Documentation - Forest wood
Content
Inputs
The amount of wood from forests has to be preprocessed and is used in BEAST via the input file forest_in.csv located in a .beast file. The csv table should contain biomass potentials in tons dry mass for the entire research area in 10 year time intervalls. Such data can be generated from inventory data combined with growth simulation models. Two scenarios should be processed: with and without FSC certification. Results are seperated into three basic assortments: stem, industrial, and residual wood. The following table shows the structure of forest_in.csv.
| Column | Type | Unit | Description |
|---|---|---|---|
| year | Integer | a | Start year of harvesting interval |
| fsc | Boolean | - | Is the area treated under the restrictions of FSC certification |
| stemWood | Integer | tons (dry) | Potential biomass from harvesting in stem wood assortment in the corresponding harvesting interval (10 yrs. by default) |
| industrialWood | Integer | tons (dry) | Potential biomass from harvesting in industrial wood assortment in the corresponding harvesting interval |
| restWood | Integer | tons (dry) | Potential biomass from harvesting in residual wood assortment in the corresponding harvesting interval |
| harvestedArea | Integer | ha | The sum of areas on which the harvestings in the corresponding harvesting interval took place |
Parameters
Following parameters from parameters.xml are used for the Forest submodel (section forestParams):
| Name | Unit | Description |
|---|---|---|
| startyear | a | Start year of period the parameters are valid for |
| periodLength | a | Length of simulation step |
| yieldPeriodLength | a | Length of yield period |
| interestRate | % | Imputed interest rate |
| tAtro2MWh | MWh/ton (dry) | Conversion factor from tons (dry) to MWh |
| fm2tAtro | ton (dry)/fm | Conversion factor from solid cubic meter to tons (dry) |
| fsc | - | Is the region treated as FSC certified |
| percentFirewood | % | Portion of fire wood from industrial wood assortment |
| percentRestwoodUsage | % | (mean) forest residual wood usage for each area |
Additional, following parameters are specified for each assortment seperately (stem, industrial, and residual wood):
| Name | Unit | Description |
|---|---|---|
| basePrice | EUR/cubic meter | Basic price per solid cubic meter at the beginning of simulation period |
| priceChange | % | Annual price change in simulation period |
| baseCosts | EUR/cubic meter | Basic costs per solid cubic meter at the beginning of simulation period |
| costChange | % | Annual costs change in simulation period |
Processes
The length of the harvesting period is 10 years by default. Therefore, within a 20 years simulation period two harvestings take place. First, the total potential of the harvesting period read from the input file for the research area is reduced to the available part (taken into account, if the FSC scenario was selected).
For residual wood:
$potential_{available_t}=potential_t*{percentRestwoodUsage \over 100}$
For fire wood (part of the industrial wood not used as industrial wood):
$potential_{available_t}=potential_t*{percentFirewood \over 100}$
For industrial wood (part of the industrial wood not used as fire wood):
$potential_{available_t}=potential_t*(1-{percentFirewood \over 100})$
with $t$ = year in the middle of yieldPeriod (started with 0 at the beginning of a simulation period and incremented over periodLength)
For stem wood just the potential of input file is sumed up over a simulation period and devided by the length of the simulation period.
The conversion of available biomass potential (for each assortment) is done using a standard (averaged) conversion factor for wood into energy:
$energyPotential_{available_t} = potential_{available_t} * tAtro2MWh$
For the economic valuation the costs and prices have to be converted from EUR per solid cubic meter to EUR per tons (dry) (for each assortment):
$basePrice_{tatro}={basePrice \over fm2tAtro}$
$baseCosts_{tatro}={baseCosts \over fm2tAtro}$
It is assumed that harvesting takes place in the middle of the yieldPeriods. Therefore, the base prices and costs are prolongated accordingly (for each assortment):$price_t = basePrice_{tatro} * (1+{priceChange \over 100})^t$
$costs_t = baseCosts_{tatro} * (1+{costChange \over 100})^t$
The contribution margin of a yieldPeriod is calculated as the difference of prices and costs multiplied with the available potential (for each assortment):
$cm_t = (price_t - costs_t) * potential_{available_t}$
Then, this contribution margin is discounted to the beginning of the simulation period (for each assortment):
$cm_{discount_e} = {cm_t \over {(1 + {interestRate \over 100})^t}} $
with $e$ = number of yieldPeriod $[1,({periodLength \over yieldPeriodLength})]$
This calculation is repeated for every yieldPeriod within the simulation period. The discounted contribution margins are summed up to the net present value (for each assortment):
$netPresentValue = \sum_{e=1}^{periodLength \over yieldPeriodLength} cm_{discount_e}$
Lastly, the total net present value is transformed into an annual annuity (for each assortment):
$annuity = \begin{cases} {netPresentValue * {{i^{(periodLength-1)} * (i - 1)} \over {i^{periodLength} - 1}}} & \quad \text{, if } interestRate > 0\\ {netPresentValue \over periodLength} & \quad \text{, else}\\ \end{cases} $
with $i = 1 + {interestRate \over 100}$
The discounted contribution margins ($cm_{discount_e}$) as well as the total net present values and annuities are also related to one hectare by dividing by the harvesting area as follows (for each assortment):
$cm_{ha_t} = {{(price_t - costs_t) * potential_{available_t}} \over harvestedArea}$