tools is manyfold. NZL Above: Authors, Dr Stephan Hoffmann (left) and Professor Rien Visser. Below: Chainsaws today have progressed to compact, hi-tech machines.

Source: FNR Forestry 2019.