The carbon dioxide emission balance and ability to chip wood by 10 kW machines used in urban areas in terms of increasing interest in using wood biomass resources for personal use

Urbanized areas are spaces that provide interesting amounts of wood wastes to address as renewable resources. Due to limited working space in these areas, small, low-power wood chippers are used. Machines with similar power but different cutting mechanisms are available on the market. The article presents a study of four machines with four different cutting mechanisms: disc, drum, two cylinders, and flail. Wooden beams of three wood species (ash, pine, spruce) with varying hardness according to the Janka classification and ten cross-sectional dimensions ranging from 10 × 10 mm to 100 × 100 mm, along with a moisture content (MC) of 10 ± 2%, were chipped. In the tested machines, stopping the working mechanism caused slippage of the V-belt transmission, protecting the machine from the consequences of overload. It was shown that in terms of chipping capabilities, drum, disc, two cylinders, and flail chippers, respectively, exhibit the highest to lowest capabilities. The range of materials shredded by the tested machines varies from 80 × 80 mm to 10 × 10 mm depending on the wood type and cutting mechanism. The average energy consumption of the tested machines is 2.07 ± 0.73 kWh, and the maximum value recorded for the drum chipper is 5.21 ± 0.2 kWh. Wood species and cross-section are key factors in energy consumption, while the chipper model has little impact. Considering that the average emissions during the production of electricity from fossil fuels are 0.95 kg CO2 per 1 kWh, these machines produce from 0.5 kg CO2 h-1 to a maximum of 4.49 kg CO2 h-1 (mean 1.97 kg CO2 h-1). Assuming that one tree absorbs from 7 kg CO2 per year, it can be assumed that one tree reduces CO2 emissions from 3 hours of machine work over a year. This is a time significantly shorter than the time required to chip the branches of a single tree subjected to the pruning process. This allows for maintaining a positive CO2 reduction balance.