WOOD EXTRACTION FOR ENERGY

WOOD EXTRACTION FOR ENERGY Hide descriptions

The effects of harvesting forest residues and/or stemwood on forest carbon stock are examined in this calculator. This analysis reflects a scenario where forest residues are harvested instead of being left to decay in forest and/or stemwood is harvested instead of being left in forest to grow. Thus, the results are differences in the forest carbon stock development (i.e. forest carbon) between harvest and no-harvest scenarios.

ANNUAL HARVEST RATE

Defines the annual amount of forest residues and/or stemwood harvested. Harvest rate can be given in cubic meters (m³), in tonnes of carbon (t C), or in energy (GJ).

Harvest rate

PROPORTIONS OF HARVESTED FOREST BIOMASS

The proportions of forest residues and stemwood harvested can be defined by the user, or the calculation can be carried out with the given default values that reflect roughly the typical proportions of residues and stemwood in the energy wood harvested.

Harvest residues

Proportion of branches from the harvested energy wood (%) Proportion of stumps from the harvested energy wood (%)

Stemwood

Proportion of first thinnings from the harvested energy wood (%) Proportion of commercial thinnings from the harvested energy wood (%) Proportion of final fellings from the harvested energy wood (%)

THE BEGINNING OF THE PLANNING HORIZON

Defines the year the wood extracting begins

PERIOD OF WOOD HARVESTING

Defines the number of years of consecutive annual energy wood harvesting. This may for example correspond to the assumed operating life of a power plant.

The period of wood harvesting (years)

PLANNING HORIZON

Determines the length of the period over which the effect of wood harvesting on forest carbon is examined.

The planning horizon (years)

An example: We would like to examine the effect of a power plant, that uses annually 50 000 m³ of wood biomass and has 30 years lifespan, to the forest carbon during the planning horizon of 100 years. Thus, we set the annual harvesting rate to 50 000 m³ using the default or custom values for the proportions of harvested biomass, beginning of the planning horizon as we like, the period of wood harvesting to 30 years, and the planning horizon to 100 years.

RESULTS

The diminished forest carbon resulting from wood extraction over the planning horizon

The result above can be compared to cumulative emissions of an activity in a corresponding period.

Average annual diminishment of the forest carbon stock resulting from wood extraction over the planning horizon

The result above can be compared to annual emissions of an activity in a corresponding period.

The diminishment of the forest carbon per unit of carbon and per energy content in the harvested biomass

This represents the amount the forest carbon has diminished at the end of the planning horizon (or the amount the forest carbon sink has cumulatively diminished during the planning horizon) in relation to the amount of carbon that has been cumulatively harvested in the period of wood harvesting. This dimensionless number is also converted to CO2 per energy content of the harvested wood, which is comparable for example to the CO₂ emissions resulting per energy content from burning of fossil fuels.

The diminishment of the forest carbon resulting from the wood harvesting as a function of time (t CO₂)

The figure above represents the amount the forest carbon is diminished annually, as a result of wood harvesting, compared to the year before as a function of time. The annual diminishment of the forest carbon (positive value in the figure) corresponds to the annual emissions, and the avoided diminishment of the balance (negative value in the figure) corresponds to the avoided emissions resulting from the harvesting of wood.

Methods of calculations

Created by Head of Unit Sampo Soimakallio, Senior Research Scientist Laura Saikku, Researcher Jari Niemi and Senior Specialist Janne Pesu